|1st Species||Leptocleidus superstes|
|2nd Species||Leptocleidus capensis|
|3rd Species||Leptocleidus clemai|
|Time Range||140-125 mya|
|Location||South Africa, Australia, United Kingdom|
|Name Meaning||Slender clavicle|
|Physical Dimensions||1.5 meters long for L.superstes; 3 meters long for L.capensis and L.clemai|
Leptocleidus is a leptocleidid plesiosaurian reptile from the Early Cretaceous of South Africa, Australia, and the United Kingdom. It was named in 1922 by Roy Chapman Andrews. It was a unique plesiosaur, as it was able to live in fresh water; as well as this, and was thought to be a species of Plesiosaurus before finally being described as its own genus.
Leptocleidus was a plesiosaur with a slender body, 4 flippers, a short tail with a small fin on its end, a moderately long neck, and a small, conical head with a mouth filled with sharp, interlocking teeth. Its body would have been covered in scaly skin.
Leptocleidus was a predator, preying mainly on fish and cephalopods, but also snacking on small crocodylomorphs from time to time. Its conical teeth had knife-like serrations from front to back, and were used to cut into the hides of prey.
Unlike other plesiosaurs, which lived out in the open ocean, Leptocleidus made itself at home in freshwater rivers and estuaries, as well as in brackish water lagoons. In fact, some may speculate that it was anadromous, usually living in brackish water, but migrating into freshwater in order to give birth to young; there, the adults would care for their young until they were large enough to look after themselves, right before returning to saltier waters. This freshwater lifestyle can probably be seen as a refuge from large marine predators; pliosaurs and sharks were the main predators of the ocean, and elasmosaurs, even with their relatively small heads, were more than capable of preying on Leptocleidus from time to time. As well as this, unlike those of other plesiosauroids, its teeth were conical and partially serrated, which best suited the generalist predator of small-midsized prey that it was; it mainly preyed on fish and cephalopods, but it may have chosen to snag small crocodylomorphs with its toothy jaws from time to time.