The Dunleith Formation echinoderms lived on a shallow water carbonate platform (Benthic Assemblages outer 2 and 3 during the latter part of the Dunleith Regressive Cycle). The echinoderms were buried rapidly by storms or a volcanic ash bed in one example. The presence of complete specimens, entire crowns, attachment structures, and excellent preservation strongly suggests that these assemblages reflect in situ communities on the seafloor that have not been significantly mixed, transported, or concentrated in time. Most taxa are suspension feeders, namely 21 crinoids, one glyptocystitid rhombiferan, a paracrinoid, and two edrioasteroids, but a deposit feeding pleurocystitid rhombiferan is also common. Three assemblages are recognized and defined by their dominant taxa; in order of increasing depth, these are the Cotylacrinna sandra, Pleurocystites strimplei, and Cupulocrinus crossmani assemblages. Substrates ranged from hard- or firm-ground carbonates to soft carbonate and siliciclastic muds. Diverse attachment structures are recognized: the recumbent stems of calceocrinids, lichenocrinids on shells, small distal stem tips, and round to lobate calcite pads cemented to shells or the substrate, open distal stem coils directly on the seabed or coiled around soft objects thereon, and large conical and highly modified cirrus holdfasts on hard- or firm-grounds. The echinoderms were located at levels ranging from the seafloor to almost a meter above, with maximum diversity at about 50 mm above the seafloor. The size frequency distributions of food particles and the ranges of ambient current velocities for successful feeding by the juveniles and adults of the common crinoids are modeled using filtration theory. The food particle size distributions and the current velocities for feeding are correlated with the arm or filtration fan morphology of the crinoids. Differences between these parameters tend to partially separate the feeding ecologies of species located at the same elevation. Nevertheless, considerable overlap remains between species for small sized food particles and the lower ranges of ambient current velocities for feeding. Except for the Cotylacrinna sandra Assemblage, competition for space does not seem to have been important in regulating the ecological structure of the Dunleith crinoids. However, the deposit feeding pleurocystitids possibly competed for food and space in one example. The Dunleith assemblages are much more diverse with greater ecological complexity than seen in the relatively deep water fauna from the Upper Ordovician Trenton Group of the Walcott-Rust Quarry in New York (Benthic Assemblage 5).

Two new species, Harpactocarcinus yozgatensis from the early Eocene (Ypresian) Yoncali Formation of Turkey and H. dalmatius from the middle Eocene (Bartonian) Foraminiferal limestones of Hvar Island, Croatia, are described. Harpactocarcinus yozgatensis suggests an early Eocene origin of the genus. Their discovery posits a more easterly point of origin for the genus than was previously known, a position which is supported by the foraminiferal assemblages of both localities. Evaluation of species referred to Harpactocarcinus has resulted in one new combination, Neozanthopsis achalzicus (Bittner in Abich, 1882).

Ostracod faunas from the Lower to Middle Ordovician rocks of the Argentine Precordillera Basin (Gualcamayo and Las Aguaditas Formations) are studied. A new family, Garcianidae, is erected. One new genus, Jeanvannieria, and six species are recognized, two of which are new (Jachalipisthia bicornata and Jeanvannieria bulbosa). The diversity and composition of the Precordilleran ostracods is evaluated on the basis of previous taxonomic analysis and the fauna studied here. The diversity is moderate, with a peak of 50 species during the early Caradoc. The composition of the fauna is characterized by the dominance of podocopes with a high percentage of binodicopes and a lack of palaeocopes, which is in agreement with a deep shelf environment. The carbonate slope setting of the Las Aguaditas Formation is the deepest environment yet found with Ordovician ostracods and records a relatively diverse fauna. The presence of Ectoprimitioides suggests biogeographic affinities between the Precordillera and Laurentia. The rest of the fauna contains a high percentage of endemic genera and a mixture of genera with several affinities, Baltic, peri-Gondwanan, and Australian.

Macropyge (Promacropyge) scandinavica new species is described from the Furongian Peltura minor Zone on northwestern Mount Kinnekulle, southcentral Sweden. It represents the first macropyginid trilobite recorded in Baltica. M. (P.) scandinavica closely resembles other species of the same subgenus from southeast China, suggesting a correlation between the Scandinavian P. minor Zone and the Lotagnostus americanus-Hedinaspis regalis Zone of China. The specimens are preserved in two limestone lithologies, interpreted as representing alternating normal and storm deposits, supporting the idea of an intrabasinal paleohigh in Västergötland, southcentral Sweden.

New specimens of Gabelia pedunculus Rigby and Murphy, 1983, and of the new species Gabelia giganta and Gabelia fascicula are described from the Siluro-Devonian(?) Roberts Mountains Formation from Loomis Creek Canyon in the Snake Mountains, northeastern Elko County, Nevada. Stalk fragments of G. pedunculus are similar to the holotype from the northern Roberts Mountains, Eureka County, Nevada. Gabelia giganta n. sp. is a large species with skeletal elements in the stalk twice the size of elements in G. pedunculus. Gabelia fascicula n. sp. is based on thick-walled, cup-like upper parts where a gastral layer of coarse, diagonally oriented spicules contrasts to a dermal layer of regular vertical and horizontal bundles of hexactine-based spicules of at least two orders around parietal gaps. The specimens are all part of a probably transported seafloor assemblage.

We document and quantify one of the oldest predator–prey interactions between naticid gastropods and molluscan prey, on the basis of drill holes in shells, from the Late Jurassic (Oxfordian) beds of Kutch, western India. Previously, many workers recorded naticid-like drill holes on prey taxa from the Triassic and the Jurassic, but in the absence of associated naticid body fossils, they remained equivocal.

The present gastropod community is dominated by turritellines (98% of the sample) that form the turritelline-dominated assemblage, and the naticid drilling predation is restricted almost entirely to turritellines among gastropods. Confamilial naticid predation takes place occasionally. Within the bivalve community, corbulids and nuculids are most abundant and are drilled more often than other taxa. These observations indicate that prey selection was opportunistic and based solely on availability. Drilling intensities at both assemblage and lower taxon levels are low. Behavioral stereotypy of naticid predation in some cases is moderately high.

Turritellines are often the preferred prey of naticid gastropods since the late Early Cretaceous. These two groups form a recurrent association reflecting prey–predator interaction. Here we suggest that both turritellines and naticids evolved during the Jurassic, and the prey–predator interaction between them was established shortly thereafter. Among bivalves, corbulids also became important prey of naticids in the same spatiotemporal framework. Corbulids are older than naticids and first appeared during the Middle Jurassic. After their first encounter with naticids, corbulids evolved conchiolin layers within the valves to resist predation.

Representatives of 12 conodont species, including Oulodus equirectus n. sp., have been recovered from the Silurian Lilley Formation, Lilley–Peebles transition unit, and Peebles Dolomite at six localities in southern Ohio. The Lilley, Lilley–Peebles transition unit, and Peebles belong in the Kockelella ranuliformis–K. amsdeni to Ozarkodina? crassa Chronozone and are late early to middle Wenlockian in age.

The Lilley is conformable and transitional with the underlying Bisher Formation and overlying Peebles. The unconformity between the upper Niagaran Peebles and overlying lower Salinan Greenfield Dolomite represents middle Wenlockian to late Ludlovian or early Pridolian time.

The Lilley, Lilley–Peebles transition unit, and Peebles were deposited in a gradually shoaling sea that was controlled by eustatic sea-level fall during the late early to middle Wenlockian. Uplift along the Cincinnati Arch, probably due to northward tilting of the arch, began during/after deposition of the Peebles in the middle Wenlockian. The combined effects of uplift and eustatic sea-level fall caused the sea to withdraw from southern Ohio. The Peebles was exposed and eroded prior to return of the sea to begin Greenfield deposition in the late Ludlovian or Pridolian (Ozarkodina remscheidensis Chronozone).

Elasmostoma bajaensis n. sp., a pharetronid calcareous sponge, is described from the lower Eocene (P8 or P9 Zone) portion of the Bateque Formation, Baja California Sur, Mexico. This is the first Tertiary record of this genus and its first Western Hemisphere occurrence. Elasmostoma has been previously reported only from Jurassic and Cretaceous strata of Western Europe.

Vidal and Ford (1985) described a rich, well-preserved acritarch biota from the late Proterozoic Chuar Group in northern Arizona. The biota includes Chuaria circularis (Walcott) Vidal and Ford, whose diagnosis was emended. A SEM micrograph of a specimen supposedly deriving from the Kwagunt Formation of the Chuar Group was included (Vidal and Ford, 1985, p. 357). However, the figured specimen derives from the Late Proterozoic Eleonore Bay Group in east Greenland (Vidal, 1979, Pl. 4, a, b) and was erroneously included as a consequence of an inadvertent replacement of films during the preparation of paper prints for publication. The author of this note alone bears responsibility for this regrettable mistake.

Silicified encrinurine trilobites from Telychian strata of the Whittaker Formation east of Avalanche Lake, District of Mackenzie, Canada, include Briania jeffersoni n. gen. and sp. and Johntempleia pamae n. gen. and sp. Morphology of Briania suggests an origin near the divergence of Pacificurus from the variolaris plexus. Johntempleia also includes Rhuddanian–Aeronian diversity from Scotland, and is resolved as the basal branch of the punctatus plexus. Briania jeffersoni and Johntempleia pamae co-occur with rare taxa of the variolaris plexus (“Nucleurus” spp. A and B) in a deep-water assemblage dominated by Cromus and the odontopleurid Stelckaspis. Stratigraphic range data for encrinurine genera identify the late Telychian to early Sheinwoodian as a time of taxonomic turnover.

We present here the first report based on phylogenetic analyses of small subunit (SSU/18S) and large subunit (LSU/28S) ribosomal DNA (rDNA) sequences from a wider-than-token sample of rhynchonellide articulate brachiopods, with data from 11 of ∼20 extant genera (12 species) belonging to all four extant superfamilies. Data exploration by network and saturation analyses shows that the molecular sequence data are free from major aberrations and are suitable for phylogenetic reconstruction despite the presence of large deletions in four SSU rDNA sequences. Although molecular sequence analyses cannot directly illuminate the systematics of fossils, the independent, genealogical evidence and phylogenetic inferences about extant forms that they make possible are highly relevant to paleontological systematics because they highlight the limitations of evolutionary inference from morphology. Parsimony, distance, maximum likelihood (no clock) and Bayesian (relaxed-clock) analyses all find a tree topology that disagrees strongly with the existing superfamily classification. All tested phylogenetic reconstructions agree that the taxa analyzed fall into three clades designated A1, A2, and B that reflect two major divergence events. The relaxed-clock analysis indicates that clades A and B diverged in the Paleozoic, while clades A1 and A2 reflect Permo-Triassic (and later) events. Morphological homoplasy and possible gene co-option are suggested as the main sources for the discord between the morpho-classification, the results of cladistic analyses of morphology, and the relationships reconstructed from molecular sequences. The origin, function and evolutionary implications of the deletion-bearing rhynchonellide SSU rDNA sequences are briefly discussed in relation to pseudogenes and concerted evolution in the rDNA genomic region.

Flume studies conducted on models and specimens of the helically twisted columns from Mississippian platycrinitid crinoids revealed two unique hydrodynamic interactions. Water is deflected up the column from levels near the sediment-water interface where food particles are more abundant. Turbulence, both in the lee and on the upstream side of the column, removes nutrient-poor water and replaces it with nutrient-rich water from near the sediment-water interface. Subsequently, the nutrient-rich water would have been filtered through the feeding apparatus of the crinoid. An upward deflection of as little as 10 percent bottom water would have resulted in a substantial increase in food particle load. Thus, the form of platycrinitid columns gave the crinoid a feeding advantage over otherwise similar crinoids of the same time period. The most diverse and abundant group of Mesozoic–Cenozoic stalked crinoids shows similar column modifications which suggests that the morphology may impart some competitive advantage to the organism.

The brachiopod genus Dicoelosia is generally considered a typical deep-water taxon. New data suggest that some species of the genus may have invaded relatively shallow-water habitats during its geological history. However, there is scant evidence for its invasion of shallow-water environments after the terminal Ordovician mass extinction. Dicoelosia occurs in the shallower-water benthic shelly assemblages of the lower Niuchang Formation (upper Rhuddanian, Llandovery) of Meitan County, northern Guizhou Province, South China. Evidence of a move to shallow water includes its morphology and population structure, regional paleogeography, sedimentology, together with the abundance and diversity of its shallow-water associates. Following the biotic crisis, deep-water environments were barely habitable, and may have driven Dicoelosia into shallower-water niches. The taxon endured the less suitable shallow-water environments until the deep-water benthic zones ameliorated after the recovery, implying a shallow-water refugium existed after the biotic crisis. A new species Dicoelosia cathaysiensis is erected herein. There is only one record of this genus in South China and this unique occurrence may reflect the distinctive paleobiogeography and environments of this region.

Trilobites assigned to 29 genera and 39 species are reported from the Deadwood Formation in the Black Hills of South Dakota. Two new species, Prosaukia lochmani and Arcifimbria pahasapaensis, are described. Brachiopods are reported from the Taenicephalus Zone.

A biostratigraphic zonation is established for the upper part of the Deadwood Formation. The Taenicephalus Zone in the lower part of the study interval is succeeded upsection by the Ellipsocephaloides Zone, both of which are assigned to the Franconian Stage. These two zones are overlain in turn by the Illaenurus and Saukia Zones of the Trempealeauan Stage. These zones are used to correlate this part of the Deadwood with coeval strata in Montana and Wyoming, central Texas, Oklahoma, and Alberta, Canada. The lowstand of sea level that occurred in the Great Basin at the time of the deposition of the Saukiella junia Subzone of the Saukia Zone probably extended eastward into the Black Hills, resulting in the absence of this fauna in the Black Hills.

Cretaceous aquatic ecosystems were amazingly diverse, containing most clades of extant aquatic vertebrates as well as an array of sharks and rays not present today. Here we report on the chondrichthyan fauna from the late Maastrichtian site that yielded the Tyrannosaurus rex skeleton FMNH PF 2081 (“SUE”). Significant among the recovered fauna is an unidentified species of carcharhinid shark that adds to the fossil record of this family in the Cretaceous, aligning with estimates from molecular evidence of clade originations. Additionally, a new orectolobiform shark, here named Galagadon nordquistae n. gen. n. sp., is diagnosed on the basis on several autapomorphies from over two-dozen teeth. Common chondrichthyan species found at the “SUE” locality include Lonchidion selachos and Myledaphus pustulosus. Two phylogenetic analyses (Maximum Parsimony and Bayesian Inference) based on twelve original dental character traits combined with 136 morphological traits from a prior study of 28 fossil and extant taxa, posited Galagadon n. gen. in two distinct positions: as part of a clade inclusive of the fossil species Cretorectolobus olsoni and Cederstroemia triangulata plus extant orectolobids from the Maximum Parsimony analysis; and as the sister taxon to all extant hemiscyllids from the Bayesian Inference. Model-based biogeographical reconstructions based on both optimal trees suggest rapid island hopping-style dispersal from the Western Pacific to the Western Interior Seaway of North America where Galagadon n. gen. lived. Alternatively, the next preferred model posits a broader, near-global distribution of Orectolobiformes with Galagadon n. gen. dispersing into its geographic position from this large ancestral range.

UUID: http://zoobank.org/61e32ffc-4f87-4ff7-820d-0bb33a80f0a0

Devonian bactritids are described for the first time from South America. They come from siliciclastic rocks of the Talacasto Formation in the Precordillera Basin, west-central Argentina. The host strata span the Lochkovian–Emsian and contain other non-ammonoid cephalopods as well, thus refuting the alleged virtual absence of cephalopods in circumpolar Devonian basins from southwestern Gondwana (the Malvinokaffric Realm). We report Bactrites gracilis and Devonobactrites? sp., whose wide distribution contrasts with the endemic paleobiogeographic signature of some other taxonomic groups in these basins. Furthermore, new Lochkovian and Pragian records of Bactrites sp. provide new insights into the earliest bactritid records worldwide.

Mandalacystis dockeryi n. gen. and sp. is known from seven complete or nearly complete thecae, six partial thecae, and numerous separate plates from the Oil Creek Formation in south-central Oklahoma, and a single thecal plate from the Antelope Valley Limestone in Nevada. Details of skeletal microstructure (stereom) are well preserved, permitting scanning electron microscopy for the first time in the Eocrinoidea, and demonstrating that plate thickness on thecal faces is only 60–70 μm. Mandalacystis is characterized by labyrinthine ridges on both faces of the theca, relatively short brachioles, and a normal stem with holdfast (at least in juvenile stages). Based on the normal biserial arrangement of brachiolar plates in the brachioles and the possession of a normal stem, Mandalacystis appears to be one of the most primitive rhipidocystids, closely related to Petalocystites.

Mandalacystis dockeryi lived in a storm-dominated, shallow-water offshore habitat on patches of skeletal debris surrounded by soft, terrigenous mud. This setting may have been conducive to the transition from an erect, attached mode of life to the prone, unattached lifestyle of later rhipidocystids.

Fossils of the giant short-faced bear, Arctodus simus (Cope, 1879), have been recovered from over 100 localities in North America, extending from Mexico to Alaska and California to Virginia. Despite this large range, the species has never been recorded from the southeastern United States. The lesser short-faced bear, Arctodus pristinus Leidy, 1854 is well represented from this region, particularly Florida, but all known occurrences are late Pliocene – middle Pleistocene in age (about 2.5 to 0.3 Ma). Differentiating A. simus from A. pristinus can be difficult because large individuals of A. pristinus overlap in size with small individuals of A. simus, and there are few morphological differences. However, these two taxa can be clearly separated based on the relative proportions of their molars and premolars. Two Pleistocene records of A. simus representing a minimum of three individuals from the Withlacoochee River drainage of central Florida are reported here, substantially extending the distribution of this massive bear into southeastern North America. A late Pleistocene age for these occurrences is corroborated by an associated Rancholabrean fauna and rare earth elemental analyses. One of the reported individuals is quite large, supporting the hypothesis of extreme sexual dimorphism in A. simus and rejecting a hypothesis of two subspecies.

New finds of Hyolitha in the Devonian of Bolivia consist of the hyolithid Bolithes crasquinae new genus and species, which is the first well-preserved hyolithid from strata of this age in the region. In addition, specimens of the orthothecids Bolitheca steinmanni (Knod, 1908) and Neobactrotheca pharetra Marek and Isaacson, 1992 serve to increase knowledge concerning the range of morphologic variability within those taxa. Incompletely preserved hyoliths include Hyolithes sp. indet.? which would be the first definitive representative of that genus from South America. Two polyclaviculate hyolithid opercula, and an unusually large hyolithid conch are left in open nomenclature. The large conch is noteworthy because of signs of failed predation, making this only the second hyolithid on record on which the effects of predation can be recognized, and the first from the Devonian of South America. Hyolithes dorbignyi Kozlowski, 1923 is transferred to ‘Hyolithes’ owing to poor preservation.