A: *Plesiosaurus australis*, B-C: *Polycotylus tenuis*

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**Animalia** — Chordata

Classis : Reptilia   
Ordo : Plesiosauria   
Familia : Polycotilidae   
Subfamilia : Polycotylinae   
Genus : *Polycotylus*   
Cope, 1869  
   
Palaeontologia

100–66 m.a.: Cretaceum superius 
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Subdivisiones: Species\* †*P. latipinnis* Cope, 1869
* †*P. ichthyospondylus* Seeley, 1869
* †*P. tenius* Hector, 1874
* †*P. suprajurensis* Sauvage, 1876
* †*P. ischiadicus* Williston, 1903
* †*P. dolichops* Williston, 1906

**Nomina dubia:**

* †*P. balticus* Bogolubov, 1911
* †*P. brevispondylus* Bogolubov, 1911
* †*P. epigurgitis* Bogolubov, 1911
* †*P. orientalis* Bogolubov, 1911
* †*P. ultimus* Bogolubov, 1911
* †*P. donicus* Pravoslavev, 1915

Species typica

*Polycotylus latipinnis* Cope, 1869

***Polycotylus*** (ex Graecis verbis πολύ- 'multi-' et κοτύλη 'cavitas, cotula') est genus Plesiosauriorum familiae Polycotylidarum, typus generis (generitypus), *P. Latipinnis,* ab Eduardo Drinker Cope palaeontologus Americano anno 1869 nominatus. Duodecim aliae species agnoscuntur. Hoc animal in maribus Americae Septentrionalis, Russiae, et Australiae, Cretaceo exeunte habitabat. Unum *Polycotyli latipinnis* fossile singulum adultum magno fetu intra corpore conservat, quod *Polycotylum* fuisse viviparum significat—inusitatus inter reptilia mos.

Descriptio
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*Polycotylus,* sicut omnia plesiosauria, erat magnum reptile marinum, cauda breve, magnis membris remiformibus (Anglice: *flippers*), latoque corpore praeditum. Ei erat collum breve caputque longum, et omne animal erat circa 5 m longum.

Classificatio
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Hic est cladogramma ex investigatione anni 2004:

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Plesiosauroidea  | 

|  |  |
| --- | --- |
|  | *Plesiosaurus* |
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|  | 

|  |  |
| --- | --- |
|  | *Brancasaurus* |
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|  Cryptocleidoidea  | 

|  |  |
| --- | --- |
|  | *Muraenosaurus* |
|  |
|  | *Cryptocleidus* |
|  |
|  | 

|  |  |
| --- | --- |
|  | *Tricleidus* |
|  |
|  | 

|  |  |
| --- | --- |
|  | Cimoliasauridae |
|  |
|  Polycotylidae  | 

|  |  |
| --- | --- |
|  | ***Polycotylus*** |
|  |
|  | *Edgarosaurus* |
|  |
|  | 

|  |  |
| --- | --- |
|  | *Dolichorhynchops* |
|  |
|  | *Trinacromerum* |
|  |

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Anno 2007, *Polycotylus* in Polycotylinis, nova Polycotylidarum subfamilia, positus est. *Eopolycotylus,* alia polycotylida nuper descripta, ex Glen Canyon Utae, habetur artissima *Polycotyli* cognata. Hic est cladogramma ex investigatione anni 2007:

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Plesiosauroidea  | 

|  |  |
| --- | --- |
|  | *Plesiosaurus* |
|  |
|  | *Tricleidus* |
|  |
|  Polycotylidae  | 

|  |  |
| --- | --- |
|  | *Thililua* |
|  |
|  | 

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
|  Palmulainae  | 

|  |  |
| --- | --- |
|  | *Paluma* |
|  |
|  | UMUT MV 19965 |
|  |

 |
|  |
|  Polycotylinae  | 

|  |  |
| --- | --- |
|  | *Dolichorhynchops* |
|  |
|  | 

|  |  |
| --- | --- |
|  | *Trinacromerum* |
|  |
|  | 

|  |  |
| --- | --- |
|  | ***Polycotylus*** |
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|  | *Eopolycotylus* |
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Notae
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1. ↑
2. ↑
3. ↑  "Fossil 'suggests plesiosaurs did not lay eggs'". 11 August 2011
4. ↑  Albright, L.B. III; Gillette, D.D.; and Titus, A.L. (2007). "Plesiosaurs from the Upper Cretaceous (Cenomanian-Turonian) Tropic Shale of southern Utah,
Part 2: Polycotylidae". *Journal of Vertebrate Paleontology* **27** (1): 41-58