A fossil of4 million yearsof antiquity found in a desert area of Peru and described in the magazineJournal of Vertebrate Paleontologyreveals new data onancestors of the dreaded white sharks.
Finding shark fossils is rare because sharks have most of their skeleton made up ofcartilage. Of the new specimen, however, much of the spinal column, 45 vertebrae, the head, and a 22-tooth mouth have been preserved.
The finding could end a long-standing debate about the evolutionary tree of these animals. For more than 150 years paleontologists have been locked in a debate about whether theWhite shark (Carcharodon carcharias) is a smaller relative of the species line to which the hugeCarcharodon megalodon, or if it comes from the wide-toothed mako.
Based on the size of theteethand in the analysis of the intervertebral growth rings, the researchers have concluded that the primitive shark must have been about 20 years old and measure from 5 to 5.5 meters in length. The results suggest that it is a species of white shark closely related toIsurus disease, a wide-toothed mako shark that grew to about 8 meters in length and lived 9 million years ago. The thick serrated teeth of the shark fossil are evidence of a transition between broad-toothed mako sharks, which eat primarily fish, and modern white sharks. “Here we have a shark that is acquiring saw teeth and that is turning into a white shark, but it is not yet,” explained Dana Ehret, from the University of Florida.
The fossil shark specimen came from an area known as thePisco Formationthat 9 million years ago was a sheltered shallow marine environment, ideal for the conservation of skeletons. In addition to the shark, fossils of whales, aquatic sloths and sea turtles have been found.
