When Did Megalodon Become Extinct?

Megalodon, the giant prehistoric shark, is believed to have gone extinct around 3.6 million years ago during the late Miocene to early Pliocene epoch. Various factors, including changes in ocean temperatures, shifts in prey availability, and competition with other marine predators, likely contributed to its extinction.

Historical Context of Megalodon

Megalodon first appears in the fossil record around 20 million years ago and enjoyed a 13 million-year reign before becoming extinct just 3.6 million years ago. This period is considered relatively short compared to other massive sea creatures. The primary method of dating fossilized Megalodon teeth, the only part of the species to survive to the present, involves dating the strata they were found in.

Environmental Changes Affecting Megalodon

Global Cooling Trends: The Earth experienced a cooling trend starting in the Oligocene, 350 million years ago, ultimately leading to glaciation at the poles. Geological events such as the closure of the Central American Seaway and changes in the Tethys Ocean contributed to the cooling of the oceans. The stalling of the Gulf Stream prevented nutrient-rich water from reaching major marine ecosystems, potentially affecting the food sources of Megalodon. The largest fluctuation of sea levels in the Cenozoic era occurred between 5 million and 12,000 years ago due to the expansion of glaciers at the poles, negatively impacting coastal environments and contributing to its extinction along with several other marine megafaunal species.

Fossil Evidence and Climate Impact

The Earth's climate during the time Megalodon existed imposed significant challenges on the species. The cooling of oceans and sea level drops may have restricted many of the suitable shallow warm-water nursery sites for Megalodon, hindering reproduction. Nursery areas are crucial for the survival of many shark species, as they protect juveniles from predation. As its range did not extend into colder waters, Megalodon was restricted to shrinking warmer waters, and evidence confirms the species' absence in regions where water temperatures had significantly declined during the Pliocene. However, an analysis of the distribution of Megalodon over time suggests that temperature change did not play a direct role in its extinction. Its distribution during the Miocene and Pliocene did not correlate with warming and cooling trends, while abundance and distribution declined during the Pliocene, showing that it could inhabit colder latitudes.

Competition and Ecological Factors

Megalodon's extinction correlates with the decline of many small mysticete lineages, indicating a potential food source dependency. Additionally, a marine megafauna extinction during the Pliocene eliminated 36% of all large marine species, including 55% of marine mammals, 35% of seabirds, 9% of sharks, and 43% of sea turtles. This selectivity for endotherms and mesotherms implies causation by a decreased food supply, consistent with Megalodon being mesothermic. Competition from large odontocetes, such as macropredatory sperm whales, including species like Orcinus citoniensis, is also assumed to have contributed to the decline and extinction of Megalodon. However, recent studies show that orcinine dolphins were not macrophagous and fed on small fishes, while gigantic macropredatory sperm whales like Livyatan-like forms disappeared during the Pliocene.

Impact on Marine Ecosystems

The extinction of Megalodon resulted in significant changes within marine communities. The average body size of baleen whales increased significantly after its disappearance, possibly due to other climate-related causes. Conversely, the increase in baleen whale size may have contributed to the extinction of Megalodon as they may have preferred to go after smaller whales. Megalodon may have become coextinct with smaller whale species like Piscobalaena nana. The extinction of Megalodon had a positive impact on other apex predators of the time, such as the great white shark, as they spread to regions where Megalodon became absent.