The Early Pliocene extinction of the mega-toothed sharkOtodus megalodon: a view from the eastern North Pacific

Abstract

The extinct giant shark Otodus megalodon is the last member of the predatory megatoothed lineage and is reported from Neogene sediments from nearly all continents. The timing of the extinction of Otodus megalodon is thought to be Pliocene, although reports of Pleistocene teeth fuel speculation that Otodus megalodon may still be extant. The longevity of the Otodus lineage (Paleocene to Pliocene) and its conspicuous absence in the modern fauna begs the question: when and why did this giant shark become extinct? Addressing this question requires a densely sampled marine vertebrate fossil record in concert with a robust geochronologic framework. Many historically important basins with stacked Otodus-bearing Neogene marine vertebrate fossil assemblages lack well-sampled and well-dated lower and upper Pliocene strata (e.g., Atlantic Coastal Plain). The fossil record of California, USA, and Baja California, Mexico, provides such an ideal sequence of assemblages preserved within well-dated lithostratigraphic sequences. This study reviews all records of Otodus megalodon from post-Messinian marine strata from western North America and evaluates their reliability. All post-Zanclean Otodus megalodon occurrences from the eastern North Pacific exhibit clear evidence of reworking or lack reliable provenance; the youngest reliable records of Otodus megalodon are early Pliocene, suggesting an extinction at the early-late Pliocene boundary (∼3.6 Ma), corresponding with youngest occurrences of Otodus megalodon in Japan, the North Atlantic, and Mediterranean. This study also reevaluates a published dataset, thoroughly vetting each occurrence and justifying the geochronologic age of each, as well as excluding several dubious records. Reanalysis of the dataset using optimal linear estimation resulted in a median extinction date of 3.51 Ma, somewhat older than a previously proposed Pliocene-Pleistocene extinction date (2.6 Ma). Post-middle Miocene oceanographic changes and cooling sea surface temperature may have resulted in range fragmentation, while alongside competition with the newly evolved great white shark (Carcharodon carcharias) during the Pliocene may have led to the demise of the megatoothed shark. Alternatively, these findings may also suggest a globally asynchronous extinction of Otodus megalodon.

Ontogenetic growth pattern of the extinct megatooth shark Otodus megalodon—implications for its reproductive biology, development, and life expectancy

“…Yet, deciphering the life-history strategy of prehistoric sharks is often challenging because the vast majority of species are represented by teeth as their poorly mineralised cartilaginous skeleton usually does not fossilise (Cappetta 2012). In this regard, our vertebra-based study is a rare exception, where the life-history traits for Otodus megalodon proposed here have a significant bearing on various hypotheses and biological issues, such as its potential use of nursery grounds (Pimiento et al 2010;Herraiz et al 2020), its proposed competition with Carcharodon carcharias during the early Pliocene (Boessenecker et al 2019), and ontogenetic effects on its thermophysiology (Ferrón 2017). However, addressing these issues is beyond the scope of this paper primarily because our study rests on multiple assumptions, such as growth bands in IRSNB P 9893 representing annual cycles and the unconventional application of VBGF to a single individual (see Materials and Methods).…”

“…The megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), is an iconic extinct shark known mostly from its gigantic teeth in the late Neogene marine fossil record (e.g. Cappetta 2012;Boessenecker et al 2019;Perez et al 2019). The species was previously placed in various genera such as Carcharocles, Procarcharodon, and Megaselachus, as well as the white shark genus Carcharodon (Lamnidae), but it is now generally regarded as a species of Otodus in order to avoid Otodus nonmonophyly (Shimada et al 2017) and direct phylogenetic linkage to Carcharodon or Lamnidae (Ehret et al 2012).…”

Sharks, rays and skates (Chondrichthyes, Elasmobranchii) from the Upper Marine Molasse (middle Burdigalian, early Miocene) of the Simssee area (Bavaria, Germany), with comments on palaeogeographic and ecological patterns

“…Remarks. The taxonomic classification of C. hastalis has been widely debated in the last years (see Purdy et al 2001 ; Cappetta 2012 ; Cione et al 2012 ; Ehret et al 2012 ; Boessenecker et al 2019 ). Ehret et al ( 2012 ) proposed a reconstruction of the evolutionary history of the genus Carcharodon based on dental characters shared between the fossil and extant species.…”

“…Therefore, the evolutionary transition from C. hastalis to C. carcharias occurred within a span of 6.9–5.3 Ma. (Long et al 2014 ; Boessenecker et al 2019 ).…”

The tooth of a giant sea creatureOtodus(Megaselachus) in the material culture of Neolithic maritime hunter‐gatherers at Sharbithat (Sultanate of Oman)

“…Whereas Otodus (Megaselachus) chubutensis lived during a period between the early and middle Miocene, O. (Megaselachus) megalodon lived from the middle Miocene to the early to mid-Pliocene(Boessenecker et al, 2019;…”