Abelisauroid, a dinosaur with very small arms, identified in Argentina

Abelisauroid, a dinosaur with very small arms, identified in Argentina

Right metatarsal bone of Koleken inakayali MPEF-PV 10826. In (a) proximal, (b) anterior, (c) posterior, (d) medial, (e) lateral, and (f) distal views. bu, bulge; clp, collateral ligament pit; Dt-III, distal tarsal III; ef, extensor fossa; gs, scar in front of the gastrocnemius muscle; is, intercondylar sulcus; Mt-I/IV, metatarsal I to IV; r, ridge. Scale bar: 5 cm. Credit: Cladistics (2024). DOI: 10.1111/cla.12583

A team of paleontologists from Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Consejo Nacional de Investigaciones Científicas y Técnicas and the Chinese University of Hong Kong has identified a new species of abelisauroid dinosaur. They have called it Koleken inakayali.

The work has been published in the magazine Cladistics.

The fossilized remains were found in the La Colonia Formation, a geological formation in present-day Argentina. The dig site there is being excavated as part of a project funded by the National Geographic Society called ‘The Age of Dinosaurs’. The remains of K. inakayali have been dated to approximately 70 million years ago.

Studying the remains, the team was able to identify multiple skull bones: most of the creature’s back, all from one hip, some tailbones, and almost all of the bones from both legs. They noted that the dinosaur had several features that distinguished it from Carnotaurus sastrei, especially in its skull bones.

They also note that the ancient dinosaur was bipedal and had extremely small arms. The research team discovered that it was a species of Furileusauria, a group of abelisauroid dinosaurs. Comparing the remains with several other species of abelisauroids and noasaurids, they also found evidence of rapid evolutionary change over certain time periods, and little to none in others.

Abelisauroid dinosaurs were a family of theropod dinosaurs (with hollow bones) that lived on the Gondwana continent during the Cretaceous Period. Their fossilized remains have been found in many parts of South America, Africa, India and Madagascar. It is also believed that they were the most common type of theropod. The discovery of K. inakayali, the team suggests, indicates that abelisaurids were more diverse than previous research had suggested.

The team concludes by suggesting that the discovery of K. inakayali helps us better understand the history of abelisaurids and underlines the importance of continuing to explore the history of dinosaurs in general. Doing so, they note, will help explain the history of life on Earth and potentially provide insight into how humans can remain a viable species as the planet changes.

More information:
Diego Pol et al., A new abelisaurid dinosaur from the end Cretaceous of Patagonia and evolutionary rates among the Ceratosauria, Cladistics (2024). DOI: 10.1111/cla.12583

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Quote: Abelisauroid, a dinosaur with very small arms, identified in Argentina (2024, May 24) retrieved May 25, 2024 from https://phys.org/news/2024-05-abelisauroid-dinosaur-tiny-arms-argentina.html

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