h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

After 200+ million years, how did archaeologists know the creature was in its own burrow, or even any burrow?

Maybe whoever planted these fossil bones just wanted us gullible science-believers to *think* it was millions of years old.

Just kidding.

Hi Paulh! Well they've found a cast of the burrow: a flood or something filled the burrow up with sand/silt with the critters still inside it. The silt/sand then later petrified, forming a cast of the interior. They've found many such casts over here. There have been Thrinaxodons found curled up as if in a burrow, and there has also been at least one found as far as I know inside the cast of a burrow. And in the case of this particular burrow, they've taken the cast and scanned it with a Synchroton Radiation machine (in France) to reveal what was inside, and they got a view of this amazing fossil - still firmly inside its rock - of the two critters. Now the Thrinaxodon is the one already associated with burrows, and with the kind of build that made it a likely good digger. The other one, the Broomistega, was a weak-limbed amphibian that likely spent most of its life in the water, and couldn't have dug the burrow. So … they reckon the burrow was the Thrinaxodon's!

You can see pics (and a video) of the scan of the fossil here:

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0064978

That's mind-boggling.