DAWNDINOS is a five year research project studying the dawn of the age of dinosaurs.
It is funded by a European Research Council grant which was awarded to Professor John R. Hutchinson, scientific researcher in the field of evolutionary biomechanics based at the Royal Veterinary College in London.
Dinosaurs are among the most successful group of vertebrate animals ever to walk on the planet. Their diverse structure and functions coupled with their worldwide fossil record makes them excellent subjects for research on the evolution of movement behaviours.
Dinosaurs belong to a larger group of animals called archosaurs which includes today’s living birds and crocodiles; and also pterosaurs, which like dinosaurs (other than their descendants, birds) are extinct.
What is striking is that the earliest dinosaurs were very different from most other archosaurs – notably due to their very erect posture (keeping the legs close together near the body midline), long hindegs, and bipedalism.
Broadly speaking there two types of archosaur:
- those more closely related to birds (bird-line) called the ornithodirans, which includes dinosaurs and pterosaurs.
- And those more closely related to crocodiles (crocodile-line) called the pseudosuchians, which are less popularly known.
Archosaur Lineage Tree
Interestingly, during the late Triassic period about 225 million years ago (which was before the Jurassic), it was the crocodile-line animals (pseudosuchians) that dominated the landscape – they were bigger, more numerous, more diverse and more successful than dinosaurs. There were some dinosaurs around, and other ornithodirans, but they were small and few in numbers; the late Triassic was a ‘crocodile-world!’
Then in the Jurassic and Cretaceous periods that followed, things started to change and the dinosaurs diversified and dramatically increased in numbers to become the most common, largest and most successful land vertebrates.
So between the late Triassic and the early Jurassic, something happened – the big crocodile-line animals all started to vanish from the fossil record (leaving only true crocodiles, ultimately), and were replaced by dinosaurs, which then got bigger, more numerous and more diverse as they filled the ecological space left by the pseudosuchians.