Abstract Detail

Paleobotanical Section

Rubalcava Knoth, Marco Antonio [1], Cevallos Ferriz, Sergio Rafael Silvestre [1].

Palaeoecology of the Oligocene-Minocene Tehuacan Formation as determined from wood anatomical characters.

In order to establish the general climatic conditions that prevailed during the Oligocene-Miocene in the Tehuacán Formation (Mexico), a statistical model of climate prediction based on anatomical characteristics of wood was used. Additionally, mesomorphy and vulnerability indexes of the paleocommunity were calculated. The wood anatomy of 6 extant Mexican (Chamela, Ocuilán, Tehuacán, Mesófilo, Tuxtlas, and Campeche), 3 South American (Manaus, Portobello and Tafelberg) and 3 fossil Mexican (Panotla, Chajul and El Cien) communities were compared through various statistical analyzes. The results suggest that the conditions under which the Tehuacán Formation paleocommunity grew were humid and warm, similar to the conditions under which the tropical rainforest grows today. These results are supported by mesomorphy and vulnerability indexes which are similar to those of the tropical rain forest: they share a high efficiency in water transport and high vulnerability to embolism (high frequency of vessels and large diameter of the vessel elements). This is further supported by the absence of growth rings in some fossil woods and the current distribution of some taxa (e.g., Prioria). However, the statistical analysis and the presence of growth rings in other woods indicate that the Tehuacán Formation paleoflora has wood anatomical characters suggesting some affinity to more xeric communities (Dry Tropical Forest), as suggested by the presence of Dalbergia and Cordia currently common elements of the Dry Tropical Forest. This apparent contradiction proposes that the Tehuacán Formation was a peculiar plant association with mixed characteristics: plants were efficient in conducting water at the High Forests, though the taxonomic affinities of some elements are with xeric communities.

1 - Universidad Nacional Autonoma de Mexico, Facultad de Ciencias , Ciudad Universitaria, Mexico City, D.F, 04510, Mexico

Keywords:
Wood
Palaeoecology
Mexico
Miocene
Oligocene
fossil.

Presentation Type: Oral Paper:Papers for Sections
Session: 15
Location: Salon 5/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 1:45 PM
Number: 15002
Abstract ID:251
Candidate for Awards:Isabel Cookson Award