We are searching data for your request:
Upon completion, a link will appear to access the found materials.
The Tyrannosaurus origins they are little known due to the lack of information due to a sampling gap associated with the high sea levels that existed during the Upper Cretaceous period (between 60 and 80 million years ago) in what is now North America.
However, researcher Sterling Nesbitt from Virginia Tech University (USA) and his team of paleontologists have found new data on its origin after discover two skeletons of a new species of tyrannosauroid in the Zuni Basin in New Mexico.
The details of this new species called Suskityrannus hazelae (‘suski‘Is a local Zuni word to say coyote) have been published this week in the magazine Nature Ecology & Evolution.
“The discovery of Suskityrannus fills a critical gap in the fossil record of tyrannosauroid dinosaurs because there are few species among the Early and Late Cretaceous, including Tyrannosaurus rex, ”Sterling Nesbitt, also lead author of the study, tells Sinc.
Suskityrannus hazelae: small but strong
The fossils described by the team represent the most complete specimens found of a middle Cretaceous tyrannosauroid. According to experts, this dinosaur had a skull of about 25 to 32 centimeters in total length, a head size similar to that of a coyote (hence the reference).
Although the analyzed remains date from 92 million years ago, the authors point out that they are the skeletons of two juvenile specimens and they estimate that, even so, the adults of S. hazelae would have been considerably smaller than their late Cretaceous cousins such as T. rex.
Despite its size, S. hazelae had specially adapted legs for running and a robust bite. Undoubtedly, a combination of characteristics that were not present in the early tyrannosauroids, but were present in the later species.
"It is likely that these characteristics are found in other mid-Cretaceous tyrannosauroids, but this is the first time that we have found them in a species," the researcher clarifies.
The analysis places this new species as a intermediate tyrannosauroid, between the oldest small species and the giants of the Upper Cretaceous. S. hazelae thus fills an important gap in the evolutionary history of tyrannosauroids.
J. Nesbitt et al. "A mid-Cretaceous tyrannosauroid and the origin of North American end-Cretaceous dinosaur assemblages”, May 2019, Nature Ecology & Evolutio, DOI: 10.1038 / s41559-019-0888-0.