Leptocleidus


Leptocleidus is an extinct genus of plesiosaur, belonging to the family Leptocleididae.

Etymology

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

Description

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 long. Leptocleidus superstes however, was found to be almost 50% smaller making it the smallest known species.

Distribution and habitat

Leptocleidus, unlike many pleisiosaurs, lived in shallow lagoons and likely visited brackish and fresh water systems. This led Arthur Richard Ivor Cruickshank 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:
A specimen from the Vectis Formation, Isle of Wight, found in 1995 and seen as a "Leptocleidus sp.", was named as a separate genus Vectocleidus in 2012.
Cladogram based on Ketchum and Benson :