Late Miocene Otodus (Megaselachus) megalodon from Brunei Darussalam: Body length estimation and habitat reconstruction

Otodus (Megaselachus) megalodon is the biggest macro-predatory shark that ever lived on the Earth. The presence of this enigmatic shark in the fossil record of the Indo-Australian Archipelago has been generally overlooked; therefore a brief overview is given here about its occurrences. So far, its fossils have only been reported from Java and Madura in Indonesia and recently from Brunei on the island of Borneo. Here a detailed description of the Bruneian teeth is given and based on the tooth sizes, total body lengths (TL) are estimated. This is achieved by comparison with the great white shark, which is considered the closest modern ecological analogue of the megalodon. Our results show that the late Miocene megalodons of Brunei had a TL range between 5.5 and 7.1 meters. This is considered to be juvenile life stage as adults (>10 m) could have reached more than 16m. The teeth derived from shallow marine coastal settings, hence the presence of the juvenile megalodons in the fauna could indicate either (1) looking for easy food resource, which was abundant in terms of smaller sharks, rays and bony fishes and/or (2) staying in the shallows might have served protection avoiding larger predators such as mature megalodons or toothed whales.