Sporomorph Taxa Research Articles

Regional-scale spatial heterogeneity in the late Paleocene paratropical forests of the U.S. Gulf Coast

The study of spatial patterns in biotic compositional variability in deep time is key to understanding the macroecological response of species assemblages to global change. Globally warm climatic phases are marked by the expansion of megathermal climates into currently extra-tropical areas. However, there is currently little information on whether vegetation in these “paratropical” regions resembled spatially modern tropical or extra-tropical biomes. In this paper we explore spatial heterogeneity in extra-tropical megathermal vegetation, using sporomorph (pollen and spore) data from the late Paleocene Calvert Bluff and Tuscahoma Formations of the formerly paratropical U.S. Gulf Coast (Texas, Mississippi, and Alabama). The data set comprises 139 sporomorph taxa recorded from 56 samples. Additive diversity partitioning, nonmetric multidimensional scaling, and cluster analysis show compositional heterogeneity both spatially and lithologically within the U.S. Gulf Coastal Plain (GCP) microflora. We then use sporomorph data from Holocene lake cores to compare spatial patterns in the late Paleocene GCP with modern tropical and extra-tropical biomes. Distance decay analysis of the Holocene data reveals a higher rate of spatial turnover in tropical versus extra-tropical vegetation types, consistent with a latitudinal gradient in floral compositional heterogeneity. The specific combination of rate and scale dependency of distance decay in the Holocene assemblages prevented us from associating the late Paleocene GCP with any particular modern biome. Our results demonstrate the importance of spatial scale, taphonomy, and lithology in determining patterns of spatial heterogeneity, and show the potential of the fossil sporomorph record for studying spatial patterns and processes in deep time.

Regional-scale spatial heterogeneity in the late Paleocene paratropical forests of the U.S. Gulf Coast

The study of spatial patterns in biotic compositional variability in deep time is key to understanding the macroecological response of species assemblages to global change. Globally warm climatic phases are marked by the expansion of megathermal climates into currently extra-tropical areas. However, there is currently little information on whether vegetation in these “paratropical” regions resembled spatially modern tropical or extra-tropical biomes. In this paper we explore spatial heterogeneity in extra-tropical megathermal vegetation, using sporomorph (pollen and spore) data from the late Paleocene Calvert Bluff and Tuscahoma Formations of the formerly paratropical U.S. Gulf Coast (Texas, Mississippi, and Alabama). The data set comprises 139 sporomorph taxa recorded from 56 samples. Additive diversity partitioning, nonmetric multidimensional scaling, and cluster analysis show compositional heterogeneity both spatially and lithologically within the U.S. Gulf Coastal Plain (GCP) microflora. We then use sporomorph data from Holocene lake cores to compare spatial patterns in the late Paleocene GCP with modern tropical and extra-tropical biomes. Distance decay analysis of the Holocene data reveals a higher rate of spatial turnover in tropical versus extra-tropical vegetation types, consistent with a latitudinal gradient in floral compositional heterogeneity. The specific combination of rate and scale dependency of distance decay in the Holocene assemblages prevented us from associating the late Paleocene GCP with any particular modern biome. Our results demonstrate the importance of spatial scale, taphonomy, and lithology in determining patterns of spatial heterogeneity, and show the potential of the fossil sporomorph record for studying spatial patterns and processes in deep time.

Palynological studies on manganese ore layers in Úrkút (Transdanubia), Hungary

Samples of manganese carbonate and oxide layers from the Úrkút ore deposit were investigated for organic remains, especially for spores and pollen grains. Light (LM), Transmission Electron (TEM), and Scanning Electron Microscopy (SEM) methods were used. LM revealed several new sporomorph taxa; a microstratigraphic standard was established by reconstructing vegetation zones surrounding the sedimentary basin. Index fossils of palynomorphs and the relative abundance of other taxa support a Liassic (Lower Jurassic) age for these layers. TEM data were used to establish: (1) important new understanding about the phylogeny of the pollen-exine ultrastructure and, in particular, the tectate columellar ectexine of the Mesozoic gymnospermous pollen grain, Spheripollenites; and (2) the degree of destruction of the exine ultrastructure helps to reconstruct taphonomical processes during sedimentation and to unravel biopolymer-type molecular structures in the walls of palynomorphs. The SEM method aided in the taxonomy of the microfossils. Combined TEM and SEM methods revealed that submicroscopic surface degradation may be a consequence of bio-degradation during deposition of manganese ore.

Comparison of Middle Eocene Sporomorph Assemblages from Southern California and Gulf Coast: ABSTRACT

Fifteen samples from the Delmar Formation and Ardath Shale (lower middle Eocene) and six from the Mission Valley Formation (middle or upper part of the middle Eocene) of San Diego contain about 180 sporomorph (pollen and spore) taxa. The high diversities of Pinaceae-Podocarpaceae, Ephedra-Ephedripites, Palmae, Onagraceae, Bombacaceae-Sterculiaceae-Tiliaceae, and perhaps Euphorbiaceae are similar to those of the modern flora of the region. The flora apparently represents a warmer climate than does the coeval flora of the Gulf Coast. The Eocene flora of San Diego only moderately resembles the present flora of southern California and northwestern Mexico--for example, Fagaceae (oaks, etc) are very rare or absent; this suggests a different climate from that of the present (pro ably more moist and perhaps summerwet rather than summer-dry). In contrast, the middle and upper Eocene assemblages of the Gulf Coast are rich in Fagaceae pollen; these assemblages suggest that the Eocene climate was somewhat warmer but otherwise rather like the present climate of this region. Relatively few sporomorph taxa are common to the middle Eocene of southern California and the Gulf Coast. Sporomorph correlations between the two regions are also difficult at present because the ranges of the San Diego taxa are unknown above or below the middle Eocene in southern California. Nevertheless, Milfordia hungarica and Yeguapollis may prove to be useful for correlating the middle Eocene from southern California with the palynologically better known Gulf Coast units. End_of_Article - Last_Page 927------------

Paleogene sporomorphs from south carolina and quantitative correlations with the gulf coast

Abstract This paper presents the observed stratigraphic ranges of 99 sporomorph (spore and pollen) taxa in the lower Paleocene to upper Oligocene part of the core from the U.S. Geological Survey Clubhouse Crossroads corehole 1 near Charleston, South Carolina. Morphologic and taxonomic data are given for some of these taxa, and three new species are proposed: Nyssapollenites paleocenicus, Osculapollis? colporatus, and Triporopollenites microgranulatus. Fifty‐four sporomorph taxa in the core samples also are found in significant numbers in Gulf Coast Paleogene deposits. The Gulf Coast Paleogene section is divided into 18 provisional sporomorph assemblage zones by using occurrence data from the literature on these 54 taxa. Each South Carolina sample is compared numerically with each Gulf Coast assemblage zone, producing a binary SCMC (presence‐absence Similarity Coefficient Matrix Contour) diagram. Use of this method indicates that sporomorph correlation of “packages”; of Paleogene strata is generally feasible between South Carolina and the Gulf Coast with the data now available. Sporomorph correlations are also possible using a binary Shaw diagram and a ranked relative‐frequency SCMC diagram, but neither of these two methods suggests such detailed correlations as the binary SCMC diagram.

Paleogene sporomorph biostratigraphy, Northeastern Virginia

Abstract This paper discusses the morphology, taxonomy, and stratigraphic occurrences of 62 forms of spores and pollen grains and four forms of freshwater(?) microplankton, in the Paleogene part of the Oak Grove core from northeastern Virginia. The known geologic ranges of these taxa in southeastern United States are also given. Seven new species are proposed: Lusatisporis indistincta, Momipites flexus, Nuxpollenites psilatus, Piolencipollis endocuspoides, Porocolpopollenites virginiensis, Triatriopollenites triangulus, and Tricolpites crassus. Sporomorph occurrences in seven samples from the upper Sabinian (lower Eocene) and lower Claibornian (lower part of the middle Eocene) of the Gulf Coast are also listed; these samples were analyzed to provide additional control for correlating the assemblages from Virginia with those in southeastern United States. Several sporomorph taxa, including Carya and Kyandopollenites anneratus, appear to range lower in the section (into probable Midwayan rocks) in Virginia ...