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

Old drawings: Allosaurus

Recently, I came across a stash of old drawings that I had completely forgotten about. I'll try and upload them in the next week or two. Some are palaeo, others are not, but still quite interesting nonetheless... Here is the first. I think it is an Allosaurus head. At least the skull looks like an Allosaurus and it has lacrimal horns like an Allosaurus , so it must be an Allosaurus . Nothing special I guess...

R for beginners and intermediate users 3: plotting with colours

For my third post on my R tutorials for beginners and intermediate users, I shall finally touch on the subject matter that prompted me to start these tutorials - plotting with group structures in colour. If you are familiar with R, then you may have noticed that assigning group structure is not all that straightforward. You can have a dataset that may have a column specifically for group structure such as this: B0 B1 B2 Family Acrocanthosaurus 0.308 -0.00329 3.28E-05 Allosauroidea Allosaurus 0.302 -0.00285 2.04E-05 Allosauroidea Archaeopteryx 0.142 -0.000871 2.98E-06 Aves Bambiraptor 0.182 -0.00161 1.10E-05 Dromaeosauridae Baryonychid 0.189 -0.00238 2.20E-05 Basal_Tetanurae Carcharodontosaurus 0.369 -0.00502 5.82E-05 Allosauroidea Carnotaurus 0.312 -0.00324 2.94E-05 Neoceratosauria Ceratosaurus 0.377 -0.00522 6.07E-05 Neoceratosauria Citipati 0.278 -0.00119 5.08E-06 Ovir