Leptocleidus

Leptocleidus
Temporal range: Early Cretaceous, 140–125 Ma
Leptocleidus capensis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Superorder: †Sauropterygia
(unranked): †Eusauropterygia
Order: †Plesiosauria
Suborder: †Plesiosauroidea
Family: †Leptocleididae
Genus: †Leptocleidus
Andrews, 1922
Species
  • L. capensis (Andrews, 1911 [originally Plesiosaurus capensis]) Cruikshank, 1997
  • L. clemai Cruikshank and Long, 1997
  • L. superstes Andrews, 1922 (type)
Synonyms
  • Peyerus capensis (Andrews, 1911) Stromer, 1935

Leptocleidus is an extinct genus of pliosaurid plesiosaur,[1] belonging to the family Leptocleididae.[2] It is the only known pliosaur to be found in sediments on the Isle of Wight.

Etymology

In short, the term Leptocleidus means "slender clavicle". It comes from a merge of the Greek words λεπτοσ, meaning "slender" and κλειδ (also spelled κλεισ) meaning clavicle.

Description

Leptocleidus sp.

With large clavicles and interclavicle and small scapulae, Leptocleidus resembled the Early Jurassic Rhomaleosaurus and members of the Cretaceous family, Polycotylidae. The animal had 21 teeth on either side of its maxilla and approximately 35 teeth on each side of the mandible. The Leptocleidus' triangle-shaped skull had a crest running from a ridge on the end of the nose to the nasal region. Differing from other pliosaurids, Leptocleidus had single-headed cervical ribs and a deep depression in the centra of the neck vertebrae. Leptocleidus was on an average of 3 meters (10 feet) long. Leptocleidus superstes however, was found to be almost 50% smaller (1.5m, 5 ft) making it the smallest known species.

Distribution and habitat

L. capensis (Andrews, 1911)
Skull in dorsal view
Skull in palatal view
L. superstes Andrews, 1922
Cranium (lateral view, top left; ventral (palatal) view, top right) and vertebrae. Length of vertebral series approx. 45 cm
Pectoral girdle in dorsal view (left), anterior view (top right), lateral view (bottom right), right humerus (center), and ribs (left). Length of pectoral girdle approx. 40 cm

Leptocleidus, unlike many pleisiosaurs, lived in shallow lagoons and likely visited brackish and fresh water systems (such as the mouths of large rivers). This led A. R. I. Cruikshank to infer that this movement to fresh water was an attempt to flee larger plesiosaurs and pliosaurs. Most species are known from The British Isles but L. capensis was discovered in Cape Province, South Africa.

Species

Leptocleidus is known from the following sediments:

Cladogram based on Ketchum and Benson (2011):[4]

Leptocleididae

Nichollssaura

Brancasaurus

Umoonasaurus


Leptocleidus

L. capensis

L. superstes






See also

References

  1. ↑ Ketchum, H. F.; 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 (2): 361–392. doi:10.1111/j.1469-185X.2009.00107.x. PMID 20002391.
  2. ↑ Smith AS, Dyke GJ. 2008. The skull of the giant predatory pliosaur Rhomaleosaurus cramptoni: implications for plesiosaur phylogenetics. Naturwissenschaften e-published 2008.
  3. ↑ Cruikshank A. R. I. (1997). "A lower Cretaceous Pliosauroid from South Africa". Annals of the South African Museum. 105: 206–226.
  4. ↑ 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.

Further reading

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