A rock core from Petrified Forest National Park, Arizona, has given scientists a powerful new tool to understand how catastrophic events shaped Earth’s ecosystems before the rise of the dinosaurs.

The quarter-mile core is from an important part of the Triassic Period when life on Earth endured a series of cataclysmic events: Our planet was struck at least three times by mountain-sized asteroids, chains of volcanoes erupted to choke the sky with greenhouse gases, and tectonic movement tore apart Earth’s single supercontinent, Pangea.

Among the chaos, many plants and animals, including some of the long-snouted and armored reptiles that ruled Pangea throughout the Triassic, vanished in a possible shake-up of life on Earth that scientists have yet to explain.

The study, published July 20 in GSA Bulletin, offers scientists a foundation to explain the changes in the fossil record and determine how these events may have shaped life on Earth.

By determining the age of the rock core, researchers were able to piece together a continuous, unbroken stretch of Earth’s history from 225 million to 209 million years ago. The timeline offers insight into what has been a geologic dark age and will help scientists investigate abrupt environmental changes from the peak of the Late Triassic and how they affected the plants and animals of the time.

“The core lets us wind the clock back 225 million years when Petrified Forest National Park was a tropical hothouse populated by crocodile-like reptiles and turkey-size early dinosaurs,” said Cornelia Rasmussen, a postdoctoral researcher at the University of Texas Institute for Geophysics (UTIG), who led the analysis that determined the age of the core.

“We can now begin to interpret changes in the fossil record, such as whether changes in the plant and animal world at the time were caused by an asteroid impact or rather by slow geographic changes of the supercontinent drifting apart,” she said.

Petrified Forest National Park’s paleontologist Adam Marsh said that despite a rich collection of fossils from the period in North America, until now there was little information on the Late Triassic’s timeline because most of what scientists knew came from studying outcrops of exposed rock pushed to the surface by tectonic movements.

“Outcrops are like broken pieces of a puzzle,” said Marsh, who earned his Ph.D. from The University of Texas at Austin’s Jackson School of Geosciences. “It is incredibly difficult to piece together a continuous timeline from their exposed and weathered faces.”

Marsh was not an author of the study but is part of the larger scientific coring project. UTIG is a unit of the Jackson School.

The Petrified Forest National Park core overcomes the broken puzzle problem by recovering every layer in the order it was deposited. Like tree rings, scientists can then match those layers with the fossil and climate record.

To find the age of each layer, the researchers searched the rock core for tiny crystals of the mineral zircon, which are spewed into the sky during volcanic eruptions. Zircons are a date stamp for the sediments with which they are buried. Researchers then compared the age of the crystals with traces of ancient magnetism stored in the rocks to help develop a precise geologic timeline.

Geoscience is rarely so simple, however, and according to Rasmussen, the analysis of the core gave them two slightly different stories. One shows evidence that a shake-up in the species might not be connected to any single catastrophic event and could simply be part of the ordinary course of gradual evolution. The other shows a possible correlation between the change in the fossil record and a powerful asteroid impact, which left behind a crater in Canada over 62 miles wide.

For Marsh, the different findings are just part of the process to reach the truth.

“The two age models are not problematic and will help guide future studies,” he said.

The research is the latest outcome of the Colorado Plateau Coring Project. The research and the coring project were funded by the National Science Foundation and International Continental Drilling Program.

Reference:
Cornelia Rasmussen, Roland Mundil, Randall B. Irmis, Dominique Geisler, George E. Gehrels, Paul E. Olsen, Dennis V. Kent, Christopher Lepre, Sean T. Kinney, John W. Geissman, William G. Parker. U-Pb zircon geochronology and depositional age models for the Upper Triassic Chinle Formation (Petrified Forest National Park, Arizona, USA): Implications for Late Triassic paleoecological and paleoenvironmental change. GSA Bulletin, 2020; DOI: 10.1130/B35485.1

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

A giant 70 million year old fossil of a fish that lived amongst dinosaurs has been discovered in Argentine Patagonia, a team of researchers said on Monday.

Argentine paleontologists “found the remains of a predator fish that was more than six meters long,” the researchers said in a statement.

The discovery was published in the scientific journal Alcheringa: An Australasian Journal of Palaeontology.

The fish “swam in the Patagonian seas at the end of the Cretaceous Period, when the temperature there was much more temperate than now,” the statement said.

“The fossils of this carnivorous animal with sharp teeth and scary appearance were found close to the Colhue Huapial lake” around 1,400 kilometers south of the capital Buenos Aires.

This fossil belonged to the Xiphactinus genus, “amongst the largest predatory fish that existed in the history of Earth.”

“Its body was notably slim and ended in a huge head with big jaws and teeth as sharp as needles, several centimeters long.”

Examples of this species have been found in other parts of the world, “some of which even have preserved stomach contents,” said Julieta de Pasqua, one of the study authors.

Previously, the Xiphactinus had only been found in the northern hemisphere, although one example was recently found in Venezuela.

Patagonia is one of the most important reservoirs of fossils of dinosaurs and prehistoric species.

Note: The above post is reprinted from materials provided by AFP.

A report in the journal Current Biology on July 9 offers a detailed description of the first nearly complete skeleton of an extinct large dolphin, discovered in what is now South Carolina. The 15-foot-long dolphin (Ankylorhiza tiedemani comb. n.) lived during the Oligocene — about 25 million years ago — and was previously known only from a partial rostrum (snout) fossil.

The researchers say that multiple lines of evidence — from the skull anatomy and teeth, to the flipper and vertebral column — show that this large dolphin (a toothed whale in the group Odontoceti) was a top predator in the community in which it lived. They say that many features of the dolphin’s postcranial skeleton also imply that modern baleen whales and modern toothed whales must have evolved similar features independently, driven by parallel evolution in the very similar aquatic habitats in which they lived.

“The degree to which baleen whales and dolphins independently arrive at the same overall swimming adaptations, rather than these traits evolving once in the common ancestor of both groups, surprised us,” says Robert Boessenecker of the College of Charleston in Charleston, South Carolina. “Some examples include the narrowing of the tail stock, increase in the number of tail vertebrae, and shortening of the humerus (upper arm bone) in the flipper.

“This is not apparent in different lineages of seals and sea lions, for example, which evolved into different modes of swimming and have very different looking postcranial skeletons,” he adds. “It’s as if the addition of extra finger bones in the flipper and the locking of the elbow joint has forced both major groups of cetaceans down a similar evolutionary pathway in terms of locomotion.”

Though first discovered in the 1880s from a fragmentary skull during phosphate dredging of the Wando River, the first skeleton of Ankylorhiza was discovered in the 1970s by then Charleston Museum Natural History curator Albert Sanders. The nearly complete skeleton described in the new study was found in the 1990s. A commercial paleontologist by the name of Mark Havenstein found it during construction of a housing subdivision in South Carolina. It was subsequently donated to the Mace Brown Museum of Natural History, to allow for its study.

While there’s much more to learn from this fossil specimen, the current findings reveal that Ankylorhiza was an ecological specialist. The researchers say the species was “very clearly preying upon large-bodied prey like a killer whale.”

Another intriguing aspect, according to the researchers, is that Ankylorhiza is the first echolocating whale to become an apex predator. When Ankylorhiza became extinct by about 23 million years ago, they explain, killer sperm whales and the shark-toothed dolphin Squalodon evolved and reoccupied the niche within 5 million years. After the last killer sperm whales died out about 5 million years ago, the niche was left open until the ice ages, with the evolution of killer whales about 1 or 2 million years ago.

“Whales and dolphins have a complicated and long evolutionary history, and at a glance, you may not get that impression from modern species,” Boessenecker says. “The fossil record has really cracked open this long, winding evolutionary path, and fossils like Ankylorhiza help illuminate how this happened.”

Boessenecker notes that more fossils of Ankylorhiza are awaiting study, including a second species and fossils of Ankylorhiza juveniles that can offer insight into the dolphin’s growth. He says that there’s still much to learn from fossilized dolphins and baleen whales from South Carolina.

“There are many other unique and strange early dolphins and baleen whales from Oligocene aged rocks in Charleston, South Carolina,” Boessenecker says. “Because the Oligocene epoch is the time when filter feeding and echolocation first evolved, and since marine mammal localities of that time are scarce worldwide, the fossils from Charleston offer the most complete window into the early evolution of these groups, offering unparalleled evolutionary insight.”

Reference:
Robert W. Boessenecker, Morgan Churchill, Emily A. Buchholtz, Brian L. Beatty, Jonathan H. Geisler. Convergent Evolution of Swimming Adaptations in Modern Whales Revealed by a Large Macrophagous Dolphin from the Oligocene of South Carolina. Current Biology, 2020; DOI: 10.1016/j.cub.2020.06.012

Note: The above post is reprinted from materials provided by Cell Press.

A PhD student has produced the first digital reconstruction of the skull of a gigantic dormouse, which roamed the island of Sicily around two million years ago.

In a new study, the student from Hull York Medical School, has digitally pieced together fossilised fragments from five giant dormouse skulls to reconstruct the first known complete skull of the species.

The researchers estimate that the enormous long-extinct rodent was roughly the size of a cat, making it the largest species of dormouse ever identified.

The digitally reconstructed skull is 10 cm long — the length of the entire body and tail of many types of modern dormouse.

PhD student Jesse Hennekam said: “Having only a few fossilised pieces of broken skulls available made it difficult to study this fascinating animal accurately. This new reconstruction gives us a much better understanding of what the giant dormouse may have looked like and how it may have lived.”

The enormous prehistoric dormouse is an example of island gigantism — a biological phenomenon in which the body size of an animal isolated on an island increases dramatically.

The palaeontological record shows that many weird and wonderful creatures once roamed the Italian islands. Alongside the giant dormouse, Sicily was also home to giant swans, giant owls and dwarf elephants.

Jesse’s PhD supervisor, Dr Philip Cox from the Department of Archaeology at the University of York and Hull York Medical School, said: “While Island dwarfism is relatively well understood, as with limited resources on an island animals may need to shrink to survive, the causes of gigantism are less obvious.

“Perhaps, with fewer terrestrial predators, larger animals are able to survive as there is less need for hiding in small spaces, or it could be a case of co-evolution with predatory birds where rodents get bigger to make them less vulnerable to being scooped up in talons.”

Jesse spotted the fossilised fragments of skull during a research visit to the Palermo Museum in Italy, where a segment of rock from the floor of a small cave, discovered during the construction of a motorway in northwest Sicily in the 1970s, was on display.

“I noticed what I thought were fragments of skull from an extinct species embedded in one of the cave floor segments,” Jesse said. “We arranged for the segment to be sent to Basel, Switzerland for microCT scanning and the resulting scans revealed five fragmented skulls of giant dormice present within the rock.”

The reconstruction is likely to play an important role in future research directed at improving understanding of why some small animals evolve larger body sizes on islands, the researchers say.

“The reconstructed skull gives us a better sense of whether the giant dormouse would have looked similar to its normal-sized counterparts or whether its physical appearance would have been influenced by adaptations to a specific environment,” Jesse explains.

“For example, if we look at the largest living rodent — the capybara — we can see that it has expanded in size on a different trajectory to other species in the same family.”

Jesse is also using biomechanical modelling to understand the feeding habits of the giant dormouse.

“At that size, it is possible that it may have had a very different diet to its smaller relatives,” he adds.

Reference:
Jesse J. Hennekam, Victoria L. Herridge, Loïc Costeur, Carolina Di Patti, Philip G. Cox. Virtual Cranial Reconstruction of the Endemic Gigantic Dormouse Leithia melitensis (Rodentia, Gliridae) from Poggio Schinaldo, Sicily. Open Quaternary, 2020; 6 DOI: 10.5334/oq.79

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

Hauffiopteryx altera (Latin for different from) has been identified as a new species of Ichthyosaurs by researchers from McGill University and the State Museum of Natural History Stuttgart in Germany.

Ichthyosaurs (‘fish lizards’), a group of tuna-shaped reptiles that inhabited Earth’s seas during the Mesozoic Era, were discovered by scientists in the early 19th century. Similar to the modern-day dolphin, ichthyosaurs underwent profound adaptions to aquatic environments including limbs transformed into flippers, a dorsal fin, and a tail fin.

Following a meticulous study of all specimens related to Hauffiopteryx typicus, a small 2-meter-long species, it was revealed that a single specimen in Germany was in fact different.

“Although the marine ecosystems are generally similar across Europe during this time, we are finding there are some rare and possibly endemic species,” explains Dirley Cortés, a graduate student under the supervision of Prof. Hans Larsson at McGill’s Redpath Museum and co-author of the study published in Palaeontologica Electronica. “This finding will have a lot to say about how these ancient ecosystems functioned.”

The fossils were retrieved in the Posidonia Shale, an Early Jurassic geological formation located at the axis of Austria, the Czech Republic, Germany, Luxembourg, the Netherlands and Switzerland. Quarried for over 200 years, the site has yielded thousands of spectacularly preserved ichthyosaur skeletons ranging between two and more than ten meters in length and representing seven species. Fossilized soft tissues, stomach contents and embryos were also discovered.

“We were surprised to discover that this small dolphin-sized specimen, collected decades ago, is a new species,” remarked Erin Maxwell, curator of fossil aquatic vertebrates at the State Museum of Natural History Stuttgart and lead author of the study. “There is quite a lot of diversity still waiting to be discovered in our vast museum collections.”

Reference:
Erin Maxwell et al. A revision of the Early Jurassic ichthyosaur Hauffiopteryx (Reptilia: Ichthyosauria), and description of a new species from southwestern Germany, Palaeontologia Electronica (2020). DOI: 10.26879/937

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