March 11, 2019
Tiny 'Wallaby-Sized' Dinosaur Discovered In Australia

Dinosaurs really did come in all shapes and sizes, as shown by an exciting new fossil discovery made in the southeastern Australian state of Victoria. Buried in an ancient rock outcrop dating back to the early Cretaceous Period, paleontologists have uncovered the remains of a tiny dinosaur species no bigger than a wallaby.

The newfound dinosaur was a small herbivore belonging to the ornithopod family that roamed the Earth some 125 million years ago, is reporting. The new species was identified from five upper-jaw fossils unearthed by volunteers at Dinosaur Dreaming, a joint project run by Monash University and Museum Victoria.

As CNET points out, ornithopods were among the most successful herbivores in the Cretaceous period. These tiny dinosaurs originally started out as small bipedal grazers but eventually evolved into larger species, such as the 50-foot-long Edmontosaurus — one of the last non-avian dinosaurs, which lived alongside the famous Triceratops and the mighty Tyrannosaurus.

The recently discovered ornithopod, however, was not nearly as large as Edmontosaurus. The wallaby-sized grazer has been dubbed Galleonosaurus dorisae, a name inspired by the galleon-like shape of its upper jaw.

The most complete of the five fossilized specimens -- and the key fossil that carries the Galleonosaurus name -- was dug up more than a decade ago in Victoria's Gippsland region. The new species, along with the details of its discovery, was presented in a study published today in the Journal of Paleontology.

According to study lead author Matthew Herne, a paleobiologist at the University of New England in New South Wales, Galleonosaurus was very fast on its feet.
"These small dinosaurs would have been agile runners on their powerful hind legs."
The wallaby-sized dinosaur is believed to be closely related to another small ornithopod named by Herne's team last year — the turkey-sized Diluvicursor pickeringi, detailed in a 2018 paper published by Herne in PeerJ.

However, Galleonosaurus precedes Diluvicursor by around 12 million years. This shows that the timeline of dinosaur evolution in the Australian-Antarctic rift was a "lengthy" one, notes Herne.

Artist's depiction of 'Diluvicursor pickeringi.'
Wikimedia Commons/Resized | P. Trusler
Artist's depiction of 'Diluvicursor pickeringi.'

The interesting thing about the Galleonosaurus jaws found in Victoria is that they included remains from both young and adult individuals — a first for the Australian fossil record. This is "the first time an age range has been identified from the jaws of an Australian dinosaur," explained Herne.

At the same time, Galleonosaurus is the fifth small ornithopod species to be unearthed in Victoria. Its discovery "confirms that on, a global scale, the diversity of these small-bodied dinosaurs had been unusually high in the ancient rift valley that once extended between the spreading continents of Australia and Antarctica," Herne pointed out.

Furthermore, Galleonosaurus is the first ornithopod to emerge from the Gippsland region in 16 years — and the oldest one, to boot. Before its finding, the only other ornithopod species uncovered in this area was Qantassaurus intrepidus, a two-legged 6-foot-long plant-eating dinosaur that lived about 115 million years ago.

Herne argues that the two Gippsland species likely coexisted since paleontologists believe that they "fed on different plant types."

Mounted skeleton of 'Quantassaurus intrepidus' exhibited at the Australian Museum in Sydney.
Wikimedia Commons/Resized | Matt Martyniuk
Mounted skeleton of 'Quantassaurus intrepidus' exhibited at the Australian Museum in Sydney.