Coprolite morphotypes from the Upper Cretaceous of Sweden: novel views on an ancient ecosystem and implications for coprolite taphonomy

Eriksson, M.E., Lindgren, J., Chin, K. & Månsby, U. 2011: Coprolite morphotypes from the Upper Cretaceous of Sweden: novel views on an ancient ecosystem and implications for coprolite taphonomy. Lethaia, Vol. 44, pp. 455–468. Coprolites (fossilized faeces) are common, yet previously unreported, elements in the Campanian (Upper Cretaceous) shallow‐marine strata of Åsen, southern Sweden. They are associated with a diverse vertebrate fauna and comprise at least seven different morphotypes that suggest a variety of source animals. Their faecal origin is corroborated by several lines of evidence, including chemical composition (primarily calcium phosphate), external morphology and nature of the inclusions. Preservation in a fossil coquina, interpreted as a taphocoenosis, suggests early lithification promoted by rapid entombment. This would have prevented disintegration of the faecal matter and facilitated transportation and introduction to the host sediment. The coprofabrics can generally be correlated to specific gross morphologies, supporting a morphology‐determined coprolite classification. Moreover, having been deposited under presumably comparable taphonomic conditions, variations in coprofabrics infer differences in diet and/or digestive efficiency of the host animal. Size and morphology of the coprolites imply that most, if not all, were produced by vertebrates and the largest specimens infer a host animal of considerable size. Two spiralled coprolite morphotypes yield bone fragments and scales of bony fish, suggesting that the producers were piscivorous sharks. Other coprolites contain inclusions interpreted as the remains of shelled invertebrates, thus indicating that they may have derived from durophagous predators and/or scavengers. The occurrence of small scrapes, tracks and traces on several specimens suggest manipulation of the faeces by other (presumably coprophagous) organisms after deposition. The collective data from the Åsen coprolites provide new insights into a shallow‐water Late Cretaceous marine ecosystem hitherto known solely from body fossils. □ Coprolites, vertebrates, coprofabrics, taphonomy, trophic levels, Upper Cretaceous, Sweden.     

The formation of collective silk balls in the spider mite Tetranychus urticae Koch

Tetranychus urticae is a phytophagous mite that forms colonies of several thousand individuals. These mites construct a common web to protect the colony. When plants become overcrowded and food resources become scarce, individuals gather at the plant apex to form a ball composed of mites and their silk threads. This ball is a structure facilitating group dispersal by wind or animal transport. Until now, no quantitative study had been done on this collective form of migration. This is the first attempt to understand the mechanisms that underlie the emergence and growth of the ball. We studied this collective behaviour under laboratory conditions on standardized infested plants. Our results show that the collective displacement and the formation of balls result from a recruitment process: by depositing silk threads on their way up to the plant apex, mites favour and amplify the recruitment toward the balls. A critical threshold (quorum response) in the cumulative flow of mites must be reached to observe the emergence of a ball. At the beginning of the balls formation, mites form an aggregate. After 24 hours, the aggregated mites are trapped inside the silk balls by the complex network of silk threads and finally die, except for recently arrived individuals. The balls are mainly composed of immature stages. Our study reconstructs the key events that lead to the formation of silk balls. They suggest that the interplay between mites' density, plant morphology and plant density lead to different modes of dispersions (individual or collective) and under what conditions populations might adopt a collective strategy rather than one that is individually oriented. Moreover, our results lead to discuss two aspects of the cooperation and altruism: the importance of Allee effects during colonization of new plants and the importance of the size of a founding group.     

Biotic interactions of mites, plants and leaf domatia

Leaf domatia, minute structures that typically house mites and other small arthropods, are produced by an impressive number of plants; however, their role in mediating plant-mite mutualism has only recently been elucidated. New evidence indicates that domatia function primarily as refuges for beneficial mites against predators. The presence of domatia therefore results in more beneficial mites on leaves, fewer pathogen attacks and reduced leaf herbivory. Unexpectedly, herbivorous mites are specialized domatia inhabitants of some plants. By providing refuges for herbivores, however, domatia may stabilize interactions between predator and their mite prey and thereby reduce the chances of herbivore outbreaks. Understanding the ecological mechanisms that promote beneficial interactions between mites and plants could have important implications for pest management.     

Plant diversity and habitat structure affect tree growth,herbivory and natural enemies in shelterbelts

Shelterbelts have become a refuge and source of food for wildlife because of habitat loss in farmlands. However, effects of shelterbelt attributes such as plant diversity and habitat structure on different trophic levels within shelterbelts are unclear. Effects of shelterbelt woody plant diversity and habitat structure (lower vegetation strata, logs, litter and rocks) were measured on the growth and herbivory of Eucalyptus blakelyi saplings that were caged from birds, caged from birds and arthropods and un-caged. Arthropod diversity of E. blakelyi saplings and shelterbelts was evaluated. Height and stem diameter of saplings in all treatments was positively correlated with plant diversity. Habitat structure was negatively correlated with numbers of leaves on E. blakelyi saplings and positively correlated with herbivory, which was greater in saplings caged from birds. The overall abundance of arthropods inhabiting shelterbelts correlated positively with plant diversity, but negatively with habitat structure. Araneae and Formicidae were the most common taxa on E. blakelyi saplings and were more numerous on saplings caged from birds, suggesting an important role of these vertebrates as predators of shelterbelt arthropods.     

Callospermarion ovules from the Early Permian of northern China: palaeofloristic and palaeogeographic significance of callistophytalean seed-ferns in the Cathaysian flora

A distinctive kind of anatomically preserved cardiocarpalean ovule is described from the Early Permian Taiyuan Formation of northern China. Ovules are small, have 180° rotational symmetry, and possess variably thick integuments with prominent secretory cavities that may be empty, filled with resinous materials and in several instances appear to contain animal coprolites. Comparisons show that (where known) these features conform to those of Callospermarion undulatum (Neely) Rothwell, to which they are assigned, previously only known from the Pennsylvanian of Euramerica. These fossils represent the first indisputable occurrence of the genus Callospermarion in the Early Permian Cathaysian floras, and show the presence of callistophytalean seed-ferns in this palaeofloristic realm for the first time. These data combined with results from previous investigations now support the Early Permian northern Cathaysian flora including the Taiyuan Formation having evolved from the Late Carboniferous and earliest Permian Euramerican flora, with which it shares far too many generic level similarities for these co-occurrences to be coincidental. Our hypothesis is therefore that the Early Permian flora of the northern Cathaysian realm represents the continued evolution of wetland Euramerican-type coal-swamp floras, and as such is likely to present a model for evolutionarily driven floral change as opposed to the climatically driven floral changes observed in the Euramerican flora after the demise of coal-swamp environments. The distribution of coprolites in and immediately around glandular cavities in this species suggests specialised syndromes of herbivory existed in Early Permian Cathaysian ecosystems, with herbivores preferentially selecting these areas of the ovule integument.     

Multi‐proxy analyses of Late Cretaceous coprolites from Germany

A total of 462 coprolites from three localities exposing Upper Cretaceous deposits in the Münster Basin, northwestern Germany, have been subjected to an array of analytical techniques, with the aim of elucidating ancient trophic structures and predator–prey interactions. The phosphatic composition, frequent bone inclusions, size and morphology collectively suggest that most, if not all, coprolites were produced by carnivorous (predatory or scavenging) vertebrates. The bone inclusions further indicate that the coprolite producers preyed principally upon fish. Putative host animals include bony fish, sharks and marine reptiles – all of which have been previously recorded from the Münster Basin. The presence of borings and other traces on several coprolites implies handling by coprophagous organisms. Remains of epibionts are also common, most of which have been identified as the encrusting bivalve Atreta. Palynological analyses of both the coprolites and host rocks reveal a sparse assemblage dominated by typical Late Cretaceous dinoflagellates, and with sub‐ordinate fern spores, conifer pollen grains and angiosperm pollen grains. The dinoflagellate key taxon Exochosphaeridium cenomaniense corroborates a Cenomanian age for the Plenus Marl, from which most studied coprolites derive. The findings of this study highlight the potential of a multi‐proxy approach when it comes to unravelling the origin, composition and importance of coprolites in palaeoecosystem analyses.     

山东太原组煤核中鳞木类茎——三点“鳞木”的解剖构造

描述了一种产自山东省南部的陶枣煤田和兖州煤田太原组煤核中的鳞木类茎的解剖构造特征。根据叶座的形态,该种茎曾被归入大青山“鳞木”(“Lepidodendron”tachingshanense Lee)种,但此次重新仔细研究后转归三点“鳞木”(“Lepidodendron”tripunctatum Stock.et Math.)种内。与欧美植物区和华夏植物区已有的具解剖构造的鳞木类茎进行了详细对比,认为与奇木属Diaphorodendron很接近,但叶座的形态和解剖差别较大。此外,当前标本的分枝方式还不清楚,因此,还不能将当前标本归入奇木属内。当前标本与奇木属的关系及其分类位置有待于今后对更多更好的标本进行深入研究。     

Attracting friends to feast on foes: engineering terpene emission to make crop plants more attractive to herbivore enemies

When attacked by herbivorous insects or mites, some plant species call on other arthropods for help. They emit mixtures of volatile compounds, dominated by terpenes, to attract carnivorous arthropods that prey on or parasitise herbivores and so reduce further damage. This fascinating defence strategy offers a new, environmentally friendly approach to crop protection. Using recent advances in the biochemistry and molecular genetics of terpene biosynthesis, it should now be possible to engineer crop plants that release terpenes for attracting herbivore enemies. By introducing or selectively altering the existing rate of terpene emission and composition, plant breeders could enable attacked plants to attract enemies and reduce additional herbivory, without compromising the effectiveness of other modes of defence.     

New insights into early land ecosystems: a glimpse of a lilliputian world

Small, relatively uncompressed, very fragmentary plant remains (mesofossils) are described from a Silurian (P ídolí) and a Lower Devonian (Lochkovian) locality in the Welsh Borderland. Excellent cellular preservation provides characters leading to the demonstration of diversity in plants of simple gross morphology and allows deliberations on functional anatomy (e.g. of stomata), and reproductive biology (including development and dehiscence of sporangia). A survey of in-situ spores is presented, and preliminary comparisons made with dispersed spore assemblages especially in relation to reconstruction of vegetation on local and regional scales. The earliest body fossils of unequivocal terrestrial arthropods isolated from the same locality as the P ídolí plants suggest that the decomposer/microherbivore/predator soil and litter communities found in the Lower and Middle Devonian extend back at least into the Silurian. Evidence for plant—animal interaction in the Lower Devonian comes from spore-dominated coprolites believed to have been produced by litter-feeding myriapods.     

High-resolution coproecology: using coprolites to reconstruct the habits and habitats of New Zealand's extinct upland moa (Megalapteryx didinus)

Knowledge about the diet and ecology of extinct herbivores has important implications for understanding the evolution of plant defence structures, establishing the influences of herbivory on past plant community structure and composition, and identifying pollination and seed dispersal syndromes. The flightless ratite moa (Aves: Dinornithiformes) were New Zealand's largest herbivores prior to their extinction soon after initial human settlement. Here we contribute to the knowledge of moa diet and ecology by reporting the results of a multidisciplinary study of 35 coprolites from a subalpine cave (Euphrates Cave) on the South Island of New Zealand. Ancient DNA analysis and radiocarbon dating revealed the coprolites were deposited by the extinct upland moa (Megalapteryx didinus), and span from at least 6,368±31 until 694±30 (14)C years BP; the approximate time of their extinction. Using pollen, plant macrofossil, and ancient DNA analyses, we identified at least 67 plant taxa from the coprolites, including the first evidence that moa fed on the nectar-rich flowers of New Zealand flax (Phormium) and tree fuchsia (Fuchsia excorticata). The plant assemblage from the coprolites reflects a highly-generalist feeding ecology for upland moa, including browsing and grazing across the full range of locally available habitats (spanning southern beech (Nothofagus) forest to tussock (Chionochloa) grassland). Intact seeds in the coprolites indicate that upland moa may have been important dispersal agents for several plant taxa. Plant taxa with putative anti-browse adaptations were also identified in the coprolites. Clusters of coprolites (based on pollen assemblages, moa haplotypes, and radiocarbon dates), probably reflect specimens deposited at the same time by individual birds, and reveal the necessity of suitably large sample sizes in coprolite studies to overcome potential biases in diet interpretation.     

Arbuscular mycorrhizal fungi species-specifically affect induced plant responses to a spider mite

It is widely recognized that arbuscular mycorrhizal fungi (AMF) improve plant growth and nutrient conditions, but their effects can vary from negative to positive depending on AMF species. Since the performance of herbivorous arthropods varies with plant quality, different AMF species should differently affect the density of herbivorous arthropods on plants and the herbivore-induced plant responses. We examined the indirect effects of AMF on the number of spider mites (Tetranychus urticae) and the number of damaged leaves in an outdoor glass-chamber experiment, using Lotus japonicus plants inoculated with one of four different AMF species (Gigaspora margarita, Glomus etunicatum, Gl. intraradices, and Acaulospora longula). Plants with Gi. margarita and A. longula had significantly fewer female mites than plants with Gl. etunicatum and Gl. intraradices, and plants with Gi. margarita had the fewest damaged leaves, followed by plants with A. longula, Gl. intraradices, and Gl. etunicatum. To examine species-specific effects of AMF on herbivore-induced plant responses, we carried out a bioassay with eggs laid by spider mites, and analyses of leaf chemicals (carbon, nitrogen, phosphorus, and total phenolics) using plants subjected or not subjected to herbivory. The bioassay showed that mite egg production and its changes following mite herbivory changed depending on the AMF species. In addition, Principal component analysis for leaf chemicals revealed not only mite-induced changes in leaf chemical composition, but also AMF effects on the herbivore-induced response in a species-specific way. Thus, we need to pay more attention to the species identity of AMF as an important factor in determining the strength of effects of belowground AMF on the performance and/or preferences of aboveground herbivores.     

Host plant manipulation of natural enemies: leaf domatia protect beneficial mites from insect predators

Acarodomatia are small tufts of hair or invaginations in the leaf surface and are frequently inhabited by several taxa of non-plant-feeding mites. For many years, ecologists have hypothesized that these structures represent a mutualistic association between mites and plants where the mites benefit the plant by reducing densities of phytophagous arthropods and epiphytic microorganisms, and domatia benefit the mite by providing protection from stressful environmental conditions, other predaceous arthropods, or both. We tested these hypothesized benefits of domatia to domatia-inhabiting mites in laboratory and growth chamber experiments. In separate experiments we examined whether domatia on the wild grape, Vitis riparia, provided protection against drying humidity conditions or predaceous arthropods to two species of beneficial mite: the mycophagous species Orthotydeus lambi, and the predaceous species Amblyseius andersoni. For both taxa of beneficial mite, domatia significantly increased mite survivorship in the presence of the predatory bug, Orius insidiosus and the coccinellids Coccinella septempunctata and Harmonia varigata. There was no evidence for a protective effect of domatia with a third species of predatory arthropod, lacewing larvae Chrysoperla rufilabris. In contrast, there was no evidence for either species of beneficial mite that domatia provided any protection against low humidity. Thus in this system the primary mechanism by which domatia benefit beneficial mites is by protecting these organisms from other predatory arthropods on the leaf surface.     

The last diadectomorph sheds light on Late Palaeozoic tetrapod biogeography

Diadectomorpha is a clade of Late Palaeozoic vertebrates widely recognized as the sister group of crown-group Amniota and the first tetrapod lineage to evolve high-fibre herbivory. Despite their evolutionary importance, diadectomorphs are restricted stratigraphically and geographically, with all records being from the Upper Carboniferous and Lower Permian of North America and Germany. We describe a new diadectomorph, Alveusdectes fenestralis, based on a partial skull from the Upper Permian of China. The new species exhibits the derived mechanism for herbivory and is recovered phylogenetically as a deeply nested diadectid. Approximately 16 Myr younger than any other diadectomorph, Alveusdectes is the product of at least a 46 Myr ghost lineage. How much of this time was probably spent in Russia and/or central Asia will remain unclear until a specimen is described that subdivides this cryptic history, but the lineage assuredly crossed this region before entering the relatively isolated continent of North China. The discovery of Alveusdectes raises important questions regarding diadectomorph extinction dynamics including what, if any, ecological factors limited the diversity of this group in eastern Pangea. It also suggests that increased sampling in Asia will likely significantly affect our views of clade and faunal insularity leading up to the Permo-Triassic extinction.     

Trophic cascades in tropical rainforests: Effects of vertebrate predator exclusion on arthropods and plants in Papua New Guinea

Insect herbivores have the potential to consume large amounts of plant tissue in tropical forests, but insectivorous vertebrates effectively control their abundances, indirectly increasing plant fitness accordingly. Despite several studies already sought understanding of the top-down effects on arthropod community structure and herbivory, such studies of trophic cascades in old tropics are underrepresented, and little attention was paid to top-down forces in various habitats. Therefore, we examine how flying insectivorous vertebrates (birds and bats) impact arthropods and, consequently, affect herbivore damage of leaves in forest habitats in Papua New Guinea. In a 3-month long predator exclosure experiment conducted at four study sites across varying elevation and successional stage, we found that vertebrate predators reduced arthropod density by ∼52%. In addition, vertebrate predators decreased the mean body size of arthropods by 26% in leaf chewers and 47% in non-herbivorous arthropods but had only a small effect on mesopredators and sap suckers. Overall, the exclusion of vertebrate predators resulted in a ~ 41% increase in leaf damage. Our results, across different types of tropical forests in Papua New Guinea, demonstrate that flying vertebrate insectivores have a crucial impact on plant biomass, create a selective pressure on larger and non-predatory prey individuals and they prey partition with mesopredators.     

PHYSOSTOMA CALCARATUM SP. NOV., A TENTACLED SEED FROM THE MIDDLE PENNSYLVANIAN OF KANSAS

A new species of Physostoma is described from Kansas coal balls of Middle Pennsylvanian age. The seed is small, ovoid, and radially symmetrical. The integument consists of 6–10 rounded segments, fused in the lower half of the seed but free in the upper. Distinct spurs are formed by the segments near the base of the seed. The integument is essentially non-sclerified and has a distinct blow-off epidermis. Each segment is supplied by a single vascular trace. The pollen reception mechanism consists of a short cylindrical salpinx, a bell-shaped lagenostome, and a shallow plinth. A central column is present within the salpinx. It is suggested that the Upper Carboniferous seed genera Conostoma and Physostoma may have been derived from the Lower Carboniferous genera Salpingostoma-Euryostoma and Genomosperma-Hydrasperma, respectively.     

Leaf domatia mediate mutualism between mites and a tropical tree

Although associations between mites and leaf domatia have been widely reported, their consequences for plants, especially for natural tree populations, particularly in the tropics, are largely unknown. In experiments with paired Cupania vernalis (Sapindaceae) saplings in a semi-deciduous forest in south-east Brazil, we blocked leaf domatia to examine their effect: (1) on mites and other arthropods, and (2) on damage caused by fungi and herbivorous arthropods. In general, plants with resin-blocked domatia had fewer predaceous mites on leaves than control plants with unaltered domatia, but the total abundances of fungivorous and of phytophagous mites remained unchanged. However, phytophagous eriophyid mites, the most numerous inhabitants of domatia, decreased on leaf surfaces with the blocking treatment. In a second experiment, treated plants lacking functional domatia developed significantly greater numbers and areas of chlorosis, apparently due to increased eriophyid attacks, whereas fungal attack, epiphyll abundance and leaf-area loss were unaffected. This seems to be the first experimental study to demonstrate that leaf domatia can benefit plants against herbivory in a natural system. The possible stabilizing effect of leaf domatia on predator-prey interactions is discussed.     

Leaf domatia and mites on Australasian plants: ecological and evolutionary implications

Leaf domatia, specialized chambers in the vein axils on the underside of leaves of many plant species, have remained an enigma for over a century. In this study we show a strong association between foliar domatia and mites in 37 plant species in Australasia. Overall, mites accounted for 91% of the arthropods observed in domatia. Across all species, a median of 51% of domatia were occupied and 71% of leaves showed mite evidence in domatia. The level of mite association did not depend on domatia type (pit, pouch, pocket, or tuft) or provenance (Papua New Guinea, Queensland, Victoria, or New Zealand). Mite association with domatia commonly varied between plant species, between individuals within species, and between shoots within individuals. The leaf developmental stage probably explains much of the variation in association for many of these species. The presence of a variety of life history stages of mites within domatia indicates that these structures act as shelters for development and reproduction. Furthermore, in 12 of 13 plant species examined, domatia concentrate mites in particular locations on the leaf. Mite taxa that we classify as largely predaceous (e.g. phytoseiids, stigmaeids and tydeids) or fungivorous (e.g. acarids and oribatids) were most common in domatia and dominated the association in 21 of 24 plant species in which the relative abundance of herbivorous, fungivorous and predaceous groups was quantified. We evaluate hypotheses that explain the role of leaf domatia, including non-functional hypotheses (e.g. architectural constraints), physiological function (e.g. gas exchange and water uptake), bacterial symbiosis and antagonistic and mutualistic associations with mites. Our quantitative results confirm anecdotal accounts of mite association with leaf domatia and are most consistent with Lundströem's century-old hypothesis of plant-mite mutualism in which leaf domatia billet predaceous and fungivorous mites that prey on plant enemies. Leaf domatia are widespread among woody angiosperms and abundant in many temperate and tropical regions of Australasia. Mites, an ancient group of arthropods whose diversity and abundance parallels that of insects, are likely to be important selective agents on terrestrial plants. Our results (1) indicate that mite-domatia association represents a relationship of comparable scope to plant-ant associations mediated by specialized plant structures such as extrafloral nectaries, food bodies and specialized domatia; (2) suggest that sociality is not a necessary prerequisite for widespread and diverse mutualisms between arthropods and plants; and, (3) extend the diversity of organisms that produce specialized mite ‘houses’ from lizards, and wasps and bees to woody angiosperms.     

Plant microfossil analysis of coprolites of the critically endangered kakapo (Strigops habroptilus) parrot from New Zealand

We present here the results of the analysis of pollen, spores, starch and other microscopic plant material in 52 coprolites of the critically endangered kakapo (Strigops habroptilus), a New Zealand endemic parrot. The six sampling sites (caves, rock overhangs) are in widely separate geographic regions in the South Island, across an altitudinal range encompassing lowland, montane and sub-alpine environments. Radiometric testing gives average ages of discrete coprolite groups ranging from modern to 2514 ± 43 ¹⁴C yr BP (Wk-19164). A wide variety of plant taxa is identified in the coprolites, comprising cones, flowers, leaves and fronds of ~ 30 podocarps, dicotyledonous trees, shrubs and lianas, grasses, ferns, lycopods, mosses and liverworts. This supports previous observations that kakapo are versatile feeders, using a broad spectrum of foods that may only be available for short periods and intermittent years. Many of the food taxa we identify are consistent with the studies of modern kakapo diet. We also identify several new foods, potentially of value in developing food supplements to increase breeding frequency of the current kakapo population. The most commonly identified plant parts in coprolites were fern fronds (monoletes, Hymenophyllum, Cyathea smithii), followed by podocarp cones and leaves. Lack of starch in the coprolites suggests that the lycopod and fern rhizomes reported in modern kakapo diet were not commonly eaten. The data provide initial botanical evidence of diet from coprolites of an extant bird.     

Top-down control of herbivory by birds and bats in the canopy of temperate broad-leaved oaks (Quercus robur)

The intensive foraging of insectivorous birds and bats is well known to reduce the density of arboreal herbivorous arthropods but quantification of collateral leaf damage remains limited for temperate forest canopies. We conducted exclusion experiments with nets in the crowns of young and mature oaks, Quercus robur, in south and central Germany to investigate the extent to which aerial vertebrates reduce herbivory through predation. We repeatedly estimated leaf damage throughout the vegetation period. Exclusion of birds and bats led to a distinct increase in arthropod herbivory, emphasizing the prominent role of vertebrate predators in controlling arthropods. Leaf damage (e.g., number of holes) differed strongly between sites and was 59% higher in south Germany, where species richness of vertebrate predators and relative oak density were lower compared with our other study site in central Germany. The effects of bird and bat exclusion on herbivory were 19% greater on young than on mature trees in south Germany. Our results support previous studies that have demonstrated clear effects of insectivorous vertebrates on leaf damage through the control of herbivorous arthropods. Moreover, our comparative approach on quantification of leaf damage highlights the importance of local attributes such as tree age, forest composition and species richness of vertebrate predators for control of arthropod herbivory.     

Stratigraphic occurrences and vegetational patterns of Pennsylvanian pteridosperms in Euramerican coal swamps

The vegetation of many Euramerican coal swamps is known from coal-ball peats in the tropical rainy zone across the paleocontinent of Laurussia in the Upper Carboniferous. The stratigraphic occurrences of coal balls in Europe (lower Westphalian) and in North America (upper Westphalian and lower Stephanian) are largely complementary and a revised correlation chart is given. Quantitative analyses of the vegetation from these autochthonous peats are combined with coal palynology to determine on overview of swamp vegetation patterns during the Westphalian and early Stephanian. In comparison to the dominance and great diversity of pteridosperms in the Upper Carboniferous compression floras, seed ferns were minor to subdominant elements in the coal-ball peats. The quantitative composition of organ assemblages of the principal pteridosperms is given with stratigraphic occurrences of Medullosa and Sutcliffia (Medullosaceae), Heterangium, Lyginopteris, Microspermopteris, and Schopfiastrum (Lyginopteridaceaea) and Callistophyton (Callistophytaceae). The major peat contributors among pteridosperms are Lyginopteris (?90%) in the Westphalian A and Medullosa (?95%) in the Westphalian D and Stephanian. Lyginopteris became extinct in the early Westphalian B and Medullosa became abundant during the Westphalian C–D transition and a subdominant in the Stephanian contributing 13–21% of the permineralized peats. Paleoecological interpretations indicate that medullosan trees were most abundant but patchy in distribution in drier swamp stages with enriched nutrients and near major channels in swamps during the Westphalian D. It is suggested that the swamp pteridosperms are probably quite similar to or identical with some of the representatives in the more diverse compression floras. The evolution and diversity noted in swamp pteridosperms are considered principally the product of adjacent lowland communities which repeatedly introduced seeds into the wetlands. The swamp pteridosperms exhibit the greatest fluctuation in abundance (biomass) from site to site in the same coal, probably the highest level of diversity and the only steady pattern of increase in importance during the Late Carboniferous with the possible exception of the Westphalian B–C interval. The close relationships inferred between swamp pteridosperms and their lowland seed sources are also compatible with the frequent association of tree ferns and seed ferns during the Westphalian D and in the Stephanian when these two kinds of frond-bearing trees formed most of the vegetation in both lowland and swamp environments.