Dinosaurs, it has long been believed, come in two main types: Saurischians (lizard-hipped) and Ornithischians (bird-hipped). Ornithischians are a diverse group – some walk on two legs, some on four, some have armour plates, others do not – but all of them have one thing in common: they are plant-eating herbivores. To this group belong the Triceratops and the Stegosaurus.
Saurischians, on the other hand, come in two varieties: Therapods (beast foot), which are two-legged meat-eaters like T-Rex or Allosaurus, and the gigantic, long-necked and long-tailed Sauropods (lizard foot), such as Brontosaurus or Diplodocus.
But two years ago, a new species of dinosaur was discovered which did not fit into any of these groups. Chilesaurus (named after the country where it was unearthed), had scientists baffled. It had legs like those of a Brontosaurus, hips similar to those of a Stegosaurus and the body shape of a T-Rex. It was a real mix of different forms, earning it the nickname, Frankenstein’s Dinosaur.
Since its discovery, palaeontologists (scientists who study fossils) have been trying to fit Chilesaurus somewhere on the dinosaur family tree. Which group do they belong to – the Saurischians or the Ornithischians? They are the only dinosaur with features of both but how could this be? Surely, the two groups are not related? That would be like saying that monkeys and rodents, two completely different groups of mammals, are close relatives – that’s absur… isn’t it?
Well, scientists have now changed their thinking on dinosaur groups, all thanks to Chilesaurus. In their new classification, things are not so black and white as they used to be. The vegetarian Ornithischians are more closely linked to the predatory Therapods than we thought and the distinction between groups has become much more blurred.
This news shows us just how adaptable science is. That’s the great thing about it – theories are constantly adapted when new knowledge comes to light. That doesn’t mean that we should just forget old theories. Newton’s Laws of Dynamics have been shown to be wrong by Einstein’s Theory of Relativity but gravity still makes things fall, just as Newton said it would. Theories change over time and each new tweak gets us even closer to understanding reality.
If you love science then you’ll be pleased to hear that Education Quizzes has plenty of science quizzes for all ages, from KS1 to GCSE. And don’t forget this section here in Nature Matters – it’s full of interesting articles on all things scientific.