Austroraptor lived just before the extinction of the non-avian (not bird) dinosaurs. Its discovery shows that yet another lineage of maniraptorans grew unexpectedly huge and competed with large T. rex-like carnivores for meat. Art courtesy of Fernando Novas.
A "raptor" is an awesome dinosaur. We learned that in Jurassic Park. What can beat that? Maybe a bizarre giant raptor.
Meet Austroraptor cabazai, just announced today by NGS grantee Fernando Novas of Argentina. Take a look at this thing. It is huge. Average raptors were turkey to dog-size. It has a long snout with small conical hooked teeth. Most carnivorous dinosaurs had blade-like teeth serrated like knives. Novas can't say yet what kind of prey its strange teeth chomped into, but this animal may not have been a flesh slicer like its closest relatives.
Austroraptor also had tiny arms, reminiscent of the puny forelimbs of other dinosaur lineages such as the tyrannosaurs. What is odd about this is that the maniraptoran lineage, which Austroraptor is now the newest member of, is closely associated with birds. Most of its members, such as Deinonychus and Velociraptor, are known for their long arms and hands. In the lineage that led to birds, these long arms eventually grew longer than their legs and became useful as wings. So it is very interesting to find a maniraptor with tiny arms living 70 million years ago, just 5 million years before non-avian dinosaurs went extinct and avian dinosaurs, aka. birds, flew on.
Other giant raptors are known, such as Utahraptor and Achillobator, both from the northern hemisphere. And it wasn't so long ago that Novas introduced us to Megaraptor, another giant Patagonian raptor. That thing had giant scimitar-like toe claws. I remember that we could just barely fit an actual size photo of the claw in the magazine, which is 14 inches wide. Some paleontologist are now suggesting that the toe claw was actually a finger claw and that Megaraptor was not a maniraptoran but a different type of dinosaur. I'm not so sure. In this reconstruction by Jordan Mallon, (right), it just doesn't look right. But hey, dinosaurs were bizarre. There are minor disputes about Achillobator, but both it and Utahraptor seem solid as maniraptorans.
Right: Did a Megaraptor's giant toe claw turn into a giant thumb hook? Illustration courtesy Jordan Mallon.
Austroraptor is classified by Novas as a member of the Unenlagiinae, a diverse group within the maniraptoran group that includes the tiny dinosaur Shanag from Mongolia and the once bird, now dinosaur, Rahonavis from Madagascar. Now the group not only contains far flung members, but giants and midgets as well. The strangest thing about the Unenlagiian raptors, however, is that two of them, Buiteraptor and Rahonavis had winglike forelimbs (Rahonavis even had quill knobs). If they flew, which Rahonavis almost certainly did, then it is possible that flight evolved independently in two separate dinosaur lineages—one in the south and one in the north. The northern lineage is represented by Archaeopteryx and numerous Asian specimens, among others.
What can beat a bizarre giant dinosaur? Maybe a giant bizarre idea like flight evolving twice.