Pictures of the first alligator to walk the earth?

Answer 1

Here's a site from National Geographic that includes a picture of Junggarsuchus sloani - a terrestrial sphenosuchian that was likely closely related to the lineage that led to the crocodilians (including modern crocodiles, alligators and garials). http://news.nationalgeographic.com/news/2004/08/0825_040825_crocodiles_fossils.html

The earliest crocodilians were actually land-living carnivores, and there was an entire lineage that went on to become successful, dominant predators on land before the dinosaurs ever evolved.

One group of these terrestrial crocodiles adapted to aquatic and semi-aquatic habitats, and it was the descendants of this group that survive today as crocodiles and alligators.

The earliest of these semi-aquatic crocodilians known is Isisfordia duncani from 98 to 95 million years ago in Australia. Here's a site that shows a picture of one http://www.crystalinks.com/fossilcrocodile.html Note that it looks pretty much like a modern crocodile. This is likely about the time that the lineage of our modern, aquatic crocodiles formed. Note that being at most 100 million years old, this was well after dinosaurs evolved, and also well after birds and mammals had evolved as separate groups.

Nature shows and such always like to talk about alligators and crocodiles as being some sort of holdover from the primordial ooze, an ancient group older than dinosaurs. The truth is that the adaptations and species we see today in crocodiles and alligators are not actually that ancient.

Incidentally, the same goes for our modern species of sharks - most of those groups evolved in the Cretaceous or later, and so are actually younger than groups like penguins, loons, possums, even owls.

Answer 2

Check this page, then scroll down to where it says: "Some Ancient, Extinct Crocydilians".

http://www.enchantedlearning.com/subjects/Alligator.shtml