How are the two Alligator species so far apart?

twistedspark

In my understanding, the only two extant species of Alligators exist exclusively in the US and China. *Nowhere else.
They are said to have existed for 200 million years, but Pangea broke up 250 M years ago.
Just for the sake of argument, say they had evolved on Pangea and just got separated; the lands that are now China and America were on opposing ends of the super continent. They lived on opposite ends and nowhere in between?
The Pacific ocean in now smaller than it was then and there's no way I can see a group of them crossing such a massive span of water. Not today. No way then.
I've tried finding an answer on Google without success.
Do any of the geniuses here have an answer I can fathom?

P.S. - why does this site fill in asterisks whenever I try to put a space? Is grammar a dirty word here?

Simon Bridge

Consider: a creature spreads out across an entire continent, but the ones in the middle all die out. You end up with examples of the creature in only a few, widely separated, places.

220M years ago - the ancestors of the modern alligator were quite different from their current shape.
http://www.all-about-reptiles.com/barbarenasuchus.html

You are talking about a very long time, so you need to consider modern crocodiles, caimans, and gavials as well. Also remember that the dinosaurs all died out during that time... these pre-crocodilians also suffered heavy number loss. Also the last glaciation maximum was 18000 years ago. So, overall, it is hardly surprising that these creatures, and many others, exist in pockets here and there.

DaveC426913

leading to the question: why did they die out?

I postulate a correlation between allie populations and worldwide distribution of wetlands/swamps (Florida/Louisiana, Yangtze River).

epenguin

Quote related to Dave's point this article published yesterday:
http://www.economist.com/node/21538078

Simon Bridge

A good theory should lead to more questions :)

Considering there was an ice-age and whatever took-out the dinosaurs in the time period concerned, we can take our pic for extinction mechanisms. The wonder is that any survived at all. Whatever was left evolved in place to modern crocodilians.

Yep - look at how those locations compare with the extent of glaciation too.