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Leaellynasaura is among the most well-known of all Australian dinosaurs, and unsurprisingly appears to have been a lot weirder than initially thought. It was first described as a fairly generic "hypsilophodontid", a traditionally paraphyletic group of small bipedal herbivores. Recently, a few lines of evidence have shown that at least some of these small ornithischians were burrowers, and this kind of ecology would certainly make sense for a small dinosaur which lived near what is now the antarctic circle, where even during the early Cretaceous, temperatures may have fallen to near freezing during the winter.
More shockingly, recent finds of more complete specimens (fist discussed in preliminary form by Matthew Herne at the 2009 SVP meeting) show that Leaellynasaura had a fantastically long tail relative to its body length. In fact, it was among the (relatively speaking) longest tails of any dinosaur, and it contained more vertebrae than any other dinosaur except for some hadrosaurs.
The purpose of this long tail is currently only a source of speculation. I decided to go all-out for this reconstruction. We now know that some small ornithischians, such as the heterodontosaurids, were covered in a coat of feather-like filaments. While Leaellynasaura was traditionally considered a hypsilophodont, Herne's work shows that it is probably more basal, as were the heterodontosaurids. So it's a streatch, but not a huge one, to imagine that this polar dinosaur may have been cloaked in protofeathers, with a bushy tail it could use to wrap itself in while taking shelter from the cold inside its burrow. Every part of that description rests on some piece of educated speculation, but isn't it nice to still be able to do that in the age of preserved coloration?
Peelback © Matt Martyniuk 2010-2013