Ultrastructure and affinity of Lower Carboniferous megaspores from the Moscow Basin, Russia

Ten megaspore species isolated from Moscow Basin lignites of Lower Carboniferous (Viséan) age have been studied by scanning and transmission electron microscopy (SEM and TEM). These species belong to seven megaspore genera: Lagenicula, Sublagenicula, Crassilagenicula, Setosisporites, Zonalesporites, Caudatosporites, and Cystosporites. Megaspores of the genus Caudatosporites have only been described previously from the Duckmantian (Westphalian B); a new species is duly erected. The ultrastructure of megaspore walls from the genera Crassilagenicula and Zonalesporites has not been previously described. This study also places them in context with other contemporaneous megaspores. The study shows that during the Viséan, in the Moscow Basin, megaspores expressed a similar wall ultrastructure despite large differences in external appearance. The genus Crassilagenicula may represent a group of megaspores from plants that had evolved from those bearing gulate megaspores here typified by Lagenicula acuminata, Setosisporites brevispinosus, and Sublagenicula hirsutoida. Zonalesporites brasserti also appears to show affinities to this group, and may be representative of a plant species in a transitional state between the Lagenicula bearing lycopsids and those more isoetalean in nature.     

Diversity of exine structure in Upper Carboniferous (Westphalian) selaginellalean megaspores

Studies of wall structure in Mesozoic and Recent selaginellalean megaspores have been well documented. However, Palaeozoic examples have received minimal attention. The principal Palaeozoic megaspore genus of likely selaginellalean affinity is Triangulatisporites, extending from the Upper Devonian to the Upper Carboniferous. The particulate wall ultrastructure of a previously published Carboniferous (Duckmantian) megaspore assigned to this genus suggested that this form of wall construction may have been the ancestral wall structure of the group, an observation which posed difficulties in relating selaginellalean ultrastructure to that of other contemporaneous lycopsid megaspores. Subsequent investigation showed that the genus also contains more laminate exines similar to those of other extinct lycopsids and extant Selaginella species. Our new examples of Triangulatisporites ultrastructure from the Langsettian, Duckmantian and Westphalian D yield more information regarding early variation of wall structure within Carboniferous selaginellalean megaspores and suggest that a more laminate wall composition is at least as old as the particulate form. However, without further investigation of Lower Carboniferous forms, we are unable to state which is indeed ancestral. The laminate structure reported here and elsewhere is, none the less, more easily related to comparable ultrastructure in other groups of Carboniferous lycopsid megaspores and could suggest a link with such genera as Zonalesporites and early Lagenicula. This would be in keeping with current concepts regarding the most primitive ultrastructural type within lycopsid megaspore walls.     

Paleoecology of some Carboniferous Pectinacea

Pectinacean bivalves in the Carboniferous of northern California, USA, occur in all observed biotic communities except bioherms of corals and productoid brachiopods. They show equal abundance in offshore, brachiopod-dominated habitats and nearshore, bivalve-dominated habitats, and are among the only common invertebrates in a 'black shale', restricted marine community. Different morphologic forms of the superfamily show little ecologic division. Pectinacea are least abundant in limestone, and most abundant in terrigenous beds, and bottom type was more important in controlling their distribution than water depth, current activity, or salinity.     

Kulm trilobites (Lower Carboniferous) from S-China

Some trilobite remains are described from the Lower Carboniferous/Mississippian (Tournaisian/Viséan boundary) of S-China, representing two species:Liobole (Liobole) devuysti n. sp. andLiobole (Sulcubole) xiangzhouensis n. sp.Liobole is a typical member of the central European Kulm Facies and index fossil for the Erdbachian. For the first time, twoLiobole species are recorded from outside of Europe. They demonstrate that a passage existed between Europe and East Asia across the Palaeotethys through which Kulm trilobites have occupied new geographical regions.      

Predatory boreholes in Tournaisian (Lower Carboniferous) spiriferid brachiopods

A brachiopod fauna from the uppermost part of the Tournaisian Tournai Formation (Belgium) contains an undetermined species of Crurithyris (Spiriferida, Ambocoeliidae), which displays numerous bored shells. About 8% of the 432 specimens with conjoined valves display single, small (≤ 1 mm) boreholes, which are smooth-sided, cylindrical or weakly conical, circular to slightly elliptical in plan view, perpendicular to the shell surface and generally complete. Of the 35 bored articulated specimens, 27 were drilled on the ventral valve. Most of the boreholes are located in the posterior half of the shell, and no case of edge-drilling has been observed. The boreholes were drilled by a predator, or possibly a parasite, which selected individuals greater than 2.5 mm long. Crurithyris sp. may have represented an attractive (in terms of energy cost) and easy target for a small-sized predator because of its thin shell and ornament of minute spines.     

New offset-associated structures in some Carboniferous rugose corals

Tubular structures termed ducts, which extend from the base of offsets axially and upwards through the disscpimental tissue of the parent corallite, are described from some Carboniferous rugose corals. Two ducts are usually associated with each offset, one from each extremity where the offset wall meets that of the parent. The ducts may merge to form a tangentially elongate slit at higher levels in the disscpimcntarium of the parent. The structures served to prolong gastric and nervous communication between parent and daughter polpys following budding. Ducts and slits are well developed in cerioid Lonsdaleia but are absent in fasciculate Lonsdaleia , a distinction lending credence to the recognition of the former group of species as a distinct genus, Actinocyathas , within the Axophyllidac. In addition, less well developed ducts are present in at least some cerioid species of Lithostrotion , whereas they are absent from fasciculate species, supporting separation of the latter from Lithostrotion sensu stricto and their assignment to the genus Siphonodendron. The form and distribution of duets also confirms polyphyly in Thysanophyllum. The separation of T. pseudovermiculare (as Dorlodotia ), without ducts, from Thysanophyllum sensu stricto , with weak ducts similar to those in some Lithostrotion spp., is supported. Both arc assigned to the T. pmedictum has well developed ducts, however, which reinforces other evidence suggesting its removal from Thysanophyllum and classification in the Axophyllidac in close affinity with Actinocyathus, Rugosa, offsets, ducts, functional morphology, taxonomy, Carboniferous.     

Chondrichthyans from the Lower Carboniferous of Yakutia,Russia

Paleontological Journal - Teeth of Cladodoides cf. wildungensis (Jaekel), fin spines of Ctenacanthus cf. angulatus Newberry et Worthen and Ctenacanthus sp. occur in the Lower Carboniferous Emyaksin...     

Morphology and wall ultrastructure of some Middle Devonian dispersed megaspores from northern Poland

Specimens of dispersed Middle Devonian megaspores have been isolated from core samples from the Miastko 1 borehole in Western Pomerania. Comprehensive investigations using light, scanning and transmission electron microscopy supplement previous information on morphology and gross structure and provide data on spore wall ultrastructure of four megaspore species. Corystisporites acutispinosus is azonate; the inner layer is laminate, and the lumen is lined by a thick, laterally continuous lamina. The outer layer consists of small, tangentially aligned tabular elements that become wider, more extensive and irregularly arranged toward the outside. Coronispora variabilis is a coronate megaspore; the inner layer appears homogenous and is probably lamellate. The outer layer consists of elongate, cylindrical, branching elements that are overlaid within the proximal part of the body by a lamellate, compact, almost homogenous layer. Grandispora ciliata is pseudosaccate. The inner body is laminate with laminae thickening and becoming less continuous and less tightly packed toward the outside. The outermost region of the inner body and the innermost region of the outer envelope consist of tabular and cylindrical elongate units. The bulk of the outer wall is almost homogenous, and near the surface it is granular. Pomeranisporites subtriangularis is pseudozonate. The inner layer appears homogenous except for the presence of a single innermost lamina. The inner part of the outer layer may represent small tabular and cylindrical elements, and the outer part comprises folded laminae. The megaspores studied share numerous features of morphology and wall ultrastructure with the lycopsids, putative lycopsids, and some enigmatic Devonian plants.     

The First Stem Tetrapod from the Lower Carboniferous of Gondwana

The first stem tetrapod from Gondwana, Ossinodus pueri gen. et sp. nov, is described from fragmentary material that includes a skull table and many important parts from the postcranial skeleton. It was recovered together with a typically non-marine to marginal (near) marine fish fauna from the Lower Carboniferous (mid Viséan) Ducabrook Formation, Queensland, Australia. Phylogenetic analysis hypothesises that Ossinodus belonged to a clade that includes Whatcheeria and Pederpes , positioned on the stem of the crown tetrapods, one step crownward of Tulerpeton . Hind limb morphology suggests that small specimens of Ossinodus were primarily aquatic but that larger ones were less so.     

A bryozoan buildup from the Lower Carboniferous of North Wales

A carbonate buildup dominated by trepostome Bryozoa is described from Dinantian (Asbian) strata near Llandudno in North Wales. A three-phase ecological succession is recognised within the buildup: (i) a basal diverse community with fenestrate, ramose, encrusting trepostome and cystoporate bryozoans in a mud rich wackestone; (ii) a bulk facies, dominated by encrusting and foliaceous, trepostome bryozoans in a fine packstone, and (iii) a thin capping phase, dominated by unilaminar, encrusting trepostome bryozoans in a slightly coarser lithology, including skeletal debris derived from the mound top and possible flanking beds. The buildup probably had topographic relief and developed in a shallow marine environment. The internal tripartite zonation reflects the growth of the structure into a shallower, higher energy regime, with the capping beds being deposited just below wave base. The buildup developed to the north of St. George's Land, on a carbonate shelf edge bordering the deeper basinal facies of the Irish Sea Basin. Dinantian, Asbian, buildup, trepostome Bryozoa, Foraminifera, corals, calcareous algae, Carboniferous, North Wales .     

Controls on the distribution of calcareous Foraminifera in the Lower Carboniferous of Ireland

Microfacies analyses of thin sections from over 650 samples of Asbian and Brigantian (late Viséan) platform carbonates from Ireland shows that foraminiferal assemblages are controlled by the relative abundance of echinoderms (mainly crinoids), bryozoans and calcareous algae: Koninckopora, Ungdarella and palaeoberesellids. Archaediscidae, Valvulinella and Tetrataxidae thrived in algal-poor crinoid and bryozoan thickets at or below fair-weather wavebase. Late Viséan algal limestones contain abundant Endothyridae and Palaeotextulariidae, and are interpreted to have been deposited at depths between 5 and 10 m. The morphology of the Foraminifera studied is related closely to their facies distribution. Many taxa inhabited high energy shallow marine algal meadow facies, these include: Bibradya, Cribrospira, Nevillella and Bradyina with cribrate apertures and other specialised test features that protected the protoplasm from damage, Gigasbia, Omphalotis, Globoendothyra and Pseudoendothyra with large, rotund or keeled, multilayered tests and Forschiidae with large thick-walled tests. Infaunal taxa such as the Lituotubella, Nevillella, Gigasbia and the palaeotextulariids are recorded from algal facies and appear to have been unable to survive on bryozoan and crinoidal substrates. Pseudoammodiscus and Earlandia, characterized by simple morphologies and single layered walls, and Endothyranopsis, Endothyra and Eostaffella, planispirally coiled with multilayered micritic tests, are regarded as the least facies-controlled of the taxa studied. The encrusting nature of Pseudolituotuba and Scalebrina ensured survival in a wide range of platformal palaeoenvironments, though algal meadows were not generally suitable substrates for the Pseudolituotubidae. The secondary deposits in the umbilical region of the Asteroarchaediscinae may have been an adaptation for survival in the dense crinoidal bryozoan thickets where they lived. Delicate Planoarchaediscus occurs in algal-poor wackestone to packstone facies typical of low energy palaeoenvironments possibly at depths below 20 m. Howchinia, which occurs with Fasciella (a probable alga) in intraclastic wackestone facies may also have lived in water deeper than 20 m. Major changes in foraminiferal assemblages through the Asbian and Brigantian stages of the late Viséan are attributed to changes in associated biotic constituents. Early Asbian endothyrid and forschiid dominated assemblages were controlled by the relative abundance of bryozoans, Koninckopora and palaeoberesellids. By the late Asbian, the foraminiferal assemblages were controlled by the presence or absence of palaeoberesellids, Ungdarella and to a lesser extent bryozoans. Asbian assemblages were similar, although foraminifers such as bradyinids, Cribrospira and Globoendothyra became abundant in the late Asbian. A switch to predominantly echinoderm (mainly crinoid) and bryozoan substrates in the Brigantian may have caused the major change from late Asbian endothyrid and palaeotextulariid assemblages to archaediscid and tetrataxid dominated assemblages.     

Stages in development of Selaginella diffusa megaspores

In mature megaspores of Selaginella diffusa (C. Presl) Spring the units of the exospore are ordered and become unordered toward the outer and inner surfaces. The exospore surface is coated with silica at maturity. The insertion of the future gap begins in early stages with formation of many minigaps within the inner part of the exospore distally. The mesospore, like the exospore, is resistant to the acetolysis reaction and can, thus, provisionally be considered to consist of sporopollenin. Unit structures within the outer part of the mesospore are unordered, but become ordered in the middle and inner parts. The inner surface of the mesospore appears verrucate. In maturing megaspores, the mesospore is mostly disintegrated and the inner exospore, which encapsulated the mesospore, remains as a somewhat isolated structure, and is again near the outer exospore. There are connecting strands across the gap between the inner surface of the outer exospore and the surface of the inner exospore. There are also spheres on the outer surface of the inner exospore.     

Enigmatic Fossils from the Lower Carboniferous Shrimp Bed,Granton, Scotland

The Lower Carboniferous (Visean) Granton Lagerstätte (Edinburgh, Scotland) is principally known for the discovery of the conodont animal, but has also yielded numerous crustaceans and other faunas. Here we report on small branching colonies, reaching 10 mm in length. They are small, erect, arborescent, and irregularly branched with predominant monopodial and dichotomous growth. They bud in a single plane. In one specimen the wall microstructure is well preserved and it is composed of evenly spaced, linear fibers, running parallel to the axis of the stems, and connected by transverse bars. We discuss possible biological affinities of these organisms; we consider algal, poriferan, hydrozoan and bryozoan affinities. The general pattern of branching, presence of fan-like structures (interpreted here as possible gonophores) and microstructure suggests affinity to Hydrozoa, affinity to non-calcifying algae is less likely. Assuming hydrozoan nature; the microstructure might suggest affinities with the extant family Solanderiidae Marshall, 1892 that possess an internal chitinous skeleton. The EDS analysis shows that fossils discussed here are preserved as phosphates. The skeletons were probably not mineralized, the presence of phosphorus suggests that the colonies were originally composed of chitin. We describe these organisms as Caledonicratis caridum gen. et sp. nov. (Solanderiidae?, Capitata?). Colonies of C. caridum gen et. sp. nov. sometimes encrust the exuviae of crustaceans, which very probably lived in fresh to brackish water thus indicating a likely habitat of Caledonicratis.     

Lageniastrum macrosporae (fossil Volvocales, Lageniastraceae nov. fam.), an endophyte in megaspores from the Carboniferous of the French Massif Central

Sublagenicula nuda lycophyte megaspores from the upper Visean of central France frequently host a colonial green alga as an endophyte. This association was first recorded more than 100 years ago by the French paleobotanist B. Renault, who introduced the name Lageniastrum macrosporae for the alga. However, the biological significance of the discovery was not fully assessed until recently. The L. macrosporae-S. nuda association represents the oldest compelling fossil evidence for algal endophytes in land plants, and the only example to date of an alga residing in the interior of spores of vascular cryptogams. Here we present a detailed re-evaluation and photographic documentation of the surviving original specimens from the Visean of Combres/Lay and Esnost. Moreover, a newly discovered specimen from the Stephanian of central France represents the first record of this association from the Upper Carboniferous. An emended diagnosis for L. macrosporae Renault, 1896 is provided, and a lectotype and paralectotype are designated. Although L. macrosporae displays a striking suite of morphological characters found in members of the extant chlorophyte family Volvocaceae (especially the genus Volvox), the peculiar biology of the fossil necessitates establishment of a new family, for which the name Lageniastraceae is proposed. Considerations of the adaptive advantages for the alga of occupying the interior of megaspores are offered. These include the possible effectiveness of the spores in protection during periods of desiccation and against plankton-feeding animals, and use of the spores as potential vectors for dispersal from one isolated body of water to another by spore-feeding animals.     

Taphonomy of Lower Carboniferous crinoids from the Hook Head Formation, Ireland

Ausich, W.I. & Sevastopulo, G.D. 1994 10 15: Taphonomy of Lower Carboniferous crinoids from the Hook Head Formation, Ireland.
Lower Carboniferous strata at Hook Head, County Wexford, Ireland, record tempestite deposition on a mixed carbonate and siliciclastic shelf-ramp. Crinoidal remains occur in all facies, which allows for a comparative taphonomic analysis of crinoid preservation. Preservation of crinoid crowns was controlled by a balance between mean storm intensity and frequency. The best preservation occurs at moderate depths. Taphonomic resistance among Hook Head crinoids is interpreted as follows (from most to least resistant to disarticulation): monobathrid camerates -cladids - diplobathrid camerates — flexibles (with Platycrinites and Dichocrinus disarticulation more like cladids). Crinoidea, taphonomy, preservation, Lower Carboniferous, Ireland .     

Melissiotheca: a new pteridosperm pollen organ from the Lower Carboniferous of Scotland

Melissiotheca is based on fusainized pollen organs of pteridospermous affinities which occur abundantly in an Upper Visean limestone at Kingswood, near Pettycur (Scotland). The new species is a pedicellate synangium composed of 50–150 sporangia each of which is embedded at its base in a parenchymatous cushion divided into lobes. The sporangia are fused along their proximal half but are free distally. Dehiscence is longitudinal. Each sporangium is supplied at its base by a single vascular strand. Prepollen is small, spherical and trilete with a rugulate exine. In ultrastructure, the nexine appears homogeneous; the sexine shows internal sculpture of granae and rod elements. Melissiotheca has not been assigned to any family, but it shows many affinities with pollen organs attributed to the Lyginopteridaceae.     

Melissiotheca: a new pteridosperm pollen organ from the Lower Carboniferous of Scotland

Melissiotheca is based on fusainized pollen organs of pteridospermous affinities which occur abundantly in an Upper Visean limestone at Kingswood, near Pettycur (Scotland). The new species is a pedicellate synangium composed of 50–150 sporangia each of which is embedded at its base in a parenchymatous cushion divided into lobes. The sporangia are fused along their proximal half but are free distally. Dehiscence is longitudinal. Each sporangium is supplied at its base by a single vascular strand. Prepollen is small, spherical and trilete with a rugulate exine. In ultrastructure, the nexine appears homogeneous; the sexine shows internal sculpture of granae and rod elements. Melissiotheca has not been assigned to any family, but it shows many affinities with pollen organs attributed to the Lyginopteridaceae.     

Carotenoid Pigments of some Lower Ascomycetes

Protomyces pachydermus and P. inouyei contains ß-,-carotene and lycopene, with ß-carotene predominating.Taphrina deformans and T. communis contains no carotenoid pigmentsalthough the colour of methanol extracts of all four speciesis yellow. A quick way of differentiating between these twogenera is by showing the presence of carotenoid pigments inProtomyces and absence of these in Taphrina. It is suggestedthat a knowledge of individual carotenoid pigments in fungimight be useful as a taxonomic tool among fairly closely relatedspecies.