Paleontologists on vertebrae of ancient shark named reasons for their extinction

The study of the fossil vertebrae of the giant chalk shark poultry (Ptychodus) gave paleontologists from the University of Vienna an answer about the features of shark life and the reasons for their extinction. The results of research into the remains of an ancient shark were published by scientists in the scientific journal Plos one. Austrian scientists studied the structure of the vertebrae of a bird found in 1996 in Spain. Since sharks are cartilage fish, their skeleton is very rare, and palaeontologists get only teeth by which they restore the appearance of sharks. The discovery of vertebrae allowed many discoveries to be made. It is known that birds lived in the Cretaceous period about 125 72 million years ago. The vertebrae studied helped determine the duration of their extinct host. There are concentric circles on the transverse sections of the vertebrae, which as year-long rings in trees show the age of the creature. Palaeontologists on rings on vertebrae determined that the age of the animal was 31 years. Shark sizes could range from four to seven meters. Researchers noted that the distances between the rings on the section hardly changed with age, which means that the rate of shark growth before death did not decrease it continued to grow and was not sexual. On this basis, scientists believe that the length of birds could reach an impressive ten meters. From the first ring, palaeontologists determined that at birth the body length of the bird was 65 to 107 centimeters. Many modern living sharks have such sizes of babies. According to the total data obtained, palaeontologists assumed that the birds were living sharks, grew for a very long time and reached sexual maturity late. This resulted in poultry offspring being small, and changes in the environment could be precisely the reason why these sharks became extinct.