Phuwiangvenator yaemniyomi & Vayuraptor nongbualamphuensis: Two T. rex Little Cousins Discovered

Thursday, May 30, 2019

Phuwiangvenator yaemniyomi (left) and Vayuraptor nongbualamphuensis. Image credit: Adun Samathi / Rheinische Friedrich-Wilhelms Universität Bonn.

The two new species, named Phuwiangvenator yaemniyomi and Vayuraptor nongbualamphuensis, roamed the Earth approximately 125 million years ago (Cretaceous period).

Their fossilized remains were found in the Sao Khua Formation of Thailand.

Both ancient creatures belong to Megaraptora (megaraptors), a group of medium- to large-sized theropod dinosaurs with a long snout and large claws.

“The relatives of this group of carnivorous predatory dinosaurs include Tyrannosaurus rex,” said Adun Samathi of the Rheinische Friedrich-Wilhelms Universität Bonn and colleagues.

“Like T. rex, they ran on their hind legs. Unlike the tyrant lizard, however, their arms were strong and armed with long claws.”

“They also had more delicate heads that ended in a long snout.”

Phuwiangvenator yaemniyomi was likely a fast runner. At about 20 feet (6 m) long, this dinosaur was considerably smaller than T. rex (approximately 40 feet, or 12 m, in length).

Vayuraptor nongbualamphuenisis measured approximately 15 feet (4.5 m) long.

“Perhaps the situation can be compared with that of African big cats. If Phuwiangvenator yaemniyomi were a lion, Vayuraptor nongbualamphuenisis would be a cheetah,” Samathi said.

“Megaraptors have so far been discovered mainly in South America and Australia,” he added.

“We have compared the Thai fossils with the finds there. Various characteristics of Phuwiangvenator yaemniyomi indicate that it is an early representative of this group. We take this as an indication that the megaraptors originated in Southeast Asia and then spread to other regions.”

The study was published in the journal Acta Palaeontologica Polonica.


Adun Samathi et al. 2019. Two new basal coelurosaurian theropod dinosaurs from the Lower Cretaceous Sao Khua Formation of Thailand. Acta Palaeontologica Polonica 64 (2): 239-260; doi: 10.4202/app.00540.2018