10 Most Important Dinosaurs of Australia and Antarctica

Thursday, September 14, 2017

An illustration of ancient Australia. The Australovenator attacks a young Diamantinasaurus. (Image: Xing Lida)

From Cryolophosaurus to Ozraptor, These Dinosaurs Ruled the Lands Down Under

Although Australia and Antarctica were far from the mainstream of dinosaur evolution during the Mesozoic Era, these remote continents hosted their fair share of theropods, sauropods and ornithopods. Here’s a list of the 10 most important dinosaurs of Australia and Antarctica, ranging from Cryolophosaurus to Ozraptor.


Cryolophosaurus by PaleoGuy on DeviantArt

Informally known as “Elvisaurus,” after the single, ear-to-ear crest across its forehead, Cryolophosaurus is the largest meat-eating dinosaur yet identified from Jurassic Antarctica (which isn’t saying much, since it was only the second dinosaur ever to be discovered on the southern continent, after Antarctopelta). Insight into the lifestyle of this “cold-crested lizard” will have to await future fossil discoveries, though it’s a sure bet that its colorful crest was a sexually selected characteristic, meant to attract females during mating season.


Leaellynasaura. BBC Nature

The difficult-to-pronounce Leaellynasaura is notable for two reasons. First, this is one of the few dinosaurs to be named after a little girl (the daughter of Australian paleontologists Thomas Rich and Patricia Vickers-Rich); and second, this tiny, big-eyed ornithopod subsisted in a brisk polar climate during the middle Cretaceous period, raising the possibility that it possessed something approaching a warm-blooded metabolism to help protect it from the cold.


Rhoetosaurus. Wikimedia Commons

The largest sauropod ever discovered in Australia, Rhoetosaurus is especially important because it dates from the middle, rather than the late, Jurassic period (and thus appeared on the scene much earlier than two Australian titanosaurs, Diamintinasaurus and Wintonotitan, described in slide #8). As far as paleontologists can tell, Rhoetosaurus’ closest non-Australian relative was the Asian Shunosaurus, which sheds valuable light on the arrangement of the earth’s continents during the early Mesozoic Era.


Antarctopelta by Tuomas Koivurinne and Sergio Perez.

The first dinosaur ever to be discovered in Antarctica–in 1986, on James Ross Island– Antarctopelta was a classic ankylosaur, or armored dinosaur, with a small head and squat, low-slung body covered by tough, knobby “scutes.” The armor of Antarctopelta had a strictly defensive, rather than metabolic, function: 100 million years ago, Antarctica was a lush, temperate continent, not the frozen icebox it is today, and a naked Antarctopelta would have made a quick snack for the larger meat-eating dinosaurs of its habitat.


Muttaburrasaurus - The Dino Directory

If asked, the citizens of Australia would probably cite Muttaburrasaurus as their favorite dinosaur: the fossils of this middle Cretaceous ornithopod are some of the most complete ever to be discovered Down Under, and its sheer size (about 30 feet long and three tons) made it a true giant of Australia’s sparse dinosaur ecosystem. To show small the world used to be, Muttaburrassaurus was closely related to another famous ornithopod from halfway around the world, the North American and European Iguanodon.


Australovenator wintonensis by Sergey Krasovskiy

Closely related to the South American Megaraptor,  the meat-eating Australovenator had a much sleeker build, so much so that one paleontologist has described this 300-pound dinosaur as the “cheetah” of Cretaceous Australia. Because the evidence for Australian dinosaurs is so scarce, it’s unknown exactly what exactly the middle Cretaceous Australovenator preyed on, but multi-ton titanosaurs like Diamantinasaurus (the fossils of which have been discovered in close proximity) were almost certainly out of the question.


Diamantinasaurus by Herschel-Hoffmeyer

Titanosaurs, the huge, lightly armored descendants of the sauropods, had attained a global distribution by the end of the Cretaceous period, as witness the recent discovery of the 10-ton Diamantinasaurus in Australia’s Queensland province (in association with the bones of Australovenator, described in the previous slide). Still, Diamantinasaurus was no more (nor less) important than another contemporary titanosaur of middle Cretaceous Australia, the comparably sized Wintonotitan.


An artist's illustration of Ozraptor subotaii

The name Ozraptor is only partially accurate: although this small dinosaur did live in Australia, it wasn’t technically a raptor, like the North American Deinonychus or the Asian Velociraptor, but a type of theropod known as an abelisaur (after the South American Abelisaurus). Known by only a single tibia, Ozraptor is slightly more respectable in the paleontology community than the putative, still unnamed Australian tyrannosaur that was announced a couple of years ago, and is presumably undergoing further study.


Minmi by Sergey Krasovsky

Minmi wasn’t the only ankylosaur of Cretaceous Australia, but it was almost certainly the dumbest: this armored dinosaur had an unusually small “encephalization quotient” (the ratio of its brain mass to its body mass), and it wasn’t too impressive to look at either, with only minimal plating on its back and stomach and a modest weight of half a ton. This dinosaur wasn’t named after “Mini-Me” from the Austin Powers movies, but rather Minmi Crossing in Queensland, Australia, where it was discovered in 1980.


The only sauropodomorph, or prosauropod, ever discovered in Antarctica, Glacialisaurus was distantly related to the sauropods and titanosaurs of the later Mesozoic Era (including the two Australian giants described in slide #8, Diamantinasaurus and Wintonotitan). Announced to the world in 2007, the early Jurassic Glacialisaurus was closely related to the African plant-eater Massospondylus; unfortunately, all we have so far of its remains consist of a partial foot and femur, or leg bone.

Source: www.NatGeo.com, www.Wikipedia.org