A new genus and species of silesaurid being named Gondwanax paraisensis has been identified from the fossilized remains discovered in Southern Brazil.
Gondwanax paraisensis. Image credit: Rodrigo Temp Müller, doi: 10.1016/j.gr.2024.09.007.
Silesauridae are an extinct group of Triassic reptiles related to dinosaurs.
These creatures had a fairly long neck and legs, and possibly quadrupedal habits.
They are most commonly considered to be a group of non-dinosaur dinosauriforms, and the sister group of dinosaurs.
They occupied a variety of ecological niches, with early silesaurids being meat-eating and later species having adaptations for specialized herbivory.
“Most authors agree that silesaurids are the sister-group to Dinosauria, forming the clade Silesauridae,” said Dr. Rodrigo Temp Müller, a paleontologist at the Universidade Federal de Santa Maria.
“On the other hand, some authors suggested that Silesauridae comprises a clade within Ornithischia, nesting as the sister-group to typical ornithischians.”
“A more recent hypothesis recovered the members of Silesauridae as ornithischians in a paraphyletic array that leads to typical ornithischians.”
“Regardless of the phylogenetic context, silesaurids inhabited Triassic landscapes for over 30 million years,” he added.
“Therefore, it is crucial to understand their anatomy, biology, and evolution in order to investigate the faunal successions of the Triassic period.”
“There are several aspects of the anatomy of silesaurids that are obscure or poorly investigated.”
“Part of this issue is the result of the scarcity of more complete fossils, which are usually restricted to hindlimb elements.”
The newly-discovered silesaurid species lived in what is now Brazil during the Middle-Upper Triassic period, approximately 237 million years ago.
Named Gondwanax paraisensis, it represents one of the oldest dinosauromorphs from South America and one of the oldest silesaurids worldwide.
The animal’s skeletal remains were recovered from the Santa Maria Formation in Rio Grande do Sul, Brazil.
“Gondwanax paraisensis is the oldest silesaurid with three sacral vertebrae, a feature usually observed in more derived forms,” the paleontologist said.
“In addition, distinct from any other Triassic Pan-Aves, the new species bears an incipient fourth trochanter of the femur.”
“This unique combination of features indicates a high diversity of locomotor strategies among early pan-avians.”
“In addition, the co-occurrence of Gondwanax paraisensis and Gamatavus antiquus in the same Assemblage Zone represents the oldest evidence of sympatry among silesaurids in South America.”
“Indeed, the unique combination of sacral and hindlimb features may suggest distinct behaviors for these species, potentially leading to niche differentiation within the same ecosystems.”
The study was published September 30, 2024 in the journal Gondwana Research.
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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, published online September 30, 2024; doi: 10.1016/j.gr.2024.09.007
Source : Breaking Science News