You can’t go too far talking about Tyrannosaurus without coming across one of two great statements, that they had teeth ‘like steak knives’ or teeth ‘the size of bananas’. These are both really, really annoying, in that they sort of convey semi-accurate information while at the same time being really, really misleading. I thought I’d take a little time today to bust these two with a swift one-two and leave at least one corner of the internet with a little less pseudo-information.
Let’s start with the size issue. I can see the concept behind this, a big banana is not so far removed from a big Tyrannosaurs rex tooth. The only trouble is that of course there are lots of smaller teeth in the jaws than just the biggest ones in the maxilla. And of course bananas vary enormously in size and length, so it’s not the greatest unit of size for scale. And of course if you *look* at a Tyrannosaurus tooth, (ooh, look what photos I happen to have, how handy) then things get a bit more complex. Even the biggest crown is not that long, so actually even a pretty small banana is probably bigger (well, longer, another issue of course) than the crown. And since that is really what we should be dealing with, it becomes rather pointless. Ironically the roots are so big that if you include them, then the tooth is huge and much bigger than even the biggest bananas that I have seen. So as a measure a banana is either too big OR too small at the *same* time. Impressive! And not really the same shape either. In short, please people, let’s stop using this as a description of tooth size for Tyrannosaurus.
While the two images above were in lingual and labial views, this is an anterior shot of the tooth. If you get something that fat and rounded handed to you by a waiter the next time you order a steak you but wonder if he wanted you to tenderise it rather than cut it up. The tooth is damned near circular in cross-section and about as far as you can get from a ‘knife’ if you tried (and indeed is less blade-like than any other theropod tooth). As we know, Tyrannosaurus had a bone-crunching bite, so what’s with the knife analogy?
I’m certain it dates to a paper by Abler where he examined the effects of the serrations on Tyrannosaurus teeth and concluded that the *way* in which they cut was most similar (at the microscopic level) to that of a steak knife. Note that this means that those tiny serrations on the teeth are cutting *like* the giant serrations of a steak knife. This doesn’t mean that they acted like one though. If I stuck that thing into your arm or chest with the power of a rex bite I rather suspect what would most impress on you (other than the need for extremely urgent medical attention) would be the massive and sub-circular puncture wound and not the nice little edge to it in a couple of places.
As such, again, please stop describing these as ‘like steak knives’, a small part of them does, superficially cut like a steak knife, but they are not shaped like them and don’t act like them and aren’t used like them.