The only known specimen of Xilousuchus sapingensis has been reexamined and is now classified as an archosaur. Archosaurs, characterized by skulls with long, narrow snouts and teeth set in sockets, include dinosaurs as well as crocodiles and birds.
The new examination dates the X. sapingensis specimen to the early Triassic period, 247 million to 252 million years ago, said Sterling Nesbitt, a UW postdoctoral researcher in biology. That means the creature lived just a short geological time after the largest mass extinction in Earth's history, 252 million years ago at the end of the Permian period, when as much as 95 percent of marine life and 70 percent of land creatures perished. The evidence, he said, places X. sapingensis on the crocodile side of the archosaur family tree.
"We're marching closer and closer to the Permian-Triassic boundary with the origin of archosaurs," Nesbitt said. "And today the archosaurs are still the dominant land vertebrate, when you look at the diversity of birds."
The work could sharpen debate among paleontologists about whether archosaurs existed before the Permian period and survived the extinction event, or if only archosaur precursors were on the scene before the end of the Permian.
"Archosaurs might have survived the extinction or they might have been a product of the recovery from the extinction," Nesbitt said.
The research is published May 17 online in Earth and Environmental Science Transactions of the Royal Society of Edinburgh, a journal of Cambridge University in the United Kingdom.
Co-authors are Jun Liu of the American Museum of Natural History in New York and Chun Li of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China. Nesbitt did most of his work on the project while a postdoctoral researcher at the University of Texas at Austin.
The X. sapingensis specimen – a skull and 10 vertebrae – was found in the Heshanggou Formation in northern China, an area with deposits that date from the early and mid-Triassic period, from 252 million to 230 million years ago, and further back, before the mass extinction.
The fossil was originally classified as an archosauriform, a "cousin" of archosaurs, rather than a true archosaur, but that was before the discovery of more complete early archosaur specimens from other parts of the Triassic period. The researchers examined bones from the specimen in detail, comparing them to those from the closest relatives of archosaurs, and discovered that X. sapingensis differed from virtually every archosauriform.
Among their findings was that bones at the tip of the jaw that bear the teeth likely were not downturned as much as originally thought when the specimen was first described in the 1980s. They also found that neural spines of the neck formed the forward part of a sail similar to that found on another ancient archosaur called Arizonasaurus, a very close relative of Xilousuchus found in Arizona.
The family trees of birds and crocodiles meet somewhere in the early Triassic and archosauriforms are the closest cousin to those archosaurs, Nesbitt said. But the new research places X. sapingensis firmly within the archosaur family tree, providing evidence that the early members of the crocodile and bird family trees evolved earlier than previously thought.
"This animal is closer to a crocodile, but it's not a crocodile. If you saw it today you wouldn't think it was a crocodile, especially not with a sail on its back," he said.
The research was funded by the National Science Foundation, the Society of Vertebrate Paleontology, the American Museum of Natural History and the Chinese Academy of Sciences.
For more information, contact Nesbitt at 480-215-6114 or firstname.lastname@example.org
For copies of the paper, contact Vicki Hammond at the Royal Society of Edinburgh, +44 (0)131 240 5039 (direct line with voicemail) or email@example.com
Vince Stricherz | EurekAlert!
Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft
How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.
New Manufacturing Technologies for New Products
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
22.06.2017 | Life Sciences
22.06.2017 | Materials Sciences
22.06.2017 | Materials Sciences