Resumo

BREA, Mariana  e  ZUCOL, Alejandro F.. Fossil woods of Boraginaceae from the Peñas Coloradas Formation (Upper Paleocene), Puerto Visser, Chubut, Argentina. Ameghiniana [online]. 2006, vol.43, n.1, pp.139-146. ISSN 1851-8044.

Petrified woods of a new species of the family Boraginaceae from Upper Paleocene sediments of Puerto Visser locality, Chubut are described. The comparison within members of Boraginaceae shows that Cordioxylon prototrichotoma sp. nov. is similar to the extant Cordia trichotoma (Vell.) Arráb. ex Steud. The fossil species shows the following diagnostic features: growth rings absent; diffuse porous; pores in clusters and solitary, rarely in radial multiples of 2 elements and occasionally in radial multiples of 3, 4 and 5 elements; perforation plate simple; alternate intervascular pitting; rays short, broad and numerous, heterocellular and heterogenous, multiseriate, rarely uniseriate and biseriate; axial parenchyma apotracheal diffuse and diffuse-in-aggregates and paratracheal scanty and banded of one cell wide. The presence in the Upper Paleocene of this new floristic element, Cordioxylon prototrichotoma , suggests the existence of rainforests, with a warm and humid climate for this region.

Palavras-chave : Argentina; Chubut; Peñas Coloradas Formation; Upper Paleocene; Petrified woods; Boraginaceae.