Hadrosaur
The hadrosaur was a genus of Earth dinosaur that lived in the Cretaceous Era. 

It was the most highly evolved cold-blooded organism to develop from the Eryops known to Humans, and was believed to have vanished when a mass extinction occurred at the end of the Cretaceous Era. 

It was discovered in the 24th century that a population of hadrosaur had survived the extinction event by living on an isolated continent, which was later destroyed by geological processes. Over the centuries, they evolved into a sentient space-faring  species, the Voth, and departed Earth for the Delta Quadrant. ()

In 2399, Deanna Troi had kept her son Thad's toy hadrosaur. It was on a shelf next to some toy cars. ()

External link 
 

de:Hadrosaurier
Earth animals