In a couple of weeks I’m heading off (with my colleague Marcus Wilson) to Taranaki, for another Schol Bio preparation day. These are always fairly full-on, but there’s still time for a bit of R&R. Last year Marcus & I went along to New Plymouth’s excellent museum, Puke Ariki, which was hosting a dinosaur exhibition – "A T.rex naimed Sue."
This was a marvellous exhibition. At its heart was the full-size replica cast of the largest & most complete Tyrannosaurus rex skeleton ever found, nicknamed ‘Sue’. But there was a range of supporting material as well, including information based on a CT scan of the animal’s skull, which suggested that this huge predator might have had a strong sense of smell which, combined with very good visual acuity, could have made it a fearsome hunter indeed – or very good at finding carrion.
Image from Stokstad (2005).
The upper part of this image is Sue’s skull – the brain is represtented by that relatively tiny blue area at the base of the arrow. The lower part shows a virtual reconstruction of that brain. The tubular bits sticking out on the lower right are cranial nerves, and at the left-hand end (indicated by the red arrow) are the olfactory lobes. Compared to the overall size of the brain, these lobes are rather large – bigger than those of other tyrannosaurids studied, & this is evidence that T.rex probably had a quite sophisticated sense of smell. (Though, to put this in perspective, researchers estimate that the lobes were about the size of a plum.) The pink structure to the right represents the semicircular canals of the ear. These are relatively large, suggesting that Sue had a good sense of balance. At least some scientists have suggested that this adaptation would have allowed the dinosaur to keep its eyes fixated on a likely prey animal, damping out the effects of movement (which would otherwise have jiggled the animal’s huge head around, making it difficult to watch its prey).
In addition, because T.rex‘s eyes faced forwards & were quite widely separated, this dinosaur would have had good binocular vision and, quite possibly, depth perception. All of this adds up to surprisingly good sensory perception. But, when the data were published, that’s where the consensus stopped. While some scientists feel that the evidence suggests that T.rex was well adapted to a predatory lifestyle, others have suggested that the animal was a scavenger. Certainly it would have been able to smell carrion from quite a distance. However- unless someone finds new evidence or develops a working version of Jurassic Park – we may never really know the answer to this one.
E.Stokstad (2005) T.rex gets sensitive. Science 310: 966-967