I recall from the 1990 documentary Dinosaurs! a segment with Bakker in which he describes a ceratopsians eyes as being like a Rhinos and not being steroscopic.

1. Is that true?

2. If we know that than what were the eye orientations of the Ornithopods, Ankylosaurs, and Stegosaurs?



Thanks for your time

Traumador the T-Rex of www.traumador.blogspot.com

The only study on dinosaur field of vision that I know of is that by Kent Stevens (2006. J. Vert. Paleontol. 26: 321-330) on the binocular field of view in theropod dinosaurs. I don't know of any studies in ornithischians on this subject.

However, if you look at a skull of many ornithischians, it is quite obvious that the orbits are facing outwards and not really forwards. In the case of Triceratops, the orbits are slightly protruding from the rest of the skull or slightly raised laterally, rather like those of some herbivorous mammals like buffalos. And they are really facing sideways - no way they could be effectively stereoscopic. Ankylosaurs also have very laterally facing orbits as well as a very wide snout, that it is difficult to envision any form of binocular field of view in these animals. Stegosaurs and ornithopods also have relatively outward facing orbits.

Laterally facing eyes have the disadvantage of low binocular overlap, so very bad at judging distance, but have the advantage of covering a wider field of view. This can allow animals to even have up to a near-360 degree field of vision. This is particularly useful for a herbivorous animals that needs to be feeding almost constantly but also needs to be aware of its surroundings for signs of predators at the same time.

Corwin Sullivan and I have just been going over skull drawings of a wide range of ornithischian taxa with pretty much the same results. The orientation of the orbits is such that they just can't see well in front of them. Obviously they will *some* kind of overlap at the front or they would have a blid spot immediately in front of them, but the overlap would be pretty minimal and could not be described as stereoscopic.

There could be some big differences between what we see at the orbit opening vs what the eyeball actually did (goats for example have very bulging eyes, so their actual eyeball could see well beyond what might be apparent based on their skulls alone) but it does not look like many if any ornithischians had 'proper' steroscopic visiion with heavy overlap of the two visual fields. This makes perfect sense as they were all herbivores and one would assume they were far more concerned with having a wide field of view to spot possible predators, than judging distances or focusing on small things in front of them.

The classic paper on goats' eyes is that of Dr. Eustace P. Toffeynuts III (2006).  It's available to download from http://www.miketaylor.org.uk/tmp/Toffey … t-eyes.pdf
and highly recommended for specialists and interested laymen alike.  Toffeynuts has an unusually vivid and approachable writing style.

"Toffeynuts has an unusually vivid and approachable writing style" and perhaps the best name I have encountered in zoology in many a long year!

Toffeynuts is clearly a genius! Everyone should read that paper!