Fossilized vertebrae told about the long childhood of the giant sharks duration

Giant Cretaceous shark prihoda grew very slowly, were viviparous, and brought a little of the offspring, reported in PLoS ONE. This conclusion paleontologists made on the basis of vertebral Ptychodus, which are found on the Northern coast of Spain. The researchers suggest that these characteristics prikhodov could contribute to their extinction.

Sharks are cartilaginous fish, their skeleton is rarely ossified. This is the reason fossil species of sharks are represented mostly by teeth and restore their shape falls in the teeth (they are harder than cartilage, which is rarely culicifacies, and better preserved). The Swiss zoologist Louis Agassiz in 1835 described the fossil teeth of sharks, with many folds and called their owner Ptychodus, from the Greek πτυχός — “plate”, “layer” and ὀδούς — “tooth”. Presumably, such a structure teeth helped prihodom to grind the shells of mollusks and other hard food, that is, they were duriage.

Prihodi, like all the family priodonta, lived in the Cretaceous period 125-72 million years ago. Judging by the size of fossil material, they can reach lengths of 10 meters or more. Building a few vertebrae which were found next to the teeth prikhodov, suggests that they were similar to modern sharks, although this issue is not yet finally clarified.

Paleontologists Patrick Jambura (Patrick L. Jambura) and jürgen Kriwet (Jürgen Kriwet University) described the vertebrae and fragments of the scales of prihoda that in 1996 he discovered German student Kurt Opperman (Kurt Oppermann) from Soto de La Marina (Cantabria, Spain). Although there was no shark’s teeth, features of the structure of these vertebrae indicated to scientists that they are dealing with a representative of the genus Ptychodus. Sea urchins and bivalve molluscs, whose remains lay in the same layer was characteristic for the Santonian layer (of 86.3 to 83.6 million years ago).

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