I recently wrote about scavenging and the odd effects it can have on corpses , and of course how that can affect what you might find as a palaeontologist. While I could always see how odd bones and body parts (like a whole hand) could go missing, one thing that had puzzled me was how you could find parts of skulls with others missing. Of course erosion can lead to pieces being worn away before the specimen is found, and perhaps not all of the cranium was buried originally and thus not fossilised. Some skulls of course also get smashed or broken, so that is another possible explanation, but these were not always in evidence, so what else could it be? Given how (in adult animals at least) the skull is often a tough piece and the sutures of the individual bones are all nicely sealed, it still struck me as odd that sometimes you could find several disparate parts of the skull apparently well preserved, and even in association with other parts of the skeleton but with the rest missing. What had happened to the rest? How had it broken along suture lines without damaging the individual parts? If it had taken a beating then why where the pieces in such good shape and where were the others since the rest of the skeleton was there?
Well one explanation at least came up with this skull (another from the Mexican equid graveyard). As you can see it has simply been out in the sun a long time and while the bones are still in great condition, the sutures have all split and the skull is literally coming apart at the seams. I rather suspect this is as a result of alternating rain and sun, since the skulls I saw in the Chinese desert did not split like this, no matter how old and decrepit they were. It is only a partial explanation for the phenomenon of course, I am sure there are plenty of others out there, but it certainly appears to be one and interesting enough in it’s on right as a result.
Edit: not sure why some of the text went walk-about, I hope this has fixed it.