Polycotylidae

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title: "Polycotylidae" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["polycotylidae", "sauropterygian-families", "cretaceous-plesiosaurs", "aptian-first-appearances", "maastrichtian-extinctions"] description: "Extinct family of reptiles" topic_path: "general/polycotylidae" source: "https://en.wikipedia.org/wiki/Polycotylidae" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Extinct family of reptiles ::

| name = Polycotylids | fossil_range = Early - Late Cretaceous, | image = Martinectes transparent background.png | image_upright = 1.15 | image_caption = Martinectes in the Rocky Mountain Dinosaur Resource Center | image2 = Sulcusuchus erraini.png | image2_caption = Life restoration of Sulcusuchus erraini | taxon = Polycotylidae | authority = Williston, 1909 | subdivision_ranks = Genera | subdivision = *Edgarosaurus

• Manemergus
• Mauriciosaurus
• Piratosaurus?
• Rarosaurus?
• Thililua
• Occultonectia
  • Plesiopleurodon
  • Sulcusuchus
• Palmulasaurinae
  • Pahasapasaurus
  • Palmulasaurus
• Polycotylinae
  • Eopolycotylus
  • Georgiasaurus
  • Polycotylus
  • Scalamagnus
  • Serpentisuchops
  • Trinacromerum
  • Dolichorhynchia
    • Dolichorhynchops
    • Martinectes
    • Unktaheela

Polycotylidae is a family of plesiosaurs from the Cretaceous. Polycotylids first appeared during the Albian stage of the Early Cretaceous, before becoming abundant and widespread during the early Late Cretaceous. Several species survived into the final stage of the Cretaceous, the Maastrichtian around . The possible latest surviving member Rarosaurus from the late Maastrichtian is more likely a crocodylomorph.

With their short necks and large elongated heads, they resemble the pliosaurs, but phylogenetic studies indicate that they are plesiosauroids, being most closely related to Leptocleididae and more distantly to Elasmosauridae. They have been found worldwide, with specimens reported from New Zealand, Australia, Japan, Morocco, the US, Canada, Eastern Europe, and South America.

Phylogeny

Cladogram after Albright, Gillette and Titus (2007).

|label1=Plesiosauria |1={{clade |1=Plesiosaurus |2=Tricleidus |label3=Polycotylidae |3={{clade |1=Edgarosaurus |2={{clade |1=Thililua |2={{clade |label1=Palmulainae |1={{clade |1=UMUT MV 19965 (from Japan) |2=Pahasapasaurus (=AMM 98.1.1) |3=Palmulasaurus }} |label2=Polycotylinae |2={{clade |1=Dolichorhynchops |2={{clade |1=Trinacromerum |2={{clade |1=Eopolycotylus |2=Polycotylus

Cladogram after Ketchum and Benson (2010).

|label1=Plesiosauroidea |1={{clade |1=Cryptoclididae |label2=Leptocleidia |2={{clade |1=Leptocleididae |label2=Polycotylidae |2={{clade |1=Plesiopleurodon |2={{clade |1=Edgarosaurus |2={{clade |1=QM F18041 |2={{clade |1=Eopolycotylus |2={{clade |1=Trinacromerum |2={{clade |1=Dolichorhynchops herschelensis |2={{clade |1=Dolichorhynchops |2=Manemergus |3=Palmulasaurus }} }} }} }} }} }} }} }} }} }}

Below is a cladogram of polycotylid relationships from Ketchum & Benson, 2011.

|label1=Plesiosauroidea |1={{clade |1=Cryptoclididae |label2=Leptocleidia |2={{clade |1=Leptocleididae |label2=Polycotylidae |2={{clade |1=Edgarosaurus |2={{clade |1={{clade |1=Plesiopleurodon |2=QM F18041 }} |2={{clade |1={{clade |1=Eopolycotylus |2=Polycotylus |3=Thililua }} |2={{clade |1=Trinacromerum |2={{clade |1=Manemergus |2={{clade |1=Dolichorhynchops herschelensis |2={{clade |1=Dolichorhynchops |3=Palmulasaurus }} }} }} }} }} }} }} }} }} }}

References

References

1. (2018). "The evolutionary history of polycotylid plesiosaurians". Royal Society Open Science.
2. (2023-12-24). "A new genus of small polycotylid plesiosaur from the Upper Cretaceous of the Western Interior Seaway and a clarification of the genus ''Dolichorhynchops''". [[Cretaceous Research]].
3. (March 2018). "The evolutionary history of polycotylid plesiosaurians". Royal Society Open Science.
4. (2024). "Recovering lost time in Syria: New Late Cretaceous (Coniacian-Santonian) elasmosaurid remains from the Palmyrides mountain chain". Cretaceous Research.
5. (2009). "Earliest North American Occurrence Of Polycotylidae (Sauropterygia: Plesiosauria) From The Lower Cretaceous (Albian) Clearwater Formation, Alberta, Canada". Journal of Paleontology.
6. Albright III, L. B., Gillette, D. D., and Titus, A. L., 2007b. [http://www.plesiosaur.com/database/pdf/albrightetal_2007_part2.pdf Plesiosaurs from the Upper Cretaceous (Cenomanian-Turonian) Tropic Shale of southern Utah, part 2: polycotylidae] {{webarchive. link. (2011-09-28 . Journal of Vertebrate Paleontology, v. 27, n. 1, p. 41-58.)
7. Schumacher, B. A., 2007, A new polycotylid plesiosaur (Reptilia; Sauropterygia) from the Greenhorn Limestone (Upper Cretaceous; lower upper Cenomanian), Black Hills, South Dakota: In: The Geology and Paleontology of the Late Cretaceous marine deposits of the Dakotas, edited by Martin, J. E., and Parris, D. C., The Geological Society of America, Special Paper 427, p. 133-146.
8. (2010). "Global interrelationships of Plesiosauria (Reptilia, Sauropterygia) and the pivotal role of taxon sampling in determining the outcome of phylogenetic analyses". Biological Reviews.
9. (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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