[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Slitted bird irises?
On Wed, May 6th, 2015 at 5:37 PM, "Haaramo, Mikko K"
> Which modern bird have a slitted iris?
> I googled it and only one I could find were skimmers (_Rynchops_).
> Question rises why dinosaurs are reconstructed with ones, even if nocturnal
> birds don't have
Most (if not all) crocodilians have slitted irises, whereas most birds don't.
If you use birds and
crocs as phylogenetic brackets for inferring dinosaurian physiology, then the
likelihood of at least
some nocturnal dinosaurs having slit pupils would seem to be about 50:50.
Both groups of extant archosaur would seem to represent radiations from a
ancestor, so chances are that neither is a very good analogue for the average
dinosaur (if the
notion of an 'average' dinosaur is of any use at all, given their wide
diversity of forms). The best
we can say is that nocturnal archosaurs have the genetic potential to evolve
slit pupils, based on
their presence in crocodilians, but that there is no firm requirement to do so,
based on the lack of
split pupils in nocturnal birds.
Spatial Data Analyst Australian Dinosaurs
Melbourne, Australia http://home.alphalink.com.au/~dannj