Can someone please tell me what Sega Genesis game this is!?

Well I can't remember what the name of it is because I haven't played it in like 7 years, but it involves dinosaur creatures. You can be a pterodactyl or a few others. The game is set up playing from the left side of the screen to the right side of the screen like Super Mario Bros. But it is a shooting game. Your character shoots missiles and bullets. In some levels you go underwater and fight prehistoric creatures and such. Can someone please help me figure out what game this is? I wanna play it so bad. Thank you.