Eurypterus

Eurypterus remipes is a species of sea scorpion from Silurian period it is also the state fossil of New york. Eurypterus is a top predator and it can take on most of it's contemporaries. Eurypterus didn't have claws like other sea scorpions but it had grasping arms.

In the series...
Eurypterus appeared in the the episode prehistoric new york. A bunch of them were seen on a deck looking for food later more eurypterus are seen hunting ammonites in the ocean.