An analysis of hundreds of fossilized skulls and jaws reveals that Mesozoic sea monsters – plesiosaurs , ichthyosaurs , and mosasaurs – abound onto the scene and rapidly reign . The findings are publish inPaleobiologythis week .
Reptiles were top predator in maritime ecosystems during theMesozoic Era , which is made up of the Triassic , Jurassic , and Cretaceous periods . The era lasted from 252 million to 66 million old age ago . Previous studies found that marine reptiles were wildly various and display a variety of specialised alimentation mode during the Middle Triassic in the backwash of thePermian - Triassic quenching . But their origins and early ascension to the top has been a mystery . And until now , most of these studies were based on estimates of biodiversity ( or species numbers ) over time .
University of Bristol ’s Thomas Stubbs and Michael Benton wanted to study variation in the form and function of marine reptilian jaws and tooth . In one of the heavy relative and quantitative investigations of evolution in Mesozoic marine reptiles , the team examined the skull of 354 mintage and the jaws and dentition of 206 species .
" We show that when marine reptiles first entered the ocean in the Triassic menses , they rapidly became very various and had many structural adaptations related to feed in on wide-ranging prey , " Stubbs said in astatement . " Within a comparatively myopic space of time , maritime reptilian start feed on hard - blast invertebrate , fast - moving fish , and other large marine reptiles . "
This range of eating - related adaptations of Triassic marine reptiles was never exceeded again afterward during the rest of the Mesozoic . " They expanded into near every mode of animation , indicated by their alimentation habits and compass of body sizes , really much quicker than might have been imagined,“Benton added . However , just 30 million long time after this initial evolutionary burst , most groups of marine reptilian were wiped out duringLate Triassic extinction events . For the most part , Jurassic marine reptilian failed to thrive into those vacated roles .
( A ) Pliosaurus , ( B ) Tylosaurus , ( C ) Ophthalmosaurus , and ( D ) Placochelys . Scale bars on the jaw illustrations represent 20 centimetre ( A - C ) and 5 centimeters ( D ) . Tom Stubbs
