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Re: Nocturnal crocs?



> Dinosaur diversity was probably not affected much at the K/T
> (inasmuch as bird diversity making it through may well have
> been greater than non-avian esxtinction).

Dinosaur diversity was reduced to a few species of Neornithes... I don't
understand something here.

> Instead, the K/T represents the
> death of a niche--that filled by large oviparous species in terrestrial
> locations.  This niche has been practically empty ever since!

Why should there be extra niches for _oviparous_ animals? How does this
affect their ecology?

> Today,
> mammals and birds (and, to a lesser extent, reps) appear to be the agents
> keeping that niche empty.  The question then becomes: at what time did
> this first start being the case?

IMHO modern mammals occupy quite closely the same niches as dinosaurs
earlier (some niches for large animals being empty since we emptied them in
the Pleistocene).

> Mammals of the K/T in the western interior had reached the size where they
> _could_ have preyed on nests and hatchlings (judging by comparisons of
> today's pred and prey ratios, e.g., a hairy armadillo preying on rhea eggs
> is broadly comparable to a Didephodon preying on a dino egg).

Well, *Gobiconodon* also had such a size, and *Repenomamus* (*-nus*?) was
even larger.
Such animals (along with LK varanoids) would have produced a selection
pressure for better nest defense/concealment, and obviously dinosaurs
survived this.

> > > Small jackals today
> > > cannot approach ostrich nests in the day time but have no trouble at
> > > night.
> >
> > Really? I thought the male sits on the nest at night?
>
> Whichever sex it is, it is driven off the nest by jackals taking advantage
> of their superior night vision.

Jackals have better night vision than ostriches? How come?