Otodus chubutensis

Otodus chubutensis, meaning "ear-shaped tooth of Chubut", from Ancient Greek ὠτ (ōt, meaning "ear") and ὀδούς (odoús, meaning "tooth") – thus, "ear-shaped tooth", is an extinct species of prehistoric megatoothed sharks in the genus "Otodus", that lived during Oligocene, Miocene, and Pliocene epochs, approximately 28 – 5 million years ago. This shark is considered to be a close relative of the famous prehistoric megatoothed shark, "O. megalodon". However, as is the case with "O. megalodon", the classification of this species is disputed.
Taxonomy.
As is the case with other known megatoothed sharks, the genus of "C. chubutensis" remains in dispute. The Swiss naturalist Louis Agassiz first identified this shark as a species of "Carcharodon" in 1843. In 1906, Ameghino renamed this shark as "C. chubutensis". In 1964, shark researcher, L. S. Glikman recognized the transition of "Otodus obliquus" to "C. auriculatus". In 1987, shark researcher, H. Cappetta reorganized the "C. auriculatus" - "C. megalodon" lineage and placed all related megatoothed sharks along with this species in the genus "Carcharocles". Finally, the complete "Otodus obliquus" to "C. megalodon" progression became clear and has since gained the acceptance of many shark researchers.
Within the "Carcharocles" lineage; "C. chubutensis" is the succeeding species of "C. angustidens" and is followed by "C. megalodon". In short, "C. chubutensis" is considered a possible ancestor of "C. megalodon". However, due to its co-existence with "C. megalodon" during the Miocene and Pliocene epochs, it is regarded as a morpho-species.
Size.
"Otodus chubutensis" was larger than "O. angustidens". Teeth of "C. chubutensis" can approach in slant height (diagonal length), which according to a size estimation method proposed by Gottfried "et al.", in 1996, indicate a long specimen.
Paleoecology.
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.
Diet.
"Otodus chubutensis" was likely an apex predator and commonly preyed upon fish, sea turtles, cetaceans (e.g. whales), and sirenids.
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, South America, Africa, and Europe.