THE PIEDRA CHAMANA FOSSIL WOODS AND LEAVES (39 MA, PERU): A RECORD OF LOWLAND TROPICAL VEGETATION DURING THE LATE MIDDLE EOCENE

The Piedra Chamana fossil woods and leaves from northern Peru (paleolatitude of 15°S) provide a record of coastal vegetation growing near/alongside the Pozo embayment in northern Peru and southern Ecuador at 39 Ma. The fossils are preserved in volcaniclastic sediments and include material buried in lahars and in situ in an ashfall deposit. The woods, which vary in degree of preservation, include thirty-one dicot taxa from 18 families, as well as a diversity of monocots. Many of the taxa and groups represented are elements of present-day New World forests, with Malvales present in some diversity (one-third of total taxa). Anatomical/morphological characteristics of the woods and leaves indicate that the vegetation was lowland tropical forest with a dry aspect and that conditions were warm (MAT 26-35°C, MAP ~1300 mm). Floristic affinities of the woods are consistent with this interpretation and further establish the presence of mangroves (Avicennia), seasonally flooded forest, and higher diversity interfluvial forest, with additional associated pioneer or early successional elements. It is rare to have mangroves represented in the rock record. Further analysis of the paleosols and substrates will allow for better characterization of these coastal/near-coastal ecosystems and development of a highly resolved record across a range of near-shore marine to terrestrial environments in the New World tropics during the late Middle Eocene.