Named By: Rainer Zangerl - 1953.
Classification: Chordata, Reptilia, Testudines, Cryptodira, Protostegidae, Chelospharginae.
Species: C. gemma (type).
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.
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.
- 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.