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

Abstract

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 as Calnalia hidalguensis gen. 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 hidalguensis has 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 to Emporia lockardii Mapes and Rothwell, Walchia goeppertiana Florin, Walchia mucronata Florin, and Otovicia hypnoides Kerp, 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 of C. hidalguensis and 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.Keywords: conifer, Mexico, morphotaxa, Permian, Walchia. Resumen Este artículo describe la primera conífera pérmica "walchiana" con base en varias compresiones e impresiones fósiles de la Formación Tuzancoa en el Estado de Hidalgo, Centro de México. Se describe como Calnalia hidalguensis gen. nov. et sp. nov., un nuevo morfotaxón de coníferas basados en ramas laterales y hojas. Esta nueva conífera tiene unas de las ramas más pequeñas descritas hasta ahora para los miembros "walchianos" en el registro fósil, y cuenta con dos tipos de ramas (ovoide y deltoide), las cuales portan hojas simples con filotaxia helicoidal. Las hojas son ligeramente triangulares a lineares; lateralmente son ligeramente cóncavas a abiertas (penúltimo orden), y ligeramente cóncavas a ligeramente en forma de "S" (último orden

Avances en el conocimiento de la macroflora de la Formación Tuzancoa, Hidalgo, México, Pérmico inferior

“…En el caso de la Formación Olinalá (Guerrero) se han reportado tres géneros, una especie, así como una afinidad (Silva-Pineda et al, 2003). Por último, en la Formación Tuzancoa (Hidalgo) que es motivo de este estudio, los trabajos han sido intermitentes y en la mayoría de los casos se trata de material escaso y mal preservado (Silva-Pineda, 1987;Hernández-Castillo et al, 2014;Ortiz-Martínez y Velasco-de León, 2019). Como se puede observar, hasta el momento las unidades con mayor diversidad de flora fósil son las pertenecientes a las formaciones Matzitzi y Tuzancoa, esto debido en parte a la extensión de sus afloramientos y a sus ambientes de depósito que favorecieron un abundante registro de plantas (Weber, 1997;Rosales-Lagarde, 2005;Centeno-García et al, 2009); sin embargo, el descubrimiento de nuevas localidades en la For-mación Tuzancoa hace necesaria una descripción del nuevo material.…”

“…Todos estos datos indican un ambiente de depósito marino somero y transicional (Carrillo-Bravo, 1965;Rosales-Lagarde et al, 2005;Sour-Tovar et al, 2005;Quiroz-Barroso et al, 2012;Buitrón-Sánchez et al, 2017;Gutiérrez-Alejandre, 2018). Desde el punto de vista paleobotánico se tienen como antecedentes algunos trabajos taxonómicos (Silva-Pineda, 1963;Hernández-Castillo et al, 2014;Ortiz-Martínez y Velasco-de León, 2019;Velasco-de León et al, 2020). La sección tipo de esta formación aflora en las cercanías del poblado Otlamalacatla, Hidalgo (Rosales-Lagarde et al, 2005).…”

Three new Cenomanian conifers from El Chango (Chiapas, Mexico) offer a snapshot of the geographic mosaic of the Mesozoic conifer decline

“…This fossil record reveals that conifers first evolved during the Carboniferous, likely from an ancestor in the Cordaitales, an extinct group of seedplants (Beck, 1988). During the rest of the Paleozoic, conifers increased in diversity and geographic extent, leaving behind traces of lineages that are known only from the fossil record, such as the Walchian and Voltzian conifers (Looy, 2007;Hernández-Castillo et al, 2014). Though most of the Paleozoic conifer lineages went extinct around the Permian-Triassic boundary, the groups that persisted became widespread in the Mesozoic (Beck, 1988;Farjon, 2008).…”

“…Despite being massively outnumbered by extant angiosperms (angiosperms account for ∼ 89% of extant plant species vs ∼ 0.29% for gymnosperms; Crepet and Niklas, 2009;Hassler, 2021) conifers were dominant for the first half of the Mesozoic (Miller, 1977;Taylor et al, 2009). This former ecological dominance is documented in a particularly rich fossil record (e.g., Contreras et al, 2019;Hernández-Castillo et al, 2014;Looy, 2007), which is partially due to the fact that conifers have sturdy structures-i.e., cones, wood, and thick leaves-that are more prone to fossilize than are the more delicate structures of other plant groups. This fossil record reveals that conifers first evolved during the Carboniferous, likely from an ancestor in the Cordaitales, an extinct group of seedplants (Beck, 1988).…”

An Analysis of a New Foliar Architecture of the Permian Period in Mexico and Its Ecological Interactions

“…Filicales, Calamitales and Conifers have been recorded, such as Walchia Sternberg and Cordaites Unger. Lastly, in the Tuzancoa Formation, the presence of Calnalia hidalguensis with microphyll leaves has been described [13]. By means of the analysis of flora and lithology of the locality, we are going to know the causes of growth to the new morphotype in the early Perm period.…”