The elasmosaurid plesiosaurAristonectesCabrera from the latest Cretaceous of South America and Antarctica

First record of Elasmosaurid Plesiosaurs (Sauropterygia: Plesiosauria) in upper levels of the Dorotea Formation, Late Cretaceous (Maastrichtian), Puerto Natales, Chilean Patagonia

“…In vertebral centrum 'v6' the suture between the vertebra and its neural arch is observed. In mature individuals, the arches are strongly fused to the vertebral centrum and most of the sutures are erased (Gasparini et al, 2003b). The absence of a complete fusion between these bony elements in the studied material suggests a sub-adult condition for this individual (Brown, 1981).…”

“…4D, E, respectively), from Seymour Island, Antarctica. Both species are considered as synonyms (Gasparini et al, 2003b). In Late Cretaceous elasmosaurids, the articular face presents this typical shape (dumb-bell), due to the development of a well-marked cavity in the ventral surface of the cervical centra.…”

“…Since the XIX century, previous occurrences of plesiosaurs in Chile have been widely reported in the scientific literature (Gay, 1848;Philippi, 1887;Steinmann et al, 1895;Wetzel, 1930;Colbert, 1949;Casamiquela, 1969;Gasparini, 1979). Recent studies on this group in this country and Argentina (Suárez, 2000;Gasparini and Salgado, 2000;Suárez and Fritis, 2002;Gasparini et al, 2003a) indicate that most of the regional material belongs to plesiosaurs of the Elasmosauridae family, the latter being the best represented group of marine reptiles in the Late Cretaceous of southern South America and Antarctica (Gasparini et al, 2003b).…”

The oldest elasmosaurs (Sauropterygia, Plesiosauria) from Antarctica, Santa Marta Formation (upper Coniacian? Santonian–upper Campanian) and Snow Hill Island Formation (upper Campanian–lower Maastrichtian), James Ross Island

“…Moreover, the limited elongation of MLP 86-X-28-(2-6) may be due to its juvenile condition (Welles 1952(Welles , 1962O'Keefe & Hiller 2006). Another element to take into account is that the genus Aristonectes has been recorded in the James Ross Basin, Ló pez de Bertodano Formation, upper Maastrichtian (Chatterjee & Small 1989;Gasparini et al 2003;O'Gorman et al 2010). The phylogenetic relationships of Aristonectes parvidens have been debated recently and it has been located within the Elasmosauridae (Ketchum & Benson 2010) or Aristonectidae (O'Keefe & Street 2009).…”

Reptiles Extintos - Volumen en Homenaje a Zulma Gasparini

“…They are probably the most distinctive elasmosaurid group from the Weddellian Province (Gasparini et al, 2003b; The only taxon far related to other lineages from the Weddellian Province is Sulcusuchus erraini, probably because only few polycotylid specimens are known throughout this province (Welles and Gregg, 1971;Novas et al, 2015).…”