Mesozoic Sea Reptile Body Types

The Mesozoic era had large oceans, with many prehistoric sea life calling the ancient ocean their home, but none were as memorable as the marine reptiles.
marine reptiles were not dinosaurs and their placement in the relationship between other reptiles is still up for debate, with some stating they are a branch from Archosauromorphs and others saying they are distantly related to turtles
Each marine reptile had a unique body plan that fitted it's needs and helped them to service in there oceanic environment in different ways.

ICHTHYOSAUR (Fish Lizards)
These animals existed from the early Triassic 248 million years ago
Their body plans could be described as a reptilian dolphin with many fish like qualities like flippers and fins showing a very strong example of convergent evolution with both animals filling a very similar niche, they also possessed narrow snouts similar to dolphins.
Their were also super gigantic members of this group, effectively being reptilian whales of their time.

PLESIOSAUR & PLIOSAUR (Near to Lizards & More to Lizard)
These powerful beasts swam the open oceans from the very end of the Triassic to the end of the Cretaceous, with 4 paddle like limbs they swam in a similar way to sea turtles perfectly adapted for carrying their bodies through the water, these animals also possessed a very small tail flukes that they most likely used as a turning mechanism to aid in mobility.
. PLESIOSAURS can be identified by their small heads and long necks they most likely fed on small fish using their necks to add extra reach when hunting, the length of the necks ranged from noticeable long like in Plesiosaurus to absurdly long like with Elasmosaurus, there has also been recent discoveries showing that some Plesiosaurs actually filter fed like modern baleen  whales.
. PLIOSAURS are a type of Plesiosaur which were identified by their short necks and large heads, this shows that they were feeding on much larger prey, like Ichthyosaurs and other Plesiosaurs, using their powerful jaw strength to grab onto prey and crush it, they were stronger built than the other plesiosaurs meaning they probably would have hunted like great white sharks with sudden high impact surprise attacks.

MOSASAUR (Meuse Lizards)
Unlike most marine reptiles we actually know that they were actually Lepidosaurs, meaning that they were closer related to snakes and monitor lizards than they are to crocodiles making the Mosasurs a very unique group of animals.
these animals were massive hyper carnivores, with bodies that resembled whale snakes, they possessed 2 rows of teeth in there jaws similar to a snakes, this would have helped with gripping onto prey which would have been very large as there is evidence showing that the mosasaurs had cannibalistic tenancies with large adults devouring smaller, younger Mosasaurs whole.
They had short limb flippers and a powerful tail complete with a large tail fluke propelling them forward in a manner similar to how a shark or crocodile swims, these animals out competed the pliosaurs leading to the extinction of the short necked plesiosaurs, leading them to be the apex of the cretaceous oceans, eating anything they could get their jaws on.



not the BEST image i have done i will admit but still i took it as more of a way to show aquatic reptile diversity back in the Mesozoic
i mainly just hope to inspire others to make a chart like this but better
i do hope you all still like this though, i had fun doing the picture because it was my very 1st time drawing any of the marine reptiles
i mainly had fun with the Mosasuaurus, maybe i'll make an actual full image for all these body types some time in the future

i WAS debating if i should have had Nothosaurus or not but A.) i don't think i had room and B.) i went for fully aquatic animals