The planet that holds Metamor Keep has gone through many different ages that are similar but not the same as the Real Life Earth's. There was an age of dinosaurs followed by several ages which also ended with mass extinctions. The last such mass extinction is believed to be about 12,000 years ago but details are uncertain.
The result is that there are many now long extinct species. For writers any species that existed in the past on Real life earth can be assumed to have existed in MK at one time. Although extinct they can (and have) reappeared among the animal morph Keepers. A good example of this is panno who is a Beardog or Amphycon.
Dinosaurs: Always popular and they deserve a mention. Dinosaur fossils do turn up and some groups are starting to actively study them. Sometimes these bones are mistaken for dragon bones - much to the annoyance of the dragons. Later, some species of dinosaurs (with no fossils yet recovered) will only be known through animal morph Keepers who take their species because of the curse.
Some species that have gone extinct on Real life Earth do still exist in small numbers in the MK world.
sabercat Suspected to be the sabertooth tiger - Smilodon Fatalis.