Articulated remains of the extinct shark Ptychodus (Elasmobranchii, Ptychodontidae) from the Upper Cretaceous of Spain provide insights into gigantism, growth rate and life history of ptychodontid sharks

Author(s)
Patrick Leopold Jambura, Jürgen Kriwet
Abstract

Due to their cartilaginous endoskeleton and the continuous tooth replacement, the chondrichthyan fossil record predominantly consists of isolated teeth, which offer diagnostic features for taxonomic identifications, but only provide very limited information of an organism’s life history. In contrast, the calcified vertebral centra of elasmobranchs (sharks, skates and rays) yield important information about ecological and biological traits that can be utilized for constructing age-structured population dynamic models of extant species and palaeoecological reconstructions of such aspects in extinct groups. Here, we describe two large shark vertebrae from the Santonian (Upper Cretaceous) of Spain, which show a unique combination of characters (asterospondylic calcification pattern, with concentric lamellae and numerous parallel bands that are oriented perpendicular) that is only known from ptychodontid sharks, a distinct, extinct group of giant durophagous sharks of the Cretaceous era. Based on linear regression models for large extant sharks a total length between 430 and 707cm was estimated for the examined specimen. Our results indicate that ptychodontid sharks were large viviparous animals, with slow growth rates, matured very late and, therefore, show typical traits for K-selected species. These traits combined with a highly specialized feeding ecology might have played a crucial role for the success but also, eventually, extinction of this group.

Organisation(s)
Department of Palaeontology
Journal
PLoS ONE
Volume
15
Pages
1-16
No. of pages
16
ISSN
1932-6203
DOI
https://doi.org/10.1371/journal.pone.0231544
Publication date
04-2020
Peer reviewed
Yes
Austrian Fields of Science 2012
106012 Evolutionary research, 105118 Palaeontology
Keywords
Portal url
https://ucrisportal.univie.ac.at/en/publications/4b8a10db-2d87-43c8-ad31-0b44a38e5d5b