Morphology and affinities of an Early CretaceousEphedra(Ephedraceae) from China

Abstract

Detailed investigations on Lower Cretaceous Ephedra L. fossils (Gnetopsida) reveal morphological characters similar to those of extant Ephedra rhytidosperma Pachomova, including articulate branches with many fine longitudinal striations, a dichasial branching pattern, uni- or bi-ovulate cones with paired bracts, cones terminal on branchlets, and seeds with a short, straight micropylar tubes, covered by numerous regular and prominent transverse laminar protuberances. Fossils are similar to extant E. rhytidosperma reproductive organs but differ in some vegetative structures and are described and discussed here as Ephedra archaeorhytidosperma Y. Yang et al. Because E. rhytidosperma is currently considered one of the most specialized members in Ephedra L. section Pseudobaccatae Stapf, the occurrence of E. archaeorhytidosperma in the Yixian Formation suggests that Ephedra L. was perhaps a more diverse genus in the Lower Cretaceous. Perhaps the evolution and diversity of Ephedra L. was already in place by the Lower Cretaceous and certainly before the end of the Mesozoic.

Itajuba yansanae Gen and SP NOV of Gnetales, Araripe Basin (Albian-Aptian) in Northeast Brazil

“…Although due to the type of preservation of the fossils studied, this could not be observed in detail, this ornamentation resembles that mentioned by various authors [15,26,[31][32][33]. Although not connected organically to the main stem, the seed was attached to a female cone identical to others, organically connected to the main branch.…”

“…[26] shares the striated stem and single terminal female cones composed of 2 pairs of bracts, although the shape and size are different. Moreover, E. archaeorhytidosperma seems to have been a herb, whereas I. yansanae seems to have been a woody plant.…”

“…This new species was compared (see tables 1 and 2) with other gnetalean fossils found in lithostratigraphic units of the Lower Cretaceous in both the Northern and Southern hemispheres. It was compared with Drewria potomacensis Crane et Upchurch [25] from the Aptian of the Potomac Group of Virginia in the USA, and with Ephedra archaeorhytidosperma Yang et al [26], Liaoxia changii (Cao et S.Q. Wu) Rydin, S.Q.…”

Revisión taxonómica y distribución geográfica de Ephedra (Ephedraceae) en México

“…Los cálculos de fechamiento a través de un reloj molecular, indican que el género pudo haberse originado hace 8 a 32 millones de años (Yang et al, 2005). Los estudios filogenéticos más recientes indican una división geográfica basal que engendra al clado americano a partir del linaje primitivo del Viejo Mundo.…”

“…Se conocen escasos macrofósiles relacionados con Ephedra, los cuales han sido ubicados en los géneros Ephedrites Saporta, Chaoyangia Duan y Eoanthus Krassilov (Yang et al, 2005), aunque el registro palinológico es relativamente abundante. Recientemente se encontraron macrofósiles que datan del Cretácico Inferior, en la formación de Yixian, en China, a partir de los cuales en 2005 se describió Ephedra archaerhytidosperma Y. Yang, B. Y. Geng, D. L. Dilcher, Z. D. Chen y T. A. Lott.…”