Microcleidus
Extinct genus of reptiles
title: "Microcleidus" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["plesiosauroids", "early-jurassic-plesiosaurs-of-europe", "toarcian-genera", "jurassic-england", "fossils-of-england", "jurassic-france", "fossils-of-france", "jurassic-germany", "fossils-of-germany", "posidonia-shale", "fossil-taxa-described-in-1909", "sauropterygian-genera"] description: "Extinct genus of reptiles" topic_path: "geography/united-kingdom" source: "https://en.wikipedia.org/wiki/Microcleidus" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Extinct genus of reptiles ::
| fossil_range = Toarcian ~ | image = Microcleidus NHM.jpg | image_caption = Fossil M. homalospondylus | taxon = Microcleidus | authority = Watson, 1909 | type_species = Plesiosaurus homalospondylus | type_species_authority = (Owen, 1865) | subdivision_ranks = Other species | subdivision =
- M. macropterus (Seeley, 1865)
- M. tournemirensis (Sciau et al., 1990)
- M. melusinae Vincent et al., 2019 | synonyms = M. macropteus
- Plesiosaurus macropteus Seeley, 1865
- Eretmosaurus macropterus Benton and Spencer, 1995 M. tournemirensis
- Plesiosaurus tournemirensis Sciau et al., 1990
- Occitanosaurus tournemirensis Bardet et al., 1999
Microcleidus is an extinct genus of sauropterygian reptile belonging to the Plesiosauroidea. The species has 40 neck vertebrae and a short tail of 28 vertebrae. Fossils of the genus have been found in France, the Posidonia Shale in Germany and Luxembourg, and the Alum Shale Formation of England.
Description
::figure[src="https://upload.wikimedia.org/wikipedia/commons/0/02/Microcleidus_homalospondylus.png" caption="Restoration of ''M. homalospondylus''"] ::
The type species, M. homalospondylus, was the largest, measuring 5.1 m long and weighing 650 kg. Other species were smaller: M. tournemirensis was about 4 m long and weighed 300 kg, and M. melusinae was about 3 m long and weighed 120 kg.
Classification
::figure[src="https://upload.wikimedia.org/wikipedia/commons/4/42/'Microcleidus'_macropterus.jpg" caption="''M. macropterus'' skeleton in [[Sedgwick Museum"] ::
Species include: Microcleidus homalospondylus (Owen 1865) and Microcleidus macropterus (Seeley 1865).
Occitanosaurus tournemirensis (originally "Plesiosaurus" tournemirensis), was named by Sciau et al. in 1990, based on a nearly complete skeleton of an animal approximately 4 meters (13 ft) long.Ketchum HF, Benson RBJ. Global interrelationships of Plesiosaur (Reptilia, Sauropterygia) and the pivotal role of taxon sampling in determining the outcome of phylogenetic analyses. Biological Reviews It was later found to be a species of Microcleidus.
The following cladogram follows an analysis by Ketchum & Benson, 2011. |label1=Pistosauria |1={{clade |1="Pistosaurus postcranium" |2={{clade |1=Augustasaurus hagdorni |2=Bobosaurus forojuliensis |3=Pistosaurus |4=Yunguisaurus liae |label5=Plesiosauria |5={{clade |label1=Pliosauroidea |1={{clade |label1=Pliosauridae |1={{clade |1=Thalassiodracon hawkinsii |2={{clade |1=Hauffiosaurus spp. |2={{clade |1=Attenborosaurus conybeari |2=advanced pliosaurids }} }} }} |label2=Rhomaleosauridae |2={{clade |1=NHMUK OR 49202 [now Anningasaura lymense] |2={{clade |1=advanced rhomaleosaurids |2={{clade |1="Plesiosaurus" macrocephalus |2={{clade |1=Archaeonectrus rostratus |2=Macroplata tenuiceps }} }} }} }} }} |label2=Plesiosauroidea |2={{clade |1=OUMNH J.10337 [now Stratesaurus taylori] |2={{clade |label1=Plesiosauridae |1={{clade |1=Seeleyosaurus guilelmiimperatoris |2={{clade |1=OUMNH J.28585 |2=Plesiosaurus dolichodeirus }} }} |2={{clade |1=Elasmosauridae and Cryptoclidia |2={{clade |1=Microcleidus homalospondylus |2={{clade |1=Hydrorion brachypterygius |2=Occitanosaurus tournemiensis }} }} }} }} }} }} }} }} }}
References
References
- (2020). "A new elasmosaurid plesiosaurian from the Early Cretaceous of Russia marks an early attempt at neck elongation". Zoological Journal of the Linnean Society.
- Paul, Gregory S.. (2022). "The Princeton Field Guide to Mesozoic Sea Reptiles". Princeton University Press.
- (2011). "A new pliosaurid (Sauropterygia, Plesiosauria) from the Oxford Clay Formation (Middle Jurassic, Callovian) of England: evidence for a gracile, longirostrine grade of Early-Middle Jurassic pliosaurids". Special Papers in Palaeontology.
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