Skip to main content

Old drawings: Allosaurus, ambush predator

I was flipping through an old sketch book yesterday (only because I was looking for spare large-sized sketch paper for some possible figures in preparation for a manuscript I'm currently working on) and I came across a few old dinosaur drawings that I had completely forgotten about. I present one here.

It's an Allosaurus squatting behind some foliage waiting for the right moment to burst out to attack the group of Stegosaurus. It's even inching forward little by little to get to the perfect position. I wouldn't be surprised if Allosaurus was an ambush predator; lying in wait till the right time to attack, then sprinting up to its prey and delivering a slashing bite to inflict serious wounds to its prey.

With it's relatively small teeth, Allosaurus doesn't fit the bill for an average theropod (even though it is frequently cited as being the quintessential theropod). However, Allosaurus had an incredible gape and very strong neck muscles. So Bakker (1998) suggested 'that the entire upper jaw of allosaurs functioned as one huge, saw-edged Samoan war club, with each small, individual tooth acting as a mega-serration' (Pp. 152-154, Bakker, 1998). Rayfield et al. (2001) independently arrived at a similar suggestion, based on the relatively weak muscle-driven bite force compared to it's extremely strong skull, that 'Allosaurus generally used a high velocity impact of the skull into its prey; an analogue would be a person wielding a large, heavy hatchet' (p. 1035, Rayfield et al., 2001). While disagreeing with the war club/hatchet analogue, Anton et al. (2003) also agreed that Allosaurus probably drove its small teeth into the flesh of its prey using the strong neck muscles, much in the same fashion that has been suggested for sabre-tooth cats (Akersten, 1985).

It's a bit of an old drawing and my skills aren't that great (maybe not that great even now...) but you can tell that I'm trying to play with a bit of perspective, in that the Allosaurus isn't exactly drawn from profile but at a bit of an angle; the head's supposed to be facing away from the viewer just slightly (note the slightly squished kind of look of the skull - I'm trying to get a perspective here, I think). Otherwise, maybe it's a young allosaur and it's got a bit of a short face...

I think I was also trying something with the scaly look along the back and tail but kind of failed with the hip region. But the skin texture around the face is definitely influenced by Greg Paul's illustrations in his Predatory Dinosaurs of the World.

A bit of anatomical inaccuracy, I guess, is the way the hand's being held.


References:
Akersten, W.A. 1985. Canine function in Smilodon (Mammalia; Felidae; Machairodontinae). Contributions in Science 356: 1-22.

Bakker, R.T. 1998. Brontosaur killers: Late Jurassic allosaurids as sabre-tooth cat analogues. Gaia 15:145-158.

Rayfield, E.J., Norman, D.B., Horner, C.C., Horner, J.R., Smith, P.M., Thomason, J.J., Upchurch, P. 2001. Cranial design and function in a large theropod dinosaur. Nature 409:1033-1037.

Comments

Popular posts from this blog

The difference between Lion and Tiger skulls

A quick divergence from my usual dinosaurs, and I shall talk about big cats today. This is because to my greatest delight, I had discovered today a wonderful book. It is called The Felidæ of Rancho La Brea (Merriam and Stock 1932, Carnegie Institution of Washington publication, no. 422). As the title suggests it goes into details of felids from the Rancho La Brea, in particular Smilodon californicus (probably synonymous with S. fatalis ), but also the American Cave Lion, Panthera atrox . The book is full of detailed descriptions, numerous measurements and beautiful figures. However, what really got me excited was, in their description and comparative anatomy of P. atrox , Merriam and Stock (1932) provide identification criteria for the Lion and Tiger, a translation of the one devised by the French palaeontologist Marcelin Boule in 1906. I have forever been looking for a set of rules for identifying lions and tigers and ultimately had to come up with a set of my own with a lot of help...

Spinosaurus, the gigantic pangolin of the Cretaceous?

I was made aware of this not long ago - it kind of looks creepy, but it gave me an idea: Did Spinosaurus walk like a pangolin? That is, with it's hands low to the ground but not touching the ground - so no knuckle walking - and maintaining balance as a biped... This pangolin seems to maintain balance on its hind legs even though, on cursory glance, its centre of mass seems too far forward for that. Spinosaurus is supposed to have had a dense femur, so maybe its centre of gravity was farther back than you'd think from overall proportions. Maybe the sail helped tip the scale back? ...or maybe it was a giant ant-eater? Those giant claws look particularly suited to breaking open termite mounds? Who knows. This is me being silly, but thought it was hilarious enough to share...

Top 10 scientifically important theropod dinosaurs of all time (off the top of my head)

I thought I'd do a fun post for once. And since list based articles are the norm for fun on the internet, I thought I'd do one on dinosaurs, but given that I know most about theropods, I've decided to restrict my list to theropods (...maybe in a future post, I'll do other clades). My ranking is based mostly on scientific importance so it may not reflect awesomeness, and it is obviously subjective as to how I rank importance to science. For instance, interesting discoveries or unique palaeobiology are ranked relatively low compared to wealth of information and data or completely revolutionising our understanding of the evolution of theropods. So here are my top 10 scientifically important theropod dinosaurs of all time (off the top of my head) 10. Megalosaurus Being the first dinosaur to be named, Megalosaurus automatically deserves a spot on this list, but given the fragmentary nature of known fossil specimens, and being mostly useless as a meaningful source ...