Re-appearance of hypercarnivore ichthyosaurs in the Cretaceous with differentiated dentition: revision of 'Platypterygius' sachicarum (Reptilia: Ichthyosauria, Ophthalmosauridae) from Colombia. (18th July 2021)

• Record Type: Journal Article
• Authors: Cortés, Dirley; Maxwell, Erin E.; Larsson, Hans C. E.
• Is Part Of: Journal of systematic palaeontology. Volume 19:Number 14(2021)
• Page Start: 969
• Page End: 1002
• Publication Date: 2021-07-18
• Subjects: Platypterygius sachicarum -- Ophthalmosauridae -- Early Cretaceous -- South America -- Colombia -- Paja Formation; Paleontology -- Periodicals; Paleontology -- Methodology -- Periodicals; 560.5
• DOI: 10.1080/14772019.2021.1989507
• Languages: English
• ISSNs: 1478-0941

Abstract

Abstract : Early Cretaceous ichthyosaur diversity has markedly increased in recent years with the discovery of new taxa in the field and in museum collections. This has led to new characters, and a better understanding of taxonomically informative anatomy. Here, we re-describe the holotype of the ophthalmosaurid Platypterygius sachicarum from the Barremian–Aptian of Colombia and place these data in a phylogenetic context. The validity of the species is supported by several new characters of the narial region, mandible and dentition. The dentition is unique among ichthyosaurs in that it presents several discrete tooth morphologies that range from piercing to cutting to crushing. In combination, these cranial specializations imply a large vertebrate diet and make this taxon the first Cretaceous hypercarnivorous ichthyosaur. Differences from the type species of Platypterygius, P. platydactylus, include a suite of characters associated with differing feeding ecologies and the complex external nares. The large number of character differences and revised phylogenetic relationships are used to remove the Colombian taxon from Platypterygius and recognize it as a new genus, Kyhytysuka sachicarum comb. nov. A revised set of taxonomic definitions are proposed for Ophthalmosauria to maintain stability at this important node. Kyhytysuka sachicarum opens new questions regarding the diversity and paleobiogeography of Early Cretaceous ichthyosaurs from northern Gondwana and highlights the importance of individually assessing each ' Platypterygius ' species and, potentially, specimen to better understand the diversity of this broadly distributed taxon. http://zoobank.org/urn:lsid:zoobank.org:pub:E3FD55AF-2AD1-46CA-A49C-1FB4B102AB2C