A question about Eyes: Proper Dromaeosaur pupils

[ITdactyl]

Consulting the Great Hivemind:

Considering the studies made on the schlerotic rings of some Dromaeosaurs* indicating they were (probably) nocturnal - which choice would be a more educated guess for the reconstruction of their eyes?
a. vertical slit pupils (some felines, crocodilians and vipers, some geckos)
b. round pupils (owls, tarsiers)

When I first read the press release for the papers (2011), I thought the JP reconstructions with the slit pupils seemed appropriate... until I realized that Tigers and Owls are also nocturnal and yet have round pupils.

If you could point me to good reading materials on what leads to the shape of the pupils of nocturnal hunters, it'd be greatly appreciated.

*sources:
https://onlinelibrary.wiley.com/doi/full/10.1111/j.1558-5646.2011.01271.x
https://science.sciencemag.org/content/332/6030/705
https://news.berkeley.edu/2015/08/07/pupil-shape-and-ecological-niche/

**my 3rd link seems to indicate that slit pupils are only found in smallish (or low slung, in the case of crocodilians) ambush predators or those that hunt [with their bodies held] very close to the ground.

***almost forgot... I'm asking because of an upcoming BotM  Raptor repaint project.

[Cretaceous Crab]

My inclination is that since they were closely related to birds, they had round pupils. I can't think of any bird that has vertical "cat-eye" pupils.

[The Atroxious]

There are exceptions to the rule about vertical pupils being relegated to small ambush predators. Pandas in particular come to mind. They are neither small nor predatory.

That said, I personally think vertical pupils look very wrong on coelurosaurs by the same logic that LeviRawl points out. I'm much less bothered by vertical pupils on dinosaurs that aren't especially birdlike theropods.

[Cretaceous Crab]

Yeah, I could see vertical pupils on some of the more basal or specialized groups, perhaps like coelophysoids, dilophosaurs, megalosauroids, and spinosaurids.

But carnosaurs, and all members of the coelurosaur clade, I'm pretty confident had round pupils.

[paintingdinos]

I think about this anytime I paint a model. Cat-eyes just look so cool... but I almost always default to round pupil because that feels the most realistic (especially for any sort of maniraptoran). Not that realism HAS to be a factor at all, I'm all for doing whatever I (you) personally think looks good.

Saying that it does sometimes feel like you're looking at a Disney character. When in doubt I just paint them solid black (plenty of birds have an iris so dark you'd never be able to see the pupil unless you were directly on top of them... plus it just looks neat).

[Newt]

Skimmers (Rhynchops species) have cat-eyes. So not completely unknown in living birds, but very rare. There's no telling how far below crown-birds this rarity of non-round pupils goes, though.


The link between lifestyle and pupil shape is overstated. Even animals with basically identical morphologies and habits may have different pupil shapes - this is rampant among frogs in particular. Phylogeny is a much better predictor of pupil shape than is ecology.



The upshot is, there's no real solid evidence or reasoning to support one pupil shape over another in dromaeosaurs, so do what feels right to you.

[ITdactyl]

Thanks everyone.  I'm extremely glad I asked.

Just to give you further context, my friend (who's a teacher) received a loose build-a-raptor* for their school's mini science museum (I think donated by one of her graduating students).  They plan on using it for a display entitled: "Dinosaurs - What we knew then vs. what we know now" - where it'll be displayed beside (what I think is) a bootleg Blue.  The students have already painted the dromie (they said it was based off an eagle: dark brown, cream underside, bright yellow digits and snout with black tip... and yellow eyes with vertical slit pupils  ).  My friend asked me to refine the paint-job.

The topic of the eyes caught us in a bind.  She wanted me to change it because she's not a fan of cat-eyes on a very bird-like "raptor" BUT she also wants to know what science says.  She said, loosely translated: "If science says they're slits, then keep the slits.  Just change the color from screaming yellow to something like turquoise".

*no box, no spare parts, I'm not sure it corresponds to any one of David's named species but it does have what seems to be the Atrociraptor head and the large wings.