The Deep Past of the White Shark, Carcharodon carcharias, in the Mediterranean Sea: A Synthesis of Its Palaeobiology and Palaeoecology

Abstract

The white shark, Carcharodon carcharias, is the main top predator of the present-day Mediterranean Sea. The deep past of C. carcharias in the Mediterranean is witnessed by a rather conspicuous, mostly Pliocene fossil record. Here, we provide a synthesis of the palaeobiology and palaeoecology of the Mediterranean white sharks. Phenetically modern white shark teeth first appeared around the Miocene–Pliocene transition in the Pacific, and soon after in the Mediterranean. Molecular phylogenetic analyses support an origin of the Mediterranean white shark population from the dispersal of Australian/Pacific palaeopopulations, which may have occurred through the Central American Seaway. Tooth dimensions suggest that the Mediterranean white sharks could have grown up to about 7 m total length during the Pliocene. A richer-than-today marine mammal fauna was likely pivotal in supporting the Mediterranean white sharks through the Pliocene and most of the Quaternary. White sharks have seemingly become more common as other macropredators declined and disappeared, notwithstanding the concurrent demise of many potential prey items in the context of the latest Pliocene and Quaternary climatic and environmental perturbations of the Mediterranean region. The overall generalist trophic habits of C. carcharias were likely crucial for securing ecological success in the highly variable Mediterranean scenario by allowing the transition to a mostly piscivorous diet as the regional marine mammal fauna shrank.

Analysing Trophic Competition in †Otodus megalodon and Carcharodon carcharias through 2D-SEM Dental Microwear

“…A potential biotic factor in the extinction of † O. megalodon is the competition with other marine raptorial macropredatory taxa, with large odontocetes being classically considered competitors (see Pimiento et al, 2016;and references therein). Also of special importance is the emergence of morphologically recognisable modern Carcharodon dental remains on the Mio-Pliocene fossil record (Ehret et al, 2009(Ehret et al, , 2012Pimiento et al, 2016;Collareta et al, 2023a) Herraiz et al, 2020;Cooper et al, 2020Cooper et al, , 2022 and are apex predators occupying higher trophic levels (Martin et al, 2015;Kast et al, 2022;McCormack et al, 2022). These facts, combined with evidence from the fossil record (see Purdy, 1996;Godfrey & Altman, 2005;Aguilera et al, 2008;Kallal et al, 2012;Antunes et al, 2015;Carrillo-Briceño et al, 2016;Collareta et al, 2017a;Godfrey et al, 2018Godfrey et al, , 2021Godfrey & Beatty, 2022), have led to propose that both species could compete for the same trophic resources.…”

Late Miocene transformation of Mediterranean Sea biodiversity

“…In the lowermost Pliocene, published occurrences taxa like Carcharocles megalodon and Hemipristis serra hint at the persistence of the Miocene structure of the Mediterranean fauna during the Early Zanclean ( 122 ). Other relic Miocene species (e.g., Megascyliorhinus miocaenicus , Pachyscyllium dachiardii , Pachyscyllium distans , Cosmopolitodus plicatilis and Parotodus benedeni ) even persisted in the Mediterranean until the mid-Pliocene at least ( 123 , 124 ). In the Late Miocene and Early Pliocene, Carcharhinus was likely the most speciose shark genus in the Mediterranean.…”

The Palaeobiology of the False Mako Shark, Parotodus benedenii (Le Hon, 1871): A View from the Pliocene Mediterranean Sea

“…Even if false makos did not exceed the more conservative 7.6 m total length estimate, this figure would make the largest individuals of P. benedenii much larger than any modern or fossil specimen of white shark (Carcharodon carcharias) for which a total body length has been reliably measured/estimated (up to ca. 7 m or slightly more; [63,64]).…”

“…Unlike what is known for C. carcharias, a predilection for farshore, essentially pelagic settings would have made coastal animals such as seals only rarely available as potential prey items for P. benedenii [73]. In turn, it is reasonable to hypothesise that large vertebrate carcasses drifting in the open sea would have provided the piercing-lacerating dentition of the essentially pelagic P. benedenii with relatively soft carrion to dismember and forage on, especially in the cetacean-rich Pliocene Mediterranean palaeobiotopes [64,74]. All things considered, significant differences in tooth design and dentition, which we interpret as witnessing to an only partial overlap of dietary spectra, suggest that a certain degree of trophic partitioning existed between P. benedenii and other elasmobranch apex predators of the Mediterranean Basin and other Neogene mid-latitude seas, including, in Pliocene times, the extant species C. carcharias, Carcharhinus leucas and Galeocerdo cuvier.…”