Martinectes Temporal range: Late Cretaceous (late Campanian), | |
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Skeleton mount, University of Michigan Museum of Natural History | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Superorder: | † Sauropterygia |
Order: | † Plesiosauria |
Family: | † Polycotylidae |
Subfamily: | † Polycotylinae |
Clade: | † Dolichorhynchia |
Genus: | † Martinectes Clark, O'Keefe & Slack, 2023 |
Type species | |
†Martinectes bonneri Adams, 1997 | |
Synonyms | |
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Martinectes is an extinct genus of polycotylid plesiosaur from the Late Cretaceous (Campanian stage) of North America and possibly European Russia. The genus contains a single species M. bonneri, known from multiple skeletons and skulls. Martinectes was historically considered to represent a species of the genus Trinacromerum and later Dolichorhynchops before it was moved to its own genus. [1] It was a large polycotylid measuring around 5.5–7 metres (18–23 ft) long.
Two very large specimens of a polycotylid plesiosaur (KUVP 40001 and 40002 [2] ) were collected from the Pierre Shale of Wyoming and later reported on by Adams in her 1997 Masters thesis, and in the same year, she officially described the specimens as a new species of Trinacromerum (T. bonneri). The specific name honoured University of Kansas preparator Orville Bonner. [3] Unknown to her at the time, Carpenter (1996) had revised the Polycotylidae and separated Dolichorhynchops from Trinacromerum, raising the question as to whether or not the specimens represented a separate species or just larger individuals of D. osborni. [4] A study in 2008 found that T. bonneri is a valid species of Dolichorhynchops, D. bonneri. [5] In 2023, Clark, O'Keefe and Slack assigned D. bonneri from the Sharon Springs Formation of the United States to a new genus Martinectes, which means "Martin's swimmer". [1] In 2025, polycotylid teeth material from the Rybushka Formation of European Russia were referred to cf. Martinectes. [6]
Martinectes was a large polycotylid plesiosaur. In 2017, Everhart suggested that KUVP 40001 would have measured up to 6–7 metres (20–23 ft) in length. [7] In 2025, Zverkov and Meleshin suggested that Martinectes would have been similar in size to Polycotylus, around 5.5 metres (18 ft) long. [6]
Clark, O'Keefe & Slack (2023) recovered Martinectes as a polycotylid member of the plesiosaur clade Leptocleidia, as the sister taxon to an unnamed polycotyline from the Niobrara Formation. This clade, in turn, is sister to Unktaheela . These species, together with Dolichorhynchops spp. (D. osborni and D. herschelensis), form the clade Dolichorhynchia within the Polycotylinae. The results of their phylogenetic analyses are shown in the cladogram below: [1]