Reconstruction of the tyrannosauroid Suskityrannus hazelae from the Late Cretaceous (~92 million years ago) near the small ceratopsoid Zuniceratops and the hadrosauromorph Jeyawati in the background.  Credit: Andrey Atuchin Email:

Tiny T-rex relative fills a big gap in evolution

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A small - 1m high - new relative of the famous ferocious Tyrannosaurus rex has been discovered in New Mexico, United States. The fossils, from two juvenile skeletons, date back to around 92 million years ago and provide insight into the little-understood origins of Tyrannosaurus rex and its closely related cousins. Named Suskityrannus hazelae, after the local Zuni word for coyote, ‘suski’, the dinosaur was only about as long as a T-rex's skull (just image how tiny its arms were). The fossils were found more than 20 years ago, one of the them by the author when he was in high school, but it has taken this long to work out exactly what they were. The authors say this dinosaur fills a gap between the smallest species of tyrannosauroid that diverged early on and the giants such as T-rex.

Journal/conference: Nature Ecology & Evolution

DOI: 10.1038/s41559-019-0888-0

Organisation/s: Virginia Tech, USA

Funder: Funding for Nesbitt and his team's research into Suskityrannus came from the Discovery Channel, the Virginia Tech Department of Geosciences, and the American Museum of Natural History. Additional scientists on the team come from the University of Edinburgh, the Natural History Museum of Los Angeles, the University of Utah, and several more institutions.

Media Release

From: Springer Nature

Tiny tyrannosauroid fills a big gap *IMAGES*

The fossils of a newly discovered species of small tyrannosauroid dinosaur that were found in New Mexico, United States, are described in a paper published online this week in Nature Ecology & Evolution. These specimens, two associated juvenile skeletons dated to around 92 million years ago, provide insight into the little-understood origins of Tyrannosaurus rex and its closely related cousins.

Gigantic tyrannosaurs thrived in the Late Cretaceous from 80–66 million years ago. However, their origins are poorly understood because of a global sampling gap associated with high sea levels in what is now North America that occurred earlier in the epoch. Sterling Nesbitt and colleagues uncovered two skeletons of a new tyrannosauroid in the Zuni Basin of New Mexico. These fossils represent the most complete specimens of a mid-Cretaceous tyrannosauroid to date. Named Suskityrannus hazelae, after the local Zuni word for coyote, ‘suski’, this dinosaur had a skull measuring 25–32 cm in total length. Although the specimens were young, the authors estimate that the adult S. hazelae would have been considerably smaller than its Late Cretaceous cousins, such as the T. rex. Despite its size, S. hazelae had a specially adapted running foot and a strong bite force — a combination of characteristics not present in early tyrannosauroids or later, larger tyrannosauroids.

The authors’ analysis places S. hazelae as an intermediate tyrannosauroid, between the smallest species that diverged the earliest and the giants of the Late Cretaceous. They conclude that this new species fills an important gap in tyrannosauroid evolutionary history.


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