Early Cretaceous plesiosaurs

Kronosaurus ( ) is an extinct genus of large short-necked pliosaur that lived during the Aptian to Albian stages of the Early Cretaceous in what is now Australia. The first known specimen was received in 1899 and consists of a partially preserved mandibular symphysis, which was first thought to come from an ichthyosaur according to Charles De Vis. However, it was in 1924 that Albert Heber Longman formally described this specimen as the holotype of an imposing pliosaurid, to which he gave the scientific name K. queenslandicus, which is still the only recognized species nowadays. The genus name,

Umoonasaurus is an extinct genus of plesiosaur belonging to the family Leptocleididae. This genus lived approximately 115 million years ago during the Early Cretaceous period (Aptian-Albian stages), in shallow seas covering parts of what is now Australia. It was a relatively small animal around long. An identifying trait of Umoonasaurus is the presence of three crest-ridges on its skull.

Leptocleidus is an extinct genus of plesiosaur, belonging to the family Leptocleididae. It was a small plesiosaur, measuring only up to in length.

Sinopliosaurus (meaning "Chinese more lizard") is a dubious genus of pliosauroid plesiosaur. It lived during the Aptian and Albian stages of the Early Cretaceous (disputed Sinopliosaurus remains have been dated to the Toarcian age and were found in the Ziliujing Formation) of the People's Republic of China - its exact age is unknown. The type species, Sinopliosaurus weiyuanensis, was named and described in 1944 by Yang Zhongjian. One species, "S." fusuiensis, was later shown to be based on teeth from a spinosaurid theropod dinosaur which is now known as Siamosaurus. S. weiyuanensis was conside

Eromangasaurus is an extinct genus of elasmosaurid known from northern Queensland of Australia.

Woolungasaurus ('Woolunga lizard', named after an Aboriginal mythical reptile, Persson 1960) is a dubious genus of plesiosaur, an extinct marine reptile, belonging to the Elasmosauridae.

Callawayasaurus is a genus of plesiosaur from the family Elasmosauridae. When the holotype was first described by Samuel Paul Welles in 1962, it was described as Alzadasaurus colombiensis before being moved into its current genus by Kenneth Carpenter in 1999.

Leptocleididae is a family of small-sized plesiosaurs that lived during the Early Cretaceous period (early Berriasian to early Albian stage). They had small bodies with small heads and short necks. Leptocleidus and Umoonasaurus had round bodies and triangle-shaped heads. Leptocleidids have been found in what were shallow nearshore, freshwater and brackish habitats. Hilary F. Ketchum and Roger B. J. Benson (2010), transferred Brancasaurus, Kaiwhekea, Nichollssaura and Thililua to this family. However, Ketchum and Benson (2011) reassigned Kaiwhekea and Thililua to their original positions, as an

Opallionectes andamookaensis (meaning "the opal swimmer from Andamooka") is the name given to a 5 m (16 ft) long cryptoclidian plesiosaur, which is thought to have lived during the early Cretaceous period (Lower middle Aptian), 115 million years ago, in shallow seas covering what is now Australia.

Stenorhynchosaurus is an extinct genus of pliosaurid plesiosaurs which lived in the Early Cretaceous of South America. The type species and only known is Stenorhynchosaurus munozi.

Monquirasaurus ("Monquirá lizard") is an extinct genus of giant short-necked pliosaurs who lived during the Early Cretaceous (Aptian) in what is now Colombia. One species is known, M. boyacensis, described in 2021 from an almost complete fossil skeleton, discovered in 1977 in the town of Villa de Leyva, located in Boyacá. Published descriptions of the holotype specimen estimate that it should reach a total size approaching in length and weighing , making Monquirasaurus a large representative of the pliosaurids.

Luskhan (meaning "water spirit chief") is an extinct genus of large pliosaurid plesiosaurs from the Lower Cretaceous of western Russia. The only known species is L. itilensis, first described in 2017 from a well-preserved and nearly complete skeleton discovered in the Ulyanovsk region. As an early-diverging brachauchenine, Luskhan consequently exhibits an intermediate combination of traits seen in more basal (less specialized) and more derived (more specialized) pliosaurs. However, Luskhan departs significantly from other pliosaurs in that it exhibits a lack of adaptations in its skull to feed

Leivanectes is a genus of plesiosaurs of the family Elasmosauridae known from Late Aptian marine deposits in central Colombia. It contains a single species, L. bernadoi, which was described in 2019.

Eiectus is a potentially valid genus of extinct short-necked pliosaur that lived in the Early Cretaceous period. Fossil material has been recovered from the Wallumbilla Formation (Aptian) of Queensland was initially classified under the related genus Kronosaurus until 2021.