Umoonasaurus is a small (~2.5 m long) leptocleidid that lived during the Early Cretaceous in Southern Australia. The holotype specimen (AM F99374), a spectacular opalised skeleton including the skull, is nicknamed ‘Eric’. It is the most complete opalised plesiosaur skeleton (and fossil vertebrate) known.
It was originally described briefly as Leptocleidus sp. by Kear (2006) who figured the skull and parts of the postcranium. Soon after, Kear et al. (2006) described the skull in detail and erected the name Umoonasaurus for it. Kear et al. (2006) described Umoonasaurus as a ‘crested plesiosaur’ because it has a thin crest on the snout and crests above the orbits. The type and only species, U. demoscyllus, is represented by several additional specimens including a juvenile.
Etymology: ‘Umoona’ is the indigenous name for the Coober Pedy area where the holotype is from, ‘sauros’ is the Greek for lizard.
