Third party material on animals and prehistoric mammals?

[Ahnehnois]

Frostburn in particular has a number of prehistoric-type animals, and the environment series in general has stats for some of what you might consider "offbeat" animals.

 

[Wycen]

Did you click on my link above?

I did but this

I suspect you're thinking of the Animal Archives series from Blackdirge.

was the right answer.

 

[freyar]

For something free, try paging through the EN World Creature Catalog. It's all kinds of monsters, but there are many, many real world animals (prehistoric and otherwise) and D&D-ized "monstrous" or "giant" versions there.

 

[Dannyalcatraz]

The Nyambe RPG has a wide variety of regular animals in their books, as does its sister product, Northern Crown, both from Atlas Games.

Also check out the Dinosaur Planet sourcebook Broncosaurus Rex from Goodman Games.