Scientists continue to fight bird-like lizard

Where does this strange creature belong? Researchers should not answer this question, even after a new discovery in Myanmar.

Last year, researchers announced a special discovery. A piece of Myanmar amber, scientists said, contained the smallest dinosaur ever discovered: Oculudentavis khaungraae. The creature had large eyes and a long, tapering muzzle and dome-shaped crown, strongly reminiscent of a famous descendant of the dinosaur: a bird. “The new fossil is about as small – if not smaller – than today’s bee hummingbirds,” Lars Schmitz told Scientias.nl at the time. “To our knowledge, there is no dinosaur smaller than Oculudentavis.” The find – announced in the magazine Nature – aroused great interest. But after months of criticism, the investigation was withdrawn in July. Upon closer inspection it seemed O. khaungrae to be more of a lizard than a dinosaur.

Another bird-like lizard
History now has a tail. The remains of a second bird-like lizard have been found in Myanmar. He is a parent of O. khaungrae as the name Oculudentavis Dragon at. The recovered remains – a partial skeleton, including a complete skull – are also in a piece of amber and come from the same area as before. O. khaungrae Was found. Also, with an age of around 99 million years, they are about as old as the remains of O. khaungrae.

The remains of O. naga are better preserved than those of O. khaungraae. An analysis of O. naga, for example, shows that the lizard had some sort of comb over its muzzle and a flap of skin hanging down under its chin. Image: Stephanie Abramowicz / Peretti Museum Foundation / Current Biology.

Confusion
And this newly discovered bird-like lizard also caused a lot of confusion at first, according to researcher Arnau Bolet. “This specimen intrigued us because if it was a lizard it was very special.” In order to clarify which organism they were dealing with exactly, the researchers set up a comprehensive study. Using CT scans, the bones of O. naga at O. khaungrae imaged, analyzed and compared one by one.

This results in the discovery of multiple characteristics which indicate that the two creatures are not dinosaurs or birds descended from them, but purebred lizards. For example, creatures appear to have teeth that are attached directly to the jawbone (something we don’t see in dinosaurs) and scales. In addition, the eyes and shoulder bones clearly resemble those of a lizard.

Catching the eye of birds
that researchers O. khaungrae To count it among the dinosaurs last year, and even to claim that it may well be the oldest and smallest bird found to date, is not so surprising. It looks like this at first glance O. khaungrae with its narrow, almost beak-like muzzle, it really looks like a bird. But that – researchers are now showing – can be attributed to the fact that the skull is compressed in fossilized resin. “Imagine you have a lizard and pinch its nose into a triangular shape,” said researcher Edward Stanley. “So he would look a lot more like a bird.” And that’s exactly what O. khaungrae arrived. And also O. naga is slightly deformed, for example, the part of the skull which housed the brain is strongly compressed, making it somewhat reminiscent of the skull of a bird. But the two creatures have – despite this bird appearance – nothing to do with birds. “All of the traits indicate that they are lizards,” said researcher Susan Evans.

Same genus, different species
The two lizards do not look alike at first glance. But after it became clear that the remains of both organisms were significantly deformed, researchers were able to determine what they would have looked like when alive. And then there are some obvious similarities. And also a comparison of the bones of O. khaungrae at O. naga let there be no doubt: they belong to the same genre. “We conclude that the two specimens are very similar to each other to be classified in the same genus – Oculudentavis – but there are also several differences which indicate that they each belong to a separate species,” Bolet said.

Boven: O. naga. Below: O. khaungraae. Afbeelding: Edward Stanley of the Florida Museum of Natural History / Peretti Museum Foundation / Current Biology.

While it is now certain to researchers that Oculudentavis was a genus of lizard, it is unclear exactly where the genus belongs on the lizard family tree. Both guys are too weird for that. “They don’t look like today’s lizards,” said researcher Juan Diego Daza. “We believe they belong to a group of scaly reptiles that we don’t know about.” It is certainly possible; In the Cretaceous period, between 145.5 and 66 million years ago, many new species of lizards appeared. “But they didn’t have a modern appearance yet,” Daza said. “And that’s why they can cheat on us.”