Podcasts about late devonian

Today on the show, we'll explore the first fossil finds from Miguasha Provincial Park, a protected area near Carleton-sur-Mer on the Gaspé Peninsula of Quebec in Canada, from the mid-1800s. Miguasha is known for its exceptional preservation of Late Devonian (370 million years ago) fossil fish, including lobe-finned fish that played a crucial role in the transition of vertebrates from water to land. The park's cliffs contain fossils of various fish groups, including Agnathans (jawless fishes), Placoderms (heavily armored fish), Acanthodians (spiny fish), and Sarcopterygians (fleshy-finned fish with lungs), as well as invertebrates like crustaceans, worms, and Eurypterids (giant cousins of land scorpions). Two well-known sarcopterygians found at Miguasha are Eusthenopteron foordi and Elpistostege watsoni, which are important for understanding the transition of vertebrates from water to land. If you would like to read more about the find, head on over to www.fossilhuntress.com and click on the ARCHEA Blog for more details, photos and insights on the yummy fossil finds from the area.

The late Paleozoic ice age began in the Late Devonian and ended in the Late Permian, occurring from 360 to 255 million years ago. It was similar to the present day in two key respects: rising atmospheric CO2 and recurrent major ice sheets. In the podcast, Isabel Montañez explains how we can use proxies to learn about the climate and ocean conditions that prevailed then. And with the help of a model, she says that we can also learn about sensitivities and feedbacks of Earth systems to rising CO2. Among other things, the model suggests that when the atmosphere reaches the present day level of CO2, significant parts of the ocean may become anoxic and ocean circulation patterns alter.Montañez is a Distinguished Professor in the Department of Earth and Planetary Sciences at the University of California, Davis.

First, we go back to 1992, when off the coast of Ireland, a Swiss geology student accidentally discovered the longest set of footprints made by the first four-legged animals to walk on earth.They pointed to a new date for the key milestone in evolution, when the first amphibians left the water 385 million years ago.Dr Frankie Dunn, who is a senior researcher in palaeobiology at the Oxford University Museum of Natural History in the UK, then dives into landmark discoveries in geological history. Plus, the story of Winifred Atwell, a classically-trained pianist from Trinidad who was admired by Queen Elizabeth II and Sir Elton John. She became one of the best-selling artists of the 1950s in the UK. Then, how the Guarani, an indigenous language of South America, was designated an official language in Paraguay's new constitution, alongside Spanish.Also, the lesser known last eruption of Mount Vesuvius in 1944.Finally, Indian badminton player Rajeev Bagga who has won 14 gold medals at the Deaflympics. In 2001, he was given the ‘Deaflympian of the Century' award.Contributors: Iwan Stössel - Swiss Geologist. Dr Frankie Dunn - Senior Researcher in Palaeobiology at the Oxford University Museum of Natural History in the UK. David Olivera - Paraguayan Linguist and Anthropologist. Angelina Formisano - Evacuated from the village of San Sebastiano during the 1944 eruption of Mount Vesuvius. Rajeev Bagga - Indian Badminton Player.(Picture: Illustration of a tetrapod from the Late Devonian period. Credit: Christian Jegou/Science Photo Library)

Summary: Join Kiersten as she takes a trip through time with the fossil record of the coelacanth.   For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean   Show Notes: “Coelacanth Fish Fossils, Mawsonia Woodward, 1907,” by Prof. Dr. Sc. Norman Ali Bassam, Ali Taher, Mohammad Ahmad, Mostafa Khalaf-Prinz Sakerfalke von Jaffa. https://issuu.com “The first late cretaceous mawsoniid coelacanth (Sarcopterygii: Actinistia) from North America: Evidence of a lineage of extinct ‘living fossils'.” By Lionel Cavin, Pablo Torino, Nathan van Vranken, Bradley Carter, Micheal J. Polcyn, and Dale Winkler. PLOS ONE, https://journals.plos.org “Fossils of Cretaceous-Period Coelacanth Discovered in Texas,” by Sergio Prostak, SciNews, November 16, 2021. https://www.sci.news “Oldest coelacanth, from Early Devonian of Australia,” by Zeroing Johanson, John A. Long, John A Talent, Phillipe Javier, and James W. Warren. Bill Lett, 2006 Sep 22; 2(3): 443-446; doi: 10.1098/rsbl.2006.0470 “Earliest known coelacanth skull extends the range of anatomically modern coelacanths to the Early Devonian,” by Min Zhu, Xiaobo You, Jing Lu, Too Qiao, Wenjin Zhao, and Liantao Jia. Nature Communications 3, Article Number: 772 (2012) https://doi.org/10.1038/ncomms1764 “Ghost Lineages,” by Matt Wedel, 5/2007 and 5/2010. https://ucmp.berkeley.edu   Music written and composed by Katherine Camp   Transcript (Piano music plays) Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife. (Piano music stops) Welcome to Ten Things I Like About… I'm Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we'll find right out side our doors and some are continents away but all are fascinating.  This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won't regret it. This episode continues the coelacanth and the ninth thing I like about this animal is its fossil record. Throughout this series I've talked about the fossil's of the coelacanth and how they are sometimes called a ‘living fossil', so I thought we should take a few minutes to look at their actual fossil record. As we have discussed before coelacanths are old. The first coelacanths lived about 400 million years ago in the Devonian period. This was approximately 170 million years before dinosaurs roamed the earth. No matter how many times I say it, it still blows my mind! The fossil record of the coelacanth, just like everything else about this fish, is actually quite interesting. Throughout their long history coelacanths have been thought to be evolutionary conservative which essentially means they haven't changed much, but when we look a litter closer at the various fossils we see a different story. Our modern living coelacanths look like something that swam right out of ancient history, but throughout their existence they have had several body shapes.  Let's look at the Devonian coelacanths. The best known Devonian coelacanth fossils come from the late Middle to early Late Devonian period. There are two early coelacanths that are well known, Gavinia and Miguashaia. These two genuses are considered primitive coelacanths because they are more like primitive lungfish and less like modern coelacanths in body form. What researchers look at to determine these classifications are the skull shape, the fin placement, and the tail.  If we compare the skull shapes, in layman's terms, of Miguashaia and Latimeria (as a reminder that is our modern coelacanth) the Devonian era  coelacanth's skull is broader and shorter, the body is shorter and more stout, and the tail is dramatically different. The Miguashaia tail technically has three parts like the modern coelacanth but the top fin is tiny while the bottom fin is much larger. The puppy dog tail portion of the tail that runs between the two fins sort of curves up a bit. The majority of the tail fin is below the midline and is square as opposed to the rounded tail of Latimeria.  These are the most well known fossils from the Devonian period and they are fully formed enough that they can be placed in the coelacanth timeline based on body shape. But these are not the only fossils found from the Devonian era. There were fossils found in Australia from the early Devonian period suggesting coelacanths are even older than we previously thought. Researchers are hesitating to use these fossils when phylogenetically classifying coelacanths because it's only a lower jaw bone. The existence of a dentary sensory pore in the jaw proves it is a coelacanth, as modern day coelacanths, as well as other fossils throughout the ages, have dentary sensory pores also. Now, there have been approximately 80 species of coelacanth fossils described from the Middle Devonian to the Late Cretaceous. The Late Cretaceous dates from 360 million years to 70 million years ago. In the Cretaceous period, two families of coelacanths are represented through the fossils that we have found. One is Latimeriidae and Mawsoniidae.  A scientific paper published in 2021, discussed the discovery of Cretaceous period mawsonid coelacanth fossils found in the Woodbine Formation in northeast Texas. The reason these fossils are important is that they expand the regional location of coelacanths. These are the first coelacanth fossils found in North America. We didn't know that they lived in the area of North America until these fossils were found. Researchers postulate that these coelacanths got here during the break-up of Pangea, but we need a lot more research before we have any solid theories. One of the things I wanted to know about ancient coelacanths was how big they were. It seems like when we go back in time, animals are always bigger than they are now. Like the dragonflies that used to be as big a VW Bug, sloths that were the size of an SUV, and sea scorpions the size of small sedan. Well, some of the coelacanth fossils that we have found are complete bodies and some have enough bones to extrapolate how big the fish was when they were alive. So we have a range from about two feet to thirteen feet! Our modern coelacanths seem to have settled somewhere in the middle.  Coelacanths were believed to have gone extinct during the Late Cretaceous period. Today we know that's not true, but until 1938 we hadn't seen any or more importantly, we hand't found any younger fossils. The last record we had of the coelacanth came from the Cretaceous period. You may be wondering how this is possible, I know I was when I started researching this episode. I found a great article from UC Berkley that helped me understand what happened to the missing evidence of coelacanths for the last 60 million years.  Lineages are important when studying the fossil record of any living things. Lineages are the unbroken chains of ancestors and descendants. They tell us who is related to whom. A ghost lineage occurs when a line of descent leaves no trace in the fossil record. This is what has happened to our beloved coelacanth. Now back to our question, how is this possible? How come we can't find fossil evidence of the coelacanth after the Cretaceous period. Living coelacanths reside in deep ocean waters near volcanic islands. To create fossils, whatever dies is preserved by layers of sediment and then exposed million of years later. If you are a deep water resident your fossils have to rise above sea level and eventually become exposed in an area where humans can find it, whether through natural erosion or paleontological digging. Well, most fossils are more than 70 million years old, so we haven't found younger coelacanth fossils yet because they're still hidden in the depths of the ocean where our modern coelacanths live.  Coelacanths are considered a Lazarus taxon. A Lazarus taxon is a group of living beings that reappear after a long period during which they were thought to be extinct. The name is based on the biblical story of Lazarus who was raised from the dead. There are typically two characteristics shared by Lazarus taxons. 1- They have a limited geographic range. 2-They live in an area where fossils rarely form. This certainly sounds like the coelacanth to me.  That is all for this penultimate episode of the coelacanth. The fossil record of this majestic fish is my ninth favorite thing about this long-lived animal.   If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change.    Join me next week for the final episode about the coelacanth.     (Piano Music plays)  This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.

Summary: How does this deep sea fish find food? Just like everything else with the coelacanth, it's fascinating! Join Kiersten as she explains how the coelacanth hunts and what it likes to eat.    For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean   Show Notes: “The coelacanth rostral organ is a unique low=resolution electro-detector that facilitates the feeding strike,” by Rachel M. Berquist, Vitaly L. Galinsky, Stephen M. Kajiura, and Lawrence R. Frank. Scientific Reports 5, #8962 (2015) https://doi.org/10.1038/srep08962 “The first direct evidence of a Late Devonian coelacanth fish feeding on conodont animals,” by Michel Zaton, Krzysztof Broda, Martin Qvarnstrom, Grzegorz Niedzweidzki and Per Erik Ahlberg. The Science of Nature 104, #26 (2017), https://doi.org/10.1007/s00114-017-1455-7 Anatomy: https://www.pbs.org/wgbh/nova/fish/anatomy.html Music written and performed by Katherine Camp   Transcript (Piano music plays) Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife. (Piano music stops) Welcome to Ten Things I Like About… I'm Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we'll find right out side our doors and some are continents away but all are fascinating.  This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won't regret it. This episode continues the coelacanth and their diet and how they hunt is the sixth thing I like about them. If you remember from episode two, Anatomy, coelacanths have what is called a rostral organ. This organ is believed to help them detect electric fields in their environment. Why do they need to detect electric fields? I love this question, listeners, and I'm proud of you for asking it! Some fish have the ability to detect weak, low frequency electric fields produced by living tissue that is in contact with water. These fish typically have some kind of electrosensitive organ that detects the electric fields and these fish tend to be meat eaters. See where I'm going with this? The electric fields that living creatures give off is how the coelacanth finds its food. Let's delve into the details of their rostral organ and see how this thing works. Most fish with an electrosensitive organ that have been studied have complex labyrinths of hundreds to thousands of sensory canals. These canals are distributed throughout both the top and bottom of the head and are also often found around the mouth. These canals are typically arranged in clusters that are reminiscent of a directional antenna. All of the canals connect to an electrosensitive organ. The layout of the canals allows the fish to sense other animals near it from several different directions. This can help them find food, recognize conspecifics, or detect predators when they are at close range. Every animal's electric field will be different and our fish can use those differences to discriminate between the animals near them.  The coelacanth's rostral organ is an electrosensitive organ but, just like everything else we've learned about so far, it's not quite like other fish's. To discover more about this organ, a team of scientists used an MRI machine on a preserved specimen of Latimeria chulumnae to get a good look at it. What they found was slightly unexpected but explained a few things that we'll talk about in just a moment.  The rostral organ of the coelacanth has only three sensory canals, as opposed to hundreds or thousands seen in other extant species of fish. These canals are called tubules and they are all restricted to a small area of the upper snout. They also have no electroreceptors connected to the lower surface of the snout or lower jaw. Seeing the smaller scope and size of the rostral organ, the researchers asked what good is it really doing the coelacanth.  Using the 3D images they got with the MRI, they approximated the sensitivity of each tubule which allowed them to estimate the range of the rostral organ. What they found was that the coelacanth can only detect animals directly in front of their snout. Their rostral organ is only a low-resolution electro-detector so they do not get any complex information from the electric fields they detect and the field must be very close to them. This makes them unique in living fishes that use electrosensory organs to detect prey because they cannot track the prey items movements. They have to wait until the prey is practically in their mouths before they sense them. Remember I said this studies' findings explained something about the coelacanth, well the is it. It explains why they hunt the way they hunt. When we first developed technology that allowed us to study live coelacanths in situ, we noticed a strange behavior. Sometimes coelacanths would drift along in a current with their heads down and their tails up, essentially in a headstand posture. We had no idea what was going on, until someone saw them snatch a fish. This is the way coelacanths hunt.  It's called drift hunting and it's a passive way of hunting. The fish just floats along with the current of the water and waits for the right prey to come along. Then BAM!, dinner is served. This explains why their rostral organ is so focused on the snout region of their body.  Once the coelacanth's rostral organ indicates that an appropriate prey item has approached within 10 to 20 centimeters in front of its mouth, it snatches it out of the water. The specific feeding mechanism of the coelacanth is called suction-inhalation. I don't think that really needs too much explanation. They suck their food into their mouth along with large amounts of water. This does explain why the coelacanth has such a large mouth. If you're sucking your prey in whole, you want to have a big mouth.  Coelacanths have well-developed protrusible jaws that are capable of great forward motion. Their extremely muscular lower jaw also contributes to their powerful suction-inhalation. They also have an expandable gular structure, under the chin, that helps increase the power and gape of the mouth. The intracranial joint that coelacanths have retained, while other species of fish have lost it through millennia of evolution, may also help with the flexibility of the head which in turn helps with mobility of the jaws. This suction-inhalation does allow them to hunt animals that other fish of their size cannot reach. Researchers have seen coelacanth suck animals out of hidey holes in craggy canyon walls. And this method of cap ture is fast! It takes only a second for the coelacanth to inhale a prey item. Inside the mouth, coelacanths do have three types of teeth. It does not appear that they use the teeth for grinding or shredding their food. It is more likely the teeth are there to prevent prey from escaping their giant maw. Now that we know how coelacanth find their prey, what kind of prey are they looking for? This is a good episode for great questions, listeners. Y'all are on a roll today! Coelacanths are classified as piscivores. Pisces is the Latin word for fish, but those of you born between February 19th and March 20th already knew that!  So a piscivore is an animal that eats fish. Coelacanth are not terribly picky about what they eat and their diet can include cuttlefish, squid, octopus, snipe eels, small sharks, and other benthic fishes. So, essentially whatever fits in their mouth.  It appears they've been eating like this since the beginning of their time on earth. In a research paper published in 2017, the first direct evidence of a coelacanth eating eel like animals was discovered in the digestive tract of a fossilized specimen found in Poland. The coelacanth came from the Late Devonian period and a remnant of the eel was found preserved in the digestive tract. They also found coprolite, fossil poop, possibly from the coelacanth with the same remnants inside. We can't know how these coelacanths hunted their food but we can now say that they've been eating the same kind of food for quite some time.  In 2000, researchers looked at where coelacanths hunted, how abundant prey items were where they hunted, and how much food they might be eating. They found that coelacanths hunted between 650 feet and 1300 feet below the surface of the water. They also measured prey density in relation to depth which increased as you descended deeper. I was a bit surprised by that actually. I thought there would be less prey as you moved further down. Maybe I need to do another series on some deep-sea wildlife. They also estimated how much food the coelacanths were eating during each hunting session. Assuming the individuals studied were 100% successful on each hunt, medium-sized individuals were consuming about 122 grams of food and large females were consuming 299 grams of prey. Doesn't seem like a lot considering an average sized Gala apple weighs between 150 to 250 grams. Although, an apple a day…right? That's all for this episode on the coelacanth. I hope you found their hunting behavior and their diet as fascinating as I did because it is my sixth favorite thing about them.      If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change.    Join me next week for another episode about the coelacanth.     (Piano Music plays)  This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.

The gang discusses two papers that look at patterns of niche conservatism or niche evolution in the fossil record. The first paper looks at the pollen records of trees in Portugal to test if changing climate can explain modern tree distributions, and the second paper looks at the impact of Late Devonian extinction pulses/invasions on brachiopod communities. Meanwhile, Curt summarizes the podcast, James has brachiopod facts, and Amanda cannot control her cats.   Up-Goer Five (Curt Edition): Our friends talk about two papers that look at where animals live and what they do in the world, and also if that stays the same or changes over time. The first paper looks at tall living things that make their own food and lose a part of themselves every fall. This looks at one place that has just a few of these types of living things but in the past there were different types there. Also, back then it was not as warm and the rain was different. This paper wants to see why the tall living things we have in this part of the world are where they are right now. What they saw was that, some of the changes in the tall things seem to be tall things following where they want to live; when things get warmer or colder they move to follow the change. But some things seem to be moving into places that are very different from where they started, so they are changing what types of places they like to live in. The second paper looks at animals that live on the bottom of the big blue wet thing and take food out of the water and were found all over the world a long time ago. It looks at a time when a big change killed a lot of living things. This paper looks at how this changed the types of these animals over time. What they find is that, a lot of the animals that die because of the change have another animal from somewhere else doing the same thing move in and take that animal's place. The things that do not die just keep on doing their own thing. It does not look like there is much change in what the animals are doing either from the big change that happened, or from the new animals moving in.   References: Vieira, Manuel, et al. "Niche  evolution versus niche conservatism and habitat loss determine  persistence and extirpation in late Neogene European Fagaceae." Quaternary Science Reviews 300 (2023): 107896. Brisson, Sarah K., et al. "Niche conservatism and ecological change during the Late Devonian mass extinction." Proceedings of the Royal Society B 290.1996 (2023): 20222524.

In the late 1930s, our understanding of the transition of fish to tetrapods — and the eventual jump to modern vertebrates — took an unexpected leap forward. The evolutionary a'ha came from a single partial fossil skull found on the shores of a riverbank in Eastern Canada.  Meet the Stegocephalian, Elpistostege watsoni, an extinct genus of finned tetrapodomorphs that lived during the Late Givetian to Early Frasnian of the Late Devonian — 382 million years ago.  Elpistostege watsoni — perhaps the sister taxon of all other tetrapods — was first described in 1938 by British palaeontologist and elected Fellow of the Royal Society of London, Thomas Stanley Westoll. Westoll's research interests were wide-ranging. He was a vertebrate palaeontologist and geologist best known for his innovative work on Palaeozoic fishes and their relationships with tetrapods.  As a specialist in early fish, Westoll was asked to interpret that single partial skull roof discovered at the Escuminac Formation in Quebec, Canada. His findings and subsequent publication named Elpistostege watsoni and helped us to better understand the evolution of fishes to tetrapods — four-limbed vertebrates — one of the most important transformations in vertebrate evolution.  www.fossilhuntress.com

The gang discusses two papers that look at the complicated path tetrapods took to getting on land. The first paper looks at a more derived stem tetrapod that went back into the water, and the second paper uses trace fossils to investigate the foodweb of a community dominated by some early tetrapods. Meanwhile, Amanda has a friend over, James knows how to be silent, and Curt teaches everyone that things continue to exist even when we don't see them.   Up-Goer Five (Curt Edition): Our friends talk about two animals that are great great great great great great father and mother to all of the animals that are on the land. But these animals did not all make their way on to the land in a simple way. The first paper looks at an animal that looks like it went back into water. This animal has all of the parts that you need to live well in the water, even though it also has parts from animals that would be on the land, or at least spending some time on the land. This means that the way on to the land has a lot more steps forward and back than we like to think. The second paper looks at the places these animals were living in and tries to use the parts that are around and how they were hurt to see what may have been eating what. People have thought that these animals went on to the land to get away from things that might have been eating them. This paper shows that those animals might have been the things that were eating other animals. It seems like being one of these animals that lives in the water was a pretty good way to live.   References: Robin, Ninon, et al. "Vertebrate  predation in the Late Devonian evidenced by bite traces and  regurgitations: implications within an early tetrapod freshwater  ecosystem." Papers in Palaeontology 8.4 (2022): e1460. Stewart, Thomas A., et al. "A new elpistostegalian from the Late Devonian of the Canadian Arctic." Nature 608.7923 (2022): 563-568.

(image source: https://en.wikipedia.org/wiki/Tiktaalik by Zina Deretsky) Host Matthew Donald and guest co-host Christina Eilert discuss Tiktaalik, a real asshole that should have known what horrible things crawling onto land would eventually lead to for the world. From the Late Devonian, this 8-foot sarcopterygian has been the subject of many memes using this very image about how it's personally responsible for all of human suffering, which in all honesty might just be a tad harsh. Wait, rent is due soon and I might lose my insurance? Yeah, frick this guy. Want to further support the show? Sign up to our Patreon for exclusive bonus content at Patreon.com/MatthewDonald. Also, you can purchase Matthew Donald's dinosaur book "Megazoic" on Amazon by clicking here, its sequel "Megazoic: The Primeval Power" by clicking here, its third installment "Megazoic: The Hunted Ones" by clicking here, or its final installment "Megazoic: An Era's End" by clicking here, as well as his non-dinosaur-related book "Teslanauts" by clicking here.

Gavin teaches Fia and COVID Mike about the extinction(s)? at the end of the Devonian Period, one of the "Big 5" mass extinctions. Fia teaches Gavin about how cool cypress trees are. Follow us on Twitter Topic form Guest Form Gavin's Blog Leave us an audio message Youtube Channel

(image source: https://en.wikipedia.org/wiki/Ichthyostegalia) Host Matthew Donald and guest co-host Natasha Krech discuss Ichthyostega, one of the first vertebrates to crawl onto land, so if you hate modern things like war, taxes, or reality shows, you can blame this guy. From the Late Devonian, this 5-foot stegocephalian inadvertently paved the path forward for all land vertebrates including humanity. Kind of like that time in 1918 a Private had a limping soldier in his sights and refused to shoot him, but then that soldier turned out to be Hitler. True story. Point is, someone should have pushed Ichthyostega back into the water. Want to further support the show? Sign up to our Patreon for exclusive bonus content at Patreon.com/MatthewDonald. Also, you can purchase Matthew Donald's dinosaur book "Megazoic" on Amazon by clicking here, its sequel "Megazoic: The Primeval Power" by clicking here, its third installment "Megazoic: The Hunted Ones" by clicking here, or its final installment "Megazoic: An Era's End" by clicking here. 

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Pangea: The Worst of Times, published by John G. Halstead on the AI Alignment Forum. 260 million years ago, our planet had an unfamiliar geography. Nearly all of the landmasses were united into a single giant continent known as ‘Pangea' that stretched from pole to pole. On the other side of the world you would find a vast ocean, even larger than the present Pacific, called Panthalassa. The Pangean era lasted 160 million years, and 80 million of these were extremely inhospitable to animal and plant life, coinciding with two mass extinctions and four other major extinction events. This is why Paul Wignall, a Professor of Palaeoenvironments at Leeds has called the Pangean era ‘The Worst of Times'. Understanding why the Pangean era was so miserable helps inform several questions of interest to those studying existential risk. ● What level of natural existential risk do we face now, and have we faced in the past? ● What is the threat of super-volcanic eruptions? ● How much existential risk does anthropogenic climate change pose? 1. Background There have been five mass extinctions so far. The Ordovician–Silurian (450-440 million years ago) and the Late Devonian (375-360 million years ago) each preceded the age of Pangea. The Pangean period coincided with the two worst mass extinctions, the huge Permian-Triassic mass extinction (252 million years ago) and the Triassic-Jurassic extinction event (201 million years ago).[1] The last crisis, the Cretaceous–Paleogene event (65 million years ago), accounted for the dinosaurs and occurred once continental drift had done its business and Pangea had broken apart. With the exception of the end Cretaceous extinction, since the breakup of Pangea, it has been relatively plain sailing for Earth's various species, until humans started killing off other species themselves. [2] As one can see on this diagram, in the 145 million years since the start of the Cretaceous, the average rate of global genus extinctions from extinction events has been around 5% and never passed 15%, except for the death of the dinosaurs. But in the 80 million years from the first Pangean extinction event, the Capitanian, to the early Jurassic extinction events, the average rate of global genus extinctions in extinction events is more around 15-20%, and 12 events produced global genus extinction rates in excess of 15%. Below is a useful chart from Wikipedia on the Phanerozoic, which shows the long-term trend in biodiversity as well as the impact of different extinction events. Again, this highlights how unusually bad things were in the Pangean era - specifically the 80 million years after the Capitanian extinction event 260 million years ago. But it also highlights how good things have been since the end of the Pangean era and the start of the Cretaceous (145 million years ago). 2. What caused such ecological trauma in Pangea? Huge volcanic eruptions were implicated in all of the six major extinction events in the Pangean era. One can see this in the first diagram above, where the volcanic eruptions are shown at the top and the line traces down to corresponding extinction events at the bottom. Every Pangean extinction event coincided with the outpouring of enormous fields of lava that, once cooled, produced what geologists call Large Igneous Provinces (LIPs).[3] To put these LIPs in context, the eruption of Mount Pinatubo in 1991 produced 10 cubic km of magma, which caused the Earth to cool by about half a degree. The eruption of the Siberian Traps which appeared to cause the end Permian extinction produced 3 million cubic km of magma. You can see the volume of magma for all major LIPs at the top of the first diagram above. These volcanic eruptions emitted sulphur dioxide, carbon dioxide and halogen gases, each of which could potentially have an effect on the ecosys...

The Flannelcasters talk about the potential causes of the late Devonian extinction, as well as it's extent.

In the late 1930s, our understanding of the transition of fish to tetrapods — and the eventual jump to modern vertebrates — took an unexpected leap forward. The evolutionary a'ha came from a single partial fossil skull found on the shores of a riverbank in Eastern Canada. Meet the Stegocephalian, Elpistostege watsoni, an extinct genus of finned tetrapodomorphs that lived during the Late Givetian to Early Frasnian of the Late Devonian — 382 million years ago. Elpistostege watsoni — perhaps the sister taxon of all other tetrapods — was first described in 1938 by British palaeontologist and elected Fellow of the Royal Society of London, Thomas Stanley Westoll.  Westoll's research interests were wide-ranging. He was a vertebrate palaeontologist and geologist best known for his innovative work on Palaeozoic fishes and their relationships with tetrapods. As a specialist in early fish, Westoll was asked to interpret a single partial skull roof discovered at the Escuminac Formation in Quebec, Canada. His findings gave us the publication that would name Elpistostege watsoni and helped us to better understand the evolution of fishes to tetrapods — four-limbed vertebrates — one of the most important transformations in vertebrate evolution. Hypotheses of tetrapod origins rely heavily on the anatomy of a few tetrapod-like fish fossils from the Middle and Late Devonian, 393–359 million years ago. These taxa — known as elpistostegalians — include Panderichthys, Elpistostege and Tiktaalik — none of which has yet revealed the complete skeletal anatomy of the pectoral fin. None until 2010, that is when a complete 1.57-metre-long articulated specimen was described by Richard Cloutier et al. in 2020. The specimen helped us to understand the origin of the vertebrate hand. It revealed a set of paired fins of Elpistostege containing bones homologous to the phalanges (finger bones) of modern tetrapods and is the most basal tetrapodomorph known to possess them. Once the phalanges were uncovered, prep work began on the fins. The fins were covered in scales and lepidotrichia (fin rays). The work was tiresome, taking more than 2,700 hours of preparation but the results were thrilling. We could now clearly see that the skeleton of the pectoral fin has four proximodistal rows of radials — two of which include branched carpals — as well as two distal rows organized as digits and putative digits. Despite this skeletal pattern — which represents the most tetrapod-like arrangement of bones found in a pectoral fin to date blurring the line between fish and land vertebrates — the fin retains lepidotrichia (those wee fin rays) distal to the radials. This arrangement confirmed an age-old question — showing us for the first time that the origin of phalanges preceded the loss of fin rays, not the other way around. This was evidence for the origins of the vertebrate hand that you and I use today.

Melvyn Bragg and guests discuss the devastating mass extinctions of the Late Devonian Period, roughly 370 million years ago, when around 70 percent of species disappeared. Scientists are still trying to establish exactly what happened, when and why, but this was not as sudden as when an asteroid hits Earth. The Devonian Period had seen the first trees and soils and it had such a diversity of sea life that it’s known as the Age of Fishes, some of them massive and armoured, and, in one of the iconic stages in evolution, some of them moving onto land for the first time. One of the most important theories for the first stage of this extinction is that the new soils washed into oceans, leading to algal blooms that left the waters without oxygen and suffocated the marine life. The image above is an abstract group of the huge, armoured Dunkleosteus fish, lost in the Late Devonian Extinction With Jessica Whiteside Associate Professor of Geochemistry in the Department of Ocean and Earth Science at the University of Southampton David Bond Professor of Geology at the University of Hull And Mike Benton Professor of Vertebrate Paleontology at the School of Life Sciences, University of Bristol.

Melvyn Bragg and guests discuss the devastating mass extinctions of the Late Devonian Period, roughly 370 million years ago, when around 70 percent of species disappeared. Scientists are still trying to establish exactly what happened, when and why, but this was not as sudden as when an asteroid hits Earth. The Devonian Period had seen the first trees and soils and it had such a diversity of sea life that it’s known as the Age of Fishes, some of them massive and armoured, and, in one of the iconic stages in evolution, some of them moving onto land for the first time. One of the most important theories for the first stage of this extinction is that the new soils washed into oceans, leading to algal blooms that left the waters without oxygen and suffocated the marine life. The image above is an abstract group of the huge, armoured Dunkleosteus fish, lost in the Late Devonian Extinction With Jessica Whiteside Associate Professor of Geochemistry in the Department of Ocean and Earth Science at the University of Southampton David Bond Professor of Geology at the University of Hull And Mike Benton Professor of Vertebrate Paleontology at the School of Life Sciences, University of Bristol.

It's the next in our short series of episodes about mass extinctions! Don't worry, it won't be boring, because we're going to learn about a lot of weird ancient fish too. Further reading: Titanichthys: Devonian-Period Armored Fish was Suspension Feeder Behind the Scenes: How Fungi Make Nutrients Available to the World Dunkleosteus was a beeg feesh with sharp jaw plates that acted as teeth: Titanichthys was also a beeg feesh, but it wouldn't have eaten you (picture from the Sci-News article linked above): Pteraspis: NOSE HORN FISH: Cephalaspis had no jaws so it couldn't chomp you: Bothriolepis kind of looked like a fish in a mech suit: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. Here’s the second in our small series of episodes about extinction events, this one the Late Devonian extinction. We’ll also learn about some weird and amazing fish that lived during this time, and a surprising fact about ancient trees. The Devonian period is often called the Age of Fish because of the diversity of fish lineages that arose during that time. It lasted from roughly 420 million years ago to 359 million years ago. During the Devonian, much of the earth’s landmasses were smushed together into the supercontinent Gondwana, which was mostly in the southern hemisphere, and the smaller continents of Siberia and Laurussia in the northern hemisphere. The world was tropically warm, ocean levels were high, and almost all animal life lived in the oceans. Some animals had adapted to living on land at least part of the time, though, and plants had spread across the continents. The first insects had just evolved too. Shallow areas of the ocean were home to animals that had survived the late Ordovician extinctions. There were lots of brachiopods, bivalves, crinoids, trilobites, and corals. Eurypterids were still thriving and ammonites lived in deeper water. But while all these animals are interesting, we’re mainly here for the fish. The fish of the Devonian were very different from modern fish. Most had armor. Way back in episode 33 we talked about the enormous and terrifying dunkleosteus, which lived in the late Devonian. It might have grown up to 33 feet long, or 10 meters. Since we still don’t have any complete specimens, just head plates and jaws, that’s an estimate of its full size. However long it grew, it was definitely big and could have chomped a human in half without any trouble at all. It’s probably a good thing mammals hadn’t evolved yet. Instead of teeth, dunkleosteus had jaw plates with sharp edges and fanglike projections that acted as teeth. Another huge fish from the Devonian is called titanichthys, which might have grown as long as dunkleosteus or even bigger, but which was probably not an apex predator. Its jaw plates were small and blunt instead of sharp, which suggests it wasn’t biting big things. It might not have been biting anything. Some researchers think titanichthys might have been the earliest known filter feeder, filtering small animals from the water by some mechanism we don’t know about yet. Filter feeders use all sorts of adaptations to separate tiny food from water, from gill rakers to baleen plates to teeth that fit together closely, and many others. A study published in 2020 compared the jaw mechanisms of modern giant filter feeders (baleen whales, manta rays, whale sharks, and basking sharks) to the jaw plates of titanichthys, as well as the jaw plates of other placoderms that were probably predators. Titanichthys’s jaws are much more similar to those of modern filter feeders, which it isn’t related to at all, than to fish that lived at the same time as it did and which it was related to. Titanichthys and dunkleosteus were both placoderms, a class of armored fish. That wasn’t unusual, actually. In the Devonian, most fish ended up evolving armored plates or thick scales.

(image source: https://en.wikipedia.org/wiki/Dunkleosteus#/media/File:Dunkleosteus_terrelli_-_MUSE.jpg) Host Matthew Donald and guest co-host Ben O'Regan discuss Dunkleosteus, the literally boneheaded fish that haunted the nightmares of early sharks. From the Late Devonian, this 26-foot placoderm not only preyed on anything it could get its plated teeth on, but also might have been an early example of giving live birth. So that's weird. Want to further support the show? Sign up to our Patreon for exclusive bonus content here. Also, you can purchase Matthew Donald's dinosaur book "Megazoic" on Amazon by clicking here, its sequel "Megazoic: The Primeval Power" by clicking here, its third installment "Megazoic: The Hunted Ones" by clicking here, or its final installment "Megazoic: An Era's End" by clicking here. 

Happy New Year! As we transition into a new decade, this episode is about one of the most important and incredible transitions in the evolutionary history of life. In the Late Devonian, one particular group of bony fish spent many millions of years experimenting with new forms of fins, skulls, and lifestyles, ultimately giving rise to the first land-dwelling vertebrates and setting the stage for 300 million years of continental dominance. In the news: the earliest penguins, ancient whale swimming, dinosaur lice, and really old brains. Time markers: Intro & Announcements: 00:00:00 News: 00:04:00 Main discussion, Part 1: 00:30:30 Main discussion, Part 2: 00:59:00 Check out our blog for bonus info and pictures: http://commondescentpodcast.wordpress.com/ The Common Descent Store is open! Get merch! http://zazzle.com/common_descent Follow and Support us on: Patreon: https://www.patreon.com/commondescentpodcast Twitter: https://twitter.com/CommonDescentPC Facebook: https://www.facebook.com/commondescentpodcast/ PodBean: https://commondescentpodcast.podbean.com/ iTunes: https://itunes.apple.com/us/podcast/the-common-descent-podcast/id1207586509?mt=2 YouTube: https://www.youtube.com/channel/UCePRXHEnZmTGum2r1l2mduw The Intro and Outro music is “On the Origin of Species” by Protodome. More music like this at http://ocremix.org. Musical Interludes are "Professor Umlaut" by Kevin MacLeod (incompetech.com). Licensed under Creative Commons: By Attribution 3.0 http://creativecommons.org/licenses/by/3.0/

“It’s not over yet. We still have time to save the planet, but it is worrying that—especially going forward—where in the past a lot of our damage has been done by hunting, now we’re starting to pull these levers that are really responsible for the worst things that have happened in Earth history, these big injections of CO2. So, before we go too far down that road, because we know it leads [to mass extinction], we should consult the rocks and learn what they have to tell us.”   Peter Brannen is an award-winning science journalist with expertise in ocean science, deep time, astrobiology and the carbon cycle. Peter’s work has appeared in The New York Times, The Atlantic and The Washington Post, among many other media outlets, and he is the author of the acclaimed The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth’s Past Mass Extinctions. Today, Peter joins Ross and Christophe to walk us through the five major mass extinctions in Earth’s history, discussing what events triggered each extinction and how plant and animal life changed each time.   Peter covers the current threat to coral reefs and shares his definition of fossil fuels, explaining how past mass extinctions generated the fossil fuels we use today. Listen in for Peter’s insight around the eerie shadow of extinction that follows human migration and find out what we can learn about managing the carbon cycle from previous extinctions to avert another ‘end of times.’   Key Takeaways   [1:46] How to think about the scale of geology and deep time  Frame one footstep as century of time Walk 20 miles/day for four years to beginning of Earth’s history   [6:25] The Ordovician mass extinction (445M years ago) Underwater animal life gets off ground, reefs take off Ice age drops sea level and causes 85% of life to go extinct   [11:18] The Late Devonian mass extinction (375M years ago) Age of fish + first life appears on land Trees as mechanism of mass extinction, initiate ice age    [14:43] The End-Permian mass extinction (252M years ago) Big reptiles, animals related to mammals and reefs in oceans 96% of life wiped out by extreme volcanic eruptions   [19:50] How the Earth recovered after the End-Permian  Took 10M years to recoup, miserable time Life looks totally different in aftermath   [20:49] The ‘Permian Jr.’ mass extinction (200M years ago) Volcanic event causes breakup of Pangea Sets reign of dinosaurs in motion   [22:27] The instantaneous nature of the asteroid extinction May have taken < 20 minutes (hot as pizza oven) Less than 50K years considered fast geologically   [27:00] The current threat to the coral reefs Devastating bleaching events + acidification Tend to get wiped out in mass extinctions  Supply 25% of Earth’s biodiversity   [31:30] Peter’s definition of fossil fuels What happens when life preserved in rocks for long time Humans undo photosynthesis by releasing CO2   [32:40] What role mass extinctions play in generating fossil fuels Natural gas fracked today victim of Late Devonian Organic matter preserved at bottom of ocean   [34:36] What characterizes the current potential extinction Modern humans show up 300K years ago Eerie shadow of extinction follows where people go Foot on accelerator now but still time to avert   [41:38] Why it doesn’t matter if humans cause the rise in CO2 Geopolitical implications of immigration once tropics uninhabitable Wet bulb temperature = no way to cool off, die of overheating   [45:20] What we can learn about changing the atmospheric concentrations of greenhouse gasses from previous mass extinctions Sequester CO2 in basalt rock, turn to limestone Same process cooled Earth 200M years ago   [47:08] Why Peter has cause to be optimistic Use information to energize vs. get depressed Area of opportunity for carbon removal industry   Connect with Ross & Christophe   Nori Nori on Facebook  Nori on Twitter Nori on Medium Nori on YouTube Nori on GitHub Nori Newsletter Email hello@nori.com Nori White Paper Subscribe on iTunes Carbon Removal Newsroom   Resources   Peter’s Website Peter on Twitter The Ends of the World: Volcanic Apocalypses, Lethal Oceans, and Our Quest to Understand Earth’s Past Mass Extinctions by Peter Brannen Techstars Sustainability Accelerator Lee Kump National Center for Atmospheric Research The Sixth Extinction: An Unnatural History by Elizabeth Kolbert Lamont-Doherty Earth Observatory Dr. David Goldberg on RCC EP004 ‘We Need to Capture Carbon to Fight Climate Change’ in Nature Paris Agreement

It’s Episode 65, and you know what that means … extinction! This time, we address the ancient and confusing Late Devonian extinction. This is traditionally considered one of the “Big 5,” but it doesn’t seem to be “one” extinction at all. Geologists and paleontologists continue to work at piecing together the various causes and consequences that create an extended series – several millions years long – of very unfortunate events that altogether comprise one of the worst biological crises in Earth history. In the news: tyrannosaur smells, peccary behavior, and a talk (by us) about our podcast! Time markers: Intro & Announcements: 00:00:00 News: 00:05:00 Main discussion, Part 1: 00:33:30 Main discussion, Part 2: 00:59:30 Patron question: 01:37:30 Check out our blog for bonus info and pictures: http://commondescentpodcast.wordpress.com/ The Common Descent Store is open! Get merch! http://zazzle.com/common_descent Follow and Support us on: Patreon: https://www.patreon.com/commondescentpodcast Twitter: https://twitter.com/CommonDescentPC Facebook: https://www.facebook.com/commondescentpodcast/ PodBean: https://commondescentpodcast.podbean.com/ iTunes: https://itunes.apple.com/us/podcast/the-common-descent-podcast/id1207586509?mt=2 YouTube: https://www.youtube.com/channel/UCePRXHEnZmTGum2r1l2mduw The Intro and Outro music is “On the Origin of Species” by Protodome. More music like this at http://ocremix.org. Muscial Interludes are "Professor Umlaut" by Kevin MacLeod (incompetech.com). Licensed under Creative Commons: By Attribution 3.0 http://creativecommons.org/licenses/by/3.0/

This week we’ll learn about some terrifying extinct fish, the armored dunkleosteus and the spiral-toothed helicoprion, plus a few friends of theirs who could TEAR YOU UP. Dunkleosteus did not even need teeth: Helicoprion had teeth like crazy in a buzzsaw-like tooth whorl: Helicoprion's living relatives, chimaeras (or ghost sharks) are a lot less impressive than they sound: Helicoprion probably looked something like this: But helicoprion has been described in all sorts of wacky ways over the years: So what are the odds this rendition of edestus is correct? hmm Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. This week we’ve got a listener suggestion! Will B. suggested placoderms, which were armored fish that lived hundreds of millions of years ago. He especially recommended Dunkleosteus. I looked it up and went, “Oh holy crap,” so you bet we’re going to learn about it today. I’m also pairing that terrifying fish with a really weird shark relation called Helicoprion. And we might even take a look at a few other fishes while we’re at it. Creepy extinct fish for everyone! Oh, and Will asked that I include more metric conversions. [heavy sigh] okay I guess If you had happened to live around 350 million years ago when Dunkleosteus was alive, you would be a fish. Well, you would probably be a fish. I don’t know for sure. That was during the Late Devonian period, and the Devonian is remembered as the “age of fish” by undergraduate geology and palaeo students everywhere. While land plants were evolving like crazy, developing true roots and seeds, fish were even crazier. Ray-finned fish evolved during the Devonian and so did lobe-finned fish like coelacanths. The first amphibious critters developed in shallow lakes and started to spend time on land, and in the ocean there were early sharks, lots of trilobites, and a whole lot of armored fish. Including, eventually, dunkleosteus. Dunkleosteus terrelli was the biggest species of placoderm. It probably grew over 30 feet long OR TEN METERS, WILL, which made it bigger than a great white shark. But dunkleosteus didn’t have teeth. And before you think, oh, it must have been a filter feeder or something, oh no. It didn’t need teeth. Instead it had bony plates like a gigantic beak. It could open and close its jaws incredibly fast—something like one 50th of a second—and could bite through armor and bone no problem. One article referred to its jaws as sheet-metal cutters. Scientists think its bite was as powerful as that of a T rex, although it didn’t quite match that of megalodon, but since T rex and megalodon both lived many millions of years later than Dunkleosteus, it’s useless to speculate who would win in a fight. But my money’s on Dunkleosteus. Dunkleosteus wasn’t a fast swimmer. Its head was covered in heavy armor that probably served two main purposes. One, the armor plates gave its massive jaw muscles something substantial to attach to, and two, it kept its head safe from the bites of other placoderms. That’s right. Dunkleosteus was a cannibal. We actually don’t know exactly how long Dunkleosteus was or what most of its body looked like. The only fossils we’ve found were of the head armor. We do have complete fossils and body impressions of other, much smaller placoderms, so since all placoderms seemed to have the same body plan we can make good guesses as to what Dunkleosteus looked like. One surprising thing we do have associated with Dunkleosteus fossils are some remains of its meals. These are called fish boluses, and they’re basically just wads of partially-digested pieces of fish that either get horked up by whatever ate them or pass through the digestive tract without being fully digested. From the fish boluses, we know that Dunkleosteus probably preferred the soft parts of its prey and didn’t digest bones very well. In 2013, a fossil fish over 400 million years old was described ...

The transition of fins to limbs is one of the most significant in the history of vertebrate evolution. These were the first steps that would eventually allow tetrapods to go on to dominate so many terrestrial ecosystems. Fossils that help fill the gaps in this crucial time are invaluable, so how do we go about finding them and what happens when we do discover one? Joining us to give an overview of some of the fossils involved in this transition, and to provide insights into the fieldwork that goes into finding them, is Dr Ted Daeschler, Academy of Natural Sciences of Drexel University.  

The gang talks about two papers that detail the ecology and evolution of some early fishy vertebrates. Can we tell what early coelacanth fish might have eaten? What evolutionary changes occurred when early tetrapods started making their way onto land? Is there an evolutionary trend towards kawaii? All this and less will be discussed.   Oh, and James has made some interesting discoveries about The Legend of Zelda. Up-Goer Five (James Edition):  The group looks at two papers that are to do with animals with no legs that live in water although in one of the papers one of the animals is trying to have legs. In the first paper we see a very old animal with no legs that lives in water that has family around today that are thought to be pretty much the same but actually may be doing different things. We see that this old thing with no legs was eating a type of animal that we do not get any more, which is interesting as we have no way of telling that anything else ate this animal. In the second paper we look at things with no legs that are starting to having legs. We see that their eyes are moving on top of their heads like big angry things with hard skin and big teeth in long faces that live in the water. At the same time the eyes are moving onto the top of the head they are also getting bigger, and it is shown that the animals would have been able to see better out of the water. This seems to be happening at the same time as them starting to change their not legs into legs. The most interesting thing is that when some of the animals that then have legs go back into the water their eyes get smaller but do not move back down the side of the head; they are stuck there even though they are no good there any more!   References: MacIver, Malcolm A., et al. "Massive increase in visual range preceded the origin of terrestrial vertebrates." Proceedings of the National Academy of Sciences 114.12 (2017): E2375-E2384. Zatoń, Michał, et al. "The first direct evidence of a Late Devonian coelacanth fish feeding on conodont animals." The Science of Nature 104.3-4 (2017): 26.

Curiosity Fruit Machine by S. Qiouyi Lu "What is it?" Alliq says. Jalzy runs eir hands over the object. It's a box of some sort, made from metal with organic paneling; a narrow lever sticks out from one side. Ey finds emself reaching out to the lever, eir fingers grasping the pockmarked knob at the end as if working from unearthed muscle memory. "I have no clue," Jalzy says. "But... I kinda wanna pull this and see what happens."   CURIOSITY FRUIT MACHINE and THE SLOW ONES are both GlitterShip Originals. [Full transcript after the cut]  ----more---- Hello! Welcome to GlitterShip, episode 33 for February 14, 2017. This is your host, Keffy, and I’m super excited to be sharing these stories with you. We have two stories this week, "Curiosity Fruit Machine" by S. Qiouyi Lu and "The Slow Ones" by JY Yang. Even better, S. narrated both stories for us! S. Qiouyi Lu is a writer, artist, narrator, and translator; their stories have appeared in Strange Horizons and Daily Science Fiction, and their poetry has appeared in Liminality and Uncanny. They are a 2016 graduate of the Clarion West writers workshop and a dread member of the Queer Asian SFFH Illuminati. Find them online at s.qiouyi.lu or follow them on Twitter at @sqiouyilu. JY Yang is a queer, non-binary writer and editor who has short fiction published or forthcoming in places like Uncanny, Lightspeed, Strange Horizons and Tor.com. Their debut novellas, THE RED THREADS OF FORTUNE and THE BLACK TIDES OF HEAVEN, will be out from Tor.com Publishing in Fall 2017. They live in Singapore, edit fiction at Epigram Books, and swan about Twitter as @halleluyang.     Curiosity Fruit Machine by S. Qiouyi Lu   "What is it?" Alliq says. Jalzy runs eir hands over the object. It's a box of some sort, made from metal with organic paneling; a narrow lever sticks out from one side. Ey finds emself reaching out to the lever, eir fingers grasping the pockmarked knob at the end as if working from unearthed muscle memory. "I have no clue," Jalzy says. "But... I kinda wanna pull this and see what happens." Alliq frowns. "Don't. For all we know, that thing could be some sort of weapon. We should probably wait for the others to catch up so we can get the engineering team to take a proper look." Alliq's voice fades into a mumble. Jalzy presses eir nose to the glass front of the object and brushes a tight curl of hair out of eir face. Ey can just barely make out some lettering—PAY. Eir grasp of 21st-century English is weak, but this seems to be a money machine of some sort. Surely, ey thinks, bringing eir arm down, a money machine can't hurt em... "Don't—!" The object whirs to life, three wheels inside the glass case spinning; a few of the bulbs lining the edge buzz and spark. Jalzy jumps back. Oh crap. Ccccccclackkkclackkclackkk—didn't old-timey explosives make that sound? Or were explosives more of a tick-tock sound? One of the wheels clicks as it stops—Jalzy grabs Alliq by the wrist, drags xem to a safe spot behind a wall of heavy crates—then another click—they brace themselves—and—click! Alliq flinches. Jalzy waits a moment—a dud, perhaps?—before peeking past the edge of the crates. The object's face shows one symbol, then two of the same symbol. The first is an oblong, yellow shape, and the next two are round, red orbs connected by an inverted green V. "I think we're safe," Jalzy whispers. Alliq comes up from xyr braced position. "Goddammit, don't do this to me," Alliq hisses. Xe's sweating a little, xyr forehead shining, and Jalzy has to suppress a giggle. "Hey, we're fine, right?" Ey steps out from behind the crates and goes back to the object. Ey crouches down. There's a metal trough underneath the symbols, but it's empty. Do they need to put something in there? "Jalzy," Alliq says from over eir shoulder, "those are—those are pictures of fruit." "What's a fruit?" "Seriously?" Alliq says, voice laden with exasperation. When Jalzy gives xem a blank stare, Alliq points at the oblong symbol and says, "Look, the first one is a lemon. Those two on the right, those are cherries." Jalzy squints. "I thought 'cherry' and 'lemon' were just colors. You know, like how we also have orange nutriblocks in our sustenance packs." Alliq snorts. "You know there used to be a fruit called 'orange', right? It wasn't just a color. Those are actually flavors. They came from these." Jalzy straightens up and paces around the object. "So what is this, a fruit-making machine?" "Did you never take terrabiology?" Alliq says. "History of Earth? Anything?" "Look, I took astrophysics so I wouldn't have to deal with so much reading, okay," Jalzy says, flipping eir crown of curls over eir shoulder. "So just educate me already, O All-Knowing Alliq." Alliq crosses xyr arms over xyr chest in a huff. "Fruit comes from seeds, not machines. I mean, we perfected the science to duplicate the flavors all the way back in the 21st century, but we never really got down how to duplicate the organic material. So the best we've got now is our nutriblocks." Xe unfolds xyr arms and circles around the object. "This—this is something else entirely. I don't think it actually has anything to do with food." "So, if it doesn't seem to be a weapon, and it doesn't produce anything... wanna pull the lever again and see what happens?" Jalzy grins slyly at Alliq, who raises xyr hands in surrender. "I'm going to check out the other room. If I were you, I'd just keep doing inventory until engineering gets here and can confirm what kind of object that is." Jalzy sticks out eir tongue. "Good thing you're not me," ey says. And ey pulls the lever again.   END       The Slow Ones by JY Yang   "The grass is dying." Kira looked up from squeezing a sachet of turkey-flavored sludge into the cat's bowl. Thom was standing by the living room window in his bathrobe still, holding a chipped mug of coffee and gazing out. "What?" she asked. "The grass. In the garden. It's gone all brown." She dumped the sachet in the trash and almost rinsed her sticky fingers under the kitchen faucet. But she remembered in time, and instead wiped them on the dishtowel she'd hung up. She hurried into the living room. "There," Thom said, "see?" In the small rectangle of dirt they called a garden the sparse tufts of grass had shriveled and turned colorless like the hair on an old man's head. A flap of crisp packet gleamed in the far corner, silver-underside-up, chicken bones scattered around it. The neighborhood kids. Kira wondered how long they had been there. Maybe forever. Everything seemed stuck in stasis these days. The grass had been in decline for a long time, months before the invasion began. Once upon a time Kira had plans for that patch. She had imagined cultivating flowers: Tulips, daffodils, rosebushes. Climbing ivies for the trellis. Maybe even one of those outdoor water features. But there hadn't been any time, had there? "Hasn't rained in weeks," Thom said. "Might never rain again." Kira exhaled and stormed back to the kitchen. The clock said five to three and she wished it didn't. She took a box of porkloin out of the freezer and popped it into the fridge. "Might as well dig it all up," Thom said from the living room. "Yeah, why don't you do it?" she said, louder than she'd intended. The cat had cleaned out her bowl and now stood staring at Kira, tail stiff in expectation. Kira snatched the water dish off the floor, then gingerly ran a centimeter of water into it. "Don't waste it," she told the cat as she sat it down again. In the living room Thom had settled into the armchair, knees apart, eyes blank. "What would be the point?" "What?" He turned to look at her, framed in the doorway between the kitchen and the living room, and shrugged. "There's no point." "Whatever," she said, and went to put her boots on. The cat had followed her out of the kitchen. "Come here, girl," she heard Thom say, his voice soft and charming, like it always used to be. Kira shoved her feet into the narrow confines of her boots. "I've left pork chops in the fridge to defrost," she said. "If you have time, you could make dinner." She knew he wouldn't. The cat settled on the windowsill to watch her as she stepped outside and locked the front door. Kira pulled her coat around herself, and then, because she had to, like pulling a plaster off, to get it over with; because she couldn't just ignore it, she looked up at the sky. From horizon to horizon, the sky above their street was filled with aliens. A thick layer of massive silver bodies, like cumulus rolls made of mercury, slid by over the tops of the streetlamps, the roofs, the twisted fingers of bare trees. Sunlight sometimes leaked through their bulk, but not often; the world had been in a state of weak thunderstorm dusk for weeks. The president of the United States had called them the Slow Ones, and the name stuck. Their enormous smooth bodies slipped against one another in a never-ending parade. There were scales and faint markings on each one whose purpose was impossible to discern. Concentric discs in alternating light and dark colors, larger across than a commercial jetliner, were assumed by observers to be eyes. But the gaping maw in front of each one, leading into unfathomable darkness: That one everyone could agree on. It was a mouth. A permanently open mouth. They were sucking up all the water vapor in the atmosphere. That was what the scientists on the proper news channels—BBC, CNN, Al-Jazeera—were all saying. But even the so-called experts knew so little about what was going on that people were no worse off reading crackpot theories on the Internet. Those had sprung up like mushrooms in the wake of rain, or perhaps, in the absence of it. They offered up all kinds of explanations as to what was happening: Act of God, benign migration, hostile invasion, collective hallucination. The first few days after the Slow Ones arrived, pouring into the sky above Alaska like reflective pancake batter until they blanketed the Earth, Thom had spent hours scrolling through theory after theory after theory, the most promising of which he served up to Kira over dinner, or texted to her while he was at work. That was when he still had work. The Slow Ones were aliens. This was something almost everyone—the scientist, the conspiracy theorist, the person on the street—agreed on. They were not of this world. The prevailing theory was that these were migratory creatures and they would leave for unknown pastures in good time. And then sunlight and blue skies and rain would return to the world. Wind and weather and water evaporation, all those good things. It was unlikely a theory as anything, but it allowed people to hold on to hope. Kira put her hood up and hurried down the street. If she walked fast enough, she might catch the three-fifteen bus to the city center. She missed the bus. When Kira finally arrived at the city center, the air under the Slow Ones was still. Not a wing stirred in it, not a guttural call rang out. Gulls were a year-round phenomenon in Norwich, sailing from spire to spire and filling public spaces with their noises regardless of the season. But their numbers in the market square had been dwindling since the Slow Ones arrived, and today was the day, it seemed, they passed the point of no return. Kira noted this with an odd trill in her belly. She, like everyone else, had grown numb to the clipped tones of a Dr. Somebody explaining to a presenter, in clinical terms, how the disruption to the Earth's water cycle was killing all the fish in the ocean. But it was another thing entirely to watch all the seabirds vanish before her eyes, relegated to an unknown fate. She hurried through the semi-sparse mid-afternoon crowd. When Thom's agency had moved him here a few years ago, she had been struck by how many retirees she saw on the streets. It felt like a different kind of fabric had been sewn in place compared to London which she had just gotten used to, and Kuala Lumpur where she had grown up. It was a good move for them, Thom being promoted to Norfolk branch manager, but Kira had wondered about all the people here, aging in place. It put in her mind an image of people sinking to the bottom of a lake, like sediment. Of course, at that time tourism was still a booming industry, and Thom had glowing images in his sights, futures full of holiday cottages and ski trips to the Alps. Neither of them knew what lay on the horizon: the shrinkings and the layoffs and the final collapse that awaited them. The arrival of the Slow Ones had only been a final straw. As she walked past the market square Charles, who ran one of the fruit stalls, waved at her. "All right?" he asked. An impulse seized her then, a screaming impulse, one which wanted to ask him how could he be so calm, couldn't he see what was happening? She wanted to grab him and shake him, point him to the sky and the shuttered fish stall next to him and the sad twisted things that were left of his wares, she wanted to do that and ask, Can't you see? Can't you see? She wanted to run at all the white-haired folk shuffling down the street getting on with their business as usual and shout it at them, shout it into their hairy wrinkled ears. She smiled at Charles. "Yeah, I'm alright." By the time she had gone down all the little streets that led her to the Pushcart she was half an hour late for work. As she came through the eatery's glass-paneled wooden door she caught a glimpse of Melanie's splendid silhouette at the till and her heart did that weird flutter it always did when Melanie was around. She shoved that sensation deep inside herself, where it belonged, and put on her shop-girl smile. In the afternoons the Pushcart sold tea and scones and crepes with bacon and maple syrup. Come evenings and the menu switched to alcohol and deep-fried things served in small silver buckets. Today the sign said no tea, they were under rations, bottled drinks only please. The warm brown interior of the cafe held a handful of lethargic patrons in various states of apathy, chewing fitfully or reading the news. Some of them were watching the TV nailed to the far wall, framed by old ship ropes and seashells. They usually kept it off unless there was footy going on, but since the Slow Ones came it had been permanently fixed to BBC News. The prevailing graphic, set to an indistinct voiceover, said WHAT WE KNOW SO FAR. (Nothing. They knew nothing. When governments and scientists sent drones and instruments up to the Slow Ones they stopped working, some kind of electromagnetic interference, they said. NASA was stumped. Everybody was stumped, grasping at straws.) Melanie didn't turn around as Kira stashed her things under the counter. That was an anomaly: For the past six months Kira's work routine had always begun with her warm and buttery smile. She studied her coworker's broad back, hunched over the till, noting the crooked way the apron was fastened around her waist. "You alright?" Melanie straightened up with a speed that suggested she hadn't heard Kira come in. "Hey. How's it going?" She looked tired, a collection of messy lines and dark smudges, as though the weekend had worn her face thin somehow. "You alright?" she repeated. "Yeah, I suppose. The sky hasn't fallen in, has it?" She gave Kira a laugh, and it was the kind that spoke less of mirth than it did of defeat. "How's life at home?" Kira's fingers fumbled with her apron strings. Melanie noticed her struggling and said, "Let me get that." With her back turned Kira said, "Life goes on. Thom's still moping." A firm tug at her waist. "He'll recover. Have faith." "I'm an atheist for a reason." She turned around. "How's Angie?" "Ha. Funny you should ask." Melanie sucked in a breath. "She's gone back to Sheffield." "What, you mean—" "Yeah. Permanently. She spent the weekend packing." Melanie was staring at her knuckles, which she kept lightly punching against the counter. "I'm sorry. What happened?" "Can't quite say, really. Just th— I don't know. She'd been planning it for a while, I think. She got back with her ex without telling me." She looked at Kira suddenly, eyes bright and shining. "Might as well, eh? End of the world and all that." "I'm sorry." She reached out and touched Melanie's forearm for a brief, hot moment. "I'm surprised, honestly." "Are you." "I mean, I—" She wanted to say, I always thought you two had the perfect relationship. "You two seemed so happy." "We did, didn't we?" She laughed again, and one corner of her mouth quirked upwards. In the slant of those lips Kira suddenly saw the cracking of facade and glimpsed familiar shores: the simmering irritations, the long silent nights, the cold stretches of not-arguments that thawed slowly into not-forgiveness. "Come help me with this till," Melanie said. "Something's wrong." They fought with the till. It was an old-fashioned one, just buttons and a drawer that popped out. It was jammed. They figured out the problem—a coin had gotten stuck, down the side of the drawer, and they fished it out with a flat screwdriver. "There you are, you little bastard," Melanie said, shaking the coin like a misbehaving puppy. She put it on top of the till, a tiny victory. At six a man barged into the Pushcart and slammed into the counter as Kira was ringing up an old lady's tea. "Turn your TV on," he rasped. "It's on," Kira said, pointing. The President of the United States, looking like he had aged ten years in as many days, was speaking inaudibly. In one corner a red block declared “LIVE.” The man was youngish, clean-shaven, dressed in clothes that were well looked-after. "Turn it up. Turn it up." Kira looked around, but she had no idea where Melanie was. The woman by the TV stepped up and reached for the volume dial. The voice of the US president, clipped and nasal, rose up and filled the room. "... THAT I AUTHORIZE THE USE OF THERMONUCLEAR WEAPONS AGAINST THE PHENOMENON KNOWN AS THE SLOW ONES..." "He's going to nuke them," the man who'd burst in said. "It's mental." Titters of conversation filled the room. What could that mean? Kira felt like the ground under her was vanishing, but she couldn't tell if it was her or the planet that was evaporating. The US president said: The missiles would be released over the middle of the Atlantic Ocean, far from any centers of civilization. The US president said: America could no longer wait for world powers to deliberate on a unified course of action. The US president said: America must take steps necessary to safeguard our future. A young man near the front of house was telling his girlfriend, in loud tones, how the radiation was going to get seeded in the atmosphere and kill them all. He was a physicist, he knew. The hawks running America, drunk on their Hollywood apocalypse dreams, were going to destroy life on the planet as we knew it. "It's war, you know," the old lady at the till said to Kira. "The Russians aren't going to like it. They're going to do something, you'll see." She declared it matter-of-factly, with utter conviction, and Kira saw the young girl she had been, bent over the radio, listening for news from the frontlines. On impulse she said, "It's on the house," and closed the till. "Go on, everything's free today." The man who had run in said, "Could I get—" "No, no, we're closing." Kira walked out from behind the counter, her legs shaky but still functional, and went to the glass-paneled door. The US president was still talking. She refused to look at the sky as she flipped the “OPEN” sign over. "I'm sorry. Please, everyone, could you just leave. We're closed. Everything's on the house." The scattered handfuls looked at her and each other, uncertain. "Go home," Kira said. "Call your mother, hug your children. Go home." She watched them file out onto the dark streets. When it was just her in the Pushcart she abandoned the unwashed, undressed tables and turned the lights out. Craig, the owner, only came in on Thursdays and weekends. She'd sort it out later. She found Melanie behind the storeroom door, chest still slowly heaving in the wake of a long fit of crying. She stood up, looking embarrassed, as Kira came in. "Sorry. I—still a bit of a mess—did something happen?" Kira ghosted towards her, fixed on her red-rimmed eyes, her lips. "The world's going to end." "What?" "The Americans are going to nuke the Slow Ones. They're doing it tomorrow." Melanie exhaled. "Madness." Madness, chaos, centers not holding. Just what was she clinging on to, anyway? Kira reached up and kissed her. Melanie's body reacted with surprise at first, then hunger. She had strong arms that could lift a double carton of coffee beans over her head, and they trembled around Kira's waist. As Kira sublimed into liquid Melanie closed the door behind them, so that nobody would hear. Later, as they sat together on the floor, sticky skin to sticky skin, Melanie asked, "Why?" No modifiers, no clauses. Just ”why.” Kira remained quiet for a while, pinching her toes inside the lingering damp heat of her boots. "Thom once told me about a theory he read. You know how they said the Slow Ones might be like migratory birds?" "I've heard that one. Sounds like tosh. But pretty much everything does these days." "Well, migratory birds come back every year. So why haven't we seen the Slow Ones before? Why has no-one, out of all of human history, ever mentioned them?" "So they're not migratory." Kira could still picture Thom's face as he had grilled her over this theory at the dinner table. How his freckled face had lit up with schoolboy excitement at the prospect of humanity's destruction, something interesting happening at last. "Well, the universe operates on a different scale, doesn't it? Billions and billions. What if the Slow Ones do come back, but so long that they only appear once every geologic age?" Melanie made a grunting noise. Kira settled her soft hip against Melanie's bony one. "It's the extinction events," she said. "What are those?" "Big die-offs." She curled her fingers around one of Melanie's nipples. "Like the dinosaurs. The Cretaceous-Tertiary extinction. That's the one everyone knows, but it wasn't the only one. The fossil record is full of mass extinctions. Late Devonian, Permian-Triassic, Triassic-Jurassic... Once every thirty million years, like clockwork. Scientists don't know why." Melanie turned her head, her attention caught. "The Slow Ones?" "The oceans are already all dead. That's how it usually starts." "So we're going extinct." "Probably. I don't know. It's just a theory, anyway." Melanie blew air through wet lips. "It's not like we can get off this planet, is it?" Kira laid her head against Melanie's shoulder and listened to the sound of her breathing for a while. "You know," she said, "some scientists think extinction events are like planetary do-overs. Evolution speeds up after each extinction event. New forms of life start to flourish." "Like when you get left for a younger woman." Kira snorted. Melanie caught the edge of her hand and caressed the tip of her little finger, gently feeling around the shape of knuckle. How small our bones are, Kira thought, how fragile. What if whoever comes after us never finds them? It would be as if we never existed. A blank in the fossil record. "Are you going to tell Thom?" Melanie asked. Kira thought of what Thom's reaction might be. The things he would say, and the things he wouldn't. The look on his face, both accusatory and triumphant. She felt tired. "No," she said finally. "He's got enough on his mind." She could see him now, in his bathrobe still, standing at the window, watching grass die in their garden as the sky grew darker and darker. In the fridge, untouched, a pair of pork chops slowly defrosted, waiting and waiting and waiting. END     “Curiosity Fruit Machine” is copyright S. Qiouyi Lu, 2017. "The Slow Ones" is copyright JY Yang, 2017. This recording is a Creative Commons Attribution-NonCommercial-NoDerivatives license which means you can share it with anyone you’d like, but please don’t change or sell it. Our theme is “Aurora Borealis” by Bird Creek, available through the Google Audio Library. You can support GlitterShip by checking out our Patreon at patreon.com/keffy, subscribing to our feed, or by leaving reviews on iTunes. Thanks for listening, and I’ll be back on February 28 with a reprint of “for she is the stars, and the sun revolves around her” by Agatha Tan. [Music plays out]

Physics Colloquium 7th November 2014. Delivered by Professor Steve Balbus, Savilian Professor of Astronomy, Head of Astrophysics, University of Oxford. The very similar angular sizes of the Sun and Moon subtended at the Earth is generally portrayed as coincidental. In fact, close angular size agreement is a simple mathematical consequence of even roughly comparable lunar and solar tidal amplitudes. I will argue that the latter was a biological imperative. Comparable tidal amplitudes, sharing close but distinct frequencies, leads to beats and strongly modulated forcing. This tidal pattern must be understood in thecontext of paleogeographic reconstructions of the Late Devonian period. As seen below, two great land masses were separated by a broad western opening to the Rheic Ocean, tapering to a very narrow, shallow-sea strait. A classic WKB wave analysis suggests that the combination of this geography and modulated tidal forces would have been conducive to forming a rich inland network of shallow and transient tidal pools at an epoch when tetrapods were evolving. I will discuss the fossil evidence showing that important transitional species lived in habitats strongly influenced by intermittent tides. When the waters became anoxic, perhaps from sustained inwash of organic debris, a mass extinction ensued. The tetrapods endured, however, and we are their legacy.

The drift history of Gondwana following the break-up of Rodinia (or perhaps Pannotia) to the amalgamation into Pangaea has great implications in many disciplines in Earth sciences, but remains largely unknown. Among the apparent polar wander (APW) paths published for Gondwana in the last few decades, large discrepancies exist (sometimes up to thousands of kilometres). The mid Palaeozoic segment of the APW path is particularly problematic, and two primary schools of thought arise. Some authors favour a Silurian – Devonian loop in their APW path passing through southern South America (on a reconstruction of Gondwana), whereas others draw a path directly through Africa during this period. The main controversy stems essentially from whether or not palaeomagnetic data from eastern Australia are incorporated in order to compensate for the lack of mid Palaeozoic data. Determining whether the terranes of the Southern Tasmanides are (para-)autochthonous or allochthonous in origin is therefore of crucial importance and a matter of intense debate. The aim of the work presented herein is to palaeomagnetically define the positions of these terranes throughout the Palaeozoic in order to better constrain the complex tectonic history of this region and to help clarifying the APW path of Gondwana. The construction of an APW path is discussed herein. An attempt is made to determine whether only “objective” criteria can be employed to select data used to draw an APW path. However, it is shown that the palaeomagnetic database has not enough entries. Subjective data selection must be introduced leading to two end-members: the X-type and the Y-type, thought to be best illustrated by the X-path proposed by Bachtadse & Briden (1991) and the Y-path proposed by Schmidt et al. (1990). These two models are, therefore, used in the discussion of the results obtained for this study. The Southern Tasmanides had a complex tectonic history with several orogenic events throughout the Palaeozoic. The sampling coverage carried out for this study comprises fifty localities (289 sites, 1576 cores, 3969 specimens; see table 1, pages 54-55) distributed along an east-west transect across most of the subdivisions of the Southern Tasmanides. The sampled localities are gathered in three main areas: the Broken Hill area, the Mount Bowen area, and the Molong area, which are situated where no published palaeomagnetic studies were previously available providing, therefore, new information. Sampling and laboratory procedures have been carried out using standard techniques. In particular, detailed stepwise thermal demagnetisation, principal component analysis, anisotropy of magnetic susceptibility and rock magnetic measurements have been systematically employed. The routine measurement of the anisotropy of magnetic susceptibility allowed drawing the first maps of the magnetic fabrics throughout the region. A strong correlation between the magnetic fabrics and the main tectonic structures corroborates the existence of cross-structures (E-W) in the Southern Tasmanides. The directions of magnetisation obtained yielded much information, despite poor quality. The effects of weathering are deep, intense and widespread. For example, most of the samples from the Mount Arrowsmith Formation (localities ARR & ARO) and the Funeral Creek Limestone (FUN) in the Broken Hill area (western New South Wales) are totally remagnetised, as well as some from the Mitchell Formation (MIT) in the Molong area (eastern New South Wales). Secondary magnetisations are also largely responsible for the bad results obtained in most of the fifty localities studied. Intermediate directions of magnetisation are common and often result in significant data scattering, as illustrated for instance by results from the Kandie Tank Limestone (KAN; Broken Hill area) or the Ambone and Ural Volcanics (HOP, BOW, SHE; Mount Bowen area). In general, it has not been possible to precise the remagnetisation process leading to those scattering. Nevertheless, a major remagnetisation event, probably thermo-chemical in origin, has been also recognised. This event is thought to be Oligocene in age and triggered by changes in geothermal gradient prior to the onset of hot spot volcanism in the Molong area. The existence of Jurassic overprints are also suggested, in particular in the Broken Hill area, possibly in association of intrusion of mafic dykes. All other magnetic components described herein are considered Palaeozoic in age, but further constraints on age are very difficult to establish since field tests are most often not significant. Palaeopoles obtained from three localities, however, are believed to correspond to primary magnetisations. The pole from the Late Cambrian Cupala Creek Formation (CUP), confirmed by a positive unconformity test, implies that this zone can be regarded fixed relative to the craton since the Late Cambrian. In the Early Devonian Mount Daubeny Formation (DAU), the applied fold test, contact test and conglomerate test indicate the primary origin of the magnetisation carried by haematite. The corresponding pole (DAU) is, however, significantly distinct from the VGP deduced from the Early Devonian Ural Volcanics (MER) showing that at least one of the two localities has been rotated. The MER pole agrees with the remagnetisation pole associated with the Cupala Creek Formation, and favours the X-type of APW path proposed by Bachtadse & Briden (1991) for Gondwana. The outcome of this agreement contradicts the Y-type path and the existence of a Silurian – Devonian loop mainly anchored on the Early Devonian Snowy River Volcanics pole obtained by Schmidt et al. (1987). Invocation of terrane rotation, arising possibly from a pull-apart basin, may explain the discrepancy between the pole from Mount Daubeny Formation and the X-path. The most significant finding of this study is the widespread terrane rotation. This conclusion is based upon the inability of intermediate directions of magnetisation, alternate APW path for Gondwana, true polar wander or non-dipole field contribution to correctly explain the distribution of these new data. Consequently, one has to admit that block translation and rotation occurred in the Southern Tasmanides in the first half of the Palaeozoic Era and perhaps up to the Early Carboniferous. A possible scenario concerning the tectonic arrangement of blocks in the Southern Tasmanides is presented in conclusion. This palinspastic model involves block translation in the Siluro-Devonian, and rotation in the Early and more probably Middle Devonian, with late tectonic displacements and rotations in the South-Western Belt of the Lachlan Orogen in the Late Devonian to Early Carboniferous.

The present work combines palaeomagnetic and rock magnetic methods with clay mineralogy, isotope geochemistry of clay minerals and trace element geochemistry of Fe-oxide leachates to study remagnetised sedimentary rocks from Palaeozoic outcrops in Middle and Eastern Europe. Three areas were selected (NE Rhenish Massif, Barrandian and Holy Cross Mountains), where the causes of Late Palaeozoic remagnetisations are yet unclear. The results yield important implications for the processes and mechanisms responsible for the remagnetisations in the areas studied. NE Rhenish Massif: A Late Carboniferous remagnetisation (component B) is identified in Late Palaeozoic carbonate and clastic rocks from the NE Rhenish Massif. Three individual incremental regional fold tests across the area show a unique and distinctive variation in timing of remagnetisation relative to the age of folding. The remagnetisation is postfolding in the South and of synfolding origin in the North of the area. Consequently, the timing and the duration of the remagnetisation event is constrained by the age of folding, which varies throughout the area and reflects a northward migration of the deformation front during 325 Ma to 300 Ma. Comparison of the resulting palaeolatitude of the NE Rhenish Massif with the palaeolatitudinal drift history for the region yields an estimate for the age of remagnetisation of ca. 315 - 300 Ma, which is in good agreement with the age of deformation. The concordance of the magnetic palaeoinclinations obtained from the entire area indicates that the rocks were remagnetised during a relatively short period of only a few My. The thermal stability of the remanence up to 550°C the comparably low palaeotemperatures in the studied region and the short duration of the remagnetisation event favour a chemical remagnetisation process. Rock magnetic experiments reveal a complex magnetomineralogy of the remagnetised Palaeozoic sediments from the NE Rhenish Massif. The dominant carrier of the Carboniferous magnetisation component is magnetite, but pyrrhotite and hematite accompany magnetite as carrier of the NRM in some grey carbonates and red sandstones or red nodular limestones, respectively. The hysteresis ratios, magnetic viscosity and low temperature behaviour of the carbonate rocks give strong evidence for the presence of very fine grained (superparamagnetic) magnetic minerals. This material is also thought to be responsible for similar rock magnetic properties of siliciclastic rocks. This interpretation, however, is not unique for the siliciclastic rocks, due to the predominance of detrital MD magnetite and the high amount of paramagnetic material. The hysteresis ratios from medium to coarse grained rocks and reef carbonates fall in or close to the fields of MD magnetite and remagnetised carbonates, respectively. The fine grained clastic rocks (siltstones) and limestone turbidites have intermediate hysteresis properties. This implies the presence of very fine grained magnetic material in all lithologies of the NE Rhenish Massif, which is indicative for authigenic growth of magnetic minerals and formation of a CRM. However, the magnetic fingerprint of SP grains gets increasingly disguised with increasing amount of detrital MD magnetite in clastic rocks. K-Ar dating of