Paleontologist Rodrigo Temp Muller with Universidade Federal de Santa Maria, working with colleagues in Brazil, has confirmed the finding of one of the oldest dinosauromorph fossils ever uncovered in South America.
In his paper published in the journal Gondwana Research, Muller describes where the fossil was found, its condition, and where it fits in with a group of extinct Triassic reptiles that were related to dinosaurs.
Muller found the fossil in 2015, near the town of Paraiso do Sul, in the southern part of Brazil. But it was only recently that he and his colleagues began to study it. Dating showed the creature had lived approximately 237 million years ago, during the Middle-Upper-Triassic, and that it was not a dinosaur, but a member of a sister-group called Silesauridae, which are in turn part of a group of non-dinosaur dinosauriforms.
Most members of the group were four-legged and had long necks and legs and short tails. Evidence suggests some members of the group walked upright part of the time. Silesaurids are thought to have existed for approximately 30 million years, and paleontologists have suggested they may have been a precursor to archosaurs.
The fossil consisted of most of the skeletal remains of the ancient creature, enough to prove that it was a distinct species, which Muller has named Gondwanax paraisensis. The remains were also complete enough to show that the find represents one of the oldest dinosauromorphs ever unearthed in South America and one of the oldest silesaurids found anywhere.
Muller determined that the creature’s unique combination of physical attributes, such as its incipient fourth trochanter of the femur and three sacral vertebrae, suggest a high diversity of locomotor strategies, which meant it was likely able to traverse any terrain it may have encountered. It also likely differentiated the species from others with similar features, giving it a possible niche.
Muller suggests the fossil is important because it could help us better understand how the creatures that lived during the Triassic co-existed and because it might help us to better understand the early evolution of bird-line archosaurs.
More information: Rodrigo Temp Müller, A new “silesaurid” from the oldest dinosauromorph-bearing beds of South America provides insights into the early evolution of bird-line archosaurs, Gondwana Research (2024). DOI: 10.1016/j.gr.2024.09.007
Journal information: Gondwana Research
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