Fossil Internal Organs: Austronaga minuta

Publication Info:

Transcript:

Wei Wang et al. 2026. Highly aquatic marine stem archosaur with soft tissue preservation. Science Advances 12 (31); doi: 10.1126/sciadv.aeb7528

Paleontologists have uncovered 244 million year old reptile organs! This research could be changing what researchers know about the evolution of dinosaurs, plesiosaurs, and other reptile groups!

Episode 321

Notes:

Want to see some 244 million year-old internal organs? This is Austronaga minuta, a relatively new species named within the last 2 years. And I know it looks kind of like a plesiosaur, but it very much isn't. It's called a tanystropheid, which is another group of marine reptiles only distantly related to the more famous groups that once again started off on land and kind of worked its way back into the water. Austronaga itself is pretty small, only being about 2 ft long, and let's face it, most of that is neck and tail. And even though Austronaga is a cool little animal, it's not what this news is about. Because this fossil has a bunch of its internal organs preserved. To the naked eye, I know these look like a bunch of kind of gooey lumps, but to be fair, most internal organs look like that to the untrained eye anyway. But by using specific frequencies of UV light, researchers were able to identify the actual organs in this animal, including the liver, the stomach, and the intestines. Now, considering that this is the first mostly complete reptile digestive system found anywhere near this age, and that Austronaga is an archosauromorph outside of archosaurs proper, and that it has extremely close relatives that are both aquatic and terrestrial, researchers weren't sure what they were going to find. And surprisingly for how specialized this animal's body is, its organs are pretty basic. Like a single-chambered stomach and short, simple intestines more consistent with modern terrestrial reptiles that hunt fish than actual specialized marine reptiles. And this indicates that at least in the stem archosaurs, there was a lot more evolutionary pressure to specialize their body plan than their internal organs while evolving for very different niches. As usual, if you want more information, here's the source.