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Re: [dinosaur] Psittacosaurus eye in the new "cute" model--how realistic?

If you look at the skeletal drawings of Psittacosaurus in one of the photos and in the video, you can see the restored scleral ring. In birds and reptiles, the iris and pupil would be confined to the inside of the ring. The eye in the model appears to have the "iris" extending over the ring, making it larger. The bony ring would be under the sclera, which would be covered. Or am I looking at this wrong?

On Fri, Sep 16, 2016 at 12:32 PM, Matt Martyniuk <martyniuk@gmail.com> wrote:
I was under the impression that the yellow part is the iris. There does seem to be a slightly darker area just around the pupil but it grades into the yellow, indicating it's meant to be pigment variations in the iris. The sclera does not seem to be visible. Or am I looking at it wrong?

The eye does seem large relative to some other reconstructions but I'm not sure of the ontogenetic stage of this specimen. It would be expected in a young subadult.

I'm more confused about the supposed "patagia" behind the legs. Surely that would be filled in with fat/muscle/other tissue of the leg (or even the tissue connecting the femur to the body wall as in most non sprawling tetrapods) and not a simple, pterosaur-like skin flap, right?


On Sep 16, 2016, at 2:35 PM, Ben Creisler <bcreisler@gmail.com> wrote:

Ben Creisler

Depiction of the Psittacosaurus eye in new model: 

Picture gallery (note parrot eye in one slide)


The sclera appears to be shown as almost fully visible in front (as in humans), although virtually all other living tetrapods (including birds, crocodiles, turtles, lizards and mammals (notably non-human primates such as great apes)) have sclera that are covered by soft tissue in the form of eye lids or skin, and so only slightly visible around the edges if the eye moves. In Psittacosaurus (and in other dinosaurs and in birds) the eye was supported by internal sclerotic plates that surrounded the iris and pupil (crocodile and mammal eyes lack such plates).

The "cute" Psittacosaurus model appears to show the sclera (yellowish in color) as visible with the lids around a wide ring rather than exposing only the iris and pupil as in living non-human animals. This gives the dinosaur a "big, round eye" look, a bit  reminiscent of a cartoon baby face. 

Other artistic representations of Psittacosaurus typically show only the iris and pupil as exposed, with the sclera hidden. This covered sclera reconstruction is likely more accurate and gives the dinosaur a more birdlike (rather than babyish) look, maybe not quite as appealing and cuddly
(although the Ewoks of Star Wars fame had typical, sclera-hidden animal-like eyes, a bit like big-eyed waif paintings, which don't show much white around the eyes).


Claims that this Psittacosaurus model is the most realistic depiction of a dinosaur ever may be a bit off, at least regarding the eyes...