The phytosaurs were the Triassic

predessesors to the crocodilians. 

And they were huge!  Up to 40ft  long!)

They were an ancient thecodont reptiles

and surprisingly, were not that closely

related to alligators and crocodiles, even though

they looked so very much like them. 

But unlike the crocs, phytosaurs had their nostrils

set way back on their snouts, up close to their eyes. 

And their forward-most teeth were severe shearing blades.  They were specially adapted for catching fish, but they would have been absolutely lethal against even the dinosaurs.  However, they would be extinct by the beginning of the Jurassic period, when real crocodilians would come in to fill their niche.