Bulk sampling of the marls and marly limestones of the Hunstanton Formation (Red Chalk) and associated deposits at two sites in north-east England has yielded rich and diverse assemblages of small selachians, largely represented by dissociated teeth. This fauna contains over 35 taxa and is dominated by small to very small nectobenthic forms. A large proportion of these are new, and five new species are described: Protosqualus pachyrhiza sp. nov., Pseudospinax heterodon sp. nov, Cretorectolobus gracilis sp. nov., Parasymbolus reticularis sp. nov. and Pteroscyllium ornatum sp. nov. Cretascyliorhinus gen. nov., is erected for Scyliorhinus destombesi Cappetta and related forms. The earliest records of Squalus and the Etmopterinae are noted. The fauna is considered a specialist low-nutrient selachian fauna probably confined to the North Sea Basin.
Ordovician trilobite diversity showed a marked increase in the Anglo-Welsh area during the mid and late Arenig to a peak in the late Arenig to early Llanvirn. A slightly lower peak was also reached during the early Caradoc and following a dip in the Cheneyan Stage, a gentle rise took place during the latest Caradoc to early Ashgill followed by a sharp increase to a Cautleyan-Rawtheyan high preceding the Himantian diversity crash. Beta (between sample) diversities were probably highest during the Fennian, late Abereiddian, Cautleyan and (highest of all) Rawtheyan. The regional diversity curve differs from the global curve principally in lacking an early Arenig rise and in its diversity maximum in the Rawtheyan when global diversity was falling. Genera belonging to the Whiterock Fauna became the dominant component of the Anglo-Welsh fauna in the early Arenig, earlier than the global rise to dominance. The subsequent increase of the Whiterock Fauna in the Anglo-Welsh area was not influenced by changes in overall diversity, suggesting that it was fairly equally distributed across the range of environments sampled. The profound level of extinction in the deepest water environments during the latest Ordovician was concentrated in the Whiterock Fauna and included the demise of trilobite biofacies that had existed since the Arenig.
A total of 13 species of crocodilians, representating nine genera, have been recognized from the Lower Cretaceous (Berriasian) Purbeck Limestone Group of Dorset, southern England. Of these taxa, only Goniopholis crassidens Owen, Goniopholis simus Owen, Goniopholis (Nannosuchus) gracilidens (Owen) comb. nov., Pholidosaurus purbeckensis (Mansel-Pleydell) comb. nov. and Theriosuchus pusillus Owen are considered valid. Pholidosaurus decipiens Watson and Pholidosaurus laevis Andrews are both synonyms of Pholidosaurus purbeckensis, whereas Oweniasuchus minor Owen is a synonym of T. pusillus. The holotypes of Goniopholis tenuidens Owen and Oweniasuchus major Owen are undiagnostic, and both species are placed in nomen dubium. The presence of Bernissartia and Lisboasaurus in the Purbeck crocodilian sample cannot be confirmed. Crocodilian fossils are restricted to the Middle and Upper Purbeck Beds, with the majority of known material coming from the Marly Freshwater Beds and Cherty Freshwater Member in the upper part of the Lulworth Formation.
Measuring abundance, one measure of an organism's success, is vital for describing the ecological context and community characteristics of fossil species and evaluating biases related to preservation and sampling. All euconodont 'death assemblages' will be biased by life history; short-lived individuals or those that moulted will be overrepresented compared with long-lived individuals. If a true measure of abundance is to be obtained we have to account for this bias. By comparison with living vertebrates it has been hypothesized that the euconodont oral skeleton, the first part of the vertebrate skeleton to mineralize, was deciduous; either elements or the whole apparatus could have been shed. This hypothesis has received little scrutiny and could have a direct bearing on the biological and palaeoecological inferences that can be made from species-abundance data. Natural assemblages support retention of elements whilst histological analysis indicates polycyclic growth comprising alternating periods of function and overgrowth that probably continued throughout life. This study challenges the idea of whole apparatus shedding by utilizing biometric data from time-averaged collections of Idiognathodus natural assemblages. Scatter Plots Of element linear dimensions exhibit clustering into size cohorts that can be used to elucidate population structure. Published time-specific and dynamic survivorship curves for the Silurian ostracod Beyrichia jonesi are used as a model for the population structure of a moulting organism. These curves are similar, having roughly the same average slope and identical mean rates of mortality per age class. The same survivorship curves for the Idiognathodus collection have different average slopes and mean mortality rates. It is therefore concluded that the apparatus was retained throughout life. At least in this taxon, and in the absence of preservational or sampling biases, element-abundance data are a true measure of a species' success. However, quantitative palaeoecology of euconodonts will not become fully rigorous until the age of euconodonts can be determined.
The primary layer of calcite-shelled brachiopods lacks structure and therefore differs markedly from the highly ordered secondary layer of calcite fibres in the Rhynchonelliformea and semi-nacre in the Craniiformea. Electron backscatter diffraction demonstrates that the crystallographic orientation of the primary layer is the same as that of the secondary layer calcite. In Terebratulina retusa and Terebratalia transversa, the c-axis of the primary layer calcite is perpendicular to the shell exterior as in the secondary layer fibres. In Novocrania anomala, the c-axis of the primary layer calcite is parallel to the shell exterior as in the secondary layer semi-nacre. Thus, while the primary layer may appear somewhat disordered, biological control is exerted on calcite crystallographic orientation from the first-formed primary layer. Atomic force microscopy of T. retusa primary and secondary layers indicates that the secondary layer fibres are composed of large triangular granules of fairly uniform dimensions (600 nm long), while the primary layer is composed of triangular units whose constituents are more spherical nano-granules of about 50 nm diameter.
Cones belonging to arborescent lycopsids occur abundantly in the Pettycur Limestone facies of the Asbian (late Dinantian, Carboniferous) at Pettycur, Fife. The most abundant cones are heterosporous and have been described by Wiliamson, Scott and others under the name Lepidostrobus veltheimianus Sternberg. Jongmans subsequently named these cones L. scotii Jongmans and the species was later transferred to the cone genus Flemingites. The type specimens (which are in a thin section) are cones which contain both megaspores and microspores. The megaspores can be identified in section as Lagenicula subpilosa (Ibrahim) f. major Dijkstra ex Chaloner and have been figured by numerous authors. The microspores which occur in sporangia at the tip of the cone belong to the genus Lycospora. A new species L. chaloneri is here erected for these spores. Spores have been extracted from new specimens of cones and studied using light and scanning electron microscopy, and their ultrastructure investigated using transmission electron microscopy. Under TEM the exine of Lagenicula consists of a solid basal lamina with an inner exine composed of small globular units which become larger and interlnked in the outer exine. The microspores are small (20 micrometer) subtriangular with a distinctive distal ornament of small (1-2 micrometer) conate-echinate spines. They have a two-layered wall.
A skull and some post-cranial elements of Enchodus sp. found in the gut contents of Goulmimichthys arambourgi from the Upper Cretaceous (Lower Turonian) of Goulmima, Morocco is described. It shares similarities with E. venator from the Lower Cenomanian of Jebel Tselfat, but is not complete enough for specific identification. The skull and several other enchodontid microremains from the matrix surrounding the specimen of G. arambourgi show juvenile characters: weak state of ossification of the palatine, of the lower jaw and of the vertebral centra. The presence of an unpaired premaxillary fenestra and of a small jugular canal in the trigemino-facialis chamber are also probably juvenile characters. The large number of microremains of juvenile enchodontids at this locality suggests that it was an Enchodus nursery.
Abundant selachian remains have been recovered from a number of horizons through the Purbeck Group at Durlston Bay, Lulworth Cove and Stair Hole in southern England. The remains, primarily teeth, but additionally fin spines and dermal denticles, belong to selachians from two major groups, the Hybodontoidea and the Rhinobatoidei. The assemblage of hybodont sharks is quite diverse, comprising six species from the four genera ‘Hybodus’, Egertonodus, Polyacrodus and Lonchidion. The rhinobatoid rays include two species, one belonging to the genus Belemnobatis and another, larger, indeterminate ray. Within the Purbeck fauna, two species are new: Lonchidion inflexum sp. nov. and Belemnobatis variabilis sp. nov. Within the entirely non-marine succession of the Purbeck Group, the beds containing ray teeth also contain molluscs indicative of more saline intervals. In all of the sampled beds, the hybodont faunas recovered were relatively homogenous.
Both compressed and permineralized plants have been collected from Upper Visean tuffs and dolomitic ashes outcropping on the foreshore at Weaklaw. The assemblage is dominated by permineralized gymnosperm remains which include woody stems, rachises and foliage; these are attributed to Bilignea solida, Eristophyotn fasciculare, Pitus withamii, Lyginorachis kingswoodense, Spathulopteris obovata, and Rhacopteris lindseaeformis. Sphenopteris cf. affinis is found as compressions. The zygopterid fern Diplolabis Renault is also recorded for the first time at this locality. The plants differ from taxa previously described from this area by Gordon including Pitus dayi, P. primaeva and P.rotunda, as well as the lycopsid Lepidodendron sp. and the ferns Botryopteris and Stauropteris which had been only briefly mentioned. It is suggested that the Weaklaw fossils sensu lato are derived from several distinct original plant communities. Comparison with the nearly contemporaneous floras from Pettycur, East Kirton, Loch Humphrey Burn, Esnost and Roannais indicates that similar plant communities, dominated either by lycopods and/or ferns or by gymnosperms, existed within these volcanic areas.
Purbeck fossil insects have been collected and studied for more than 140 years, and have recently seen a revival of interest. Their remains occur in many Lower and Middle Purbeck horizons and can be very abundant. The use of species accumulation curves suggests that there are about 1400 fossil insect species in the Dorset Purbeck, although this is probably an underestimate of true diversity. At ordinal level the insect fauna is much more similar to that of the Recent than the Permian, although lacking important Recent groups such as the butterflies and moths (Lepidoptera) and social ants, bees and wasps (Hymenoptera). A low diversity aquatic insect assemblage can be recognized and could be used as a guide to palaeosalinity. The insect data broadly support the evidence for a 'Mediterranean' climate for southern England during the Early Cretaceous.
Two putative tetrapod humeri of Devonian age, ANSP 21350 from the late Famennian of Pennsylvania and GSM 104536 from the late Frasnian of Scat Craig, Scotland, are reinterpreted in the light of recent discoveries. The morphology of ANSP 21350 can be more fully homologized with those of elpistostegids and early tetrapods than previously recognized. Unique features include distally displaced dorsal muscle attachments and a ventrally rotated distal face of the bone. This suggests that a weight-bearing ventrally directed forearm was created, not by means of a flexed elbow as in other tetrapods, but by distorting the humerus. The olecranon process on the ulna was probably poorly developed or absent. Primitive characters that are absent in other tetrapods add support to the contention that ANSP 21350 is the least crownward of known tetrapod humeri. Contrary to previous claims, Acanthostega has a characteristic tetrapod ulnar morphology with an olecranon process; it does not resemble an elpistostegid ulna and is not uniquely primitive for tetrapods. This suggests that the flexed tetrapod elbow with ulnar extensor muscles attached to the olecranon evolved simultaneously with the large rectangular entepicondyle typical for early tetrapods, probably as part of a single functional complex. GSM 104536 is definitely not a primitive tetrapod humerus, nor a sarcopterygian branchial bone, but cannot be positively identified at present.
Over 30 skeletons and dozens of isolated bones of the Liassic pterosaur Dorygnathus have been recovered from the Early Jurassic (Toarcian) of Baden-Württemberg and Lower Saxony in Germany, and from Nancy, France. All but one specimen have been assigned to the species D. banthensis; the exception was assigned to a larger species, D. 'mistelgauensis', which new discoveries suggest is simply a large individual of D. banthensis. The form of the lower jaw and premaxillary teeth are diagnostic for the genus, as are several other features. Here I review the history of the understanding of Dorygnathus, describe the known specimens in public repositories, and characterize the general morphology and systematic position of the genus. Dorygnathus is distinguished by its extremely large anterior teeth (four premaxillary and three or four anterior dentary teeth), which are proportionally larger than in any other pterosaur, Its deep maxilla gives the skull a high, straight, gradual slope, and its long, deepened, upwardly curved mandibular symphysis is diagnostic for the taxon. Other features such as the proportions of the wing elements, the form of the pelvis, and the shape and proportions of the toes are equally characteristic. Dorygnathus is most closely related to Rhamphorhynchus and the Pterodactyloidea, and represents this lineage in the Early Jurassic of Europe.
Basal sauropodomorphs, historically referred to as 'prosauropods', include approximately 20 genera of Late Triassic-Early Jurassic age. Recent discoveries on several continents and taxonomic review of important species have brought to bear significant new taxon and character data. After review of the taxonomic status of Anchisaurus polyzelus, Ammosaurus major is recommended as the appropriate genus and species for basal sauropodomorph material from the Portland Formation of eastern North America. Traditional (precladistic) and cladistic interpretation of basal sauropodomorph phylogeny has varied between two extremes: a monophyletic clade of 'prosauropods' or a sequence of basal sauropodomorphs that increasingly approach the sauropod condition. Given new species that exhibit a range of derived features, future resolution will probably lie somewhere between these polar viewpoints. Conflicting results from recent analyses suggest that greater resolution of basal sauropodomorph phylogeny will come with continued clarification of anatomical details and a comparative methodology that focuses on character data rather than simply the most parsimonious tree.
In his original description of the Recent terebratellidine brachiopod J. hedleyi, Dall noted the presence of a 'calcareous plate' occupying the posteromedian lacuna of the loop which he attributed to 'coalescence of spicules'. We report on the discovery of a set of three distinctively shaped endoskeletal plates located within the mantle and lophophore tissues of the dorsal valves of adult Jolonica nipponica Yabe and Hatai, and Jolonica suffusa (Cooper). The plates consist of a central, flat and roundly pentagonal-shaped plate occupying the posteromedian lacuna of the brachidium and a pair of gently curved lateral plates enclosing the dorsal diductor muscle bases on either side of the median septum. Although all three plates exhibit a fibrous microfabric similar to the secondary shell mosaic pattern found on the valve interiors of most Rhynchonelliformea, they cannot be regarded as part of the standard secretory regime (sensu Williams 1968a). Examination of a subadult specimen of J. suffusa reveals that the plates formed as a result of amalgamation of isolated spicule-like platelets exhibiting a much less regular microfabric than that found in the plates of adult specimens; the rudimentary platelets in turn almost certainly developed as a result of clumping together of individual membrane-bounded scleroblasts containing intracellular calcite. The reassignment of the south-east African genus Compsoria Cooper, (type species C. suffusa), to Jolonica Dall substantially extends the present-day biogeographic distribution of the latter.
The Early Jurassic (Liassic) pterosaur Campylognathoides, from the Schwarzjura ε II of southern Germany, is known from three specimens of its type species, C. zitteli, nine of a smaller species, C. liasicus, and some partial material from the Kota Formation of India referred to a third species, 'C. indicus', of dubious validity. Most of the German specimens have never been described. At least one specimen previously referred to Campylognathoides now appears to belong to Dorygnathus banthensis, a second and better known contemporaneous pterosaur. Campylognathoides is diagnosed by its steeply sloping snout; rod-like jugal; triangular antorbital fenestra confined to the lower half of the skull; ventral border of the orbit reaching nearly to the level of the tooth row; 9-10 small maxillary teeth; large, broad quadrangular sternum flared at posterior ends, with short cristospine; forelimb element length ratios wph 2 > wph 1 > wph 3 > wph 4 > r/u > h > mc; large medial carpal; very short, blunt pteroid; and a short fifth toe. C. zitteli is proportionally larger than C. liasicus and has 17 or 19 instead of 12 mandibular teeth. These and other historically accepted specific differences may reflect size rather than phylogeny, a question that could be resolved by the discovery of specimens of intermediate size. The closest relative of Campylognathoides appears to be Eudimorphodon, from Late Triassic deposits in Italy; this pterosaur lineage seems to be an early divergent branch from the main line leading to the Pterodactyloidea.
Phacops sweeti Etheridge and Mitchell, 1895 and three new species of phacopid trilobites from the Lower Devonian of central Victoria are described: Nephranomma debrae, N. lynnae and N. janinae. These show closest affinities to the type species of Nephranomma, Phacopidella (Nephranomma) drepanomma Erben, 1952 from the Emsian of Germany. A review of the type species and its relationships to these Victorian and other allied species provide new perspectives on the status, affinities and phylogenetic relations of Nephranomma, which is considered of generic rank, derived from Lochkovella in the late Lochkovian.
Dinoflagellate cysts are abundant and diverse in the Eocene of southern England, with many species having restricted stratigraphic ranges. Thirteen dinoflagellate cyst assemblage zones are formally proposed, three in the London Clay, five in the Bracklesham Beds, and five in the Barton Beds. Five genera and twenty species of dinoflagellate cysts are erected, generic transfers are made for sixteen species, and the diagnoses of six genera and four species are emended. One genus and two species of acritarchs are also erected. The new genera are Cerebrocysta, Dapsilidinium, Hemisphaeridium, Lentinia, Paucisphaeridium, and Quadrina.
Recent preparation of the holotype of Coccocephalus wildi, the type species of the genus Coccocephalus, has revealed the palatoquadrate and the three-dimensionally preserved endocranium. The species is redescribed, and the two other species of Coccocephalus, from Upper Carboniferous marine beds in North and South America, are reviewed. Coccocephalus is a palaeoniscoid-grade actinopterygian displaying a mixture of numerous primitive and a few derived characters. It shares many primitive features with genera classically considered to belong to the stem-group of actinopterygians, such as Cheirolepis, Mimia, Moythomasia and Howqualepis. Advanced features indicate subsequent actinopterygian evolution towards forms such as Boreosomus and Commentrya.
Diverse Late Ordovician (late Katian and Hirnantian) shelly faunas have been known for over 150 years from southern Pembrokeshire and adjacent south-western Carmarthenshire, Wales, which formed part of the continent of Avalonia in the Ordovician. The rocks concerned are the Sholeshook Limestone Formation (and the equivalent Robeston Wathen Limestone Formation), the Slade and Redhill Mudstone Formation and the lower part of the Haverford Mudstone Formation. The Portfield Formation (between the Slade and Redhill Mudstone Formation and the Haverford Mudstone Formation) is largely without macrofossils, and the Ordovician-Silurian boundary lies within the Haverford Mudstone Formation. However, the brachiopods have never been properly monographed, and apart from a short paper by Reed (1905), the only systematic descriptions have been as a few isolated species in papers covering wider topics. Thus, the 61 brachiopods from the Sholeshook Limestone and Slade and Redhill Mudstone formations and the 16 from the lower Haverford Mudstone Formation are reviewed here and described where necessary. Many specimens are poorly preserved and so some taxa are left in open nomenclature. There is systematic revision of much of the fauna, including the transfer of the few older-named species to more modern genera and the erection of 16 new species: Acanthocrania elusa, Gunnarella mcdermotti, Mackerrovia? jinei, Eostropheodonta portfieldensis, Sampo transversa, Fardenia gwaliae, Triplesia hintsae, Kullervo grandis, Nicolella crabbi, Glyptorthis splendens, Boreadorthis sheehani, Neoplatystrophia deani, Cryptothyris magnifica, Dedzetina major, Harknessella stevensorum and Salopia posterior, as well as the new subspecies Christiania nilssoni sholeshookensis. No new genera are erected, but the widely quoted dalmanelloid Laticrura is placed within the synonymy of Salopia. The only pentamerides are sparse material of Porambonites? sp. and a camerelloid in open nomenclature. Rhynchonellides are also extremely rare, and the order is represented by a meagre three specimens, two of which are Thebesia sp; atrypoids are only known from two specimens of Eospirigerina? The late Katian faunas of the Sholeshook Limestone and Slade and Redhill Mudstone formations are largely similar, and both were deposited on the middle and deeper-water parts of the shelf, chiefly preserved in shell bands with the brachiopods broken and not in life position. Most of the assemblages consist of a variable Onniella Sowerbyella Association in both formations, which are combined at some localities with a fauna comparable with a Foliomena Fauna Association in part of the Sholeshook Limestone Formation and near the base of the Slade and Redhill Mudstone Formation, but the latter association is only represented as part of a more diverse assemblage than is usual for that well-known fauna. Two faunal turnovers can be recognized within the Haver-ford Mudstone Formation: the first at its base, at which a Hirnantia Fauna is developed in the St Martin's Cemetery horizon, which is followed higher in the formation by sporadic but much less diverse Hirnantian assemblages; however, only the species of the Hirnantia Fauna originally described from south-western Wales are reviewed here. The second turnover is at about 250 m above the base of the Haverford Mudstone Formation, where the sparse Hirnantian age faunas (dated by the trilobite Mucronaspis) are succeeded by the rich Rhuddanian faunas of the Early Silurian within the top 100 m; however, the latter are not discussed in detail. The faunas of south-western Wales are compared with those from other parts of Avalonia and also with other Late Katian and Hirnantian brachiopods from the adjacent continents of Laurussia, Baltica and north-western Gondwana, and their palaeogeography discussed: Avalonia had many genera, but few species in common with the others.
Ontogenetic material of Ovalocephalus primitivus has been recovered from the Ordovician Dawan Formation (Arenig Series) of Anhui, South China. The metaprotaspis has a forwardly arched anterior margin, anteriorly expanded glabella, and short anterior and midfixigenal spines. The Hammatocnemidae, in which Ovalocephalus has hitherto been placed, is therefore now better regarded as a separate subfamily within the Pliomeridae. Ontogenetic changes include the successive abaxial and forward expansion of the glabella, posterior shift of the palpebral lobe and related shortening of the posterior fixigenal field, abaxial shift of the posterior branch of the facial suture, reduction of the fixigenal spines, widening of the axis and the terminal area, and reduction in the number of pygidial axial rings and ribs. Ovalocephalus contains 11 species ranging from Arenig to Ashgill in age. Adults of stratigraphically later species have a more anteriorly situated palpebral lobe, a longer posterior fixigenal area, and a narrower basal part of the glabella (all immature features of the ancestral form) suggesting that paedomorphosis plays an important role in the evolution of the genus.
Upper Ordovician strata of the Bighorn Group in the subsurface of Alberta represent the western erosional edge of an extensive area of deposition of Lower Paleozoic rocks centered on the Williston Basin. The strata comprise mainly massive mottled dolostone overlying strata of Late Cambrian to earliest Ordovician age assigned to the Deadwood Formation and in turn overlain by Middle Devonian carbonates and elastics. This is the first report of fossils from these strata. Conodonts are common to abundant in samples of core and, together with rare occurrences of macrofossils, serve to provide biostratigraphical constraints on the Upper Ordovician sequence. The unit is mainly of mid-Edenian to mid-Maysvillian age and assignable to the Red River Formation. Some biostratigraphic evidence points to the preservation of younger Richmondian strata in wells in the eastern part of the area near the Saskatchewan border. These strata probably correlate with the Stony Mountain Formation of Saskatchewan and Manitoba, but no lithological evidence of the fossiliferous limestones typical of the lowest Stony Mountain Formation is known from cores in Alberta.
Ankylosaur material from the upper Lower Cretaceous to lower Upper Cretaceous (Albian-Cenomanian) of south-eastern England is reviewed systematically. 'Acanthopholis horridus' from the Lower Chalk of Folkestone (Kent) is regarded as a nomen dubium. A re-evaluation of the ankylosaur specimens from the Cambridge Greensand (mostly probably reworked from the underlying Gault Clay) suggests that all of the species of 'Acanthopholis' erected by Seeley, on the basis of fragmentary, and often composite, non-diagnostic material, are invalid. Anoplosaurits curtonotus Seeley is removed from the Ornithopoda, and provisionally regarded as a valid taxon of nodosaurid ankylosaur. A lectotype, a partial scapula, is designated for this species. Anoplosaurus appears to be a relatively primitive nodosaurid which retains several plesiomorphic features in the lower jaw, sacrum and appendicular skeleton.
Araucarian pollen cones Rabagostrobus hispanicus gen. et sp. nov. and their associated foliage Brachyphyllum obesum Heer are described from Lower Cretaceous (Albian) strata of northern Spain. Male cones consist of helically arranged microsporophylls bearing 5–8 elongate pollen sacs with in situ inaperturate Araucariacites‐type pollen. The new taxon is compared to material described previously from the Early Cretaceous of North and South Americas. Sterile twigs of B. obesum bear helically arranged leaves with wrinkled margins. Its cuticle has files of predominantly transversely oriented stomata. Both twigs and pollen cones occur as inclusions in amber from the Peñacerrada 1 outcrop (Álava Province), and as compressions are recorded from the amber‐bearing strata sediments of the Rábago/El Soplao outcrop. Inclusions of araucariacean plant remains and the co‐occurrence of amber and male cone and twig compressions suggest that the amber in these two localities, or at least some of it, was produced by araucariacean plants.
A description of a generalised phacopid trilobite, its functional morphology and mode of life is based mainly on Devonian material from Germany. The inner surface of the exoskeleton shows details of articulation and muscle attachment for the antennae and three pairs of biramous appendages in the cephalon, 11 pairs in the thorax and up to 12 pairs in the pygidium. Leg muscles are attached to long processes or apodemes. Details of appendages and intestine are known from X-ray studies of a new specimen from the Lower Devonian Hunsriick Slate. The inner surfaces of all legs were covered in bristles used to filter food particles. Given the size of legs, shape of apodemes and the need for enrollment, it is possible to suggest a basic arrangement of muscles needed for the trilobite to function. The legs of the cephalon were attached far back and the mouth was forward of these. This gives room for a short oesophagus leading into a stomach lying below the glabella. Leg and gill movements are those of an animal living on the sea floor filtering detritus. It was not an active swimmer and it lived in environments where sunlight was often blocked out by mud storms, hence the need to enroll for protection. In this environment the large eye lenses were an advantage. New transverse and longitudinal reconstructions are given.
A nautiloid assemblage collected from Upper Silurian (Pří dolí) limestone horizons at the Rauchkofel Boden section, Carnic Alps, Austria is described. The assemblage includes 13 species that may be assigned generically to Kopaninoceras, Michelinoceras, Orthocycloceras, Sphaerorthoceras, Arionoceras, Columenoceras, Geisonoceras, and Temperoceras. The dark grey micritic fossiliferous limestones from which the nautiloid assemblage was collected form part of the Cephalopod Limestone Biofacies which may be traced all along the North Gondwana margin. The fauna from the Carnic Alps shows close affinities with both Bohemian and south-west Sardinian nautiloid faunas. The paper adds more data to support the idea of faunal exchange between these North Gondwana terranes and Baltica.
Jumping bristletails (order Archaeognatha), the basalmost order of extant insects, include some of the earliest fossil records among hexapods, yet their overall geological occurrence remains sparse and has provided little insight into their evolution. The earliest representatives of crown‐group bristletails are those in Lebanese amber (Cretaceous), hitherto known only from a single species. Here we significantly expand the known fossil record of Archaeognatha, and from the prolific Lower Cretaceous (Barremian) deposits of Lebanon. One new genus and species, Glaesimeinertellus intermedius gen. et sp. nov., and one new species, Macropsontus bachae sp. nov., are described and figured from Hammana amber, whereas one additional Macropsontus species, M. azari sp. nov., and one meinertellid morphotype are described and figured from Al‐Rihan amber. The new taxa are compared with their modern and fossil relatives. Collectively, the new taxa render the Archaeognatha fauna from Lebanese amber the earliest with sufficient preservation to provide character data comparable to modern forms, highlighting the considerable morphological conservatism within the order.
Astrapotheriid postcranial elements are described from the early Miocene locality Cerro La Cruz in northwestern Venezuela. This skeletal material provides new insights into the structure and lifestyle of this enigmatic group of extinct South American mammals that lack any living analogues. A newly observed pedal character, the dorsoventral curvature of the astragalar head, is shown to distinguish the Venezuelan astrapotheres (Xenastrapo- therium christi and the Cerro La Cruz form) from the Patagonian genus Parastrapotherium. Two tibial specimens possess twisted shafts with obliquely oriented distal articular extremities, this feature appearing to characterise all known astrapothere tibiae. A cervical vertebral specimen exceeds in size any previously known specimens and brings into question the function of the astrapothere's extraordinarily thick neck and comparatively small slender limbs. The astrapotheriid postcranial elements from Cerro La Cruz indicate the presence of two coeval species of astrapothere that can be assigned to the subfamily Astrapotheriinae.
Fossil sea catfishes (Ariidae) collected from the Tropical American Neogene are essentially modern species that inhabited estuarine environments similar to those that characterize their living counterparts. Eight extant species of ariids, 'Alius' couma, 'A', dowii, 'A', herzbergii, 'A', quadriscutis, 'A', kessleri, 'A.' rugispinis, Bagre marinus and Sciadeops troscheli, are described as fossils. These taxa are represented by neurocrania from the lower Miocene Cantaure, lower Miocene Castillo, upper Miocene Urumaco (middle and upper members) and upper Miocene-lower Pliocene Cubagua (Cerro Verde Member) formations of the Venezuelan marine basin. Additional indeterminate eroded or broken neurocrania assigned to cf. 'Arms', cf. 'Cathorops', cf. 'Bagre', and Ariidae incertae sedis were also collected. Using a nonlinear regression such that total fish length (TL) in 'A', couma, 'A', dowii, and 'A', herzbergii (TL = 3-4407 +3-473 xtotal skull length), 'A', quadriscutis (TL = 0-7082 + 5-9033 x distance between both post- temporal bones), 'A', kessleri (TL = 0-2016+12-1467x ventral length of the sustentaculum), and B. marinus (TL = 3-0482 +4-9632 x distance between both lateral ethmoid processes), the total length of fossil ariids is inferred to be very close to the observed body-size range in the living counterpart. Pacific species reported here ('A', dowii, 'A', kessleri and S. troscheli) inhabited estuarine environments along the Caribbean coast of South America during the wide-open connection between the Pacific and the Atlantic Ocean, prior to the closure of the Panamanian isthmus in the early Pliocene.
North American species were among the first bradoriid and phosphatocopid arthropods to be documented and include many historically and nomenclatorially important taxa. The most abundant specimens of bradoriids and phosphatocopids in North America occur in the Canadian Atlantic Provinces, British Columbia and Arizona and, to a lesser extent, in New York State and Tennessee. The families Bradoriidae (junior synonym: Indianidae), Beyrichonidae, Hipponicharionidae, Svealutidae and Vestrogothiidae are represented; Escasona and the hitherto widely used Aluta are considered to be nomina dubia. The total known fauna, comprising 16 genera (including Matthoria gen. nov.) and 26 species (including three under open nomenclature and Liangshanella burgessensis sp. nov.), is much less diverse at the specific level than indicated in previous records (about 100 species). The genera Beyrichona, Hipponicharion, Liangshanella and others have a phosphatic carapace, thus endorsing the notion that carapace composition cannot be used as a diagnostic criterion for distinguishing bradoriids from phosphatocopids. Provinciality of the bradoriid and phosphatocopid faunas supports the notion of an Iapetus Ocean in the Cambrian. Eastern Canadian (Avalonian microcontinent) faunas are characterized by Beyrichona, Cyclotron and Hipponicharion; Arizona (Laurentian palaeocontinent) has Walcottella and Dielymella. Bradoria is known from both the Avalonian and Laurentian parts of North America; the cosmopolitan Anabarochilina occurs only in the Laurentian part. Faunas of the distal shelf of Laurentia have Asiatic (Liangshanella and cambriids) and Australian (Indota) bradoriids. Bradoriids and phosphatocopids occur throughout the Cambrian of both the Avalonian and Laurentian parts of North America. Most species are short ranging but have only local geographical occurrence. A few species have intercontinental biostratigraphical value, being coeval in Canada, Britain and Scandinavia. The bradoriid and phosphatocopid faunas of North America occur as low diversity marine assemblages and were probably mostly benthic or nekto-benthic. Shallow water cratonic sequences in Arizona and distal shelf/shelf edge deposits in Alberta, British Columbia and in Greenland (all on palaeocontinental Laurentia) have very low diversity bradoriid assemblages (one or two species). Shallow shelf sequences in New Brunswick and Nova Scotia (palaeocontinental Avalonia) contain mainly richer, but also low diversity bradoriid assemblages (three to six species). Distal shelf faunas in Newfoundland have monospecific phosphatocopid assemblages.