A Review of the Paleobiology of Some Neogene Sharks and the Fossil Records of Extant Shark Species

In recent years, new findings and new methods (stable isotopes of oxygen, zinc, and nitrogen; 2D and 3D modeling; and geometric morphometric analyses of the teeth) have enhanced our knowledge of the Neogene shark fauna and its paleobiology. Several papers deal with the large <i>Otodus</i> (<i>Megaselachus</i>) species, including the construction of a 3D model, as well as insights into its lifestyle and diet. In addition, the skeletal remains of <i>Carcharias gustrowensis</i>, <i>Carcharodon hastalis</i>, and <i>Keasius parvus</i> and a natural tooth set of <i>Carcharodon hubbelli</i> have been described in the last 13 years, and the dentition of the Neogene species <i>Carcharoides catticus</i>, <i>Megachasma applegatei</i>, and <i>Parotodus benedenii</i> has been reconstructed. Stable isotope analyses of the teeth from the Neogene species of <i>Araloselachus</i>, <i>Carcharias</i>, <i>Carcharodon</i>, <i>Galeocerdo</i>, <i>Hemipristris</i>, and <i>Mitsukurina</i> have given insights into the trophic positions of these genera during the Neogene, and shark teeth preserved near the skeletal remains of prey animals (mammals) and shark bite traces on these remains provide direct evidence of trophic interactions. The tooth shape, fossil locality, and paleoenvironment have been used to better understand the taxa <i>Carcharhinus dicelmai</i>, <i>Megalolamna paradoxodon</i>, <i>Pachyscyllium dachiardii</i>, and <i>P. distans.</i> Among extant species, <i>Galeorhinus galeus</i> can be traced back to the Eocene. <i>Alopias superciliosus</i>, <i>Rhincodon typus,</i> and possibly <i>A. vulpinus</i> can be traced back to the Oligocene. Species present by the Miocene include <i>Alopias vulpinus</i>, <i>Carcharhinus amblyrhynchoides</i>, <i>C. amblyrhynchos</i>, <i>C. albimarginatus</i>, <i>C. amboinensis</i>, <i>C. brachyurus</i>, <i>C. brevipinna</i>, <i>C. falciformis</i>, <i>C. glaucus</i>, <i>C. leucas</i>, <i>C. limbatus</i>, <i>C. longimanus</i>, <i>C. macloti</i>, <i>C. obscurus</i>, <i>C. perezi</i>, <i>C. sealei, Centrophorus granulosus</i>, <i>Cetorhinus maximus</i>, <i>Dalatias licha</i>, <i>Deania calcea</i>, <i>Galeocerdo cuvier</i>, <i>Glyphis glyphis</i>, <i>Heptranchias perlo</i>, <i>Isurus paucus</i>, <i>Lamna nasus</i>, <i>Negaprion brevirostris</i>, <i>Odontaspis ferox</i>, <i>Pseudocarcharias kamoharai</i>, <i>Sphyrna media</i>, <i>S. mokarran</i>, and possibly <i>Carcharodon carcharias</i>. First appearing in the Pliocene are <i>Scymnodon ringens</i>, <i>Somniosus rostratus</i>, and <i>Zameus squamulosus</i>. For some extant species (<i>Carcharias taurus</i>, <i>Hexanchus griseus</i>, <i>Isurus oxyrinchus</i>, <i>Notorynchus cepedianus</i>, and <i>Sphyrna zygaena</i>), it is not clear whether the assigned Neogene teeth represent the same species. The application of new methods to more fossil shark taxa, a detailed search for shark fossils, and better knowledge of the dentition of extant species (especially those with minute-sized teeth) will further enhance our knowledge of the evolution and paleobiology of sharks.