Mauisaurus

Abstract: A newly prepared elasmosaurid plesiosaur specimen, from the Haumurian (Upper Cretaceous) Conway Formation of North Canterbury, is more complete than any found previously in New Zealand. The specimen, a young adult, comprises posterior fragments of the skull, almost the entire vertebral column, fragments of the major bones of both pectoral and pelvic girdles, and portions of all four limbs. Comparison with the partial pelvic girdle and hind paddle that constitute the lectotype of Mauisaurus haasti Hector, 1874 (including the femur, diagnostic of the species), indicates that the new specimen belongs to that species, permitting a more complete description and diagnosis. The species is characterized by an estimated 86 presacral vertebrae, at least 66 of which are cervicals, other than the atlas and axis. The coracoids possess a pronounced, blunt, ventral process, and a broad, rounded, transverse ridge on their dorsal surface. In large adults the medial profile of the coracoid becomes markedly sigmoid...

Abstract: Novas et al. (2002. Ameghiniana 39:245–249) described and named a new mosasaur as Lakumasaurus antarcticus from the Late Cretaceous marine deposits of the Antarctic Peninsula. The specimen was recovered from the late Campanian Santa Marta Formation on James Ross Island. A number of characters indicate the affinities of Lakumasaurus with the Tylosaurinae. However, other characters of Lakumasaurus are unusual among tylosaurines, particularly the dentition bearing fine striae, teeth with non-serrated anterior carinae, anterior teeth without posterior carinae, relatively straight lateral margins on frontal and relatively small size. Investigation of mosasaurs from New Zealand confirms that these characters occur in the type specimen of Taniwhasaurus oweni Hector 1874, collected from the late Campanian Conway Formation of Haumuri Bluff. Size and similar morphological characters indicate the synonymy of Lakumasaurus with Taniwhasaurus. The synonymy of Lakumasaurus with Taniwhasaurus adds significantly to the evidence of endemism among marine reptiles in Antarctica, New Zealand and Patagonia (Weddellian Province) during the Late Cretaceous. Taniwhasaurus along with the possible co-occurrence of Moanasaurus are the first mosasaurs at a generic level to indicate Gondwanan endemism. The mosasaur evidence is complemented by the plesiosaur Aristonectes, which occurs in the Maastrichtian of Argentina and Antarctica and appears similar to Kaiwhekea from the Maastrichtian of New Zealand, and by Mauisaurus, an elasmosaurid which occurs in the Maastrichtian of Antarctica and medial Campanian-Maastrichtian of New Zealand. Copyright © 2007 John Wiley & Sons, Ltd.

Abstract: The most completely articulated fossil skeleton heretofore found on the continent of Antarctica is represented by a juvenile plesiosaur. The specimen was found in the Sandwich Bluff area of Vega Island east of the Antarctic Peninsula from Late Cretaceous (Maastrichtian) marine deposits from the upper Snow Hill Island Formation. The plesiosaur skeleton is represented by a nearly complete torso, partial paddles, and neck and tail sections. Along the ventral margin of the torso are articulated gastralia, some that are unusual in being forked. Numerous small gastroliths are associated within the trunk cavity, indicating that even juveniles ingest gastroliths. Coupled with other known specimens, the skeleton indicates shallow marine environment may have been an area where marine reptiles had their young, and the young remained until reaching maturity prior to facing open marine environments. The morphology of the specimen suggests the skeleton represents a juvenile Mauisaurus, an elasmosaurid plesiosaur taxon originally described from New Zealand and endemic to the Weddellian Province of the austral region.

Abstract: Research carried out on austral plesiosaurs from the Weddellian Biogeographic Province in the decade since the last attempt to characterise the New Zealand elasmosaurid, Mauisaurus haasti Hector, 1874 (On the Fossil Reptilia of New Zealand. Transactions and Proceedings of the New Zealand Institute 6: 333–358), has prompted a reappraisal of this taxon and a new consideration of its relationships. The hypodigms used in previous descriptions of the species are shown to include specimens from a number of different taxa, and the defining apomorphy of Mauisaurus, a hemispherical capitulum on the femur, has now been observed in specimens known to belong to different clades. Mauisaurus is now regarded as nomen dubium with possible affinities with the Subfamily Aristonectinae. A re-assessment of the most complete specimen previously assigned to Mauisaurus suggests it is a typical long-necked elasmosaurid closely comparable to Tuarangisaurus keyesi Wiffen and Moisley, 1986 (Late Cretaceous reptiles (Familie...