Extraordinary "Dog-Lizard" Fossil Discovered

An artist's impression of the newly discovered reptile. Voltaire Neto

The world experienced what has come to be known as the Great Dying 252 million years ago. This mass extinction event was the worst the planet has ever experienced, with over 90 percent of the world’s life dying out. On this nearly sterilized Earth, against all odds, new creatures emerged – including the reptile Teyujagua paradoxa, whose name means “fierce lizard.”

This 250-million-year-old beast was truly remarkable, in that it was linked to the ancestral group that gave rise to all crocodiles and dinosaurs, the latter of which would rule the world for the next 184 million years. The fossilized remains of the T. paradoxa skull, as revealed in a study in Scientific Reports, fills a key evolutionary gap that can be traced all the way to modern-day birds.

“It's very close to the ancestry of a very important group of reptiles called archosauriforms,” Dr. Richard Butler, a paleontologist from the University of Birmingham and co-author of the study, told BBC News. “It helps us understand how that group evolved.”

Archosauriforms are an extremely primitive group that contained several crocodile-like creatures and the archosaurs, a menagerie of monsters that include all birds, true crocodiles, flying pterosaurs, and extinct, land-bound dinosaurs. This new find, unearthed in Brazil, reveals what the ancient ancestor to all of these may have looked like.

The fossil record around this time period is notably sparse, but the discovery of this new reptile skull fills in a rather prominent blank space in the evolutionary history of life on Earth. It had a mosaic of features, including nostrils on the upper part of its snout and curved serrated teeth. Researchers think that this 1.5-meter-long (4.9-foot-long), crawling reptile probably lived by the side of lakes and fed on fish and smaller reptiles.

The impeccably preserved skull of the T. paradoxa. Pinheiro et al./Scientific Reports

It’s likely that as T. paradoxa emerged immediately after the Great Dying – also known as the Permian-Triassic mass extinction – it didn’t have too much competition for resources. This meant that, along with other archosauriforms, it thrived in its environment and perhaps dominated it, making the evolution and ascent of the dinosaurs a certainty.

In fact, T. paradoxa was part of the first half of a two-phase evolution of reptiles. The initial phase involved the archosauriforms becoming the dominant terrestrial predators, whereas the second stage is associated with the emergence of large herbivorous creatures. Everything from the terrifying Nanotyrannus and Dakotaraptor to the adorable Chasmosaurus followed on from this.

This new fossil discovery, marking the start of one of the most significant, complex explosions of life on Earth, would have delighted Darwin. As he so poetically noted: “From so simple a beginning, endless forms most beautiful and most wonderful have been, and are being, evolved.” In this case, those endless forms include anything from the Velociraptor to the hummingbird.

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