Named By: Watson - 1909.
Synonyms: Plesiosaurus homalospondylus, Plesiosaurus macropterus.
Classification: Chordata, Reptilia, Sauropterygia, Plesisauria, Plesiosauridea.
Species: M. homalospondylus, M. macropterus.
Known locations: England.
Time period: Toarcian of the Jurassic.
Fossil representation: At least one almost complete specimen.
up to forty cervical vertebrae, Microcleidus had
longer neck than other plesiosaurs. This longer neck has in the
past seen Microcleidus treated as an elasmosaurid
(the group of long
necked plesiosaurs like Elasmosaurus),
although Microcleidus has
also been considered to be a cryptoclidid (the group established
On top of this some researchers consider
Microcleidus to actually be intermediate in form,
and so should be
placed between these two groups.
As a living animal, Microcleidus would have been a more specialised hunter of fish than its shorter necked brethren. This would seem to be the trend taken by the piscivorous plesiosaurs as they progressed through the Jurassic, something that was in stark contrast to the shorter necked, large skulled pliosaurs like Liopleurodon that were distantly related but evolving to hunt marine reptiles like plesiosaurs.