Teeth are a potentially rich source of character data for phylogenetic studies of living and fossil sharks, but there are many uncertainties about the homologies of tooth loci as well as structural details of teeth in different taxa. Here, we provide new developmental data on the so-called lateral cusplets of the teeth in Lamniformes. We studied the five living species of Lamnidae (Lamna nasus, L. ditropis, Isurus oxyrinchus, I. paucus, and Carcharodon carcharias) and a more basal lamniform, the Sand Tiger Carcharias taurus, using light microscopy and micro-CT scanning. We also studied a single skeletal specimen of the smalltooth Sand Tiger, Odontaspis ferox. Structures in the teeth of juvenile White Sharks, C. carcharias, were interpreted as lateral cusplets in some previous studies, but we show that they develop differently from lateral cusplets in the teeth of Lamna and Carcharias. We conclude that the structures in Carcharodon are not homologous to the lateral cusplets of Lamna and Carcharias taurus a...

This study describes the teeth, dentition, and tooth replacement pattern of the Gulper Shark, Centrophorus granulosus, using histology and micro-CT scanning. Tooth microstructure and the orthodont histotype of C. granulosus are described and illustrated, and tooth morphology is discussed in the context of squaliform phylogenetic studies. Dental characters previously used to study squaliform interrelationships need revision. The dentitions of adult and near-term pups are documented to illustrate ontogenetic changes in tooth morphology as well as the pattern of tooth replacement. Based on the positions of replacement teeth in each tooth file, the replacement pattern of the palatoquadrate dentition is best described as phased sinusoidal replacement. This study also documents the monognathic and dignathic heterodonty of pups and adults, confirming previously published descriptions of heterodonty that have proven to be of taxonomic significance. A revised dental formula is provided that better reflects the too...

Reassessment of the possible size, form, weight, cruising speed, and growth parameters of the extinct megatooth shark, Otodus megalodon (Lamniformes: Otodontida