IMC you're more likely to run across leftovers from the pliestocene, but the M'Kolo-M'Bembe (a small Apatosaur) and the Ol-Umaina (an Allosaur) can be found in the jungles of Africa, and the Lagar-Tortuga of the Caribbean is an Archelon tschyras (giant turtle). There are other "sea serpents" out there, as well...
The Cockatrice, on the other hand, is a poisonous Archaeopterix, and dragonets from the rat-sized "petty (or petit) wyvern" to the MM's version owe more to the pterosaurs then to the steroetypical six-limbed beasts...
(I'm interested to see the Animal Planet's take on dragons, however...)