Body-size trends of the extinct giant sharkCarcharocles megalodon: a deep-time perspective on marine apex predators

Abstract

The extinct shark Carcharocles megalodon is one of the largest marine apex predators ever to exist. Nonetheless, little is known about its body-size variations through time and space. Here, we studied the body-size trends of C. megalodon through its temporal and geographic range to better understand its ecology and evolution. Given that this species was the last of the megatooth lineage, a group of species that shows a purported size increase through time, we hypothesized that C. megalodon also displayed this trend, increasing in size over time and reaching its largest size prior to extinction. We found that C. megalodon body-size distribution was left-skewed (suggesting a long-term selective pressure favoring larger individuals), and presented significant geographic variation (possibly as a result of the heterogeneous ecological constraints of this cosmopolitan species) over geologic time. Finally, we found that stasis was the general mode of size evolution of C. megalodon (i.e., no net changes over time), contrasting with the trends of the megatooth lineage and our hypothesis. Given that C. megalodon is a relatively long-lived species with a widely distributed fossil record, we further used this study system to provide a deep-time perspective to the understanding of the body-size trends of marine apex predators. For instance, our results suggest that (1) a selective pressure in predatory sharks for consuming a broader range of prey may favor larger individuals and produce left-skewed distributions on a geologic time scale; (2) body-size variations in cosmopolitan apex marine predators may depend on their interactions with geographically discrete communities; and (3) the inherent characteristics of shark species can produce stable sizes over geologic time, regardless of the size trends of their lineages.

Late Miocene chondrichthyans from Lago Bayano, Panama: Functional diversity, environment and biogeography

“…For a more detailed discussion on this topic see Pimiento et al (2010). In the Chucunaque Formation, C. megalodon is intermediate in size between that of the Gatun Formation and the Yorktown Formation (Purdy et al, 2001;Pimiento et al, 2013a;Pimiento and Balk, 2015), but more closely aligns with the size range observed in the Gatun Formation, which has been proposed to be a paleonursery for C. megalodon . The lack of lateral cusplets and a broader crown are said to delineate C. megalodon from Carcharocles chubutensis, although neither of those characteristics is absolutely definitive (Kent, 1994).…”

Evolutionary pathways toward gigantism in sharks and rays

“…For instance, the largest sharks ever recorded (both ∼18 m in length) are the ectothermic, filter‐feeding whale shark ( Rhincodon typus ), and the extinct megalodon († Otodus megalodon ), a presumed mesotherm and the largest marine macropredator to ever live (McClain et al. ; Pimiento and Balk ; Ferrón ; Ferrón et al. ).…”

“…Crown group elasmobranchs have an evolutionary history of at least 250 million years (Cappetta 2012), and extremely large body sizes have arisen in phylogenetically distant and ecologically disparate species. For instance, the largest sharks ever recorded (both ß18 m in length) are the ectothermic, filter-feeding whale shark (Rhincodon typus), and the extinct megalodon ( †Otodus megalodon), a presumed mesotherm and the largest marine macropredator to ever live (McClain et al 2015;Pimiento and Balk 2015;Ferrón 2017;Ferrón et al 2017). Patterns of body size evolution, and the preadaptive underpinnings of convergent gigantism, have never previously been evaluated across elasmobranchs within a phylogenetic framework.…”

A New Early Miocene (Aquitanian) Elasmobranchii Assemblage from the la Guajira Peninsula, Colombia

“…In the Neogene deposits, Carcharocles are mainly represented by Carcharocles chubutensis Ameghino, 1901 and Carcharocles megalodon Agassiz, 1843(e.g., Pimiento et al, 2010, 2013aPimiento and Clements, 2014;Pimiento and Balk, 2015). While Carcharocles chubutensis ranges from the early to the middle Miocene, Carcharocles megalodon ranges from the middle Miocene to the late Pliocene (Pimiento and Balk, 2015).…”

“…According to Pimiento et al (2013a), the teeth of sub-adult and adult specimens of C. megalodon during the late Miocene. This phenomenon is a heterochronic process by which the ontogenetic changes mimic the changes in the Carcharocles clade throughout geologic time (Applegate and Espinosa-Arrubarrena, 1996;Ward and Bonavia, 2001;Pimiento et al, 2010Pimiento et al, , 2013aPimiento and Balk, 2015). According to Pimiento et al (2013a) Carcharocles chubutensis can be distinguished from C. megalodon based on the age of the fossils, e.g., an early Miocene specimen would be C. chubutensis while a late Miocene specimen would be C. megalodon.…”