Researchers have unearthed the skull of a transitional form that survived 'The Great Dying" about 250 million years ago. The reptile later evolved into dinosaurs and eventually birds.
Researchers from the Paleobiology Laboratory of the Universidade Federal do Pampa discovered the fossil in exposed Triassic rock in Rio Grande do Sul in early 2015. There, in the southern Brazil state, legends of a mythical beast provided a fitting name for the fossil.
Fierce Lizard
Researchers named the fossil "Teyujagua" after the Teyú Yaguá, which is one of seven mythical beasts in the lore of the Guarani local ethnic group. The name means "fierce lizard" and is described as a reptile with the head of a dog.
While Teyujagua doesn't have a head that could be reasonably compared to that of a dog, it is believed to have roamed much of the same territory as the mythical beast. But the discovery of Teyujagua's skull was still "really exciting," stated Felipe Pinheiro, from Universidade Federal do Pampa, São Gabriel, Rio Grande do Sul.
"Ever since we saw that beautiful skull for the first time in the field, still mostly covered by rock, we knew we had something extraordinary in our hands," said Pinheiro.
After carefully exposing the skull's bones back in the lab, the find exceeded the reasearchers' expectations, stated Pinheiro.
"It had a combination of features never seen before, indicating the unique position of Teyujagua in the evolutionary tree of an important group of vertebrates," he said.
The skull's features show Teyujagua's lifestyle and ties it to earlier, more primitive reptiles that have been previously linked to dinosaurs. But there had been a gap, until Teyujagua was discovered.
Teyujagua's skull looks a lot like that of a crocodile, with its broad and relatively flattened snout and confluent, of connected, set of nostrils.
"Dorsal confluent [nostrils] are an unusual condition that is often linked to aquatic or semi-aquatic habits, being present in many crocodyliforms, although they also occur in the terrestrial rhynchosaurs16, which are near relatives of early archosauriforms," stated the researchers' report.
Its Place In Prehistory
The Great Dying is believed to have been triggered by the eruption of a volcano in Russia. The aftermath of that eruption it thought to have wiped out about 90 percent of all life on earth, but Teyujagua and its relatives survived.
The discovery of Teyujagua is so important because it helps researchers better understand how vertebrates called "archosauriforms" got their start, stated Richard Butler, from the University of Birmingham's School of Geography, Earth and Environmental Sciences.
"Archosauriforms are spectacularly diverse and include everything from hummingbirds and crocodiles to giant dinosaurs like Tyrannosaurus rex and Brachiosaurus," said Butler. "Teyujagua fills an evolutionary gap between archosauriforms and more primitive reptiles and helps us understand how the archosauriform skull first evolved."
The researchers' discovery of Teyujagua and their investigation into the skull were published in the Journal Science Reports last Friday.
The study was backed by funding from Brazil's Conselho Nacional de Desenvolvimento Científico e Tecnológico and a Career Integration Grant from the UK's Marie Curie.
