Abstract Detail

Paleobotanical Section

Domínguez De La Torre, Aldo [1], Calvillo-Canadell, Laura [2], Cevallos-Ferriz, Sergio [3].

Leaflets with Leguminosae affinity from the Mioceno of San Estaban Tizatlán, Tlaxcala, Mexico.

A large variety of leaf and leaflets from the Miocene of San Esteban Tizatlán, Tlaxcala, Mexico, have been collected. Of the 72 morphotypes so far distinguished 5 have been identified based their leaf architecture. Here we describe 3 new leaflet types with leaf architecture similar to that of Ingeae (Leguminosae). The first one has an obovate, symmetrical lamina, laminar radio of 1.8:1, convex-round apex, cuneate base; pinnate first order venation, simple second order venation with regular spacing between major secondary, their fusion with the mid-vein is decurrent towards the base and excurrent towards the apex; third order venation irregular reticulated, and together with the epimedial tertiaries form a compound admedial pattern that makes contact with the arcs formed by the major secondary veins; the external tertiary veins form arcs establishing the ultimate venation; fourth-order venation is irregular forming isolate areolas with moderate to good development. Two other leaflets share their obovate lamina shape, microphyll size, convex apex, asymmetrical base and venation arrangement. However, they differ in their degree of lamina symmetry, laminar radius, the angle of insertion of the secondary veins, and especially in their fifth order venation patterns, and in that only one morphotype has inter secondary veins. Leaf architectures of the new fossil material is similar to both, Abarema and Pithecellobium, which have also great similarity in their construction. However, these genera differ in the regular/irregular spacing of secondary veins, the course of basal secondary veins, which runs parallel to the margin leaving a narrow area where exterior tertiary veins may or may not developed, and arcs formed by the secondary veins have distinct curvatures. Therefore, the first leaflet is assigned to Abarema, while the other two represent different species of Pithecellobium.

Broader Impacts:

1 - Facultad De Ciencias, Universidad Nacional Autónoma De México, Paleontología, Casuarinas #138 Izcalli Ixtapaluca, Estado De México, N/A, 56560, Mexico
2 - Instituto De Geología, UNAM, Circuito De La Investigación, Ciudad Universitaria, Coyoacan, N/A, 04510, Mexico
3 - Instituto De Geología, UNAM, Department of Palentology, Ciudad Univwersitaria, Coyoacan, MEXICO D.F., N/A, 01900, Mexico

Keywords:
Leguminoseae
Miocene
Chiapas
Pithecellobium
Abarema.

Presentation Type: Oral Paper:Papers for Sections
Session: 16
Location: Melrose/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 11:15 AM
Number: 16012
Abstract ID:709
Candidate for Awards:None