Polycotylidae Explained

Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to Leptocleididae. They are known as false pliosaurs. 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 early Maastrichtian around .[1] The possible latest surviving member Rarosaurus from the late Maastrichtian is more likely a crocodylomorph.[2]

With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetic studies indicate that they share many common features with the Leptocleididae and Elasmosauridae. They have been found worldwide, with specimens reported from New Zealand, Australia, Japan, Morocco, the US, Canada, Eastern Europe, and South America.[3]

Phylogeny

Cladogram after Albright, Gillette and Titus (2007).[4]

Cladogram after Ketchum and Benson (2010).[5]

Below is a cladogram of polycotylid relationships from Ketchum & Benson, 2011.[6]

External links

Notes and References

  1. Fischer. V.. Benson. R. B. J.. Druckenmiller. P. S.. Ketchum. H. F.. Bardet. N.. March 2018. The evolutionary history of polycotylid plesiosaurians. Royal Society Open Science. en. 5. 3. 172177. 10.1098/rsos.172177. 2054-5703. 5882735. 29657811. 2018RSOS....572177F .
  2. Alhalabi . W. A. . Bardet . N. . Sachs . S. . Kear . B. P. . Joude . I. B. . Yazbek . M. K. . Godoy . P. L. . Langer . M. C. . 2024 . Recovering lost time in Syria: New Late Cretaceous (Coniacian-Santonian) elasmosaurid remains from the Palmyrides mountain chain . Cretaceous Research . 159 . 105871 . 10.1016/j.cretres.2024.105871 . 2024CrRes.15905871A .
  3. Druckenmiller, Patrick S. . Russell, Anthony P. . amp . 2009 . Earliest North American Occurrence Of Polycotylidae (Sauropterygia: Plesiosauria) From The Lower Cretaceous (Albian) Clearwater Formation, Alberta, Canada . Journal of Paleontology . 83 . 6 . 361–392 . 10.1666/09-014.1 . 2009JPal...83..981D . 130695434 . dead . https://web.archive.org/web/20110706211048/http://www.bio.ucalgary.ca/contact/faculty/pdf/russell/335.pdf . 2011-07-06 .
  4. Albright III, L. B., Gillette, D. D., and Titus, A. L., 2007b. Plesiosaurs from the Upper Cretaceous (Cenomanian-Turonian) Tropic Shale of southern Utah, part 2: polycotylidae . Journal of Vertebrate Paleontology, v. 27, n. 1, p. 41-58.
  5. Ketchum, H. F. . Benson, R. B. J. . amp . 2010 . Global interrelationships of Plesiosauria (Reptilia, Sauropterygia) and the pivotal role of taxon sampling in determining the outcome of phylogenetic analyses . Biological Reviews . 85 . 2 . 361–392 . 10.1111/j.1469-185X.2009.00107.x . 20002391. 12193439 .
  6. Hilary F. Ketchum . Roger B. J. Benson . 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 . 86 . 109–129 .

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