Eurycleidus

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Eurycleidus
Temporal range: Early Jurassic, 199.6–198 Ma
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O
S
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C
P
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J
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Pg
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Atychodracon BW.jpg
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: †Sauropterygia
Order: †Plesiosauria
Family: †Rhomaleosauridae
Genus: †Eurycleidus
Andrews, 1922
Type species
†Eurycleidus arcuatus
(Owen, 1840)
Synonyms

Eurycleidus is an extinct genus of large-bodied rhomaleosaurid known from the Early Jurassic period (most likely earliest Hettangian stage) of the United Kingdom. It contains a single species, E. arcuatus.[1] Like other plesiosaurs, Eurycleidus probably lived on a diet of fish, using its sharp needle-like teeth to catch prey. Its shoulder bones were fairly large, indicating a powerful forward stroke for fast swimming.

Phylogeny[]

Most phylogenetic analyses find the type species of the genus, Eurycleidus arcuatus, to be a relatively basal rhomaleosaurid.[1][2][3][4] A second species, E. megacephalus (Stutchbury, 1846 [originally Rhomaleosaurus megacephalus]), was reassigned to this genus by Smith (2007).[2] However, most analyses find E. megacephalus to represent an unnamed genus, which is distinct from both Eurycleidus and Rhomaleosaurus.[3][4][5] E. megacephalus was moved to its own genus Atychodracon by Adam Smith in 2015.[6]

The cladogram below shows E. arcuatus phylogenetic position among other plesiosaurs following Benson et al. (2012).[1]

Plesiosauria 
 Neoplesiosauria 
 

Pliosauridae

 
 

Plesiosauroidea

 
 
 Rhomaleosauridae 
 

Stratesaurus taylori

 
 
 

Macroplata tenuiceps

 
 
 

Avalonnectes arturi

 
 
 

Eurycleidus arcuatus

 
 
 

Meyerasaurus victor

 
 
 

Maresaurus coccai

 
 
 

Atychodracon megacephalus

 
 
 

Archaeonectrus rostratus

 
 
 

Rhomaleosaurus cramptoni

 
 
 

Rhomaleosaurus thorntoni

 
 

Rhomaleosaurus zetlandicus

 
 
 
 
 
 
 
 
 
 
 
 

See also[]

  • List of plesiosaurs

References[]

  1. ^ a b c Roger B. J. Benson; Mark Evans & Patrick S. Druckenmiller (2012). "High Diversity, Low Disparity and Small Body Size in Plesiosaurs (Reptilia, Sauropterygia) from the Triassic–Jurassic Boundary". PLOS ONE. 7 (3): e31838. Bibcode:2012PLoSO...731838B. doi:10.1371/journal.pone.0031838. PMC 3306369. PMID 22438869.
  2. ^ a b Adam S. Smith (2007). Anatomy and systematics of the Rhomaleosauridae (Sauropterygia, Plesiosauria) (Ph.D. thesis). University College Dublin.
  3. ^ a b Adam S. Smith; Gareth J. Dyke (2008). "The skull of the giant predatory pliosaur Rhomaleosaurus cramptoni: implications for plesiosaur phylogenetics" (PDF). Naturwissenschaften. 95 (10): 975–980. Bibcode:2008NW.....95..975S. doi:10.1007/s00114-008-0402-z. PMID 18523747. S2CID 12528732.
  4. ^ a b 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.
  5. ^ Roger B. J. Benson; Hilary F. Ketchum; Leslie F. Noè; Marcela Gómez-Pérez (2011). "New information on Hauffiosaurus (Reptilia, Plesiosauria) based on a new species from the Alum Shale Member (Lower Toarcian: Lower Jurassic) of Yorkshire, UK". Palaeontology. 54 (3): 547–571. doi:10.1111/j.1475-4983.2011.01044.x.
  6. '^ Smith, Adam S. (22 April 2015). "Reassessment of Plesiosaurus' megacephalus (Sauropterygia: Plesiosauria) from the Triassic-Jurassic boundary, UK". Palaeontologia Electronica. 18 (1): 1–20.
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