Name: Calcarichelys ‭(‬rough turtle‭?)‬.
Phonetic: Kal-cah-re-shel-iss.
Named By: Rainer Zangerl‭ ‬-‭ ‬1953.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Testudines,‭ ‬Cryptodira,‭ ‬Protostegidae,‭ ‬Chelospharginae.
Species: C.‭ ‬gemma‭ (‬type‭)‬.
Diet: Omnivore‭?
Size: Around‭ ‬30‭ ‬centimetres long.
Known locations: USA‭ ‬-‭ ‬Alabama‭ ‬-‭ ‬Selma Formation.
Time period: Campanian to possibly Maastrichtian of the Cretaceous.
Fossil representation: At least two specimens.

       Calcarichelys was a relatively small late Cretaceous turtle but one with a highly specialised shell.‭ ‬Instead of the usual concave curve across the back,‭ ‬a series of enlarged spikes ran down the middle of the back.‭ ‬These are taken as being almost certainly a defensive adaptation to make it more difficult for predators such as the smaller mosasaurs to close their mouths around the body.‭ ‬With the mouth wedged open a predators teeth could not be brought to bear to damage the shell.‭ ‬The total effectiveness of these dorsal spikes however may not have been absolute since the spikes could only possibly protect against a jaw closing from‭ ‬above.‭ ‬Predators with more patience may‭ ‬have‭ ‬tried attacking exposed extremities such as flippers which were not protected,‭ ‬and some predators such as the large shark Cretoxyrhina had especially toughened teeth with thick enamel for biting through armoured prey like turtles.
       Like with its relatives Archelon and Protostega,‭ ‬Calcarichelys did not have a solid shell but instead a framework of struts that were filled in between by softer tissue.‭ ‬In terms of diet Calcarichelys probably fed like modern turtles perhaps eating everything from seaweed to jellyfish to even sponges,‭ ‬which could all have been easily tackled with its shearing beak.‭ ‬A possible close relative of Calcarichelys is Chelosphargis from the same formation and also named by Zangerl in‭ ‬1953.

Further reading
- The vertebrate fauna of the Selma Formation of Alabama. Part III. The turtles of the family Protostegidae. - Fieldiana: Geology Memoirs 3(3):63-133. - R. Zangerl - 1953.


Random favourites