A new species of the genus Atlantoceratodus (Dipnoiformes: Ceratodontoidei) from the Uppermost Cretaceous of Patagonia and a brief overview of fossil dipnoans from the Cretaceous and Paleogene of South America

AGNOLIN, FEDERICO

Brazilian Geographical Journal

Universidad Federal de Uberlandia

Año: 2010 p. 162 - 210

2179-2321

A new species of the genus Atlantoceratodus isdiagnosed and described on the basis of isolated toothplates from several localities of the Allen Formation(Campanian-Maastrichtian), Río Negro province,northern Patagonia, Argentina. The new speciesbelongs to the genus Atlantoceratodus Cione et al.,2007 (senior synonym of AmeghinoceratodusApesteguía; Agnolin; Claeson, 2007) together with A.iheringi and A. elliotti nov. comb. A new phylogeneticanalysis including tooth plates and calvarianmorphology has been conducted in order to evaluatethe relationships among post-Paleozoic dipnoans of theclade Ceratodontoidei. The first ceratodontoiddichotomy includes, on one hand the Neodipnoi nov.(Lepidosirenidae + Neoceratodontidae) and on theother side the “High Crowned Dipnoans” clade(Ceratodontidae + (Asiatoceratodontidae +Ptychoceratodontidae)). Based on this analysis, allSouth American ptychoceratodontid remains areincluded within the genus Ferganoceratodus. Theceratodontid genus Metaceratodus is restricted toinclude the single species M. wollastoni, which isrecorded from several Upper Cretaceous localities ofAustralia and Patagonia. The Late CretaceousArgentinean record of the genus Ceratodus isrepresented by Jurassic relics of ulterior Pangeandistribution. The Neoceratodontidae is here regardedas a family endemic to Gondwana. In the Cretaceous ofSouth America, three different stages in thecomposition of dipnoan faunas may be recognized: 1)the pre-Campanian record includes endemicGondwanan taxa, Jurassic relics, and South Americanendemicities; 2) record the Campanian-Maastrichtian(probably also Lower Paleocene) includes immigranttaxa from Australia and Malgasy; and finally 3) theLate Paleocene-Recent record, includes onlyLepidosirenidae of the genus Lepidosiren.