Giant prehistoric sharks left their young in nurseries

IF SHARKS HAD bony skeletons, which preserve easily as fossils, rather than cartilaginous ones, which do not, then Otodus megalodon would probably be as famous as Tyrannosaurus rex. Even though only its teeth are routinely available for study, it has starred in at least one film, “The Meg”, released in 2018. Were it better known, a whole ocean-based franchise akin to “Jurassic Park” might now exist.

No matter. It is still an intriguing animal. Adults are reckoned to have reached a length of 18 metres. (T. rex was 12 metres from snout to tip of tail.) And megalodons, as they are called colloquially, lasted as a species from the beginning of the Miocene epoch 23m years ago to 3m years ago, during the Pliocene. That is far longer than T. rex’s brief appearance 68m-66m years ago at the end of the Cretaceous. Their family life has, however, hitherto been obscure.