A mid-Cretaceous flora from the Kachaike Fm, Patagonia, Argentina

PASSALIA, M.G.

CRETACEOUS RESEARCH (PRINT)

Elsevier

Año: 2007 p. 830 - 840

0195-6671

Abstract. An overview of a new mid-Cretaceous flora from Bajo Comisión (48º 51’ lat. S 72º 9’ long. W) southern Patagonia is presented here. It was collected from previously studied deposits of the late Albian-Cenomanian Kachaike Formation in Santa Cruz Province, Argentina. The fossil assemblage consists of about twenty species mostly belonging to pteridophytes, pteridosperms, conifers as well as fronds of uncertain botanical affinity. Bryophytes, bennettites and ginkgophytes are subordinated components. The presence of angiosperm leaves is noteworthy. This flora sits in a critical time interval between the earliest Cretaceous assemblages of Springhill Formation and Baqueró Group and the younger Late Cretaceous assemblage of Mata Amarilla Formation from southern South America. A period of time when profound changes were taking place in the Earths vegetation with the radiation and diversification of angiosperms. Comparisons with others Jurassic and Cretaceous assemblages indicate links with southern and eastern Gondwanan floras. Among them, the Triton Point Formation flora of Alexander Island (Antarctica) is the most similar to that of Kachaike Formation. Both floras share the presence of Athrotaxis ungeri (=Athrotaxites ungeri), as well as taxa at generic level (e.g. Phyllopteroides, Aculea, Ptilophyllum, Ginkgoites), a similar matoniaceous species and a relatively diverse angiosperm record.