Ontogenetic parameters and life history strategies of the late Cretaceous lamniform shark, Cretoxyrhina mantelli, based on vertebral growth increments

Abstract

ABSTRACT Cretoxyrhina mantelli is a Late Cretaceous lamniform shark that possibly resembled the modern white shark (Carcharodon carcharias) in size, body form, and feeding strategies. Here, a previously identified set of growth increment (= periodic marker) bands in a vertebra from an individual of Cretoxyrhina mantelli (5 m in total length [TL]) is used as a model to quantitatively infer the ontogenetic development and life history strategies of the fossil shark. The results indicate that its length at birth was large, and that the early part of its life history was marked by a comparably rapid growth, which could have helped the neonatal C. mantelli to efficiently exploit prey items while deterring potential predators. The von Bertalanffy growth function (VBGF) experimentally fitted to the data gives the following estimated growth parameters: the length at birth (L 0) of 1.28 m TL, the asymptotic length (L ∞) of 6.91 m TL, and the rate constant with units of reciprocal time (k) of 0.073 yr−1. The large maximum length indicates that individuals may have weighed 3,400 kg. The VBGF parameters also indicate that the longevity of C. mantelli was possibly up to about 38 years. This study shows that many aspects of ontogeny and life history of C. mantelli are similar to those of the modern white shark, and that a single shark fossil may offer a wealth of biological information.