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When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record

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ABSTRACT

Carcharocles megalodon (“Megalodon”) is the largest shark that ever lived. Based on its distribution, dental morphology, and associated fauna, it has been suggested that this species was a cosmopolitan apex predator that fed on marine mammals from the middle Miocene to the Pliocene (15.9–2.6 Ma). Prevailing theory suggests that the extinction of apex predators affects ecosystem dynamics. Accordingly, knowing the time of extinction of C. megalodon is a fundamental step towards understanding the effects of such an event in ancient communities. However, the time of extinction of this important species has never been quantitatively assessed. Here, we synthesize the most recent records of C. megalodon from the literature and scientific collections and infer the date of its extinction by making a novel use of the Optimal Linear Estimation (OLE) model. Our results suggest that C. megalodon went extinct around 2.6 Ma. Furthermore, when contrasting our results with known ecological and macroevolutionary trends in marine mammals, it became evident that the modern composition and function of modern gigantic filter-feeding whales was established after the extinction of C. megalodon. Consequently, the study of the time of extinction of C. megalodon provides the basis to improve our understanding of the responses of marine species to the removal of apex predators, presenting a deep-time perspective for the conservation of modern ecosystems.

No MeSH data available.


Temporal distribution of the inferred dates of extinction of Carcharocles megalodon using the Optimal Linear Estimation (OLE) model bootstrapped 10,000 times.The orange area shows the distribution of inferred dates of extinction through time, whereas the green line shows the cumulative frequency of inferred dates of extinction. The modal peak represents the point in time by which the species was most likely to have gone extinct (2.6 Ma). Approximately 50% of simulations fell before the modal peak of inferred dates of extinction (2.6 Ma), whereas the remaining 50% are roughly evenly distributed between the mode and the present day. The two vertical dashed lines indicate the most recent and oldest inferred dates of extinction (160,000 years in the future and 3.5 Ma respectively). The horizontal bars represent the time range of each fossil occurrence. The blue bars are the occurrences used in OLE. The grey bar represents the occurrences that failed the age evaluation process and were not used in the analysis.
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pone-0111086-g001: Temporal distribution of the inferred dates of extinction of Carcharocles megalodon using the Optimal Linear Estimation (OLE) model bootstrapped 10,000 times.The orange area shows the distribution of inferred dates of extinction through time, whereas the green line shows the cumulative frequency of inferred dates of extinction. The modal peak represents the point in time by which the species was most likely to have gone extinct (2.6 Ma). Approximately 50% of simulations fell before the modal peak of inferred dates of extinction (2.6 Ma), whereas the remaining 50% are roughly evenly distributed between the mode and the present day. The two vertical dashed lines indicate the most recent and oldest inferred dates of extinction (160,000 years in the future and 3.5 Ma respectively). The horizontal bars represent the time range of each fossil occurrence. The blue bars are the occurrences used in OLE. The grey bar represents the occurrences that failed the age evaluation process and were not used in the analysis.

Mentions: Results from applying OLE to our set of most recent records show that the modal inferred time of extinction is 2.6 Ma. This suggests that C. megalodon was unlikely to have survived beyond this time, with extinction time thus likely to have occurred between 3.5 Ma (oldest inferred extinction date), and this modal value (Figure 1). Approximately 50% of the simulations inferred the extinction event to have occurred before 2.6 Ma (modal value), with the remaining 50% of simulations being roughly uniformly distributed between 2.6 Ma and 0.1 Ma (Figure 1). In a very small proportion of simulations (1.5%), the inferred date of extinction fell after 0.1 Ma. In six simulations (0.06%) the inferred date of extinction fell after the present day (and thus the species could not be considered as extinct). However, because in the vast majority of the 10,000 simulations (>99.9%) the extinction time was inferred to have occurred before the present day, we reject the hypothesis (that the species is extant) and the popular claims of present day survival of C. megalodon.


When Did Carcharocles megalodon Become Extinct? A New Analysis of the Fossil Record
Temporal distribution of the inferred dates of extinction of Carcharocles megalodon using the Optimal Linear Estimation (OLE) model bootstrapped 10,000 times.The orange area shows the distribution of inferred dates of extinction through time, whereas the green line shows the cumulative frequency of inferred dates of extinction. The modal peak represents the point in time by which the species was most likely to have gone extinct (2.6 Ma). Approximately 50% of simulations fell before the modal peak of inferred dates of extinction (2.6 Ma), whereas the remaining 50% are roughly evenly distributed between the mode and the present day. The two vertical dashed lines indicate the most recent and oldest inferred dates of extinction (160,000 years in the future and 3.5 Ma respectively). The horizontal bars represent the time range of each fossil occurrence. The blue bars are the occurrences used in OLE. The grey bar represents the occurrences that failed the age evaluation process and were not used in the analysis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4206505&req=5

pone-0111086-g001: Temporal distribution of the inferred dates of extinction of Carcharocles megalodon using the Optimal Linear Estimation (OLE) model bootstrapped 10,000 times.The orange area shows the distribution of inferred dates of extinction through time, whereas the green line shows the cumulative frequency of inferred dates of extinction. The modal peak represents the point in time by which the species was most likely to have gone extinct (2.6 Ma). Approximately 50% of simulations fell before the modal peak of inferred dates of extinction (2.6 Ma), whereas the remaining 50% are roughly evenly distributed between the mode and the present day. The two vertical dashed lines indicate the most recent and oldest inferred dates of extinction (160,000 years in the future and 3.5 Ma respectively). The horizontal bars represent the time range of each fossil occurrence. The blue bars are the occurrences used in OLE. The grey bar represents the occurrences that failed the age evaluation process and were not used in the analysis.
Mentions: Results from applying OLE to our set of most recent records show that the modal inferred time of extinction is 2.6 Ma. This suggests that C. megalodon was unlikely to have survived beyond this time, with extinction time thus likely to have occurred between 3.5 Ma (oldest inferred extinction date), and this modal value (Figure 1). Approximately 50% of the simulations inferred the extinction event to have occurred before 2.6 Ma (modal value), with the remaining 50% of simulations being roughly uniformly distributed between 2.6 Ma and 0.1 Ma (Figure 1). In a very small proportion of simulations (1.5%), the inferred date of extinction fell after 0.1 Ma. In six simulations (0.06%) the inferred date of extinction fell after the present day (and thus the species could not be considered as extinct). However, because in the vast majority of the 10,000 simulations (>99.9%) the extinction time was inferred to have occurred before the present day, we reject the hypothesis (that the species is extant) and the popular claims of present day survival of C. megalodon.

View Article: PubMed Central - PubMed

ABSTRACT

Carcharocles megalodon (“Megalodon”) is the largest shark that ever lived. Based on its distribution, dental morphology, and associated fauna, it has been suggested that this species was a cosmopolitan apex predator that fed on marine mammals from the middle Miocene to the Pliocene (15.9–2.6 Ma). Prevailing theory suggests that the extinction of apex predators affects ecosystem dynamics. Accordingly, knowing the time of extinction of C. megalodon is a fundamental step towards understanding the effects of such an event in ancient communities. However, the time of extinction of this important species has never been quantitatively assessed. Here, we synthesize the most recent records of C. megalodon from the literature and scientific collections and infer the date of its extinction by making a novel use of the Optimal Linear Estimation (OLE) model. Our results suggest that C. megalodon went extinct around 2.6 Ma. Furthermore, when contrasting our results with known ecological and macroevolutionary trends in marine mammals, it became evident that the modern composition and function of modern gigantic filter-feeding whales was established after the extinction of C. megalodon. Consequently, the study of the time of extinction of C. megalodon provides the basis to improve our understanding of the responses of marine species to the removal of apex predators, presenting a deep-time perspective for the conservation of modern ecosystems.

No MeSH data available.