Prehistoric Sharks

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Short article with Megalodon expert Dr. Catalina Pimiento telling differences between myths and reality.

https://www.bbc.com/news/science-environment-45145981

One study about Megalodon.

Quotes: 

"Life stage and total length estimates


The tooth size comparisons made in this research suggest that the small size of C. megalodonteeth from the Gatun Formation is not related to temporal differences within a chronoclinally evolving species or to the tooth position within the jaw (as described above); but rather they belong to juvenile sharks. When only the teeth of a shark species are preserved, life (ontogenetic) stages of individuals can be predicted in two different ways: (1) studying morphological features of the teeth during juvenile stages; and (2) extrapolating total length using the relationship between body size and tooth crown height.
(1) In C. megalodon, teeth of juveniles sometimes demonstrate lateral cusplets [15] or not [22]. For example, UF 237914 (a lateral tooth) exhibits lateral cusplets and is assumed to be from a juvenile. On the other hand, UF 237959 (a lower anterior tooth) and UF 237949 (an upper anterior) are both very small teeth that exhibit no lateral cusplets (Figure 2). The latter teeth are small thick, heart-shaped, and are considered to represent embryonic C. megalodon teeth (Hubbell teeth). These latter teeth retain the morphology of the species even at small sizes and do no demonstrate lateral cusplets [22].
(2) Gottfried et al. (1996) [14] made inferences about the skeletal anatomy of C. megalodonbased on comparisons with ontogenetic trends in the white shark, Carcharodon carcharias. They deduced that a C. megalodon fetus could reach ∼4 m, juveniles ∼10.5 m, and adults more than 10.5 m (∼17 m). Based on crown heights (CH) and following the work of Shimada (2003) [39], we estimate the total lengths (TL) of C. megalodon specimens from the Gatun Formation (Table 1). Based on Gottfried et al.'s inferences, the total length estimates made in this research suggest that the C. megalodon specimens from the Gatun Formation represent mostly juveniles (21 individuals), with total lengths less than 10.5 m, while a few specimens (7 individuals) are interpreted as adults, with an estimated total lengths beyond 10.5 m (Figure 5)"

Source: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010552 Reply