Name:
Microcleidus
(Small collarbone).
Phonetic: Mi-cro-clie-dus.
Named By: Watson - 1909.
Synonyms: Plesiosaurus homalospondylus,
Plesiosaurus macropterus.
Classification: Chordata, Reptilia,
Sauropterygia, Plesisauria, Plesiosauridea.
Species: M. homalospondylus, M.
macropterus, M. melusinae.
Diet: Piscivore.
Size: Roughly about 3 meters long.
Known locations: England.
Time period: Toarcian of the Jurassic.
Fossil representation: At least one almost complete
specimen.
With
up to forty cervical vertebrae, Microcleidus had
a proportionately
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
around Cryptoclidus).
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.
Further reading
- A preliminary note on two
new genera of upper Liassic plesiosaurs. - Memoirs and Proceedings of
the Manchester Literary and Philosophical Society 54(4):1-28. - D. M.
S. Watson - 1909.