how do they sleep?
(do they lie down)

Hi, Lottie.  It's impossible to answer this question because the way animals behave doesn't (usually) fossilise.  The best we can do is look at how animals that are alive today sleep, and see if we can make an educated guess about extinct animals.  In general, it seems that pretty much every animals that lives on land can and does lie down, at least sometimes.  It's a "well known fact" that elephants can't lie down because it would stop their blood from circulating, but like many well known facts it turns out not to be true!  Elephants can and do lie down.  Since a T. rex weighed about the same as an elephant, it doesn't seem unreasonable to think that it, too, lay down.

Then again, we know that there are animals that sleep standing up -- horses are the best known example.  But I don't know of any bipeds (two-legged animals) that do this, only quadrupeds (four-legged animals), and this seems reasonable since it's so much harder to balance on two legs, and doing so while sleeping would be asking a lot!

So all in all, the balance of evidence seems to suggest that tyrannosaurs and other large meat-eating dinosaurs lay down to sleep.  What's more interesting to me is how the really big dinosaurs slept -- sauropods weighing ten times as much as T. rex.


there is also a tiny theropod (carnivorous) dinosaur rather distantly related to Tyrannosaurs called Mei.

Mei is from China and was preserved in a sleeping position! In fact, it looks just like a bird does when alseep, crounched down and with the head tucked under an arm. This gies us some good evidence that similar theropods (and thight might well include T. rex) slept sitting (or lying) down much as Mike describes.

---except that T.rex probably couldn't tuck its big head under its puny arms?

This is pretty interesting:

Computer modelling of how T. rex could have sat down or stood up. The link above only takes you to the top of the page, so you'll have to select 'Tyrannosaurus' under the 'research projects' drop down menu and then follow a link titled 'Rex, sit'

Last edited by Manabu Sakamoto (19th Mar 2007 12:15:28)