Interfacial methods are a group of newly emerging techniques for recovering phosphatic microfossils from disaggregated sediment residues by exploiting the lipophilic surface properties of apatite (Freeman, 1982). When a sediment residue is placed in a two-phase mixture of water and a water-insoluble organic liquid, the organic liquid wets the phosphate particles in preference to the gangue minerals, most species of which are wetted by the water instead.

Cuticular features and details of fine venation are now widely relied upon in systematic and phylogenetic studies of fossil plants. Where fossil leaves are robust or adherent to the matrix, such features may be readily available, but should the remains be fragile and subject to damage or loss, it may be necessary to preserve their integrity immediately following recovery and during transport. Clays, shales, and fossil leaf compressions are particularly vulnerable to the drying environment; fossil specimens are commonly damaged or entirely lost due to spalling, cracking, and shrinking of the clays or due to exfoliation of the organic film caused by differential drying. In an attempt to eliminate these problems, a technique using a mixture of nitrocellulose lacquer and acetone to coat fossil leaf compressions was developed for use on freshly excavated specimens under a wide range of climatic conditions (subfreezing to warm, dry or wet) while in the field. Many other preservational techniques exist, but they are typically complex, expensive, time consuming, destructive, or were developed for use in a laboratory setting.

Oriostoma bromidensis n. sp., the oldest reported occurrence of Oriostoma Munier-Chalmas, 1876, is described from the Bromide Formation (Middle Ordovician, Blackriverian) of Oklahoma. The species is also the oldest known representative of the family Oriostomatidae Wenz, 1938. It is one of few gastropods known from the Bromide and is smaller than the widespread and abundant Oriostoma typical of the Silurian.

Three species of the Paleozoic coral Palaeacis are described from northeastern Oklahoma and northwestern Arkansas. Included are the Chesterian species P. carinata Girty and P. snideri n. nom., a replacement name for the junior homonym P. cuneata Snider, and the Desmoinesian? species P. erecta n. sp. Coralla of each species exhibit two types of microstructure that characterize two skeletal zones. The outer skeletal zone is composed of numerous parallel trabeculae, mostly between 0.2 and 0.3 mm in diameter, that lie perpendicular to, and have their accretionary surfaces on, the exterior surface of the corallum. Trabeculae are closely spaced laterally and are not organized into rows except uncommonly on the distal portion of some coralla. Where trabeculae coalesce into parallel rows, ornamentation on the corallum exterior consists of parallel ridges or rows of small nodes. Where trabeculae are irregularly arranged, external ornamentation consists of irregularly disposed nodes. The inner skeletal zone consists of radially fibrous stereoplasm arranged into discrete septal spines that coalesce into irregularly developed septal ridges in each calice. In P. erecta, septal spines merge into continuous layers of fibro-normal stereoplasm in some places. On the basis of microstructure, corallum morphology, and external ornamentation P. carinata and P. snideri can be allied with P. axinoides Smyth and P. robusta Webb. Palaeacis erecta falls within the same group on the basis of microstructure and ornament, but has a unique corallum morphology.

Two distinct types of skeletal attachment occur in these Palaeacis species. Palaeacis carinata and P. snideri exhibit an encrusting attachment surface that results in a prostrate growth habit wherein smaller substrates were entirely engulfed, producing free-living coralla. Palaeacis erecta exhibits a small, circular attachment surface and an erect growth habit wherein most skeletal accretion occurs perpendicular to, and away from, the substrate. The substrate is not engulfed and the corallum remains attached and sessile throughout astogeny. Palaeacis erecta is, to date, the only Palaeacis species known to possess this erect, sessile growth form.

Waldemaria monticola Pierce n. sp. and “Hendersonia” valida Pierce n. sp. are described from fluviatile sediments of the intermontane Flint Creek Basin of western Montana. The genus Waldemaria was previously known only from Japan. The presence of these two genera suggest a marked climatic cooling when compared with western North American Eocene–Oligocene faunas. The stratigraphy of the Flint Creek beds, and the associated vertebrate fauna, diagnostic of an early Barstovian age (17–15 Ma), is summarized.

Three productidine brachiopods of Haydenella, Paraplicatifera, and Compressoproductus are recovered from the Tak Fa Formation (Wordian, Middle Permian) of the upper Saraburi Limestone Group exposed at Khao Wong of central Thailand (the western margin of the Indochina Terrane). The latter two genera are new to the Permian of Thailand, and the new species Paraplicatifera thaica is proposed herewith. Some taxonomic and nomenclatural problems in relation to the three genera are discussed. The assemblage suggests endemism for a Middle Permian marine faunule of the Indochina Terrane.

The sparse record of Cretaceous crocodyliforms in Australia comprises only three species, all within the genus Isisfordia. Isisfordia duncani Salisbury et al., 2006 is from the Albian–Turonian Winton Formation of Queensland, and both Isisfordia molnari Hart et al., 2019 and Isisfordia selaslophensis Etheridge, 1917 have been described from opalized material from the Cenomanian Griman Creek Formation of New South Wales. Here, we describe new cranial and postcranial material, including the most complete crocodyliform skeleton from the Cretaceous of New South Wales, which is assigned to Isisfordia cf. I. selaslophensis. We also reappraise previously described crocodyliform material from the same locality. We find that much of this material displays features that are consistent with Isisfordia.

Aldebarania arenitea (Astropectinidae; Asteroidea; Echinodermata) is described from the Rocky Point Member of the Maastrichtian (Upper Cretaceous) Peedee Formation of North Carolina. A turbulent, shallow-water environment is suggested by sedimentary features, a diverse marine fauna, and the morphology of Aldebarania. Aldebarania appears to be a partial ecological equivalent of living Astropecten and Luidia; however, phylogenetic relationships within the Astropectinidae are unstudied and the origin of similarities is unknown.

Falloaster anquiroisitus new genus new species (Asterozoa, Echinodermata) is described from the Floian (Early Ordovician) Garden City Formation of Idaho. The new taxon is known from a single small specimen. Because of weathering, remaining disk elements are incomplete. Dorsal surfaces of the ambulacral ossicles of two arms are available, one well preserved, whereas those of a third arm expose the ambulacrals essentially as they would appear in ventral view. Ambulacral ossicles were all but entirely lost on the remaining two arms.

Albeit asterozoan, F. anquiroisitus is not assignable at the class level. It is suggestive of the Asteroidea in presence of a domal disk, five abruptly tapering triangular, arched arms, and ambulacral ossicles vaulted to form a furrow. Ambulacral morphology, including the presence of very large podial pores, is unlike that of early asteroids. In addition, no adambulacral or other virgal-series derivatives are present; ambital framework ossicles are absent; a single series of enlarged, plate-like arm ossicles, one series on each side of the arm, come together at the arm midline; and the plate-like series were supported laterally by recurved ambulacral margins. Only remnants of the disk near the periphery survive, these of overall expression unlike any other echinoderm, including asterozoans. The mouth frame is unknown. Falloaster anquiroisitus is argued to represent an extinct lineage apart from the four recognized asterozoan classes, thereby joining a limited number of other problematic early Asterozoa.

UUID: http://zoobank.org/a13a5417-44b6-4ac3-90cf-9dc8fb5902bd

The Meade Basin, SW Kansas, yields a rich vertebrate fossil record from the late Cenozoic. Here, we review fossil ground squirrels (Sciuridae) from the region as a contribution to the broader Meade Basin Rodent Project. We recognize 14 species in seven genera: two species of giant ground squirrels (Paenemarmota Hibbard and Schultz, 1948) from the early Pliocene, and at least 12 species in six extant genera (Ammospermophilus Merriam, 1892; Otospermophilus Brandt, 1844; Ictidomys Allen, 1877; Poliocitellus Howell, 1938; Urocitellus Obolenskij, 1927; Cynomys Rafinesque, 1817) from the Pliocene–Pleistocene sequence, including the first regional records of Ammospermophilus. Based on dental morphology and the ecology of modern congeners, we interpret faunal change through the sequence as primarily reflecting a shift from a Pliocene assemblage of “southwestern” taxa with granivorous/omnivorous diets (relatively low-crowned, transversely narrow cheek teeth) in warm and at least occasionally dry shrub or shrub-steppe habitats (Ammospermophilus, Otospermophilus, Ictidomys meadensis [Hibbard, 1941a]), to a Pleistocene temperate assemblage of grazing taxa that either exhibited relatively high-crowned, transversely wider cheek teeth (Urocitellus, Cynomys, Ictidomys tridecemlineatus [Mitchill, 1821]) or were otherwise dependent on grassland habitats (Poliocitellus). The early Pleistocene Borchers assemblage was transitional in this regard, heralding a “revolution” observed as well with other clades in the Meade Basin rodent community. This interpretation is broadly congruent with evidence of Pliocene climatic change and the staged development of regional grasslands, with the modern proportion of C3/C4 plants established in the Meade Basin during the early Pleistocene.

Tarphycerids were diverse and abundant in Ordovician marine faunas. Beginning at the Late Ordovician extinction, the diversity of tarphycerids declined throughout the Silurian, until their extinction in the latest Silurian. Two genera survived the Late Ordovician extinction: Trocholites Conrad, 1838 (from which Ophioceras Barrande, 1865 probably diverged) and Discoceras Barrande, 1867 (= Graftonoceras Foerste, 1925). Discoceras graftonense (Meek and Worthen, 1870), so far known from the US, China, and Australia, is recorded from the Silurian of Bohemia and Gotland. Discoceras stridsbergi n. sp., D. lindstroemi n. sp., and D. sp. indet. from the Wenlock of Gotland and D. amissus (Barrande, 1865) from the Llandovery of Bohemia are all endemic species probably derived from D. graftonense. The distribution of D. graftonense and the origin of four species of Discoceras in the latest Sheinwoodian and early Homerian represent the last diversification and dispersion of the Tarphycerida. No tarphycerid species originated after the mid-Homerian extinction (Mulde and Lundgreni events). Silurian Discoceras retained the morphology and habitats of their Ordovician ancestors. The hatching time and autecology of juveniles has remained unclear. Evidence from the material studied suggests that juveniles were planktonic in habit, possessing a minute curved shell with few phragmocone chambers. Discoceras lindstroemi n. sp. is exceptional owing to its heteromorphic planispiral shell with coiling that changed during ontogeny, resulting in a changing aperture orientation and decreased maneuverability.

This technique is effective for completely breaking down moderately calcareous to noncalcareous mudstones and shales to produce a concentrated residue of microfossils and non-clay minerals. I have applied this treatment to Mississippian and Pennsylvanian age mudstones and have easily retrieved abundant conodonts, ostracodes, foraminifers, spores, wood fragments, fish teeth, vertebrate bone fragments, silt, mica, pyrite crystals and framboids, and phosphate nodules. All of the above items emerge from the treatment with fine structures such as spines and surface ornamentation undamaged and completely free of surficial clay. This technique is a modification of that of Lund (1970). The chemical used by Lund (Union Carbide Amine 220) is no longer manufactured and an effective alternative is reported here. Furthermore, the additional steps in processing reported here increase the efficacity of the technique for completely dissolving indurated mudstones.

The origin and affinity of the problematic Nuia Maslov is reappraised from exceptionally preserved specimens in Upper Cambrian (Sunwaptan) rocks of the Llano Uplift, central Texas. Nuia is suggested to be a radial calcitic ooid that has nucleated on fragments of reworked filamentous calcimicrobes rather than a separate microorganism as has been assumed previously. Nuia is found predominantly in intrareef grainstone accumulations, as well as in interreef grainstones, invariably accompanied by other bioclastic debris showing similar radial calcite ooid overgrowths.

The Hawkesbury Sandstone (Hawkesbury Series, Sydney Basin) on the southeastern coast of New South Wales, Australia, preserves a depauperate but important vertebrate tetrapod body-fossil record from the Early and Middle Triassic. As with many fossil sites around the world, the ichnological record has helped to shed light on the paleoecology of this interval. Herein, we investigate historical reports of a trackway pertaining to a putative short-tailed reptile found at Berowra Creek in the 1940s. Reinvestigation of the surviving track-bearing slabs augmented by archival photographs of the complete trackway, suggests that these impressions, which consist primarily of didactyl tracks (plus less common monodactyl and tridactyl traces), represent the earliest example of a swimming tetrapod found in Australia. Another isolated specimen (possibly from a nearby locality at Annangrove) appears to represent similar didactyl swim traces of a second, larger individual. Although the identities of the trackmakers are unknown, the Berowra Creek individual had an estimated body length of between ~80 cm (short-coupled) and 1.35 m (long-coupled), and produced the subaqueous trackway while travelling upslope (against the current) on a sandbar within a braided river system of the Hawkesbury Sandstone. These trackways partially resemble amphibian swim traces in the so-called Batrachichnus C Lunichnium continuum, but appear to represent a unique locomotion trace. This reanalysis of the Berowra Creek trackway provides insight into the locomotion of tetrapods of the Triassic Hawkesbury Series, which remains a poorly understood aspect of their life history.

Palmichnium gallowayi (Sharpe, 1932) new combination from the Middle Ordovician Martinsburg Formation (proximal deltaic facies) of Rondout, near Kingston, New York State, is redescribed. It consists of opposing series of five tracks, the outer two large and pear-shaped, the inner three smaller and elliptical, arranged in a chevron converging in the direction of travel, on either side of a wide medial impression. It is attributed to a medium-sized stylonurid eurypterid using a decapodous gait, crawling onto the shoreline, traversing the intertidal zone, a behavior interpreted as part of its reproductive life cycle. This provides the earliest ichnological evidence for the ‘mass-molt-mate’ hypothesis, which proposes that eurypterids migrated en masse into nearshore environments to molt and mate.

A diverse, well-preserved radiolarian assemblage is reported from the Sandbian age Climacograptus bicornis Graptolite Biozone. This new assemblage, recovered from the Pingliang Formation in the Guanzhuang section, China, includes six new species along with 13 other previously described taxa. Geminusphaera new genus incorporates G. grandis n. sp. and G. kongtongensis n. sp. and is proposed for inaniguttids constructed from two distinct porous spheres bearing seven or more primary spines. Protopylentonema new genus is introduced to incorporate pylomate entactinarians with five-rayed initial spicules. It includes P. ordosensis n. sp. as well as P. aperta, P. rimata, and P. insueta that were formerly assigned to Kalimnasphaera. Micro-computed tomography investigation of skeletal microstructure supports establishment of the new genera together with other new spumellarian species: Haplotaeniatum implexa n. sp., Inanigutta quadrispinosa n. sp., and Kalimnasphaera pingliangensis n. sp. It also indicates that family-level reassignment of Etymalbaillella from the Proventocitidae to the Ceratoikiscidae is appropriate.

Global distribution of Late Ordovician radiolarian occurrences highlights a strong preference for areas with equatorial to tropical sea surface temperatures. This must have led to ecological stress among radiolarian communities in adapting to global cooling in the Hirnantian.

UUID: http://zoobank.org/3d3f55b8-0e70-4f9f-9738-265750d8ec3a.

The small, immature brachyopid stereospondyl Platycepsion wilkinsoni from the Early or Middle Triassic of Gosford, New South Wales, is redescribed from a developmental point of view. Whereas the sutural contact between postorbital and parietal suggested by earlier authors cannot be confirmed, a new autapomorphy, the posterior process of the interclavicle with a slightly concave posterior margin, is recognized. A further apomorphic state may be the probable presence of five pairs of ossified ceratobranchials. Soft-tissue preservation of external gills demonstrates that Platycepsion wilkinsoni represents a true larva, forming the first evidence of a larval stage in stereospondyls. Morphology and developmental stage of Platycepsion wilkinsoni indicates that brachyopids conserved the plesiomorphic ontogenetic pattern seen in most Paleozoic temnospondyls, including the early ossification of the dermal skull roof and delayed ossification of the postcranium. The strongly developed ornament, the widened lateral lines, and the well-ossified exoccipitals and stapes suggest an even faster ossification and differentiation of the skull compared to Paleozoic temnospondyls and might represent a general stereospondyl characteristic. In the vertebral column, only the poorly differentiated, still separate neural arches are ossified, whereas the centra remained cartilaginous. This implies that the plesiomorphic pattern of vertebral development was conserved in Mesozoic stereospondyls, irrespective of whether the adult vertebral morphology was rhachitomous, stereospondylous, or diplospondylous. The low degree of ossification of the postcranium, its slow differentiation, and the delayed development of the scapulocoracoid indicate an aquatic mode of life, and the strongly ossified skull and hyobranchial apparatus suggest an emphasis on powerful suction feeding.

Non-archosaur archosauromorphs are a paraphyletic group of diapsid reptiles that were important members of global Middle and Late Triassic continental ecosystems. Included in this group are the azendohsaurids, a clade of allokotosaurians (kuehneosaurids and Azendohsauridae + Trilophosauridae) that retain the plesiomorphic archosauromorph postcranial body plan but evolved disparate cranial features that converge on later dinosaurian anatomy, including sauropodomorph-like marginal dentition and ceratopsian-like postorbital horns. Here we describe a new malerisaurine azendohsaurid from two monodominant bonebeds in the Blue Mesa Member, Chinle Formation (Late Triassic, ca. 218–220 Ma); the first occurs at Petrified Forest National Park and preserves a minimum of eight individuals of varying sizes, and the second occurs near St. Johns, Arizona. Puercosuchus traverorum n. gen. n. sp. is a carnivorous malerisaurine that is closely related to Malerisaurus robinsonae from the Maleri Formation of India and to Malerisaurus langstoni from the Dockum Group of western Texas. Dentigerous elements from Puercosuchus traverorum n. gen. n. sp. confirm that some Late Triassic tooth morphotypes thought to represent early dinosaurs cannot be differentiated from, and likely pertain to, Puercosuchus-like malerisaurine taxa. These bonebeds from northern Arizona support the hypothesis that non-archosauriform archosauromorphs were locally diverse near the middle Norian and experienced an extinction event prior to the end-Triassic mass extinction coincidental with the Adamanian-Revueltian boundary recognized at Petrified Forest National Park. The relatively late age of this early-diverging taxon (Norian) suggests that the diversity of azendohsaurids is underrepresented in Middle and Late Triassic fossil records around the world.

UUID: http://zoobank.org/e6eeefd2-a0ae-47fc-8604-9f45af8c1147.

The calcareous skeletons of 17 species of Triassic demosponges from the northeastern Dolomites have been analyzed for microstructure and diagenesis. The four microstructures recognized (irregular, spherulitic, penicillate aragonitic, and homogeneous granular Mg calcite) are described in terms of mineralogy; shape, dimension, and arrangement of microstructural elements; mode of growth; and possible biomineralization. The diagenesis in these sponge carbonate skeletons is of an aggrading type that occurred in diagenetic units, semi-closed systems, delineated by organic phragmas, which controlled the flux of diagenetic fluids. We tentatively interpret these phragmas as the remains of water-insoluble macromolecules for space delineation during the biomineralization process. In the aragonitic skeletons the preservation grade is correlated with Sr content, and the replacement of aragonite by calcite is marked by a Sr value around 4,000 p.p.m. Calcitized aragonite still retains a detectable amount of Sr. In Mg calcite skeletons the continuous and regular increase of grain size is inversely correlated with Mg content and directly with the distance from the organic phragmas.

Bulk maceration of unconsolidated Potomac Group sediments collected from 12 samples of middle–late Albian and early Cenomanian age on the Elk Neck Peninsula, Maryland, yielded 14 genera and 18 species of megaspores. The identified megaspores have affinities to both heterosporous ferns, e.g., Arcellites and Molaspora, and to heterosporous lycopsids, e.g., Erlansonisporites, Minerisporites, and Paxillitriletes. Morphological variation within species is high, and most morphotypes differ from established taxa in one or more characters. Two new species—Dijkstraisporites praetextus and Verrutriletes diversus—are proposed. The composition of these middle–late Albian and early Cenomanian floras is a mixture of taxa previously recorded from Aptian and Santonian floras in North America. In addition, a fragmentary strobilus of selaginellalean affinity containing a megaspore and microspores is described.