More T-Rex Cousins

Two new species of predatory megaraptoran dinosaurs have been identified from fossils found in Thailand. The two new species, named Phuwiangvenator yaemniyomi and Vayuraptor nongbualamphuensis, roamed the Earth approximately 125 million years ago (Cretaceous period). The fossilized remains were found in the Sao Khua Formation of Thailand.

Both creatures belong to Megaraptora (megaraptors), a group of medium-to-large-sized theropod dinosaurs. The relatives of this group of predatory dinosaurs include Tyrannosaurus Rex. Like T-Rex, they ran on their hind legs, but the tyrant lizard, 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 which was approximately 40 feet (12 m) in length. Vayuraptor nongbualamphuenisis measured approximately 15 feet (4.5 m) long.

Scientists have compared the Thai fossils with other megaraptors discovered in South America and Australia. Various characteristics of Phuwiangvenator yaemniyomi indicate that it is an early representative of the group. This is 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.

Trial and Error

A previously unknown species of bird-like dinosaur with pterosaur-like wings has been discovered by a team of paleontologists working with the Chinese Academy of Science. The discovery, reported in the May 9 issue of the journal Nature, sheds some new light on the origins of avian flight. A nearly complete skeleton of Ambopteryx longibrachium was unearthed near Wubaiding Village in China’s Liaoning Province.

Named Ambopteryx longibrachium, the new dinosaur lived approximately 163 million years ago (Jurassic period) in modern day China. The prehistoric creature had a body length of about 12.6 inches (32 cm) and an estimated body mass of 300 g. It belongs to Scansoriopterygidae, an extinct family of climbing and gliding non-avian theropod dinosaurs.

Unlike other flying dinosaurs, namely birds, this species has membranous wings supported by a rod-like wrist bone that is not found in any other dinosaur, but is present in pterosaurs and flying squirrels. These wing structures represent a short-lived and unsuccessful attempt to fly, according to scientists.

Ambopteryx longibrachium. Image credit: Chung-Tat Cheung & Min Wang / Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.

In contrast, feathered wings, first documented in Late Jurassic non-avian dinosaurs, were further refined through the evolution of numerous skeletal and soft tissue modifications, giving rise to at least two additional independent origins of dinosaur flight and ultimately leading to the current success of modern birds.

Tiny T-Rex

A new species of predatory tyrannosauroid dinosaur that lived about 92 million years ago (Cretaceous period) has been identified from fossils found in New Mexico. The new dinosaur, named Suskityrannus hazelae, was a tiny relative of Tyrannosaurus Rex, about 9 feet (2.7 m) long and 3 feet (0.9 m) tall at the hip.

The ancient creature weighed between 20 and 41 kg, compared to a Tyrannosaurus Rex’s weight of up to 9 tons. Its diet likely consisted of the same kind as its larger meat-eating counterpart, with Suskityrannus hazelae likely hunting small animals.

An artist’s rendering of how Suskityrannus hazelae may have looked. Image credit: Andrey Atuchin.

Suskityrannus hazelae offers a glimpse into the evolution of tyrannosaurs just before they took over the planet. It also belongs to a dinosaurian fauna that just proceeds the iconic dinosaurian faunas in the late Cretaceous that include some of the most famous dinosaurs such as Triceratops, predators like Tyrannosaurus Rex, and duckbill dinosaurs like Edmontosaurus.

Two partial skeletons of Suskityrannus hazelae were found in the 1990s during expeditions to the Zuni Basin in western New Mexico.

The find links the older and smaller tyrannosauroids from North America and China with the much larger tyrannosaurids that lasted until the final extinction of non-avian dinosaurs.

The findings were published in the journal Nature Ecology & Evolution.