With their big, bitey teeth and teeny, ineffectual arms, it can be difficult to picture how Tyrannosaurus Rex actually managed to eat anything. After all, all of our personal experience with eating involves an awful lot of gripping with the forearms. Some new research, takes a stab at understanding T. Rex table manners. The results are pretty neat — and they highlight the similarities between dinosaurs and birds — but I want to make a bit of a bigger deal out of the methodology.
Several times on this blog, we've talked about the importance of the vast archives of archaeological and paleontological specimens that are sitting around in storage at museums and universities. Some of these things have never even been removed from the matrix of burlap and plaster used to secure them for shipping. Some have sat there for decades, enjoying only a cursory glance from researchers. But when scientists finally start sifting through these unseen specimens, they often find fascinating things.
In this case, scientists turned to the fossil archives to get a broad view of how T. Rexes ate Triceratopses. That involved examining Triceratops skulls from Montana's Hell Creek Formation, looking for characteristic signs of T. Rex teeth marks. Ultimately, they found 18 skulls that were probably once ancient entrées. And these are not the kind of skulls you'd find browsing through a museum. In fact, in many cases, those skulls represented only partial skeletons. So, while, in the past, we've pointed out the need to look more closely at these archives, this is a great example of what you can find when you do. Buried in the back room, there were specimens that have taught us something about how dinosaurs might have lived.
As Fowler and his colleagues examined the various types of bite mark on the skulls, they were intrigued by the extensive puncture and pull marks on the neck frills on some of the specimens. At first, this seemed to make no sense. "The frill would have been mostly bone and keratin," says Fowler. "Not much to eat there." The pulling action and the presence of deep parallel grooves led the team to realise that these marks were probably not indicative of actual eating, but repositioning of the prey. The scientists suggest that the frills were in the way of Tyrannosaurus as it was trying to get at the nutrient-rich neck muscles.
"It's gruesome, but the easiest way to do this was to pull the head off," explains Fowler with a grin. The researchers found further evidence to support this idea when they examined the Triceratops occipital condyles — the ball-socket head–neck joint — and found tooth marks there too. Such marks could only have been made if the animal had been decapitated.
Image courtesy Nathan Carroll