FIRST RECORD OF CONIFER WOOD FROM THE CANADON ASFALTO FORMATION (EARLY-MIDDLE JURASSIC), CHUBUT PROVINCE, ARGENTINA

A new fossil conifer wood -Brachyoxylon currumilii sp. nov.-is described from the Lower-Middle Jurassic of Chubut Province (Argentina). The specimens were collected at a locality where the Canadon Asfalto Formation is exposed, in the vicinity of the Cerro Condor village. The studied wood is characterized by mixed pitting in radial tracheid walls (predominantly uniseriate), araucarioid cross fields, low uniseriate rays and the absence of resin canals. The use of transmitted light and epifluorescence microscopy together with SEM imaging allowed the identification of additional characters such as the presence of pitting with torus-margo and compression wood. These characters are discussed in terms of their systematic relevance. On these grounds, the systematic affinity of the studied wood is discussed and linked to the extinct conifer family Cheirolepidiaceae, one of the dominant plant groups during the Jurassic and Cretaceous in Patagonia.