Lariosaurus balsami (Curioni 1847) Middle Triassic ~ 240 mya, ~80+ cm long, , was derived from a sister to Pachypleurosaurus and was basal to the Eusauropterygia, the clade of the giant plesiosaurs.

Distinct from Pachypleurosaurus, the skull of Lariosaurus was extremely low and long. The nares were dorsally oriented. The postorbital portion of the skull was lengthened and the upper temporal fenestra were enlarged. The teeth were much larger and spread laterally like a rake.

The cervical count was increased to 20, increasing the presacral count to 48. The cervical ribs were reduced to absent. The dorsal ribs enclosed a broad, shallow torso.

The limbs were early in the process of transforming into paddles.

Corosaurus alcovensis (Case 1936, Storrs 1991) had a relatively larger torso and shorter neck. The torso was wider than tall. The caudal transverse processes were elongated.

Bobosaurus forojuliensis (Dalla Vecchia 2006; Fabbri, Dalla Vecchia and Cau 2014; Dalla Vecchia 2016/2017; Late Triassic, Early Carnian; MFSN 27285) is a large eusauropterygian originally considered close to Pistosaurus and among pistosaurians, closer to plesiosaurians. It was assumed to have large flippers. Here it nests as a 3x larger sister to Corosaurus with small hands and feet, not flippers. The pectoral elements were overlooked or considered ribs.

Case EG 1936. A nothosaur from the Triassic of Wyoming. University of Michigan Contributions to the Museum of Paleontology 5(1):1-36.

Curioni G 1847. Cenni sopra un nuovo saurio fossile dei monti di Perledo sul Lario e sul terreno ceh lo rachiude. Giorn. Is.t Lombardo Sc. Lett. 16: 159-170. Milano.

Dalla Vecchia FM 2006. A new sauropterygian reptile with plesiosaurian affinity from the Late Triassic of Italy. Rivista Italiano Paleontaleontologia, Stratigraphia 112 (2): 207-25.

Dalla Vecchia FM 2016. Comments on the skeletal anatomy of the Triassic reptile Bobosaurus forojuliensis (Sauropterygia, Pistosauroidea). Gortania Geologia, Paleontolgia, Paletnologia 38:39–75.

Fabbri M, Dalla Vecchia FM and Cau A 2014. New information on Bobosaurus forojuliensis (Reptilia: Sauropterygia): implications for plesiosaurian evolution. Historical Biology 26 (5): 661-9.

Storrs GW 1991. Anatomy and Relationships of Corosaurus alcovensis (Diapsida: Sauropterygia) and the Triassic Alcova Limestone of Wyoming. Bulletin of the Peabody Museum of Natural History 44: 1-163. online pdf

Young CC 1958. On the new Pachypleurosauroidea from Keichow. South-West China. Vertebrata Palasiatica 2:69-81.

wiki/Lariosaurus
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