Torvoneustes

Torvoneustes Temporal range: Late Jurassic, 157.3–152.1 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Size of T. carpenteri
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Suborder:	†Thalattosuchia
Family:	†Metriorhynchidae
Tribe:	†Geosaurini
Genus:	†Torvoneustes Andrade et al., 2010
Type species
†Dakosaurus carpenteri Wilkinson et al., 2008
Species[1][2]
T. carpenteri (Wilkinson et al., 2008) T. coryphaeus Young et al., 2013 T. mexicanus (Wieland, 1910)
Synonyms
Dakosaurus carpenteri Wilkinson et al., 2008 Geosaurus carpenteri Young & Andrade, 2009

Torvoneustes is an extinct genus of metriorhynchid thalattosuchian. It is known from skull and postcranial remains found in the Kimmeridge Clay Formation of Dorset and Wiltshire, England, and also from Oaxaca, Mexico^[2][3] . The holotype skull of the type species was initially assigned to the species Metriorhynchus superciliosus. Postcranial remains were later discovered from the same quarry as the skull, and then these specimens were recognised as belonging to a new species of Dakosaurus, as D. carpenteri. The species was named to honour Simon Carpenter, an amateur geologist from Frome in Somerset, who discovered the fossils.^[4][5]

Dakosaurus carpenteri was later reassigned to the genus Geosaurus in 2008. Two years later, it was assigned to its own genus, Torvoneustes.^[6]

When T. carpenteri was considered a species of Dakosaurus, its relatively long snout and smaller, more numerous teeth were thought to be features retained from more basal metriorhynchids. Because of this, the species was seen as a transitional form between long-snouted, piscivorous metriorhynchids and hypercarnivorous, short-snouted species of Dakosaurus.^[4]

While Dakosaurus and Geosaurus have ziphodont dentition with teeth that are laterally compressed, Torvoneustes is unique in having a false-ziphodont dentition. The common ancestor of Dakosaurus and Geosaurus may also have had a ziphodont dentition, and as Torvoneustes is also a descendant of this common ancestor, it is possible that a ziphodont dentition was secondarily lost in the genus. However, it is also possible that Dakosaurus and Geosaurus acquired similar dentitions independently, and that Torvoneustes is not descended from a ziphodont ancestor.^[6]

Fossil teeth of a similar form were found also in the Czech Republic and formally published in 2021 (in a stratum dating to hauterivian, some 130 million years ago).^[7]

References[]

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