Early Permian conifer remains from Central Mexico and reevaluation of Paleozoic conifer morphotaxa

• Published in: Boletín de la Sociedad Geológica Mexicana Vol. 66; no. 1; pp. 85 - 96
• Main Authors: Hernández-Castillo, Genaro R., Silva-Pineda, Silvia A., Cevallos, Sergio R.S.
• Format: Journal Article
• Language: English; Portuguese
• Published: Sociedad Geológica Mexicana e Instituto de Geología de la UNAM 01.01.2014; Sociedad Geológica Mexicana, A.C
• Subjects: ARTÍCULOS / ARTICLES; Branches; Conifers; Flora; Fossils; Geology; Geosciences, Multidisciplinary; Leaves; Paleobotany; Palynology; Plants; Taxa; conífera; Permian; morfotaxa; Pérmico; morphotaxa; Mexico; México; Walchia; conifer
• ISSN: 1405-3322; 1405-3322
• DOI: 10.18268/BSGM2014v66n1a7

This paper describes the first Permian walchian conifer from Mexico based on several specimens preserved as compressions/impressions. The material comes from the Tuzancoa Formation in the state of Hidalgo, Central Mexico. It is described asCalnalia hidalguensisgen. nov. et sp. nov. a new conifer morphotaxon based on isolated lateral branches with leaves. This new conifer has some of the smallest branches and leaves found among previously described walchians.Calnalia hidalguensishas two types of branches (ovoid and deltoid) with simple and helically arranged leaves. Leaves are narrowly triangular to linear in front view, slightly concave and spreading (penultimate shoots) to slightly concave to slightly S-shaped (ultimate shoots), in side view. Leaves range from 3.2 mm long by 0.5 mm wide on penultimate shoots, to 1.3 - 2.9 mm long by 0.4 - 0.9 mm wide on ultimate shoots, with angles of leaf insertion ranging from 16º to 39º. The new species is most similar toEmporia lockardiiMapes and Rothwell,Walchia goeppertianaFlorin,Walchia mucronataFlorin, andOtovicia hypnoidesKerp, Poort, Swinkels & Verwer. However, none of these have the same ranges of morphological variation found in the leaves of Mexican species. The new taxon expands the diversity of walchian conifers at the end of the Paleozoic in America, and marks the beginning of new research of Permian floras in Mexico. The presence ofC. hidalguensisand other gymnosperms, to be described, reinforces the presence of an arc along the Oaxaquia block that connected Mexico to the North American craton during the late Paleozoic. These new data also allow us to test hypotheses about the origin and evolution of Paleozoic floras in Euramerica.