Palmoxylon (Magnoliopsida: Arecaceae) richness in the Puntudo Chico Formation (Campanian-lowermost Maastricthian), Chubut Province, Argentina: systematics, palaeoclimatic significance and comments on biogeography of Phytelepheae

Abstract

The Puntudo Chico Formation is an uppermost Cretaceous continental sequence deposited in the Cañadón Asfalto Basin, cropping out in the Chubut Province, Argentina. Fossils collected from this unit are essentially palaeobotanical remains, and comprise conifers (Agathoxylon, Brachyoxylon, Podocarpoxylon and Cupressinoxylon) and a dicotyledonous angiosperm (Aextoxicoxylon kawasianus). In this contribution, five taxa referred to the genus Palmoxylon (Arecaceae) are reported for the unit: Palmoxylon sp. 1 (Coryphoideae or Nypoideae), Palmoxylon sp. 2 (close to Coryphoideae), Palmoxylon sp. 3 (Arecoideae), Palmoxylon sp. 4 (Coryphoideae or Arecoideae) and Palmoxylon sp. cf. P. phytelephantoides; (close to Phytelephas of the Ceroxyloideae). Based on the recognised taxa, subtropical to tropical climate is postulated for the Puntudo Chico flora, which is in agreement with previous climatic inferences made for the unit. Finally, the presence of a taxon close to the extant genus Phytelephas permits discussing the diversification of the Ceroxyloidea, and the time of arrival of Phytelepheae to South America.