No crocodiles?

Here is an interesting question: If the crocodilians had also gone extinct along with the non-avian dinosaurs what animal would occupy their niche today?

My first thought is some sort of lion-otter.

My first though is varanid derivatives. Second thought, an (early) offshoot of one of the marine mammal groups (ceteceans, sirenians,

IIRC, one of the BBC 'Walking With Beasts' episodes had an early cetacean presented as a crocodile analog.

Googling finds that it was _Ambulocetus_

Or some carnivorous birds. Similary to birds like Diatryma but swimming.

Sincerely

I don't know about birds. I find it hard to imagine a giant penguin taking down a zebra as it tries to cross a river! Maybe if birds had retained their teeth...

A Croco-lizard would certainly make sense, but it would probably evolve into something fairly close to actual crocodiles. I was thinking of something warm-blooded which would fill the same niche but go about it in an entirely different way, and I was trying to imagine what that different lifestyle would look like. Your second thought is more what I was looking for. But maybe the advantages of ectothermy in this niche are just too great.

How about Croco-snakes?

Wasnt there some sort of very large fresh/swamp water shark at some point in time?

Given that evolution had 'been there before', perhaps it could get there again.

Regards

I suppose a 2-metre-long eurypterid-type water scorpion would be out of the question? I think that would be grand!

cheers

Giant version insects?

Years and years ago, I saw in an evolution textbook (Colbert?) an illustration being used to show the idea of paralell evolution. The example being used was crocodilian-form (short-legged, long-tail, toothy aquatic/marine carnivores). There were about 6 or so forms shown:

1) a group of amphibians (labrynthodonts?), 2) phytosaurs, 3) chasmosaurs, 4) mosasaurs, and 5) true crocodilians

are the ones I remember (the other may have been another group of amphibians or maybe pliosaurs). If you include long necks, the nothosaurs may fit too.

I would agree that the most likely reptilian candidate would be a varanid line (many varanids already serve the ecological funtion of crocodilians, especially the Nile monitor); although the varanids are restricted to the equatorial Africa-Asia-Australasia belt. Otters are probbaly the closest current mammals get, although something like a water civet has potential.

I find crocodilians fascinating examples of an evolutionary theory that I have, illustrating how a group of animals develops over its evolutionary history. Another good example is the rhinoceros family. Both groups started as small general forms, and rather quickly evoled to fill all sorts of ecological niches (like rodents or ungulates today). As they evolved into these niches, the various forms specialized. This ended up getting too specialized and the forms became extinct until the group has ended up with only a few specialized species with extremely limited ranges. And eventually, extinction will catch up (rather soon for both unfortunately, since my two examples have heavy human-caused pressures on them). Sort of racial senilty revised, I know; but it makes sense to me.