How Jurassic predators evolved into mega meat-eaters?
Washington: New findings have shed light on how adaptations for a mega meat-eating lifestyle extended to some full-time water dwellers as well as to certain land-based animals, like dinosaurs.
The study focused on three metriorhynchids from the Middle Jurassic to the Early Cretaceous: Dakosaurus, Geosaurus and the newly named Torvoneustes.
All three were "hypercarnivores," which lead author Marco Brandalise de Andrade, defined as a carnivore with a diet made up of at least 70 percent meat.
For the study, he and colleagues Mark Young, Julia Desojo and Stephen Brusatte analysed fossils of the prehistoric crocodile relatives, which are thought to have lived most, if not all, of their lives underwater in the Nusplingen and Solnhafen Seas that once existed near what is now Germany.
They also performed electron microscopy on teeth belonging to these meat-loving predators.
They determined the teeth of Dakosaurus were extremely sharp and serrated, comparable to those of T rex.
"Both Dakosaurus and Tyrannosaurus had proportionately large teeth, with robust, poorly flattened crowns, and macroscopic serrations," Discovery News quoted Andrade as saying.
"Taking the T Rex as an analog for tooth biomechanics, Dakosaurus would be able to deliver a fierce powerful bite, damaging flesh, bones and even armour," he said.
Dakosaurus might have even been a more successful hunter than carnivorous dinosaurs like T Rex -- thanks to its death roll.
"The coolest thing about the death roll is that it becomes exponentially more efficient with body size: the larger the Dakosaurus or Geosaurus, the greater the damage!" said Andrade.
While it's possible that large sharks could have fed on adult metriorhynchids, no physical evidence has been found to prove it.
"The only predators Geosaurus and Dakosaurus would have had were the pliosaurs. During the time Geosaurus and Dakosaurus lived, that meant Liopleurodon and Pliosaurus. Both were 33 feet plus carnivores, and would have been at the top of the food chain," said Young.
Geosaurusand Dakosaurus swam in the same seas, likely because each targeted different prey.
Dakosaurus, with its T rex-like skull and teeth, would have been able to feed on large marine reptiles, fish and cephalopods.
Geosaurus, on the other hand, had a streamlined body and a lighter skull. Its teeth were better at slicing through soft bodied, fleshy prey.
The findings were published in the Journal of Vertebrate Palaeontology.