Pronunciation: LESS-uhm-SOR-us
Meaning: Lessem lizard
Author/s: Bonaparte (1999)
Synonyms: None kmown
First Discovery: La Rioja Province, Argentina
Discovery Chart Position: #452
Lessemsaurus sauropoides
[Sauropod-like Lessem Lizard]Etymology
Lessemsaurus is derived from "Lessem" (for Don Lessem: author, journalist, and founder of the Dinosaur Society) and the Greek "sauros" (lizard).
The species epithet, sauropoides (sor-ro-POY-deez), means "sauropod-like", because its vertebrae resemble those of primitive sauropods.
Discovery
The first remains assigned to Lessemsaurus were discovered in the Los Colorados Formation (Ischigualasto-Villa Unión Basin) at Paraje (locality) la Esquina, south of Pagancillo Village, 8 km west of Provincial Road 26 at the 142 km mark, La Rioja Province, Argentina, by José Fernando Bonaparte and crew during the Lillo Palaeontologic Expedition of 1971.
The holotype (PVL 4822-1) is eight vertebral arches, individually identified by the collection numbers PVL 4822-1/1 to 4822-1/7 and PVL 4822-1/10.
Referred material (numbered PVL 4822/8, PVL 4822?9 and PVL 4822/11 to 4822/79) includes back and hip vertebrae, shoulder bones, an upper and lower arm, hand bones and fingers, pelvic bones, a thigh, a shin, and some toes. According to Bonaparte, three individuals of different sizes were present in the quarry.
Two shoulder blades (CRILAR PV-303), a tail vertebra and two pelvic bones (CRILAR PV-302) collected during IMCN-PVSJ field trips in 2004–2005 from two levels of the Los Colorados Formation midway between La Esquina and Los Jachalleros creek, and a partial thigh (PVL 6580) that José Bonaparte found at La Esquina during the 1970 Lillo expedition and catalogued as "prosauropod from Los Colorados", were referred to Lessemsaurus by Apaldetti et al. in 2018.
