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Premise of research. A third genus of anatomically preserved conifer seed cones has been recognized from a Late Jurassic deposit in northeastern Scotland. This cone is described as Bancroftiastrobus digitata Rothwell, Mapes, Stockey et Hilton.Methodology. The cone was sectioned with the classic coal ball peel technique and studied and photographed with transmission light.Pivotal results. Bancroftiastrobus digitata is a cylindrical cone with large, helically arranged ovuliferous scales subtended by short bracts, each bract/scale complex bearing two unwinged inverted seeds on the adaxial surface of the ovuliferous scale. Ovuliferous scales have abaxial plications in the midregion and divide distally, forming up to nine free distal lobes that are vascularized and covered by a dense ramentum of trichomes. The cone axis forms a continuous woody cylinder that surrounds a parenchymatous pith. There are numerous resin canals in the cortex of the cone axis that extend into each bract/scale complex, both abaxial an...

This study describes a specimen that extends the oldest fossil evidence of Pinus L. to the Early Cretaceous Wealden Formation of Yorkshire, UK (131–129 million years ago), and prompts a critical reevaluation of criteria that are employed to identify crown group genera of Pinaceae from anatomically preserved seed cones. The specimen, described as Pinus yorkshirensis sp. nov., is conical, 5 cm long, and 3.1 cm in maximum diameter. Bract/scale complexes are helically arranged and spreading. Vasculature of the axis forms a complete cylinder with few resin canals in the wood, and the inner cortex is dominated by large resin canals. Bracts are short, with two resin canals, and separate from the scale base laterally. Distally, the ovuliferous scales broaden and thicken to form a rhomboidal apophysis with a dorsal umbo, characters found only in the genus Pinus among living conifers. Resin canals enter the ovuliferous scale abaxial to the vascular tissue, which divides distally to form a row of adaxially convex bu...

Anatomically preserved Jurassic conifer seed cones originally described as Conites juddi Seward and Bancroft are reinvestigated and assigned to Hughmillerites juddii gen. et comb. nov. using the original specimens and new material from the type locality. This allows for a more thorough characterization of seed cone structure, for systematic placement of the species, and for establishing homologies of cupressaceous bract/scale complexes. Incomplete cones range 2.2–3.6 cm in diameter and 3.0–4.3 cm long, and have distinctly woody axes bearing helically arranged bract/scale complexes with a thickened bract tip. Mature complexes display three inverted seeds attached to the adaxial surface immediately proximal to three free ovuliferous scale tips. In each bract/scale complex there is a single large resin canal abaxial to the vascular bundle and three or more smaller adaxial resin canals at the level of seed attachment. Seeds are inverted at maturity, display 180° rotational symmetry, and show differentiation of sclerotesta and sarcotesta. The results of a phylogenetic analysis support placement of H. juddii among the basal grade of taxodioid Cupressaceae ( Farjon, 2005 ). A transformational series of ovuliferous bract/scale complexes from voltziacean Voltziales to crown group Cupressaceae is presented to reveal the pattern and antiquity of evolution for modern cupressaceous conifer seed cone morphologies. Developmental studies of living cupressaceous seed cones indicate that the range of mature morphologies is strongly correlated with differences in the timing and rate of development for the bract, scale, and ovules, thus supporting the hypothesis that heterochrony plays a major role in the evolution of bract/scale form. This hypothesis is further supported by our growing understanding of developmental regulatory genetics. There are no currently recognized synapomorphies for living + fossil conifers. Nevertheless, these combined results do not support the hypotheses that some conifers have ancestrally simple seed cones nor that there have been parallel origins of Northern and Southern Hemisphere conifers. The overall body of evidence from both extinct and living conifers strongly supports the hypotheses of deep homology for seed cones and of monophyly for conifers s.s.

This paper provides a whole plant concept for a new species, Emporia cryptica sp. nov. Hernandez-Castillo, Stockey, Rothwell & Mapes (Emporiaceae: Voltziales), the fourth conifer to be reconstructed from the rich fossil biota at the Late Pennsylvanian, Hamilton Quarry, Kansas. E. cryptica has an orthotropic stem, lateral plagiotropic branches with simple leaves, simple pollen cones, and compound ovulate cones. Branches have an endarch eustele with dense wood surrounding a parenchymatous pith with sclerotic nests/plates, and secondary xylem tracheids with multiseriate hexagonal bordered pits. Leaves on both penultimate and ultimate branches are simple and amphistomatic with two adaxial stomatal bands, monocyclic and dicyclic stomata, and two narrow abaxial rows of stomata with numerous trichome bases. Pollen cones are simple with helically arranged microsporophylls and adaxial pollen sacs. Prepollen is monolete, eusaccate, and monosaccate (Potonieisporites Bharadwaj). Ovulate cones are compound with bilaterally symmetrical dwarf shoots in the axils of helically arranged forked bracts. Axillary dwarf shoots bear numerous sterile scales interspersed with two megasporophylls, each bearing a single inverted terminal ovule. This plant displays morphological and cuticular characters similar to several morphogenera of Paleozoic walchian conifers but is most comparable to the fossil plant species Emporia lockardii and Hanskerpia hamiltonensis. E. cryptica is the only walchian conifer where ovules and seeds with megagametophytes, immature embryos and mature embryos have been documented, demonstrating that the most ancient conifers possessed seed dormancy and polycotyledonary embryos. This reproductive biology is similar to that of many Mesozoic and extant conifers with saccate pollen except for the presence of prepollen grains that are common among Paleozoic walchian conifers.

A new species of extinct conifer plants, Emporia royalii sp. nov. Hernandez‐Castillo, Stockey, Mapes et Rothwell (Emporiaceae: Voltziales), is described from the rich fossil biota of the Late Pennsylvanian, Hamilton Quarry, Kansas. This conifer has lateral plagiotropic branches with simple and forked leaves, “age‐dependent heterophylly,” simple pollen cones, and compound ovulate cones. Stems have an endarch eustele, dense wood, and secretory cells arranged in nests or plates in the pith. Leaves are amphistomatic with two adaxial stomatal bands and two longitudinal abaxial rows of stomata with numerous trichome bases. Pollen cones are simple and have helically arranged microsporophylls with adaxial pollen sacs. Prepollen is monolete and monosaccate (Potonieisporites Bharadwaj). Ovulate cones are compound with bilaterally symmetrical axillary dwarf shoots that bear up to 45 sterile scales and 1–2 sporophylls and occur in the axils of helically arranged bracts with forked tips. Ovules are inverted and winged...

A new plant concept for the extinct conifer species Emporia lockardii (Mapes & Rothwell) Mapes & Rothwell (Emporiaceae) is developed from fossils collected at the Late Pennsylvanian Hamilton Quarry, Kansas. Emporia lockardii has lateral plagiotropic branches with simple and forked leaves, simple pollen cones, and compound ovulate cones. Stems have an endarch eustele with dense wood surrounding a septate pith. Leaves display position‐dependent heterophylly with forked leaves on penultimate shoots and simple leaves on ultimate shoots. All leaves are amphistomatic with two stomatal bands and papillate epidermal cells on the adaxial surface and two basal stomatal bands and numerous trichome bases on the abaxial surface. Pollen cones are simple and have helically arranged microsporophylls and adaxial pollen sacs. Prepollen is monolete and monosaccate, and it conforms to the sporae dispersae genus Potonieisporites Bharadwaj. Ovulate cones are compound with helically arranged, forked bracts that subtend bilatera...

A new species of Cardiocarpus from the Sim River Basin in the southern Urals of Russia is the first anatomically preserved cardiocarpalean ovule from the Permian of the Angara floral province. Specimens are preserved in a soft organic limestone with large numbers of juvenile bactritoid protoconchs. Ovules are roughly ellipsoidal in the major plane, up to 6.0–7.5 mm in length and 5.3 mm in width, with a diminutive wing and a rounded chalaza. The outer surface of the ovules is smooth. In longitudinal sections, two vascular tissue channels traverse the sclerotesta at the chalaza, and appear to extend to near the apex within each wing. There is a simple, dome-shaped pollen chamber at the apex, which lies below a narrow micropyle. The sclerotesta consists of one or two layers of longitudinally orientated cells at the interior, and sclereids that are radially elongated towards the periphery. The sarcotesta is incompletely preserved, but displays an outer layer of cells that are somewhat elongated towards the long axis of the ovule. Numerical cladistic analysis reveals little correlation between the structure of cardiocarpalean morphotaxa and the phylogenetic relationships of the plants that produced them, where affinities are known. Cardiocarpus angarensis sp. nov. enriches our understanding of Permian spermatophytes in temperate climates of the Northern Hemisphere, and reveals that ovules similar to those of Euramerican and Cathaysian provinces characterized an Angaran spermatophyte. Journal compilation © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society, 2007, 155, 297–305. No claim to original US government works.

Discovery of a permineralized fossil cone in Mesozoic deposits of southern England provides an opportunity to document the first detailed evidence of internal pollen cone anatomy for the extinct conifer family Cheirolepidiaceae. The specimen, described here as Classostrobus crossii sp. nov., occurs in a calcareous nodule recovered from Middle Jurassic marine sediments of the Lower Callovian Sigaloceras calloviense biozone, Kellaways, near Cirencester, England. The cone is 2.0 cm long and 1.8 cm wide. Sporophylls diverge helically from the axis. Each sporophyll displays a narrow stalk and a distal lamina approx. 11 mm long that tapers to a pointed tip. There is also a basal keel that bends inward at the bottom and sides to form a shallow pocket. A single vascular bundle diverges from the cone axis, extends distally into the sporophyll stalk at the contact of two distinctly different histological zones, and further expands into the distal lamina as transfusion tracheids. Several pollen sacs are attached abaxially at the juncture of the sporophyll stalk and keel. Pollen is roughly spheroidal, 26–35 μm in diameter, with unequal polar caps separated by a striated belt with a subequatorial furrow. This specimen helps clarify the range of variation in the morphology of Mesozoic conifer pollen cones.

A new fossilized walchian (Voltziales) conifer plant from the Late Pennsylvanian Hamilton Quarry of Kansas, U.S.A. combines morphological characters of the morphogenus Walchia and the fossil plant genus Otovicia, with cuticular characters like those of the fossil plant genus Ernestiodendron, and seed cone morphology like that of the fossil plant genus Emporia. Internal anatomical characters are basically similar to the other walchian genera for which such features are known, but some are taxonomically informative. Numerical cladistic analysis reveals that this novel combination of characters defines a new fossil plant genus and species of walchian conifers Hanskerpia hamiltonensis. This analysis provides a test of hypotheses for relationships among walchian and other ancient conifers. Results of this analysis support some previously proposed relationships among the most primitive conifers and other Paleozoic coniferophytes. However, the analysis also calls to question the validity of all previously proposed familial circumscriptions for walchian conifers, and highlights the perplexing systematic challenges posed by the most ancient fossil conifers. The unexpected species richness of voltzialean conifers is interpreted as having resulted from the evolutionary ecology of unstable environments.

The Gondwana coniferophyte Buriadia heterophylla Seward and Sahni is reinvestigated from newly discovered material in eastern India, from previously described specimens of Buriadia florinii Maithy, and from specimens of B. heterophylla and Birsinghia florinii Pant, Nautiyal and Chaturvedi that previously were described as having attached seeds. Vegetative morphology and cuticular features for all of these Permian specimens from India conform to unimodal ranges of variation, and are reinterpreted as a single species. Horned seeds are commonly associated with the vegetative remains at most localities, but re-examination of specimens previously described as having attached seeds reveals that no seeds are preserved in organic connection to shoots. All of the specimens of vegetative remains are recognized as belonging to a single morphospecies, B. heterophylla Seward and Sahni that consists of compressed leafy shoots displaying distinct cuticular features as well as larger stems with some wood anatomy. The reproductive structures of B. heterophylla are unknown.

A taphonomic investigation of a fossil assemblage near Coleman, Texas, U.S.A., has revealed a rarely seen part of the cephalopod taphonomic pathway. The cephalopods occur in a brown shale with a low-diversity, gastropod-dominated fauna that is mixed together with a conifer-seed fern-dominated terrestrial flora. All of the cephalopod shells (n=2000+) are damaged. The brown shale is interpreted as representing a brackish-water or quiet, muddy beach environment, based in part on the delicate three-dimensional preservation of the terrestrial plant debris and the absence of stenohaline benthic marine fauna. Most upper Paleozoic cephalopods (especially ammonoids) are thought to have lived in offshore (middle to outer shelf) environments. The environmental interpretation and the massive damage observed on the cephalopod shells support the interpretation that this cephalopod fauna has been transported from one or more distant offshore biotopes. These cephalopods had shells with positively buoyant conchs ...

Three specimens of a medullosan seed fern stem with attached leaf bases, from the Chesterian Series of Arkansas, USA, are the earliest unequivocal occurrence of the genus Medullosa and form the basis for a new species Medullosa steinii. The stems have numerous features characteristic of vines, including stem diameters of only 2–3 cm in diameter, numerous wide, plate-like rays, relatively wide tracheids, the presence of cortical spines and variable but numerous stelar segments. In M. steinii vascular segment numbers vary from two to eight. Primary xylem bundles consist of one to several protoxylem poles with metaxylem and abundant parenchyma; each bundle is surrounded by secondary vascular tissue. Leaf traces typically diverge from a vascular segment as pairs, with the resulting bundles separating from each other at an angle of 90–100°. Paired leaf traces are separated from each other by a wedge of secondary vascular tissue, thus producing a distinctive mode of leaf trace production for the new species. Leaf traces divide repeatedly to produce the Myeloxylon rachis base configuration at the margin of the stem cortex. Rachis bases are decurrent and are separated from one another by a discontinuous row of sclerotic bundles and from the stem by a prominent periderm. The discovery of this plant demonstrates that scrambling and climbing seed ferns were part of some plant communities by Mississippian time.

A large number of vegetative and fertile branching systems of Thucydia mahoningensis provide data for interpreting the growth architecture and life‐history pattern of a primitive Paleozoic conifer. Internal anatomy is similar to modern conifers, indicating an arborescent life‐history pattern. Three categories of vegetative plagiotropic branching systems are recognized, and these resemble developmental variations among lateral branching systems in juvenile trees of the extant conifer Araucaria heterophylla (Salisb.) Franco. Thucydia mahoningensis is considered to be a small tree on the basis of the size and branching pattern of the stem and lateral branching systems and on the basis of internal anatomy. Growth architecture of T. mahoningensis conforms to Massart’s model, but fertile remains reveal interesting differences from living species. The T. mahoningensis tree has an orthotropic stem that bears two orders of plagiotropic vegetative shoots. Fertile shoots have a compound ovulate fertile zone and lack...

Triassic and Jurassic fossils record structural changes in conifer seed cones through time, provide the earliest evidence for crown-group conifer clades, and further clarify sister-group relationships of modern conifer families. A new and distinct seed-cone from the Isle of Skye in western Scotland provides the oldest detailed evidence for the ancestral morphology of the phylogenetically contentious family Cupressaceae.A single isolated cone was prepared as serial sections by the cellulose acetate peel technique, mounted on microscope slides, and viewed and photographed using transmitted light. The three-dimensional structure of the cone was first reconstructed from the serial sections and then refined through imaging with x-ray microtomography.Scitistrobus duncaanensis, gen. et sp. nov., is a 7.5 mm-diameter cylindrical seed cone with helically arranged bract-scale complexes in which three scale tips separate from a large bract, each tip bearing one adaxial seed. Seeds are near-inverted, show 180° rotational symmetry, and have a diminutive wing in the major plane.Scitistrobus duncaanensis extends the fossil record for anatomically preserved seed cones of the Cupressaceae backward from the Upper Jurassic to the Aalenian Stage of the Middle Jurassic. The cone displays a previously unknown combination of characters that we regard as diagnostic for seed cones of early-divergent Cupressaceae and helps to clarify the sequence of structural changes that occurred during the transition from ancestral voltzialean conifers to morphologically recognizable Cupressaceae. Hypotheses of homology underpinning such transformational series can be tested by ongoing reciprocal illumination between the morphology of fossil taxa and the morphogenesis and developmental genetics of their extant crown-group relatives.

New ovules from the Fayetteville Formation (Upper Mississippian) of Arkansas expand our knowledge of the morphology and anatomy of Rhynchosperma and suggest it was produced by a medullosan seed fern. Rhynchosperma has been described as radially symmetrical with a two-layered integument and vascularization in the integument only. The apical portion of the integument is ribbed; the nucellus is fused to the integument and apically differentiated into a dome-shaped pollen chamber. The vascular system is incompletely known and apparently restricted to the base of the integument. The new specimens are like Rhynchosperma in external shape, size, number of ribs, and numerous histological features. However, new data reveal that the nucellus is vascularized by a sheath of tracheids, the integument is vascularized by discrete bundles, the pollen chamber has a nucellar beak, and the nucellus is attached to the integument for a variable distance from the base. In addition, the integument is tripartite with an elaborate apical region; ribs formed by the integument are more pronounced at the apex; and internally open, hollow lobes form a stellate micropylar canal. The presence of a tripartite integument, the nature of the vascular system, the nucellus-integument attachment, the pollen chamber structure, symmetry, and the association with medullosan vegetative remains suggest medullosan affinity for these ovules and strengthens the evidence for the origin of the family before the end of the Lower Carboniferous.

Twenty permineralized ovules were recovered from a mixed marine and terrestrial assemblage from the Finis Shale near Jacksboro, Texas, USA. The strata have been dated as Virgilian (upper Pennsylvanian: Gzhelian) based on ammonoid biostratigraphy, regionally correlated based on the marine assemblage, and globally correlated based on ammonoid, fusulinacean and conodont data. These morphotaxa conform to trigonocarpalean ovules based on their three angled symmetry and the presence of a stalked nucellus attached to the integument only at the base. The ovules share many features with the genus Pachytesta but represent a new genus based on their unique exterior shape, integumentary morphology, and vascular system. In addition, these specimens represent the youngest known occurrence of trigonocarpalean ovules, thereby extending their biostratigraphic range. The presence of these plant remains in a regionally and globally correlatable marine assemblage aids correlation of continental strata with established, biostratigraphically time equivalent, marine strata.

Twenty permineralized ovules were recovered from a mixed marine and terrestrial assemblage from the Finis Shale near Jacksboro, Texas, USA. The strata have been dated as Virgilian (upper Pennsylvanian: Gzhelian) based on ammonoid biostratigraphy, regionally correlated based on the marine assemblage, and globally correlated based on ammonoid, fusulinacean and conodont data. These morphotaxa conform to trigonocarpalean ovules based on their three angled symmetry and the presence of a stalked nucellus attached to the integument only at the base. The ovules share many features with the genus Pachytesta but represent a new genus based on their unique exterior shape, integumentary morphology, and vascular system. In addition, these specimens represent the youngest known occurrence of trigonocarpalean ovules, thereby extending their biostratigraphic range. The presence of these plant remains in a regionally and globally correlatable marine assemblage aids correlation of continental strata with established, biostratigraphically time equivalent, marine strata.

Abundant fossils of a single conifer species occur in a Pennsylvanian‐age deposit of eastern North America, providing the opportunity to describe a biological taxon of primitive conifers as well as to clarify the uncertain taxonomy and systematics of walchian conifers. Thucydia mahoningensis gen. et sp. nov. is represented by up to three orders of interconnected vegetative and fertile shoots that are preserved as coalified compressions with cuticles; some also display internal anatomy. The plant has an orthotropic stem, with two orders of plagiotropic lateral branches that all bear helically arranged simple leaves. Ovulate fructifications consist of compact zones of bracts with axillary ovuliferous dwarf shoots on otherwise vegetative branches. Pollen cones are compound shoots comprising helically arranged dwarf shoots in the axils of bracts on a main axis. Polliniferous dwarf shoots produce sterile scales, sporophylls with a terminal pollen sac, and in situ Potonieisporites grains. Stems have an endarch ...

A new species of the seed fern Lyginopteris is described from a nodule in Upper Mississippian (middle Chesterian-Namurian A) shales of the Fayetteville Formation in northwestern Arkansas. The pyritized stem is 29 cm long and slightly compressed, with a diameter of about 11×5 mm, and shows seven diverging leaf bases. The primary xylem of the specimen is eustelic. Foliar bundles extend through five internodes before entering the rachis bases; they do not divide along their trajectory through the stem. Phyllotaxis of the specimen approaches 2/5. Longitudinally oriented sclerenchyma strands accompany the diverging foliar vascular bundles adaxially in the cortex, and are incorporated in the outer cortex above the level of foliar rachis divergence. In contrast to previously described Lyginopteris species, this species lacks capitate epidermal glands. A Lyginopteris type rachis with a paired vascular bundle is preserved in the same nodule. Coprolites probably produced by oribatid mites are present in different tissues of the stem. The study of the leaf trace divergence necessitated the use of a deformation model to help reconstruct the original position of the cauline bundles in the compressed stele. This occurrence of Lyginopteris confirms earlier reports of the genus from North America and emphasizes that it was not restricted to Western Europe.

Pinaceae is the most species rich and geographically dispersed group of living gymnosperms (Florin, 1963), and comprise a dominant component of modern mountain and boreal forests throughout the northern hemisphere (Florin, 1963). Although there are a few records of possible pinaceous species extending back to the Upper Triassic (Delevoryas and Hope, 1987), unequivocal evidence for the family does not appear until the Cretaceous, and Pinaceae may be the most recently derived conifer family. During the Early Cretaceous, pinaceous remains became common components of terrestrial plant communities, and a diverse array of ovuliferous cones signals an explosive evolutionary radiation within the family (Miller, 1976a). Most of this diversity is chronicled by cones that are clearly representatives of the Pinaceae, but are not assignable to a genus with living species. Cones of these types are assigned to the genera Pityostrobus Dutt, Pseudoaraucaria Fliche, and Obirastrobus Ohsawa, Nishida and Nishida, and have been discovered in a circumpolar distribution from North America, through Europe and Russia, to eastern Asia (Miller, 1976a; Ohsawa et al., 1992; Falder et al., 1998). The purpose of this paper is to extend further the known diversity of the early Pinaceae by the description of a new species of the genus Pityostrobus. This cone is the second Pityostrobus species from southwestern Russia, and it further documents the remarkable Cretaceous evolutionary radiation of Pinaceae. The ovuliferous cone is preserved in a Lower Cretaceous calcareous marine nodule from east of the Black Sea in the northwestern Caucasus of Russia. This nodule also contains an osmundaceous (?) fern rachis, a dispersed Pinus -like conifer needle, and a wood fragment. The nodule was recovered from a stream bed at the Hokodz locality (Hokodz River Basin), that has previously provided well-preserved specimens of both plant and animal fossils, including Pityostrobus milleri, wood fragments, …

A rich fossil biota from a Pennsylvanian age deposit of eastern North America contains numerous vegetative and fertile specimens that conform to a single species of primitive walchian conifers. Among the specimens is a compound pollen cone that comprises closely spaced, helically arranged, leaf-like bracts with axillary dwarf shoots. The specimen looks superficially similar to an ultimate vegetative conifer shoot, but there are small appendages in the axil of each bract that represent the fertile dwarf shoots. Dwarf shoots consist of an axis that bears sterile scales and sporophylls with erect pollen sacs. Pollen found in the sacs is monosaccate and conforms to the sporae dispersae genus Potonieisporites Bhardwaj. This cone is a compound shoot system that is morphologically equivalent to the ovulate cones of conifers and to the pollen cones of Paleozoic cordaitaleans and modern gnetophytes. Therefore, it is fundamentally different from the simple pollen cones of other fossil and modern conifers. Discovery of this specimen unexpectedly supports molecular studies that predict a close relationship between Coniferales and Gnetales, and provides fossil evidence to help reconcile the discordant phylogenetic hypotheses of seed plant systematics that have been developed from morphological and molecular data.

A conifer‐like plant occurs among the rich fossil biota at the Late Pennsylvanian–age Hamilton Quarry in southeastern Kansas. Barthelia furcata gen. et sp. nov. has irregularly branched shoots with both forked and simple leaves, simple pollen cones, and compound ovulate fructifications. Stems have an endarch eustele with dense wood surrounding a septate pith. Leaves range from ca. 1 to 5 cm long, display size‐related dimorphism, and have papillate epidermal cells with numerous trichomes and two adaxial stomatiferous bands. Stomatal complexes range from solitary to crowded, occur in longitudinal rows, and are represented by four to seven papillate subsidiary cells. Polar subsidiary cells are elongated parallel to the stomatal rows. Pollen cones are simple and have helically arranged sporophylls with a perpendicularly inserted shank, adaxial pollen sacs, and a forked distal lamina. Prepollen is monolete, monosaccate, and eusaccate. Ovulate fructifications comprise a compound conelike fertile zone of axillar...

A conifer from the uppermost Permian with small, helically arranged leaves is described from the Guangxi Autonomous Region and Guizhou Province of South China as Szecladia multinervia, new genus and species. The material includes both impression specimens and the first anatomically preserved Paleozoic conifer fossils from China. Shoots are irregularly branched, with small, helically arranged, multiveined leaves. Stems display an endarch eustele with abundant, dense wood. Leaf traces diverge from the stele as a single bundle that divides several times in the cortex and at the base of the leaves, forming about seven or eight parallel veins in each leaf. Szecladia is the earliest known conifer with multiveined leaves and it represents a distinctive coniferous element of the uppermost Permian Cathaysian flora in South China. Szecladia further demonstrates that conifers with wood and leaf venation suggestive of the Podocarpaceae may have evolved by the end of the Paleozoic.

A conifer from the uppermost Permian with small, helically arranged leaves is described from the Guangxi Autonomous Region and Guizhou Province of South China as Szecladia multinervia, new genus and species. The material includes both impression specimens and the first anatomically preserved Paleozoic conifer fossils from China. Shoots are irregularly branched, with small, helically arranged, multiveined leaves. Stems display an endarch eustele with abundant, dense wood. Leaf traces diverge from the stele as a single bundle that divides several times in the cortex and at the base of the leaves, forming about seven or eight parallel veins in each leaf. Szecladia is the earliest known conifer with multiveined leaves and it represents a distinctive coniferous element of the uppermost Permian Cathaysian flora in South China. Szecladia further demonstrates that conifers with wood and leaf venation suggestive of the Podocarpaceae may have evolved by the end of the Paleozoic.

Fast growing conifers have been recognized in disturbed habitats of the transitional Lower Middle Triassic Gres a Voltzia delta from the Buntsandstein in eastern France. These herbaceous conifer fossils reveal that some Mesozoic seed plants were capable of opportunistic growth and rapid prolific reproduction long before the origin of flowering plants. Such ruderals indicate that certain gymnosperms came to characterize river terrace floras by the evolution of reduced size and enhanced reproductive allocation, while others dispersed to dominate more arid expanses of the Mesozoic landscape before the rise of flowering plants. The widespread occurrence and quantitative distribution patterns of pollen similar to that of Aethophyllum in the Middle Triassic suggests that Aethophyllum and related conifers may have played an important role in the evolution of distinctive Mesozoic wetland communities.

A new species of permineralized Pityostrobus cone, Pityostrobus milleri Falder et al., sp. nov. has been discovered in a calcareous nodule from shallow marine sediments of Early Cretaceous (latest Aptian; Clansenian) age in the Caucasus Mountains in southwestern Russia. Nodules of this type also contain wood fragments, gastropods, bivalves, and an extremely rich assemblage of well preserved cephalopods. Russian spore and pollen analyses indicate that deposition in this region may have occurred during a temperate climate regime. The cone is cylindrical, about 2.5 cm in diameter and individual scales contain up to 17 resin canals and 18 vascular strands. Although the fossil displays many features of modern Pinus cones, including inflated scale apexes, resin canals abaxial to vascular tissue in scale base, and scale strands curved on the adaxial side, it cannot be assigned to Pinus because the bract and scale trace are not united at their origin. Tunneled borings in the cortex of the cone axis are tightly packed with frass, and resemble tunnels of modern cone boring beetles such as Conophthorus. This cone further documents the worldwide diversity of pinaceous conifers during the Cretaceous, and demonstrates a well developed syndrome of insect herbivory in the Pinaceae by the late Mesozoic.

A large number of conifer pollen cones associated with primitive walchian conifers, including Emporia, occur within an exceptionally preserved fossilized biota near Hamilton, Kansas, USA. The fossils are derived from channel deposits within the Upper Pennsylvanian (Stephanian B/C) Topeka Limestone and show excellent external morphology, internal anatomy, and cuticular features. Pollen cones are cylindrical, up to 5 cm long and 1 cm wide and are simply organized. Each pollen cone consists of a nonwoody central axis from which sporophylls diverge in a helical arrangement. Vascular tissue comprises a ring of tiny cauline bundles that divide at intervals to produce a single trace to each sporophyll. Sporophylls consist of a terete stalk and a heeled distal lamina. Sporangia are attached as a cluster on the adaxial surface of the sporophyll stalk. Stomata occur in one or two bands on the inner surface of sporophyll laminae and consist of guard cells surrounded by a ring of subsidiary cells, each with one overarching papilla. The Hamilton specimens provide conclusive evidence that pollen cones with a distinctive morphology were produced by some of the most ancient walchians from both North America and Europe. Contrary to traditional interpretations, these cones differ significantly from those of the Pinaceae. The broad geographic and stratigraphic distribution of this morphology reveals that conifer pollen cones similar to those at Hamilton are more widespread than previously suspected, and provides evidence for the potentially ancestral morphology of all conifer pollen cones.

Late Paleozoic conifer communities originated in moisture-stressed environments along the paleoequator on the Laurussian continent. By Late Permian time, northward movement of the continent displaced these communities toward subequatorial regions. North American deposits provide the most abundant and best preserved pre-Permian conifer fossils. They represent a wide spectrum of preservational modes including compression/impression, mold/cast, and cellular permineralization by carbonates, phosphates, iron sulfides, iron oxides and iron hydroxides. Some modes are associated with distinct biotic assemblages, and to some extent each can be correlated with certain depositional environments and taphonomic histories. Exceptional floras containing extensive conifer remains occur in the Rocky Mountains, the Midcontinent, and the Appalachian regions. These include: estuarine carbonates at Hamilton and Pomona, Kansas; transitional terrestrial to marine clastics at Kinney Brick Quarry, New Mexico, Garnett, Kansas and the 7–11 Mine in northeastern Ohio; and offshore marine shales in Kansas, Oklahoma and Texas that were deposited in dysoxic environments. Most specimens have been assigned to the form genus Walchia , but exceptionally well preserved specimens conform to species of Emporia (Emporiaceae) and to one or more undescribed species that may represent additional genera and/or families. These species add significantly to the growing diversity of Paleozoic conifers, and provide valuable data for testing hypotheses of conifer and coniferophyte relationships.

Upper Pennsylvanian dysoxic marine shales of midcontinent North America yield permineralized remains of apparently extrabasinal vegetation. A large percentage of the plants are surprisingly unlike the well known swamp, fluvial and lacustrian floras of the late Paleozoic paleotropics, revealing numerous aspects of the morphology, anatomy and reproductive biology of plants that may have been ancestral to the dominant taxa of the Mesozoic. Included among the assemblages are ovulate coniferophyte remains that demonstrate the occurrence of vojnovskyalean seed plants in equatorial Euramerica. Specimens consist of simple ovulate cones that are more-or-less clustered along eustelic stems in the axils of helically arranged, strap-shaped leaf bases, and are described as Sergeia neuburgii new genus and species. Individual cones are up to approximately 2 cm long and 1.5 cm in maximum diameter, with helically arranged scales and sporophylls that diverge from a eustelic axis. Scales occur in the basal region of the cone, and are laminar and pointed. Sporophylls are borne distally. One specimen shows about 45 sporophylls, each of which terminates as one erect ovule. Most of the other cones have abraded apices, and terminate in relatively terete foliar appendages that are interpreted to be sporophyll bases. Ovules are flattened and winged, approaching 180° rotational symmetry. Integument histology, vascular tissue distribution and pollen chamber structure are similar to those of cordaiteans and callistophytalean seed ferns. Sergeia adds to the number of late Paleozoic conifer-like plants that do not conform to the Pinopsida as traditionally circumscribed, and poses additional questions to assumptions of monophyly for coniferophytes and for conifers sensu lato.

Pinaceae and nonpinoid species are sister groups within the conifer clade as inferred from molecular systematic comparisons of living species and therefore should have comparable geological ages. However, the fossil record for the nonpinoid lineage of extant conifer families is Triassic, nearly 100 million years older than the oldest widely accepted Lower Cretaceous record for Pinaceae. An anatomically preserved fossil conifer seed cone described here extends the stratigraphic range of Pinaceae nearly 30 million years, thus reducing the apparent discrepancy between evidence from the fossil record and inferences from systematic studies of living species.Material was prepared as serial thin sections by the cellulose acetate peel technique, mounted on microscope slides, and viewed and photographed using transmitted light.A large cylindrical cone consisting of bract-scale complexes that diverge from the cone axis in a helical phyllotaxis has bracts and scales that separate from each other in the midregion and are of equal length and of nearly equal width. The cone has two inverted and winged seeds that are attached to the adaxial surface of each cone scale and, thus, represents an early member of the Pinaceae.Eathiestrobus mackenziei gen. et sp. nov. extends the fossil record for well-documented members of the family Pinaceae from the Lower Cretaceous to the Kimmeridgian Stage of the Upper Jurassic. This species also clarifies the set of characters that are diagnostic for seed cones of Pinaceae and reveals possible plesiomorphic characters for seed cones of the family.

Five permineralized seed fern stems from the Fayetteville Formation (middle Chesterian/Upper Mississippian) of Arkansas conform to the concept of lyginopterid seed ferns. However, these specimens are unlike all previouslyreported lyginopterids, and the name Trivena arkansana (Lyginopteridaceae) gen. et sp. nov. is proposed. The stems are up to 30 by 19 mm in diameter and have pentagonal pith and eustele of five cryptic sympodia Secondary tissues include abundant xylem with numerous wide rays and phloem surrounded by a periderm. The cortex is parenchymatous with abundant sclerotic clusters: some clusters are randomly dispersed and some are in discontinuous rows. Sclerenchyma bands form the "Dictyoxylon" -type outer cortex. Leaf traces diverge in a 2/5 phyllotaxyl. Traces, accompanied by concentric secondary xylem, increase in size as they extend through the secondary xylem of the stem. The trace assumes a squat C shape at the outer margin of the secondary xylem and in the cortex divides into three discrete bundles, each surrounded by secondary xylem. Galleries within the phloem contain arthropod coprolites and exhibit wound response, suggesting plant-arthropod coevolution. The discovery of this new lyginopterid stem adds to the growing list of unique taxa described from the Fayetteville Formation and further solidifies its reputation as one of the most important. Upper Mississippian plant fossil sites in North America.

A diverse assemblage of unusually well-preserved marine, euryhaline, freshwater, and terrestrial fossils (invertebrates, vertebrates, and plants) occurs within an Upper Carboniferous (Stephanian) Konservat Fossil-Lagerstatte near Hamilton, Kansas, USA. The Lagerstatte occurs within a paleovalley that was incised into the surrounding Carboniferous cyclothemic sequence during a time of low sea level, and was then filled-in during a subsequent transgression. The stratigraphically lowest and most voluminous facies within the valley is a cross-bedded, polymictic limestone conglomerate that contains caliche clasts and charcoal fragments as well as some normal-marine fossils apparently in situ. The origin of the conglomerate is enigmatic, but it was probably deposited by a migrating tidal channel. Overlying and interbedded with the conglomerate is an ostracode wackestone that contains plants (primarily seed ferns and ferns), eurypterids, shrimp, brachiopods, bivalves, and rare fish. The ostracode wackestone was deposited in a low-energy, marginal-marine environment. A thin sequence (

Permian specimens of Sphenophyllum with preserved cuticular anatomy have been discovered in Cathaysia and have prompted a detailed re-evaluation of the genus in the Gigantopteris flora in South China. New specimens are described and previously published material is re-examined to clarify taxonomic diversity and to establish geographic and stratigraphic ranges for each species. Recognized taxa include Sphenophyllum apiciserratum sp. nov., S. koboense Kobatake, S. meridionale sp. nov., S. minor (Sterzel) Gu and Zhi, S. sinocoreanum Yabe, S. cf. sinocoreanum Yabe, and S. aff. speciosum (Royle) McClelland. Cuticles of Sphenophyllum apiciserratum and S. koboense are hypostomatic with randomly disposed ordinary cells in intercostal regions. Specific concepts are clarified and unresolved taxonomic problems are discussed. The South China taxa are compared with those from Euramerican, Gondwanan and Angaran floras, and the South China Cathaysian species are found to be taxonomically distinct.

Descriptions of Emporiaceae and Emporia are provided in order to validly publish the names Emporiaceae Mapes & G. W. Rothwell, and Emporia Mapes & G. W. Rothwell. An emended description of Emporia lockardii (Mapes & G. W.Rothwell) Mapes & G. W. Rothwell, published as a new combination, is also provided.

Utrechtiafloriniformis Mapes & G. W. Rothwell is a primitive Palaeozoic conifer based on fossil specimens that were originally assigned under the illegitimate Lebachia Florin as L. piniformis Florin (Mapes & Rothwell, 1991). It was intended to establish the name Utrechtia floriniformis as a new genus and species of conifer plants based on specimens that previously were included in Lebachia piniformis, and the species was to be assigned to a new family to be called Utrechtiaceae (Mapes & Rothwell, 1991). Nomenclatural inadequacies in the original publication of U. floriniformis that resulted in none of these being validly published have recently come to our attention. This note is presented to validate the names by fulfilling the type citation requirements for valid publication. The holotype and paratypes designated for U. floriniformis were identified by Mapes & Rothwell (1991) by previously published plate and figure numbers in Florin (1938-1945), but the repository locations and other details for the specimens illustrated (the actual types-Art. 9.13) were not noted at that time. The specimen that we designated as the holotype is a young ovulate cone from Sudetengau (Ottendorf bei Braunau, Oberrotliegendes). Slides made from cuticular macerations of that specimen are deposited in the Geol.-Palaont. Inst. Univ., Mus. F. Naturk. Berlin. The ovulate cone that we designated as the holotype is illustrated as Tafel XIX-XX, Abb. 1 (Florin, 1938-1945). Macerations of this cone by Florin for cuticular information are mounted on microscope slides bearing the number 3322. The vegetative shoot that we designated as the paratype (incorrectly stated to be "paratypes" by Mapes & Rothwell, 1991) is illustrated as Tafel I-II, Abb. 6-22 (Florin, 1938-1945). This leafy branching system and slides made from cuticular macerations of the specimen are from Saar-Nahe-Gebiet: Nonnweiler bei BirkenfeldNahe, Lebacher Schichten, and are deposited in the Geol.-Palaont. Abteil. Naturhist. Mus. Wien as Coll. No.: 1899/0008/0041, Pb 04504. Utrechtiaceae Mapes & G. W. Rothwell, fam. nov. For the diagnosis, see Mapes & Rothwell, Neues Jahrb. Geol. Palaontol., Abh. 183: 280. 1991. Type: Utrechtia gen. nov.

Permineralized plant remains occur individually and in small mats within anoxic and dysoxic marine black shales deposited seaward of the Wedington delta (Fayetteville Formation, Middle Chester) in northwestern Arkansas. Plant debris and associated cephalopods occur within 20 km of offshore bars that developed at the mouths of delta distributary channels. The bars were produced by longshore paleocurrents flowing eastward among the southwestern margin of the Ozark Dome. The flora includes several genera of arborescent lycopods, zygopteridalean ferns, filicalean ferns, calamites, medullosan seed ferns and seed fern remains with features that are characteristic of the Lyginopteridaceae. Among the lyginopteridalean stems are specimens that have been described as Megaloxylon wheelerae, an arborescent form, as well as several undescribed species.Two stems with prominent leaf scars represent one species of a new genus. The stems measure 35 cm and 34 cm long, and are approximately 2.5 cm in diameter. Leaf arrangement is helical, approaching a 3/8 phyllotaxis, with internodal lengths of about 3 cm. Stems are eustelic with a polygonal primary body 3-4 mm in diameter. Each leaf trace diverges from the cauline bundle as a single strand. The strand trifurcates in the cortex to produce a distinctive configuration of two c-shaped lateral bundles separated by a tangentially elongated central strand.Pith cells are large with prominent walls. Some show internal contents suggestive of secretory substances. The primary body is surrounded by a distinctive zone of wood 3-4 cm wide. Large rays 2-5 cells wide and more than 8 mm high separate wedges of tracheids that typically are 2-4 cells wide. Secondary tracheids display multiseriate oval bordered pits on the radial walls. Vascular cambium and secondary phloem are present, but incompletely preserved. The cortex is differentiated into an inner parenchymatous zone with horizontally elongated “sclerotic” nests, and an outer zone of alternating bands of vertically elongated sclerenchyma and parenchyma.This material significantly increases our knowledge of Namurian floras inhabiting non peat-forming environments, and emphasizes the systematic diversity among hydrasperman gymnosperms at the base of the Upper Carboniferous.

Halletheca conica n. sp. is described from the Wewoka Formation, Ada and Okmulgee, Oklahoma. This small, simple synangium exhibits basic histology and tissue organization recognizable as medullosan and differs from H. reticulatus primarily in size, number of sporangia, and histology of central column and dehiscence tissue. This is the first report of Halletheca from a non-coal-forming environment.

Megaloxylon is a permineralized gymnospermous stem with large leaf traces and unusual medullary anatomy resembling accessory transfusion tissue. Originally described from Westphalian A strata, Lancashire, England, Megaloxylon is described here from Upper Mississippian age localities (European equivalent = Namurian A) in Arkansas. A new species, M. wheelerae, is represented by numerous stems, including one over 5 m long, providing new information regarding phyllotaxis, vascular architecture, leaf trace anatomy, and cortical tissues. These data support interpretations of arborescent growth among certain Carboniferous pteridosperms.

Recent investigations of ovulate conifer cones from southem Europe and midcontinent North America have independently documented that certain Paleozoic walchians have inverted ovules, rather than the erect ovules previously thought to characterize the most primitive conifers. Reinvestigation and consideration of other walchian conifers, including Moyliostrobus and Lebachia piniformis (sensu Florin), reveals that they also had inverted ovules. These different patterns of ovule orientation demonstrate that the nature and the polarity of the character states are dramatically different than popularly believed, and the shift from megasporophyll to ovuliferous cone-scale occurred within the Paleozoic walchians. WALCHIANS are the most ancient and presumably most primitive true conifers known. They appear first in Westphalian sediments in Europe and equivalent age deposits in North America, and are popularly perceived as a relatively homogeneous clade throughout the Carboniferous and basal Permian. Florin's landmark studies of Upper Paleozoic compression conifers clearly demonstrated the homology between ovulate cones of extant conifers and those of the earliest conifers and cordaites, and provided the basis upon which two generations of plant systematists have interpreted conifer phylogeny and evolution. Florin recognized that the ovuliferous seedscale, or cone-scale of modem conifers (e.g., Pinus) is not just a simple megasporophyll, but represents a phylogenetically modified fertile shoot (Florin, 1938-45, 195 1). Support for that view is provided by developmental study of modem ovulate conifer cones, and by documentation of a morphological series of fossil conifers whose ovulate shoots/fertile scales appear progressively fused and flattened through time. The cordaites and some walchian conifers bore their ovules on actual sporophylls, on individual fertile leaves or megasporophylls that are sometimes referred to as "fertile scales." Those simple scales, therefore, are homologous to only a portion of an ovuliferous cone-scale, I Received for publication 1 1 August 1986; revision accepted 11 December 1986. I especially appreciate J. A. Clement-Westerhof and J. H. F. Kerp, of the Laboratory of Paleobotany and Palynology, University of Utrecht, The Netherlands, for generously sharing ideas and discussions throughout this investigation. I also thank G. W. Rothwell for ongoing dialogue, and C. N. Miller and C. J. Felix for their suggestions in review. This work was initiated during tenure of a National Science Foundation Visiting Professorship of Women award with C. B. Beck, Museum of Paleontology, University of Michigan, Ann Arbor, MI. which represents an entire, reduced axillary fertile shoot. The latter is considerably more derived, and characterizes some walchians, voltzialeans, and all extant conifers. In the literature, the term "fertile scale" is also sometimes used in reference to the ovuliferous cone-scale, leading to potential confusion regarding the homologies of the described structures. In this paper I refer to sporophylls or to cone-scales, and suggest fertile scale be abandoned entirely, or limited to fertile structures with unknown homology. Florin's rather straight line view of conifer evolution emphasized themes of reduction and fusion, with particular focus in the ovulate cones on character state changes from radial to bilateral shoot symmetry, from numerous discrete parts to smaller numbers of combined elements, and from terminal, erect ovules to laterally attached, inverted ovules. This paper considers the last feature, inverted ovules, and its significance in early conifer biology and systematics. HISTORICAL CONTEXT-Currently, the most widely accepted model of a primitive early conifer is Lebachia piniformis (sensu Florin = Walchia in Clement-Westerhof, 1984), with compact, compound ovulate cones comprising a central axis and helically arranged bracts and axillary fertile shoots. Individual axillary shoots are described as radially symmetrical with numerous sterile scales, and one fertile scale with a single, erect, terminal ovule. Ovules of L. piniformis were characterized by Florin as bilaterally symmetrical, with a prominent bilobed micropyle directed distally toward the cone periphery. In contrast, recent investigations of ovulate conifer cones from the Italian Alps (ClementWesterhof, 1984) and Kansas (Mapes and Rothwell, 1984) have independently revealed

Anatomically preserved fertile marattialean pinnules from the Lower Permian (Wolfcampian) Bursum Formation in Tularosa, New Mexico, and isolated synangia from the Upper Pennsylvanian (Missourian) Stanton Formation near Tyro, Kansas, are described. The sessile synangia are partially sunken into the pinnule lamina and arranged abaxially in a single row on each side of the midrib. Comparisons are made with other fossil and modern marattialeans and the evolutionary significance WHILE the synangia of the Carboniferous marattialeans are usually radially symmetrical and pedicellate to some degree, the synangia of many extent marattialeans are bilaterally symmetrical and essentially sessile. The majority of the Mesozoic marattialeans are compression taxa which appear to be very similar to the modern genera. The transition in synangial morphology apparently occurred during the upper Pennsylvanian and the Lower Permian as indicated by the occurrence of Millaya gen. n., Eoangiopteris, Acaulangium, and various pecopterid compressions including Danaeites. Among extant marattialean genera, Danaea is

Vallitheca valentia gen. et sp. nov. is a permineralized, synangiate fructification of probable seed fern affinities from the Wewoka Formation (Desmoinesian) near Ada, Oklahoma. Synangia are oblong to pyriform, average 1 cm long, and contain 32 to 48 tubular sporangia embedded proximally in ground tissue. The sporangia are arranged within the synangia in a unique pattern: a ring of peripheral sporangia dehisces toward the center of the synangium and a central group of sporangia dehisces outward. This unique arrangement is unlike that of any currently recognized group. THE AGGREGATION of sporangia and their fusion into synangia has been noted for various unrelated groups of Paleozoic plants. Synangia are known for some homosporous pteridophytes (e.g., Yarravia Lang and Cookson, 1935) and are diagnostic for marattialean ferns (e.g., Scolecopteris Zenker, 1837; Millay, 1979) and the seed ferns. Small groups or synangia of marattialean eusporangia are com

Upland floras (Chaloner, 1958), clastic substrate inhabitors (Dimichele et al., 1985), extrabasinal floras (Pfefferkorn, 1980), dryland floras (Havlena, 1960), seamforming Flöznahe and more distant Flözfremde (Daber, 1959; Havlena, 1961) mesophilous and xerophilous floras (Havlena, 1971), Callipteris-Walchia assemblage (Gothan and Gimm, 1930; Gothan and Remy, 1957), Megalopteris-Cordaites assemblage (Cross, 1977; Leary, 1981; Read and Mamay, 1964), Gigantopteris flora and Callipteris flora (Read and Mamay, 1964), early Permian floras (White, 1934), roof nodule floras (Stopes and Watson, 1907), the Mesophytic flora (Frederiksen, 1972), and “Permian” aspect (Elias, 1936a,b), are some of the terms that have been devised in recognition of the observation that many Late Paleozoic plant communities did not form coal swamp peats and their vegetational composition changed in response to global tectonism. The peat swamps clearly changed floral composition through time (Phillips, et al., 1974; Phillips, 1981; Dapples and Hopkins, 1969), but can be reasonably easily characterized, because “coal” swamp plants were commonly deposited in situ, or very near their sites of growth.

Palaeozoic fossil conifer cones bearing mature seeds with well developed cotyledonary embryos have been recovered from Permo-Carboniferous strata of North America. These are the most ancient embryos ever discovered within gymnosperm seeds1,2. In contrast to the pteridophytic ancestors of seed plants and other major groups of Palaeozoic gymnosperms3,4, these embryos indicate that there was a significant delay between fertilization and seed germination in the earliest conifers. We suspect that this post-zygotic quiescence may be a first step in the evolution of seed dormancy.