Otodus chubutensis

As is the case with other known megatoothed sharks, the genus of O. chubutensis remains in dispute. The Swiss naturalist Louis Agassiz first identified this shark as a species of Carcharodon in 1843, naming It as C. subauriculatus based in MLP 12-3724 specimen. In 1906, Ameghino renamed this shark as Carcharodon chubutensis based in the MACN-A 12927. Some time later, it was discovered that C. subauriculatus would be a junior synonym of C. chubutensis. In 1964, shark researcher, L. S. Glikman recognized the transition of Otodus obliquus to O. auriculatus. In 1987, shark researcher, H. Cappetta reorganized the O. auriculatus - O. megalodon lineage and placed all related megatoothed sharks along with this species in the genus Carcharocles ( now Otodus). Finally, the complete Otodus obliquus to O. megalodon progression became clear and has since gained the acceptance of many shark researchers. Within the Otodus lineage; O. chubutensis is the succeeding species of O. angustidens and is followed by O. megalodon. However, due to its co-existence with O. megalodon during the Miocene and Pliocene epochs, it is regarded as a morpho-species. == Description ==

to O. megalodon'' based in teeth. Otodus chubutensis was a large lamniform shark, with the largest individuals reaching a body length maximum of . Relatively large individuals reached body lengths of . Smaller individuals were still about the size of the modern great white shark, reaching body lengths of . O. chubutensis was one of the largest sharks of its time. Teeth The teeth of O. chubutensis is very similar to O. megalodon, but It differs from O. megalodon by having concave teeth, a more robust root, the crown is more inflated and triangular, less irregular, the serrations are slightly rounded, robust, with the cusp being more visible than in O. megalodon, which has a smaller cusp than in O. chubutensis. Therefore, O. chubutensis may or may not have cusps, just as O. megalodon may have slightly visible cusps; O. chubutensis, in its broader and less common form, may have widely vestigial or absent cusps. == Paleoecology ==

like Megalodon.(by Karen Carr) O. chubutensis was the apex predator of the Miocene era and occupied an extremely high trophic level. Paleontological research suggests that this species may have changed habitat preferences through time, or it may have had enough behavioral flexibility to occupy different environments at different times. There is also evidence that eurhinodelphinids where also hunted in a similar way. Three Neogene odontocete peduncular caudal vertebrae from the Pliocene Yorktown Formation show bilateral gouge marks consistent with having been actively bitten and wedged between adjacent teeth of Megalodon or O. chubutensis. None of the vertebrae show any signs of healing. The occurrence of bite marks suggests the event was an active predation event rather than a scavenging event. == Fossil record ==

This species is also known from fossil teeth and some fossilized vertebral centra. Shark skeletons are composed of cartilage and not bone, and cartilage rarely gets fossilized. Hence, fossils of O. chubutensis are generally poorly preserved. Although the teeth of O. chubutensis are morphologically similar to teeth of O. megalodon, they are comparatively slender with curved crown, and with presence of lateral heels feebly serrated. Fossils of this species have been found in North America, and Europe. Its fossils have also been discovered in Asia and Australia. The fossil record confirmed for this species spans from the Late Oligocene to the Middle Miocene, while fossils with forms similar to this species are found as far back as the Early Pliocene strata. This suggests that O. chubutensis coexisted with Megalodon for a long time as a variant form. Locations ;South America • Chilcatay Formation, Pisco Formation, Peru • Pirabas Formation, Brazil • Jimol Formation, Colombia • Cantaure Formation, Venezuela ;North America • Culebra Formation, Panama • Arcadia Formation, Florida • Pungo River Formation, North Carolina • Calvert Formation, Delaware ;Europe • Bolognano Formation, Italy == See also ==