The Synonymy Of The Late Cretaceous Mosasaur (Squamata) Genus Lakumasaurus From Antarctica With Taniwhasaurus From New Zealand And Its Bearing Upon Faunal Similarity Within The Weddellian Province

Novas et al. (2002. Ameghiniana 39:245-249) described and named a new mosasaur as Laktanasaurus 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 Lakymasaurus 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 Laktunasaurus 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 Maastrichfian of Argentina and Antarctica and appears similar to Kaiwhekea from the Maastrichtian of New Zealand, and by Mauisaurus, an elasmosaurid which occurs in the Maastrichfian of Antarctica and medial Campanian-Maastrichtian of New Zealand. Copyright (c) 2007 John Wiley & Sons, Ltd.