Polycotylidae

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Polycotylidae
Temporal range: Cretaceous, Aptian–Maastrichtian
Trinacromerum BW.jpg
Trinacromerum bentonianum from the Late Cretaceous of Kansas
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Sauropterygia
Order: Plesiosauria
Node: Leptocleidia
Family: Polycotylidae
Williston, 1909

Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to Leptocleididae.

With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetical studies indicate that they share many common features with the Plesiosauridae and Elasmosauridae. They have been found worldwide, with specimens reported from New Zealand, Australia, Japan, Morocco, the USA, Canada, the former states of the USSR and South America.[1]

Phylogeny[edit]

Dolichorynchops (Trinacromerum) bonneri in the Rocky Mountain Dinosaur Resource Center in Woodland Park, Colorado

Cladogram after Albright, Gillette and Titus (2007).[2]

Plesiosauria 

Plesiosaurus



Tricleidus


 Polycotylidae 

Edgarosaurus




Thililua



 Palmulainae 

UMUT MV 19965 (from Japan)



Pahasapasaurus (=AMM 98.1.1)[3]



Palmulasaurus



 Polycotylinae 

Dolichorhynchops




Trinacromerum




Eopolycotylus



Polycotylus









Cladogram after Ketchum and Benson (2010).[4]

Plesiosauroidea 

Cryptoclididae


 Leptocleidia 

Leptocleididae


 Polycotylidae 

Plesiopleurodon




Edgarosaurus




QM F18041




Eopolycotylus




Trinacromerum




"D. herschelensis"




Dolichorhynchops



Manemergus



Palmulasaurus











Below is a cladogram of polycotylid relationships from Ketchum & Benson, 2011.[5]

Plesiosauroidea 

Cryptoclididae


 Leptocleidia 

Leptocleididae


 Polycotylidae 

Edgarosaurus





Plesiopleurodon



QM F18041






Eopolycotylus



Polycotylus



Thililua





Trinacromerum




Manemergus




"D. herschelensis"




Dolichorhynchops



Palmulasaurus











Websites[edit]

References[edit]

  1. ^ Druckenmiller, Patrick S. and Russell, Anthony P. (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. 
  2. ^ 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.
  3. ^ 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.
  4. ^ Ketchum, H. F., and Benson, R. B. J. (2010). "Global interrelationships of Plesiosauria (Reptilia, Sauropterygia) and the pivotal role of taxon sampling in determining the outcome of phylogenetic analyses". Biological Reviews 85: 361–392. doi:10.1111/j.1469-185X.2009.00107.x. PMID 20002391. 
  5. ^ Hilary F. Ketchum and 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. doi:10.1111/j.1475-4983.2011.01083.x.