CLAESON, K.*; AGNOL�N, F.L.; APESTEGU�A, S.; Univ. of Massachusetts, Amherst; Museo Argentino de Ciencias Naturales B. Rivadavia, Buenos Aires; Museo Argentino de Ciencias Naturales B. Rivadavia, Buenos Aires: Ceratodontiformes (Pisces: Dipnoi) of Argentina

Freshwater vertebrate remains recovered from Patagonia include many isolated dipnoan tooth plates. These fishes were prominent during the �Lacustrine Senonian� of the Late Cretaceous of Patagonia. Here we report on the oldest recorded ceratodontid (99-93 Ma), from the Cenomanian of R�o Negro Province, widening the stratigraphic distribution of this taxon. We also diagnose and discuss new specimens from the Portezuelo Formation (Turonian), Bajo de la Carpa Formation (Santonian), Los Alamitos Formation (Late Campanian), and La Colonia Formation (Maastrichtian). Specimens previously diagnosed have been reevaluated and in certain cases have been reassigned to different genera. Ceratodontiforms were considered extinct after the mid-Cretaceous, �reappearing� suddenly at the Maastrichtian before becoming definitively extinct in Laurasia. With the exception of the Lower Paleocene of Bolivia, neither South America nor Africa provides a Tertiary record. Ceratodontiforms in Gondwana occur throughout the Late Cretaceous, and are well represented in the Late Campanian especially during the first stages of the Kawas Sea transgressive event. Extant ceratodontiforms are restricted to Australia. Since Ameghino described the tooth plate of ��Ceratodus� iheringi there has been confusion about the temporal and systematic meaning of ceratodontiform tooth plates. Despite this confusion, review of fossil dipnoans of Argentina has been limited. Here we test the relationships of lungfishes from Patagonia as well as discuss the systematic value of tooth plates in phylogenetic analyses.