# Carcharodon

Carcharodon (meaning "jagged/sharp tooth" in Ancient Greek) is a genus of sharks within the family Lamnidae, colloquially called the "white sharks." The only extant member is the great white shark (Carcharodon carcharias). Extinct species include C. hubbelli and C. hastalis. The first appearance of the genus may have been as early as the Early Miocene or Late Oligocene. Carcharocles megalodon is still argued by some paleontologists (e.g. Michael D. Gottfried, Leonard Compagno, and Ewan Fordyce) to be a close relative of Carcharodon carcharias - as well as being in the same genus. When Megalodon belonged to this genus it had the scientific name Carcharodon megalodon. More recently, Megalodon has been assigned by most scientists to either the genus Carcharocles or Otodus.

## Fossil History and Evolution

The fossil ancestry of Carcharodon is an active area of research and debate, given the dearth of the fossil record and the incompleteness of found specimens. Most Carcharodon fossil remains of are in the form of teeth, along with some vertebral centra. This is the norm for fossilized Chondrichthyans, since a shark's skeleton is made of cartilage and soft tissues don't preserve well. Thus, assessing relationships between fossil species relies largely on the form of their teeth. This difficulty is compounded by the incomplete fossil record of Lamnids. However, some researchers have proffered Macrorhizodus, Isurolamna, and Cretalamna as candidates for genera ancestral to Carcharodon, taxa ranging from the Eocene to the Cretaceous.
Carcharodon is well-represented in the fossil record by the Middle Miocene. The first widespread, cosmopolitan species being C. hastalis, with fossils recovered from North America, South America, Europe, Australia, and Asia. The modern great white shark has been posited to have evolved from C. hastalis through a transitional species, C. hubbelli.
Study of white shark taxonomy is complicated by nomenclature and repeated taxonomic reassignments of various species. C. hastalis, C. subserratus, and C. planus traditionally were placed in Isurus, given their superficial similarity to the teeth of mako sharks, leading many modern shark tooth collectors to still refer to these extinct species as "makos." They were later reassigned to a new genus, Cosmopolitodus, a genus maintained as valid in some current literature, and considered a junior synonym of Carcharodon in others. C. hastalis has also been described as two morphotypes, "broad-form" and "narrow-form," which some authors have split into two species, C. plicatilis (xiphodon) and C. hastalis, respectively. C. subserratus, historically known as C. escheri under the genus Carcharomodus, has recently been reclassified back in to the genus Carcharodon as C. subserratus.
The fossil "mega-toothed" sharks like megalodon have also traditionally been placed in Carcharodon, but most current literature refutes this position, placing mega-toothed sharks in a separate family, Otodontidae, and genus, Otodus (Carcharocles). Carcharodon caifassii is the other species in genus Carcharodon. It is a debated species, and is considered dubious. It lived in the Miocene and Pliocene period and was a possible ancestor of the great white shark (Carcharodon carcharias).

## Species

* Carcharodon carcharias (Linnaeus, 1758) (the great white shark)
* †Carcharodon carcharias-f (Lawley, 1876)
* †Carcharodon hubbelli (Ehret et al., 2012) (Hubbell's white shark)
* †Carcharodon hastalis? (Agassiz, 1843)
* †Carcharodon planus? (Agassiz, 1856)
* †Carcharodon subserratus (escheri)? (Agassiz, 1843)
* †Carcharodon plicatilis (xiphodon)? (Agassiz, 1843)
* †Carcharodon caifassii (Lawley, 1876)