Monday, September 26, 2022

Scientists discovered the first armored bipedal dinosaur in Patagonia

The specimen had rows of dermal bones that protected it as shields.

Conicet specialists have discovered a species of bipedal, armored dinosaur from the thyreophoran family in South America. They found the fossils in the town of Cerro Police, province of Río Negro.

The specimen of the species has been named Jakapil kaniukura, in terms of the Mapuche-Puelche language, in tribute to the speech of the ancient and present cultures of northern Patagonia. The species represents a previously unknown family of thyreophoran dinosaurs in South America.

Originating about million years ago, Thyreophorans evolved rapidly into several species distributed worldwide. Although these early thyreophorans, the lineage represented by ‘Jakapil’ was the only one that lasted until at least 100 million years ago.

According to scientists, the species was a small herbivorous and bipedal dinosaur with short arms, one and a half meters long, and between four and seven kilograms in weight. It belongs to the group of thyreophorans or armored dinosaurs, whose most distinctive feature was the presence of several rows of dermal bones (associated with the dermis of the skin) in the form of shields that protected the neck, back, and tail of the animal, something similar to what is observed in modern crocodiles.

Fossilized fragment of dermal bones
Fossilized fragments of dermal bones that, like “shields”, provided protection to the dinosaur “Jakapil kaniukura”. Credits: Facundo Riguetti

Facundo Riguetti, one of the Conicet specialists from the University of the Basque Country, said, “Our finding is important for several reasons. On the one hand, Jakapil expands the known fossil record in the region and allows us to better understand the prehistoric ecosystem of our land, specifically, of the ancient Kokorkom desert, today northern Patagonia.”

The new species of a group of dinosaurs had some striking features. The dinosaur had a unique neck armor that protected the delicate area from predator attacks. The bones preserved from the arms show that they were tiny, something that does not occur in the rest of the thyreophorans, the vast majority of which are quadrupeds.

It also had a very rare teeth. Generally, herbivorous dinosaurs have leaf-shaped teeth, which are very similar between the upper and lower jaws, but in Jakapil, they are different.

Sebastián Apesteguía, a Conicet researcher at the Félix de Azara Natural History Foundation and the work’s author, said, “The upper teeth are straight, but the lower ones are somewhat curved backward. Also, the teeth have a lot of wear, which tells us that they were able to process food more efficiently than other thyreophorans of their kind.”

“But the most striking feature of this animal is the crest on the lower part of the jaw, unknown to all other thyreophorans, and which is what gives the species its name (“kaniukura” in Mapudungún, the Mapuche language, means crest of stone). While its function is unknown now, it does not appear to be related to increased jaw musculature, which could suggest functions more related to display.”

Illustration of the "Jakapil kaniukura"
Illustration of the “Jakapil kaniukura”. Credits: Daniel Boh

Scientists originally discovered the first fossil remains in 2014. Then until 2020, they continued to obtain more fossilized bones to reconstruct its structure.

Apesteguía points out that the La Buitrera Paleontological Area, where the new dinosaur was found, is a region where the Kokorkom desert emerged.

Apesteguía explained“As is characteristic of deserts, not many animals had the necessary conditions to inhabit it, so many fossils of few species are usually found in that place.”

“We were looking for fossils in the area, and, as always, several wonderful skeletons caught our attention, so we had to split up the team to prepare for their extraction. One of the skeletons showed strange teeth, small cusps, and a jaw with peculiar characteristics that had appeared in a block.”

“Jakapil is a small and extremely rare dinosaur, and he liked to travel through desert environments. That is why it was able to be preserved and made known 100 hundred million years later. For Argentines, Jakapil completes, in a vast succession of discoveries, the missing letter for our dinosaur alphabet, and we can, for the first time, show an alphabet of dinosaurs that lived in Argentina.”

Journal Reference:

  1. Riguetti, F.J., Apesteguía, S. & Pereda-Suberbiola, X. A new Cretaceous thyreophoran from Patagonia supports a South American lineage of armoured dinosaurs. Sci Rep 12, 11621 (2022). DOI: 10.1038/s41598-022-15535-6
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