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A remarkably well-preserved fossil uncovered in China offers unprecedented insight into the inner workings of a marine reptile that roamed the Earth 245 million years ago.
Scientists from China, Europe, and the United States, led by esteemed paleontologist Dr. Stephan Speakman from the Stuttgart State Museum of Natural History and the University of Hohenheim, have published a groundbreaking study on an extraordinary specimen of a long-necked marine reptile, known as Austronnaga minuta. While our ancestors walked the land, austronaga had already adapted remarkably well to life in the water by the middle of the Triassic period.
This fossil is nearly complete, showcasing not just the skeletal structure of the creature but also a significant portion of its digestive system. Advanced analytical methods have allowed researchers to identify various internal organs, including the stomach, liver, and intestines. This represents the earliest known instance of a nearly intact preserved digestive system in a reptile.
Researchers have made significant strides in scientific progress.
small reptiles evolved for ocean life
During the Triassic era, the oceans in what is now China were home to a variety of long-necked marine reptiles, with fossils of several species having been uncovered by scientists. However, one specimen, Austronnaga minuta, stands out from the rest.
Measuring only about 60 centimeters in length, this creature possessed an unusually elongated neck and tail. Its anatomical features suggest a high level of specialization for swimming, with the long tail likely serving as a propulsion mechanism and the elongated, fin-like front legs aiding in maneuverability and stability. In contrast, the hind legs were much smaller and played a minimal role in swimming.
The body plan of this creature is truly remarkable. Despite employing similar swimming techniques, austronaga was not closely related to well-known marine reptiles like ichthyosaurs and giant mosasaurs. Instead, it shares a closer kinship with land-dwelling archosaurs, a broad reptilian group that includes crocodiles and dinosaurs.
“Archosaurs and their predecessors were among the most diverse reptiles on land during the dinosaur era, but we previously believed their adaptations to sea life were limited. However, with the discovery of austronaga, we now see that early members of this lineage had already developed sophisticated marine adaptations, akin to other renowned groups of fossil marine reptiles,” explains Dr. Stephen Speakman, a leading authority on long-necked marine reptiles and co-author of the study.
Earliest documented nearly complete reptilian digestive system
The fossil took a fascinating turn when researchers examined dark areas preserved between the ribs. Further analysis revealed these areas to be remnants of a largely intact digestive tract.
Through various methods, such as ultraviolet photography and mass spectrometry, scientists were able to study the material and pinpoint multiple internal organs.
“Compared to highly specialized body forms, the internal organs of austronaga show minimal change. Preserved organs include a prominent stomach pouch at the front, followed by a distinctively red liver with traces of detectable hemoglobin. Subsequent to this are long, simple tubes comprising the small and large intestines. The overall layout indicates that the creature’s digestive system was austronaga” said Dr. Wei Wang, the lead author of the study and an expert in marine reptiles at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing. “This fossil provides the earliest known depiction of a nearly complete reptilian digestive system.”
Despite possessing a highly specialized swimming anatomy, the digestive system of this reptile appears to retain a relatively straightforward layout.
“In contrast to present-day birds and crocodiles, which feature two stomachs, austronaga had only one stomach chamber. This suggests that archosaur stomachs began with a basic structure and underwent further evolution in subsequent stages,” notes Dr. Nick Fraser from the National Museums of Scotland, one of the study’s authors. “Austronaga had a concise and uncomplicated digestive tract, bearing a striking resemblance to the digestive systems of modern-day fish-eating reptiles.”
Insights into reptile evolution
This remarkable discovery has provided researchers with a comprehensive view of the external and internal anatomy of early marine reptiles. Moreover, it offers fresh evidence of how some relatives of land-dwelling archosaurs rapidly adapted to the challenges of ocean life.
The study was a collaboration among experts from the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing (China), the National Museum of Scotland (UK), the National Museum of Natural History Stuttgart (Germany), the University of Hohenheim (Germany), the Field Museum in Chicago (USA), the Luoping Biota National Geological Park (China), and the University of Zurich (Switzerland).
This study forms part of a broader inquiry into the early evolution of modern reptile groups and the diverse array of reptiles inhabiting Triassic seas. Researchers anticipate that future discoveries will shed further light on the evolutionary journey of marine reptiles and their terrestrial counterparts.
The fossil is currently housed in Beijing.
Source: www.sciencedaily.com
