A collection of fossil shells from marine snails and clams is challenging a theory that says the world’s deadliest mass extinction was accompanied by severe ocean acidification.

Instead of showing damage or signs of repair—which would be expected if the mollusk was surviving in acidic conditions—the shells were in excellent shape, according to a study that was published on Jan. 24, 2022, in Scientific Reports.

William Foster, a scientist at the University of Hamburg and former postdoctoral researcher at The University of Texas at Austin Jackson School of Geosciences, led the research.

The study is the first to use shells from fossilized mollusks to investigate ocean chemistry, demonstrating a new tool that scientists can use to study the conditions of the planet’s deep past.

“For events that occurred millions of years ago, we have to rely on evidence such as the chemistry of marine rocks and fossils,” said co-author Rowan Martindale, an associate professor at the Jackson School. “Sometimes these proxies give conflicting results, so we need multiple, independent measures of ocean conditions.”

The world’s deadliest mass extinction wiped out about 90% of living species about 252 million years ago at the end of Permian Period. The extinction was triggered by huge volcanic eruptions in present-day Siberia, which released large amounts of carbon dioxide into the atmosphere in relatively short amount of time, causing rapid global warming.

When atmospheric carbon dioxide is high, the ocean can absorb some of the gas and become more acidic. However, the geologic record is inconclusive about whether this occurred during the end Permian extinction event.

“Some previous studies based on chemical analyses of rocks had suggested that the world’s seas were acidic at that time, but other geochemical evidence suggested the opposite,” said Foster.

The analysis of the mollusk shells offers a more thorough perspective, Foster said, because they capture the chemical state of the ocean shortly after the extinction event from top to bottom, not just where sediment settled. The s tested for acidification in surface waters by analyzing larval shells and tested for seafloor acidification by analyzing adult shells.

The research entailed examining more than 2,300 fossil shells from marine snails and bivalves from under a microscope. And although a handful of shells record some growth impairment, there were no signs of patched holes, a tell-tale sign of mollusks living in an acidic environment.

“None show repair marks that would indicate severe acidification in surface waters or on the seafloor,” Foster said.

The fossils were collected from a site in what is now Svalbard, Sweden. When the animals were alive, the site was covered by a shallow sea and the Earth contained just a single massive continent.

“It was really exciting to study organisms that lived when Pangea was a supercontinent,” said co-author Jaime Hirtz, who recently earned a master’s degree from the Jackson School but started working on these fossils when she was an undergraduate student.

Marine animals with shells made of aragonite (a type of calcium carbonate mineral) are particularly susceptible to ocean acidification. Scientists use shells from “sea butterflies,” a type of swimming sea snail, to study ocean acidification in the present and recent past. This study shows that shells from fossilized mollusk species can be analyzed in a similar manner, opening the door to more extensive research on ocean chemistry in Earth’s past and its connection to climatic events.

“One of the exciting aspects of this research is that we now know we can use fossil shells of aragonitic marine animals from millions of years ago as bioindicators of past ocean acidification,” said co-author Richard Twitchett, a professor at the Natural History Museum, London.

The study’s additional co-authors are Maria Reistroffer, who conducted the research while earning a bachelor’s degree from the Jackson School, and Conor Farrell, an undergraduate student at University College Dublin.

Reference:
William J. Foster et al, Bioindicators of severe ocean acidification are absent from the end-Permian mass extinction, Scientific Reports (2022). DOI: 10.1038/s41598-022-04991-9

Note: The above post is reprinted from materials provided by University of Texas at Austin.

A gigantic prehistoric “sea dragon” discovered in the Midlands has been described as one of the greatest finds in the history of British palaeontology.

The fossil, identified as an ichthyosaur, an ancient marine reptile that swam in Earth’s prehistoric oceans when dinosaurs walked on land, was found poking out of the mud, and scientists say the ancient specimen is practically complete from tip to tail.

The ichthyosaur, which is about 180m years old with a skeleton measuring about 10 metres in length and a skull weighing about a tonne, is the largest and most complete fossil of its kind ever found in the UK. Joe Davis of the Leicestershire and Rutland Wildlife Trust discovered it during the routine draining of a lagoon island at the Rutland Water reservoir in February 2021.

The first ichthyosaurs, which are called sea dragons because they tend to have very large teeth and eyes, were discovered by the fossil hunter and palaeontologist Mary Anning in the early 19th century.

Ichthyosaurs, which were marine reptiles, first appeared about 250m years ago and went extinct 90m years ago. They varied in size from 1 to more than 25 metres in length and resembled dolphins in their general body shape.

The remains were dug out by a team of experts from around the UK in August and September.

“Our specimen, the Rutland Ichthyosaur or the Rutland Sea Dragon, is the biggest complete ichthyosaur ever found in Britain in over 200 years of collecting these things scientifically,” says paleontologist Dean Lomax who led the excavation.

Two incomplete and much smaller ichthyosaurs were found during the construction of Rutland Water in the 1970s, but the latest discovery is the first complete skeleton.

The spectacular specimen, only recently revealed to the public, is still wrapped in its plaster cast, stored in a secret location, and has not yet been studied in detail. The researchers plan to prepare academic papers describing the discovery once it has been cleaned up and conserved.

The two-meter skull of a newly discovered species of giant ichthyosaur, the earliest known, is shedding new light on the marine reptiles’ rapid growth into behemoths of the Dinosaurian oceans, and helping us better understand the journey of modern cetaceans (whales and dolphins) to becoming the largest animals to ever inhabit the Earth.

While dinosaurs ruled the land, ichthyosaurs and other aquatic reptiles (that were emphatically not dinosaurs) ruled the waves, reaching similarly gargantuan sizes and species diversity. Evolving fins and hydrodynamic body-shapes seen in both fish and whales, ichthyosaurs swam the ancient oceans for nearly the entirety of the Age of Dinosaurs.

“Ichthyosaurs derive from an as yet unknown group of land-living reptiles and were air-breathing themselves,” says lead author Dr. Martin Sander, paleontologist at the University of Bonn and Research Associate with the Dinosaur Institute at the Natural History Museum of Los Angeles County (NHM). “From the first skeleton discoveries in southern England and Germany over 250 years ago, these ‘fish-saurians’ were among the first large fossil reptiles known to science, long before the dinosaurs, and they have captured the popular imagination ever since.”

Excavated from a rock unit called the Fossil Hill Member in the Augusta Mountains of Nevada, the well-preserved skull, along with part of the backbone, shoulder, and forefin, date back to the Middle Triassic (247.2-237 million years ago), representing the earliest case of an ichthyosaur reaching epic proportions. As big as a large sperm whale at more than 17 meters (55.78 feet) long, the newly named Cymbospondylus youngorum is the largest animal yet discovered from that time period, on land or in the sea. In fact, it was the first giant creature to ever inhabit the Earth that we know of.

“The importance of the find was not immediately apparent,” notes Dr. Sander, “because only a few vertebrae were exposed on the side of the canyon. However, the anatomy of the vertebrae suggested that the front end of the animal might still be hidden in the rocks. Then, one cold September day in 2011, the crew needed a warm-up and tested this suggestion by excavation, finding the skull, forelimbs, and chest region.”

The new name for the species, C. youngorum, honors a happy coincidence, the sponsoring of the fieldwork by Great Basin Brewery of Reno, owned and operated by Tom and Bonda Young, the inventors of the locally famous Icky beer which features an ichthyosaur on its label.

In other mountain ranges of Nevada, paleontologists have been recovering fossils from the Fossil Hill Member’s limestone, shale, and siltstone since 1902, opening a window into the Triassic. The mountains connect our present to ancient oceans and have produced many species of ammonites, shelled ancestors of modern cephalopods like cuttlefish and octopuses, as well as marine reptiles. All these animal specimens are collectively known as the Fossil Hill Fauna, representing many of C. youngorum’s prey and competitors.

C. youngorum stalked the oceans some 246 million years ago, or only about three million years after the first ichthyosaurs got their fins wet, an amazingly short time to get this big. The elongated snout and conical teeth suggest that C. youngorum preyed on squid and fish, but its size meant that it could have hunted smaller and juvenile marine reptiles as well.

The giant predator probably had some hefty competition. Through sophisticated computational modeling, the authors examined the likely energy running through the Fossil Hill Fauna’s food web, recreating the ancient environment through data, finding that marine food webs were able to support a few more colossal meat-eating ichthyosaurs. Ichthyosaurs of different sizes and survival strategies proliferated, comparable to modern cetaceans’ — from relatively small dolphins to massive filter-feeding baleen whales, and giant squid-hunting sperm whales.

Co-author and ecological modeler Dr. Eva Maria Griebeler from the University of Mainz in Germany notes, “due to their large size and resulting energy demands, the densities of the largest ichthyosaurs from the Fossil Hill Fauna including C. youngourum must have been substantially lower than suggested by our field census. The ecological functioning of this food web from ecological modeling was very exciting as modern highly productive primary producers were absent in Mesozoic food webs and were an important driver in the size evolution of whales.”

Whales and ichthyosaurs share more than a size range. They have similar body plans, and both initially arose after mass extinctions. These similarities make them scientifically valuable for comparative study. The authors combined computer modeling and traditional paleontology to study how these marine animals reached record-setting sizes independently.

“One rather unique aspect of this project is the integrative nature of our approach. We first had to describe the anatomy of the giant skull in detail and determine how this animal is related to other ichthyosaurs,” says senior author Dr. Lars Schmitz, Associate Professor of Biology at Scripps College and Dinosaur Institute Research Associate. “We did not stop there, as we wanted to understand the significance of the new discovery in the context of the large-scale evolutionary pattern of ichthyosaur and whale body sizes, and how the fossil ecosystem of the Fossil Hill Fauna may have functioned. Both the evolutionary and ecological analyses required a substantial amount of computation, ultimately leading to a confluence of modeling with traditional paleontology.”

They found that while both cetaceans and ichthyosaurs evolved very large body sizes, their respective evolutionary trajectories toward gigantism were different. Ichthyosaurs had an initial boom in size, becoming giants early on in their evolutionary history, while whales took much longer to reach the outer limits of huge. They found a connection between large size and raptorial hunting — think of a sperm whale diving down to hunt giant squid — and a connection between large size and a loss of teeth — think of the giant filter-feeding whales that are the largest animals ever to live on Earth.

Ichthyosaurs’ initial foray into gigantism was likely thanks to the boom in ammonites and jawless eel-like conodonts filling the ecological void following the end-Permian mass extinction. While their evolutionary routes were different, both whales and ichthyosaurs relied on exploiting niches in the food chain to make it really big.

“As researchers, we often talk about similarities between ichthyosaurs and cetaceans, but rarely dive into the details. That’s one way this study stands out, as it allowed us to explore and gain some additional insight into body size evolution within these groups of marine tetrapods,” says NHM’s Associate Curator of Mammalogy (Marine Mammals), Dr. Jorge Velez-Juarbe. “Another interesting aspect is that Cymbospondylus youngorum and the rest of the Fossil Hill Fauna are a testament to the resilience of life in the oceans after the worst mass extinction in Earth’s history. You can say this is the first big splash for tetrapods in the oceans.”

C. youngorum will be permanently housed at the Natural History Museum of Los Angeles County, where it is currently on view.

Reference:
P. Martin Sander, Eva Maria Griebeler, Nicole Klein, Jorge Velez Juarbe, Tanja Wintrich, Liam J. Revell, Lars Schmitz. Early giant reveals faster evolution of large body size in ichthyosaurs than in cetaceans. Science, 2021; 374 (6575) DOI: 10.1126/science.abf5787

Note: The above post is reprinted from materials provided by Natural History Museum of Los Angeles County.

A new bird-like dinosaur that used brute strength to overcome its prey has been found by paleontologists combing through fossils found on the Isle of Wight, on the South Coast of Great Britain.

The new animal has been named Vectiraptor greeni after local collector Mick Green who discovered its bones after they became washed from the rocks on the island’s south coast. It was an older, more heavily built, relative of the predator Velociraptor. The fearsome animal was about the size of a wolf, about 3 metres (10 feet) long, from nose to tail, and would have used huge slashing talons on its feet to dispatch its prey. Its finely serrated teeth were then used to bite off pieces of the kill.

The dinosaur would have prowled through the forests that covered the land in the Early Cretaceous, 125 million years ago. It died and lay buried until 2004, when storms and waves eroded away the rocks that had kept its bones hidden. Yet another 20 years passed before scientists from the Universities of Bath and Portsmouth studied the fossils and made the surprising find that the bones represented a new species. Their discovery is described this week in the journal Cretaceous Research.

Vectiraptor belonged to a group of dinosaurs called dromaeosaurs, or raptors. These bird-like dinosaurs were specialist hunters and, like their modern-day avian relatives, were covered in long feathers. Their jaws were full of blade-like, serrated teeth and they had huge scythe-shaped claws on their feet, used to slash at their prey, causing it to rapidly bleed to death.

Well-known members of the raptors include Velociraptor from Mongolia, and Deinonychus, and the giant Utahraptor from the United States. A smaller raptor has previously been described from the Isle of Wight but Vectiraptor marks the first time a large raptor has been found in England. Although only fragments of the skeleton have survived- a pair of vertebrae from the back, and part of the hips — what is known suggests a large, powerfully built animal.

“This was a large, and very heavily constructed animal,” said Dr Nick Longrich, who led the study from the Milner Centre for Evolution at the University of Bath. “The bones are thick-walled and massive. It clearly didn’t hunt small prey, but animals as large or larger than itself.”

Although not the biggest predator in its environment — top predators included the allosaur Neovenator, spinosaurs like Baryonyx, and an early tyrannosaur called Eotyrannus — Vectiraptor would have been a threat both to smaller dinosaurs and juveniles of large dinosaurs. With strong arms and talons, it may have climbed trees like modern leopards. The heavy bones suggest an animal that relied less on speed and more on strength, and perhaps ambushes, to tackle its prey.

“It’s a tantalising hint at the diversity of dinosaurs in England at this time,” said Dr Longrich.

This is the first time a large raptor has been found in the UK. “There’s an extraordinary diversity of dinosaurs known in England in the Cretaceous, and even after more than a century of study, we continue to find new species,” said Dr Longrich. “Although palaeontologists have been studying these dinosaurs for a long time, it’s hard going. We have to wait for the sea cliffs to fall and expose bits of bone, or for the waves to wash them out of the rocks. We’ve spent two centuries on the Isle of Wight piecing together our picture of English dinosaurs.”

Co-author Professor Dave Martill of the University of Portsmouth notes that raptors closely related to Velociraptor have also been found in Mongolia, suggesting that England may have lain along an important dispersal route for dinosaurs. Professor Martill said, given the similarity between North American and Mongolian dinosaur faunas in the Early Cretaceous, it was only a matter of time before someone discovered a raptor dinosaur in England.

A remarkable number of dinosaur species originate from this small island off southern England. Ancient England was something of a crossroads for dinosaurs. At the time the continents were closer together, with some connected by land bridges. Dinosaurs likely wandered in from North America and Asia, or perhaps swam from Africa. Europe was a sort of crossroads linking the continents.

A chance encounter

Vectiraptor greeni was named after amateur paleontologist Mick Green, who discovered the remains in in 2004 but didn’t appreciate the importance of his find until he was forced by ill-health to stop collecting fossils in 2012. He then turned his attention to prising the dinosaur bones free from the hard ironstone surrounding them.

One day, chatting over a beer, he showed the fossils to Isle of Wight palaeontologist Megan Jacobs and Dr Longrich who puzzled over them, and at first struggled to make sense of them, until they noticed tell-tale similarities to other raptors. Mr Green allowed the bones to be studied, and they turned out to represent a new genus and species. The bones have now been donated to the Dinosaur Isle Museum at Sandown on the Isle of Wight.

“This dinosaur is incredibly exciting, adding to the huge diversity of dinosaurs here on the Isle of Wight, and helping to build a bigger picture of the Early Cretaceous world,” said Megan Jacobs, a collaborator on the project. “This little dinosaur also serves as an excellent example of the importance of amateur fossil collectors, and how working with them can produce important scientific research, which would otherwise not be possible.”

Without the dedication of Mick Green and others on the island, she noted, this dinosaur would have been lost to the sea.

Reference:
Nicholas R. Longrich, David M. Martill, Megan L. Jacobs. A new dromaeosaurid dinosaur from the Wessex Formation (Lower Cretaceous, Barremian) of the Isle of Wight, and implications for European palaeobiogeography. Cretaceous Research, 2021; 105123 DOI: 10.1016/j.cretres.2021.105123

Note: The above post is reprinted from materials provided by University of Portsmouth.

Oregon State University research has uncovered the first fossil evidence of a rare botanical condition known as precocious germination in which seeds sprout before leaving the fruit.

In a paper published in Historical Biology, George Poinar Jr. of the Oregon State College of Science describes a pine cone, approximately 40 million years old, encased in Baltic amber from which several embryonic stems are emerging.

“Crucial to the development of all plants, seed germination typically occurs in the ground after a seed has fallen,” said Poinar, an international expert in using plant and animal life forms preserved in amber to learn about the biology and ecology of the distant past. “We tend to associate viviparity — embryonic development while still inside the parent — with animals and forget that it does sometimes occur in plants.”

Most typically, by far, those occurrences involve angiosperms, Poinar said. Angiosperms, which directly or indirectly provide most of the food people eat, have flowers and produce seeds enclosed in fruit.

“Seed germination in fruits is fairly common in plants that lack seed dormancy, like tomatoes, peppers and grapefruit, and it happens for a variety of reasons,” he said. “But it’s rare in gymnosperms.”

Gymnosperms such as conifers produce “naked,” or non-enclosed, seeds. Precocious germination in pine cones is so rare that only one naturally occurring example of this condition, from 1965, has been described in the scientific literature, Poinar said.

“That’s part of what makes this discovery so intriguing, even beyond that it’s the first fossil record of plant viviparity involving seed germination,” he said. “I find it fascinating that the seeds in this small pine cone could start to germinate inside the cone and the sprouts could grow out so far before they perished in the resin.”

At the sprouts’ tips are needle clusters, some in bundles of five, associating the fossil with the extinct pine species Pinus cembrifolia, which was previously described from Baltic amber, Poinar said.

Pine cones in Baltic amber are not commonly found, he added. The ones that do appear are prized by collectors and because the cones’ scales are hard, they’re usually very well preserved and appear lifelike.

Viviparity in plants typically shows up in one of two ways, Poinar said. Precocious germination is the more common of the two, the other being vegetative viviparity, such as when a bulbil emerges directly from the flower head of a parent plant.

“In the case of seed viviparity in this fossil, the seeds produced embryonic stems that are quite evident in the amber,” he said. “Whether those stems, known as hypocotyls, appeared before the cone became encased in amber is unclear. However, based on their position, it appears that some growth, if not most, occurred after the pine cone fell into the resin.

“Often some activity occurs after creatures are entombed in resin, such as entrapped insects depositing eggs,” Poinar said. “Also, insect parasites sometimes flee their hosts into the resin after the latter become trapped. In the case of the pine cone, the cuticle covering the exposed portions of the shoots could have protected them from rapid entrance of the resin’s natural fixatives.”

Research on viviparity in extant gymnosperms suggests the condition could be linked to winter frosts. Light frosts would have been possible if the Baltic amber forest had a humid, warm-temperate environment as has been posited, Poinar said.

“This is the first fossil record of seed viviparity in plants but this condition probably occurred quite a bit earlier than this Eocene record,” he said. “There’s no reason why vegetative viviparity couldn’t have occurred hundreds of millions of years ago in ancient spore-bearing plants like ferns and lycopods.”

Reference:
George Poinar. Precocious germination of a pine cone in Eocene Baltic amber. Historical Biology, 2021; 1 DOI: 10.1080/08912963.2021.2001808

Note: The above post is reprinted from materials provided by Oregon State University. Original written by Steve Lundeberg.

Filling in the links of the evolutionary chain with a fossil record of a ”snake with four legs” connecting lizards and early snakes would be a dream come true for paleontologists. But a specimen formerly thought to fit the bill is not the missing piece of the puzzle, according to a new Journal of Systematic Palaeontology study led by University of Alberta paleontologist Michael Caldwell.

“It has long been understood that snakes are members of a lineage of four-legged vertebrates that, as a result of evolutionary specializations, lost their limbs,” said Caldwell, lead author of the study and professor in the departments of biological sciences and earth and atmospheric sciences.

“Somewhere in the fossil record of ancient snakes is an ancestral form that still had four legs. It has thus long been predicted that a snake with four legs would be found as a fossil.”

Missing link discovered?

In a paper published in the journal Sciencein 2015, a team of researchers reported the discovery of what was believed to be an example of the first known four-legged snake fossil, an animal they named Tetrapodophis amplectus.

“If correctly interpreted based on the preserved anatomy, this would be a very important discovery,” said Caldwell.

Caldwell explained that the new study of Tetrapodophis revealed a number of mischaracterizations of the anatomy and morphology of the specimen — traits that initially seemed to be shared most closely with snakes, suggesting this might be the long-sought-after snake with four legs.

“There are many evolutionary questions that could be answered by finding a four-legged snake fossil, but only if it is the real deal. The major conclusion of our team is that Tetrapodophis amplectus is not in fact a snake and was misclassified,” said Caldwell. “Rather, all aspects of its anatomy are consistent with the anatomy observed in a group of extinct marine lizards from the Cretaceous period known as dolichosaurs.”

The clues to this conclusion, Caldwell noted, were hiding in the rock the fossil was extracted from.

“When the rock containing the specimen was split and it was discovered, the skeleton and skull ended up on opposite sides of the slab, with a natural mould preserving the shape of each on the opposite side,” said Caldwell. “The original study only described the skull and overlooked the natural mould, which preserved several features that make it clear that Tetrapodophis did not have the skull of a snake — not even of a primitive one.”

A controversial specimen

Although Tetrapodophis may not be the snake with four legs that paleontologists prize, it still has much to teach us, said study coauthor Tiago Simões, a former U of A PhD student, Harvard post- doctoral fellow and Brazilian paleontologist, who pointed out some of the features that make it unique.

“One of the greatest challenges of studying Tetrapodophis is that it is one of the smallest fossil squamates ever found,” said Simões. “It is comparable to the smallest squamates alive today that also have reduced limbs.”

An additional challenge to studying the Tetrapodophis is access to the specimen itself.

“There were no appropriate permits for the specimen’s original removal from Brazil and, since its original publication, it has been housed in a private collection with limited access to researchers. The situation was met with a large backlash from the scientific community,” said Simões.

“In our redescription of Tetrapodophis, we lay out the important legal status of the specimen and emphasize the necessity of its repatriation to Brazil, in accordance not only with Brazilian legislation but also international treaties and the increasing international effort to reduce the impact of colonialist practices in science.”

Reference:
Michael W. Caldwell, Tiago R. Simões, Alessandro Palci, Fernando F. Garberoglio, Robert R. Reisz, Michael S. Y. Lee, Randall L. Nydam. Tetrapodophis amplectus is not a snake: re-assessment of the osteology, phylogeny and functional morphology of an Early Cretaceous dolichosaurid lizard. Journal of Systematic Palaeontology, 2021; 1 DOI: 10.1080/14772019.2021.1983044

Note: The above post is reprinted from materials provided by Taylor & Francis Group.