First record of fossil woods from the Mariño Formation (Miocene), Mendoza, Argentina and their palaeobiogeographical implications

FRANCO, M. J.; BREA, M.; ZAVATTIERI, A.M.

ALCHERINGA

TAYLOR & FRANCIS LTD

Lugar: Londres; Año: 2015 vol. 39 p. 8 - 23

0311-5518

This paper documents the first Miocene record of silicified fossil woods from the Mariño Formation, Potrerillos area, Andes Precordillera, Mendoza province, Argentina. Rhaphithamnoxylon artabeae gen. et sp. nov. is described as the first fossil wood assigned to the Verbenaceae from Argentina. This new fossil species is related to extant Rhaphithamnus Miers 1870, sharing the following anatomical features: diffuse porosity, distinct growth ring boundaries, numerous small-to-very-small vessels and, commonly in radial multiples 1?3 seriate rays; heterocellular and scarce paratracheal axial parenchyma. Rhaphithamnus contains only two extant species: R. spinosus (A.L. Juss.) Moldenke 1937, which occurs in the Valdivian forests of Chile and Argentina, and R. venustus (Philippi) Robinson 1916, which is endemic to the Juan Fernández Islands. Representatives of Verbenaceae are distributed predominantly in the Americas from Patagonia (Argentina) to Canada, and they are inferred to have originated in South America. The fossil wood described herein provides new age and geographical constraints on the raphithanoid lineage within Verbenaceae. Other fossil woods recorded from the Mariño level are retained under open nomenclature as they combination of mostly solitary broad vessels, and smaller vessels in radial multiples or in clusters, with numerous, vasicentric to confluent axial parenchyma, and heterocellular, high rays. Thus, they have features akin to dicotyledonous lianas or vine-like or small shrub species.