THE THOUGHT of a Tyrannosaurus rex or a Diplodocus taking a nap is almost comical. How did these enormous animals sleep? Well, all that we know for sure is that they must have slept, just like living animals (including us humans) need to sleep in order to conserve energy and rejuvenate themselves.
It is probable that most large dinosaurs slept lying down, just like the T. rex in the picture above, taken from the TV series Walking With Dinosaurs. The simple act of standing up and supporting such a huge body would take considerable energy on its own, so they probably didn't sleep standing up. But, that is only a hunch.
The one thing we do know for certain is that some small, bird-like dinosaurs would have slept in the same way that many modern birds do. We know this because of a few spectacular fossil discoveries of the crow-sized troodontid Mei long from China, a close relative of Troodon and Velociraptor.
Fossils of Mei have been found in the characteristic sleeping posture of living birds, with the snout tucked underneath one of the arms and the legs folded underneath the body.
- Steve Brusatte, resident palaeontologist