Crowns broad, triangular, and erect, being broader and more vertical in anterior teeth and with increasing posterior inclination distally; labial crown face relatively flat or mildly convex, often showing short vertical infoldings of the enameloid at base of crown, lingual crown face moderately convex; crown enameloid relatively thick; chevron-shaped band of thinner enameloid on lingual crown face between base of crown and root (lingual neck), thicker in medial section becoming thinner laterally and showing fine vertical striations; cutting edge with fine, even, rounded serrations along entire margin, averaging 12–17 serrations per centimeter (cm); lateral cusplets lacking in adult teeth; root is labiolingually thick with two laterally divergent but apicobasally shallow lobes, usually similar in size and not extending much laterally beyond the lower margin of the crown; labial root face is relatively flat while the lingual root face is laterally convex and thicker in the center with a pronounced nutritive foramen medially.

LACM 59836, 59837, 115989, 129982, and SDNHM 53167, Capistrano Formation (LACM localities 4437, 5792, 61520, and SDNHM locality 3842); LACM 148311, 148312, and 149739, Fernando Formation (LACM localities 7321 and 7481); RMM A597-1, A597-9A, A597-9B, and A597-12, Lomita Marl (no locality number); LACM 59065 and SDNHM 73462, Niguel Formation (LACM locality 65187 and SDNHM locality 4080, respectively); LACM 10141, LACM 11149, LACM 159028, Palos Verdes Sand and unnamed Pleistocene strata (LACM locality 1066 and 7971); UCMP 219502, Purisima Formation (UCMP locality V-99875); LACM 10152, LACM 103448, LACM 156334, and SDNHM 29742, San Diego Formation (LACM localities 1080, 1095, 4875, and SDNHM locality 3253); LACM 131149, SDNHM 23056, 23959 (four teeth with same number), 24448, 77430, and 77343, “upper” San Mateo Formation (Lawrence Canyon local fauna; LACM locality 4297 and SDNHM locality 3161); CAS 72799.00, Santa Cruz Mudstone (no locality number); and LACM 29065–29067, 29069–29070, and 29073–29078, Tirabuzón Formation (LACM locality 6579).

Occurrence data

Pliocene-aged teeth of Otodus megalodon have been recovered or reported from several formations in California and Baja California (Fig. 1), including the Lomita Marl, Capistrano, Fernando, Niguel, Purisima, San Diego, San Mateo, and Tirabuzón Formations, the ages of which are summarized below. These specimens exhibit a combination of morphological characters including: a large overall size and labiolingual thickness, triangular shape, fine serrations, V-shaped chevron on the lingual surface between the crown and root, and loss of lateral cusplets at the base of the crown. These characters, when observed together, indicate that the specimens undoubtedly belong to Otodus megalodon. The only other sharks that could be confused with Otodus megalodon during the late Miocene and early Pliocene are those belonging to Carcharodon (C. hubbelli and C. carcharias), which have significantly smaller and labiolingually flatter teeth lacking V-shaped chevrons and have coarser serrations. Therefore, we are confident in assigning these specimens to Otodus megalodon. Additionally, we found that relatively few Otodus megalodon teeth from ENP Neogene sediments are present in museum collections; for example, a total of 145 teeth from lower Miocene through Pliocene west coast deposits are represented in LACM, SDNHM, and UCMP collections, primarily from California. In comparison, Purdy et al. (2001:131) referred 82 specimens in addition to “several hundred isolated teeth” from the Pungo River Limestone and Yorktown Formation at the Lee Creek mine alone, and countless additional teeth exist in other collections and from other stratigraphic units from the Atlantic coastal plain. Intense collecting at ENP localities like the Sharktooth Hill Bonebed suggests that this is not simply a case of collection bias and likely reflects genuine rarity (whether biogenic or taphonomic) of Otodus megalodon teeth from Pacific coast deposits. An alternative hypothesis is a geochronologically earlier extinction of Otodus megalodon in the Pacific basin than the Atlantic.