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Copyright of Spal: Revista de Prehistoria y Arqueologia de la Universidad de Sevilla is the property of Spal. Revista de Prehistoria y Arqueologia de la Universidad de Sevilla and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

New investigations of Cretaceous floristic assemblages in Mexico reveal a more complete picture of the flora at that time and its evolution up to the present. The scarce continental paleobotanical studies for the Early Cretaceous remain unpublished and are restricted to macroflora studies in Colima, Oaxaca and Puebla, citations of leaf impressions in Chihuahua and Sonora and palynological works in the states of Baja California, Durango and Michoacan. The reason for the paucity of data for this period is mainly due to the fact that at this time most of Mexico remained submerged. In contrast, palynological studies focused on the Late Cretaceous are more numerous and are mainly centered on the Olmos Formation (Coahuila) and, to a lesser extent, there are studies from the Cerro del Pueblo (Coahuila), El Gallo (Baja California), Sierra Madre (Chiapas), and Tarahumara (Sonora) formations, the Cabullona Group (Sonora) and other isolated unpublished works. New contributions to the Cretaceous of Mexico are provided, mainly by Cenomanian macroflora from the locality of El Chango (Chiapas) and new macro- and microflora records from Esqueda in Cabullona Basin (Sonora). [ABSTRACT FROM AUTHOR]

In this study we present new records of the tree fern fossil genus Tempskya Corda, 1845 from the Pinilla de los Moros Formation, late Hauterivian - early Barremian in age, in the surroundings of the village Salas de los Infantes (Burgos province, northern Spain). The studied samples exhibit similar anatomical features to those of the species T. riojana Barale y Viera, 1989, even though they present some extra characters. These additional features include the presence of sclerenchyma islets with irregularly shaped parenchymal layer in the inner bark of stems and also an intermediate bark layer which invaginates into the inner layer. These characters are identified for the first time in this taxon, and they could serve as a criterion for differentiating this species from other Tempskya Corda, 1845 species, constituting a new contribution to the knowledge of this taxon. [ABSTRACT FROM AUTHOR]

Paleobotany research has developed multiple analytical frameworks using plant macrofossils as a tool for paleoclimate inference. These frameworks can be broadly divided into two groups: the taxon independent approach (TIA) and the nearest living relative (NLR). The TIA studies climate-driven phenotypic variation in extant plants and extrapolates the relationship between climate and structure to make paleoclimatic inferences. The NLR, on the other hand, relies on the taxonomic identification of the species in fossil assemblages to assign them the climatic tolerances of their nearest living relatives. Both frameworks have proven to be useful but have intrinsic flaws due to the nature of the data used and the particular methods employed. Our target here is to highlight the significance of these frameworks, but also to point out that they do not always provide unequivocal paleoenvironmental data, which is the result of differences in both scale (geographic, temporal and taxonomic) and taphonomical processes. Here we illustrate some of the advantages and flaws of both frameworks using three examples of paleoclimate inference for some Mexican localities. In this paper we briefly review as well some of the relevant research relating leaf and wood structure to environmental variation that has served as the foundation for the field. [ABSTRACT FROM AUTHOR]

The origin of the extant vegetation and diversity of Mexico has a long history. Possibly the extent of this history is the point where the proposals differ, one states that the history begins in the Cretaceous (ca. 132 my) while other emphasize processes restricted to the Plio-Pleistocene (5.3 my), especially if referring the appearance of extant vegetation. Increased knowledge of the geological evolution of Mexico, and the constant change in physiography, along with the study of fossil angiosperms of the region, generates a clearer concept of how and when life forms differentiated and partnered. A hypothesis that combines geological processes and physiographic changes with the presence of plants and vegetation on the emerged continental parts is presented. It is proposed that existing biodiversity does indeed start ca. 132 million years ago, and although lineages that live in Mexico today can be recognized from this time, it is difficult to place their representants within a family, probably because they may represent members of the stem group. By the Paleogene (65-32 my) families, and even genera, that continue to live in Mexico are more easily recognized, but groups of extinct plants or plants growing today in other regions are still common. Based on the morphological/anatomical approach the Neogene (32-1.8 my) fossil plants resemble more those living naturally in Mexico, but still have important differences supporting the recognition of new species only. If in relatively recent times extant and fossil plants in Mexico seem closer based on their morphology/anatomy, it is to be expected that with the vegetation types a similar process can be recognized. The fossil record suggests that from communities that developed under hot-humid conditions in the Cretaceous, vegetation types with different capabilities to tolerate water stress, and communities that favored cool temperate conditions diverged. The process of divergence apparently occurred at two different times in two different regions. During the Paleogene it affected northern Mexico and during the Neogene it affected central and southern Mexico. Further geological and paleobotanical work will refine this proposal that suggests that changes that enable or constrain biological responses are part of other components of the Earth System. [ABSTRACT FROM AUTHOR]

Copyright of Recursos Rurais is the property of Universidad de Santiago de Compostela, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)