The bryozoan genus Aspidostoma Hincks, 1881 has been regarded as the only representative of the Aspidostomatidae Jullien, 1888 in Argentina to date. Its type species, Aspidostoma giganteum (Busk, 1854), is presently distributed in the Magellanic Region (Argentina and Chile) and has been recorded in Oligocene and Miocene fossil deposits of Santa Cruz and Chubut, respectively. New material from San Julián (late Oligocene), Monte León (early Miocene), Chenque (early to middle Miocene), and Puerto Madryn (late Miocene) formations suggests, however, that A. giganteum is not represented in the fossil record. Material from Puerto Madryn Formation previously regarded as A. giganteum is here recognized as Aspidostoma roveretoi new species. Aspidostoma ortmanni Canu, 1904 is revalidated for the species from the San Julián Formation. Aspidostoma armatum new species and Aspidostoma tehuelche new species are introduced for material from the Monte León and Chenque formations, respectively. Aspidostoma incrustans Canu, 1908, from the early Miocene, is redescribed. Melychocella Gordon and Taylor, 1999, which differs from Aspidostoma in having vicarious avicularia and lacking a median ridge and a quadrangular process proximal to the opesia-orifice, is so far represented by three Paleogene species from the Chatham Islands (Southwest Pacific). The material from Monte León allowed us to transfer Aspidostoma flammulum Canu, 1908 to Melychocella, resulting in the new combination Melychocella flammula (Canu, 1908). Melychocella biperforata new species is described from the lower Miocene Monte León and Chenque formations. The presence of Melychocella in the Neogene of Patagonia extends its geographic distribution and its temporal range.

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Three types of geographic isolation—land barriers, deep water barriers, and climatic barriers—resulted in three distinct evolutionary responses in Neogene and Quaternary species of the epineritic ostracode genus Puriana. Through systematic, paleobiogeographic, and morphologic study of several hundred fossil and Recent populations from the eastern Pacific, western Atlantic, Gulf of Mexico, and the Caribbean, the phylogeny of the genus and the geography of speciation events were determined. Isolation of large populations by the Isthmus of Panama during the Pliocene did not lead to lineage splitting in species known to have existed before the Isthmus formed. Conversely, the establishment of small isolated populations on Caribbean islands by passive dispersal mechanisms frequently led to the evolution of new species or subspecies. Climatic changes along the southeastern United States during the Pliocene also catalyzed possible parapatric speciation as populations that immigrated to the northeastern periphery of the genus' range split to form new species. The results provide evidence that evolutionary models describing the influence of abiotic events on patterns of evolution and speciation can be tested using properly selected tectonic and climatic events and fossil groups amenable to species-level analysis. Two new species, P. bajaensis and P. paikensis, are described.

The majority of Changhsingian orthotetid brachiopod species from the Southern Alps were described by the end of the nineteenth century, but were then neglected by subsequent authors who proposed further new species, giving rise to great taxonomical confusion. An examination of type-specimens and newly collected material permits the consideration of Orthothetina ladina (Stache, 1878) and Ombonia tirolensis (Stache, 1878), type-species of Ombonia, as the only valid species and describe Teserina nerii as a new genus and species. The former two species are mostly located within a short stratigraphic interval, which is a few centimetres thick, limited by the trigger and peak of the end-Permian mass extinction. Teserina nerii n. gen. n. sp. occurs 2–3 m above the extinction peak and represents one of the last Permian rhynchonelliform brachiopod holdovers in the Southern Alps.

Spinicaudatans (‘clam shrimps’) are small branchiopod crustaceans enclosed in a chitinous bivalved carapace that is often the only preserved element in the fossil record. However, few studies have analyzed the preservation of these carapaces, which have been found in continental facies from the Devonian to the present. The aim of this study was to contribute to a better understanding of the chemical preservation of fossil spinicaudatan carapaces, and it focused on spinicaudatan carapaces of the Cañadón Asfalto Formation from the Jurassic of Argentina. Semiquantitative energy-dispersive X-ray spectrometry (EDS) analysis provided elemental composition data that were interpreted using principal component analysis (PCA). The results showed a complex chemical mode of preservation for spinicaudatan carapaces. In some parts, EDS spectra of the specimens exhibit peaks of calcium, phosphorous, aluminum, and fluorine, representing the retention of original carapace material with some diagenetic recrystallization. Certain zones of the carapace show low-intensity peaks of the elements mentioned, while silicon and oxygen peaks (from the rock matrix) become the dominant spectral signals. These modes of preservation modify the interpretations and observations of the ornamentation of the carapace, which are used as taxonomic features. Our results suggest that specific diagenetic processes play a fundamental role in the preservation of spinicaudatans.

Open-coiled euomphalacean gastropods have been identified for the first time in the Upper Cambrian Eminence Dolomite of Missouri. These gastropods have a triangular whorl profile and are conspecific with Hyolithes walcotti described from the Upper Cambrian of Nevada. That species is questionably reassigned to the gastropod genus Macluritella, hitherto known only from the Lower Ordovician of Colorado.

Two chondrichthyan assemblages of Late Mississippian/Early Pennsylvanian age are now recognized from the western Grand Canyon of northern Arizona. The latest Serpukhovian Surprise Canyon Formation has yielded thirty-one taxa from teeth and dermal elements, which include members of the Phoebodontiformes, Symmoriiformes, Bransonelliformes, Ctenacanthiformes, Protacrodontoidea, Hybodontiformes, Neoselachii (Anachronistidae), Paraselachii (Gregoriidae, Deeberiidae, Orodontiformes, and Eugeneodontiformes), Petalodontiformes, and Holocephali. The euselachian grade taxa are remarkably diverse with four new taxa recognized here; the Protacrodontidae: Microklomax carrieae new genus new species and Novaculodus billingsleyi new genus new species, and the Anchronistidae: Cooleyella platera new species and Amaradontus santucii new genus new species The Surprise Canyon assemblage also has the youngest occurrence of the elasmobranch Clairina, previously only known from the Upper Devonian. The Surprise Canyon Formation represents a nearshore fluvial infilling of karstic channels, followed by a shallow marine bioherm reef, and finally deeper open water deposition. The early Bashkirian Watahomigi Formation represents open marine deposition and contains only two taxa: a new xenacanthiform, Hokomata parva new genus new species, and the holocephalan Deltodus. The relationship between the Surprise Canyon and Watahomigi chondrichthyan assemblages and other significant coeval chondrichthyan assemblages suggests that there may have been eastern and western distinctions among the Euamerican assemblages during the Serpukhovian due to geographic separation by the formation of Pangea.

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A new ichnogenus and ichnospecies, Spirolites radwanskii, is a spiral boring recognized in large limestone clasts deposited in a Miocene cliff-foot ramp. It is characterized by a semi-circular or inverted Ω-shaped cross section, gradually increasing width, gradual entrenching in the rock from the narrower side, consistent coiling direction, steep margin from the wider side, two-order annuli, and occasional truncation of the narrower side by the wider part. It is interpreted as a boring of vermetid gastropods, similar to the recent Dendropoma. Spirolites co-occurs with the bivalve borings Gastrochaenolites, mostly G. torpedo, sponge borings Entobia, and the spionid polychaete boring Caulostrepsis, which are typical of the Entobia ichnofacies. Spirolites was produced in very shallow, clean and warm sea waters.

Most Cambrian Series 2 faunas of Laurentia are dominated by olenelline trilobites; however, non-olenelline trilobites occur with the olenellines and sometimes dominate the assemblages. Reported here are such non-olenelline trilobites from the Harkless Formation and Mule Spring Limestone at Clayton Ridge, Nevada. At the bottom of the Saline Valley Tongue, Harkless Formation, are two assemblages that are characterized by corynexochines and/or ptychoparioids, with olenellines occurring as only rare components. The corynexochines present in these assemblages include Bonnia cf. B. brennus (Walcott, 1916), Ovatoryctocara cf. O. yaxiensis Yuan et al., 2009, Protoryctocephalus? aff. P.? arcticus Geyer and Peel, 2011, Ogygopsis sp. indet., and Oryctocephalops frischenfeldi Lermontova, 1940. These assemblages are from the mid-Dyeran Stage, below the lowermost zone in the upper Dyeran (Arcuolenellus arcuatus Biozone), and can be correlated to Series 2 Stage 4 (Cambrian) assemblages in Greenland, Siberia, and South China based on the corynexochines.

Also in the Saline Valley Tongue and the overlying Mule Spring Limestone and lowermost Emigrant Formation are olenelloid-dominated assemblages that contain the corynexochines Bonnia columbensis Resser, 1936, Zacanthopsis aff. Z. levis (Walcott, 1886), and Z. sp. indet.

The extraxial axial theory is used to investigate homology of ambulacral and oral plating because it predicts terminal branching and terminal addition of plates in the axial skeleton, although exceptions to the former may occur in some Paleozoic echinoderms. The variety of morphological designs and anomalous individuals also provide tests of plate homology. Homology of ambulacra is generally accepted, with the hydropore and/or single gonopore in Carpenter’s CD interray. In the 2-1-2 ambulacral pattern the unbranched ambulacrum is always in Carpenter’s A ray. All ambulacral morphology requires just three instructions: ‘grow,’ ‘branch,’ and ‘stop.’ The range of variation in echinoderms with fewer than five ambulacra implies that both the ‘branch’ and ‘stop’ instructions acted independently in all five rays. Numbers of ambulacra may or may not correlate with numbers of orals. Two basic patterns of ‘cystoid’ oral plating occur; with a single radial (circum-oral, CO) plate from each ambulacrum plus a sixth in the CD interray, and with all six interradial peri-oral (PO) plates, with two in the CD interambulacrum. Five ‘orals’ may involve loss of PO3 or PO6. Erect ambulacral structures are lost first in taphonomy and so poorly known. All ambulacral skeletal elements bear the same topological relationship to ambulacral soft tissues. Where branched ambulacra occur, the trunk or flooring plates are often modified first brachiolars or pinnulars. Both brachioles and pinnules may arise from facets developed on one or two flooring plates. Terminal addition of plates, spacing of brachioles/pinnules, and lack of musculature to open cover plates all suggest that ‘cystoids’ had extensions of the water vascular system in their ambulacra.

The Silurian (Wenlockian) Racine Formation of Milwaukee, Wisconsin has yielded 22 types of siliceous and silicified sponge spicules. The spicules occur in bioturbated dolomite mudstone, and they are part of a high-diversity community of small crinozoans, brachiopods, and other taxa. Siliceous desmas of the order Lithistida comprise 79 percent of recovered spicules. Siliceous triaxons of the class Hexactinellida and silicified sexiradiates of the class Heteractinida each comprise 7 percent of spicules. Eleven additional types of siliceous spicules of uncertain taxonomic affinity form 7 percent of the assemblage. No complete sponge skeletons have been observed, probably because of slow deposition and high bioturbation. The Racine spicule assemblage resembles sponge faunas of Silurian offshore deposits in the Canadian Arctic and Great Basin, which suggests moderate bathymetric relief in the Michigan Basin during Wenlockian times.

Burgess Shale-type faunas provide unique insights into the Cambrian “explosion”. Their degree of representativeness of Cambrian marine life in general is, however, less easy to establish. One line of evidence is to consider only the skeletal component of a Burgess Shale-type fauna and compare that with a typical Cambrian assemblage. This paper describes a new species of helcionelloid mollusk (Totoralia reticulata n. sp.) from the middle Cambrian Burgess Shale of British Columbia. Whilst much rarer than the co-occurring smooth shelled helcionelloid Scenella amii, the strongly costate morphology of Totoralia reinforces comparisons with Cambrian shelly faunas. The extension of the range of Totoralia from Argentina to Canada adds support to the proposed derivation of the Precordillera terrane of Mendoza from Laurentia.

The lingulid brachiopod species Bicarinatina kongakutensis n. sp. is recorded here from the Middle Devonian (Eifelian) Ulungarat unit in Arctic Alaska. A restudy of the type species, Bicarinatina bicarinata (Kutorga) from the Middle Devonian (Eifelian) of Eastern Europe, suggests close affinities to the Ordovician genus Pseudolingula and gives good reason to assign Bicarinatina to the family Pseudolingulidae. There are no important points of difference in the morphologies of Bicarinatina and the Early Carboniferous lingulid genus Liralingua and, thus, both genera have been synonymized.

New material from the Late Mississippian Fayetteville and Caney Formations of the south-central USA supports the taxonomic revision of the Mississippian actinoceroid cephalopods. New representatives of the previously poorly known Rayonnoceras solidiforme, Campyloceras striatulum, and Campyloceras imoense are described. Carbactinoceras procerum new species and Elmoceras graffhami new genus and species are described, and the genus Campyloceras is emended. Character evaluation suggests the shape of the endosiphuncular deposits in the Actinoceratida and Pseudactinocerida are homoplastic because similar patterns of endosiphuncular deposits occur in distantly related nautiloid clades. Apex shape, however, is shown to have previously unrecognized potential for taxon discrimination. Cladistic analysis of 13 actinoceroid and pseudorthocerid nautiloids supports the splitting of the Orthocerida and the creation of a sister group to the Actinoceratida which is identical with the largely neglected Pseudorthocerida.

The first Cambrian rhynchonelliformean brachiopods are described from the Precordillera mountain belt of west-central Argentina, including the new species Wimanella mollensis and Nisusia ancauchensis. Other forms are Diraphora cf. D. borealis (Walcott), Diraphora sp., and an indeterminate bohemiellid. Brachiopods come from the lowermost part of the Precordilleran Cambrian succession (El Estero and Soldano Members of the La Laja Formation, Cerro Totora Formation) and from the Ancaucha olistolith within the Los Sombreros olistostrome. The associated trilobites constrain the fossiliferous levels to the Bonnia-Olenellus, Poliella denticulata and Ehmaniella biozones. A re-assessment of paleobiogeographic affinities of lower and early middle Cambrian rhynchonelliform brachiopods using cluster analysis supports the existence of a widespread warm-water Tropical Realm—to which the described Precordilleran faunas belong—and a more restricted ‘Mediterranean’ Realm developed on the temperate, mixed clastic-carbonate platforms.

In a previous publication in this journal, Finks (1955) reported the discovery of two sponge specimens containing external molds of the conulariid Paraconularia leonardensis (Finks). The sponges were collected from the Permian Leonard and Cherry Canyon Formations, west Texas (Finks, 1955,1960). As argued by Finks (1955), the conulariids contained in the sponges probably were sessile, and two conulariids in one of the sponges may have been directly attached to the sponge in life. These interpretations are corroborated by evidence documented by several other authors, most notably Sinclair (1948) and Babcock et al. (1987).

The Wenonah Formation of New Jersey yields an ammonite fauna comprising Menuites portlocki (Sharpe, 1855), Placenticeras placenta (DeKay, 1828), P. minor n. sp., Nostoceras (Nostoceras) puzosiforme n. sp., Nostoceras (Nostoceras) aff. N. colubriformis Stephenson, 1941, Didymoceras n. sp., Didymoceras spp., Parasolenoceras sp., Baculites cf. B. scotti Cobban, 1958, Baculites sp., and Trachyscaphites pulcherrimus (Roemer, 1841). Although commonly regarded as lower Maastrichtian by micropaleontologists, the presence of M. portlocki and T. pulcherrimus is an indicator of upper, but not uppermost, Campanian in a northwest European sense, and the presence of Baculites cf. B. scotti suggests uppermost middle Campanian in terms of the Western Interior provincial substages.

Demonstrating stasis in the fossil record has proven to be problematic with respect to both data collection and analysis. A previous approach is morphometric analysis of lineages sampled temporally and geographically. A hypothesis of stasis is apparently supported if morphological distances between descendent species and ancestral species are no greater than those between geographically distant samples of the descendent species. Evidence presented in this paper conflicts with such interpretations for at least one bivalve lineage, Chione erosa–Chione cancellata, of the late Neogene of tropical America. The direction and magnitude of morphological variance were quantified between two geographically distant groups of C. cancellata from the Recent, and compared to Pleistocene samples of C. cancellata and Pliocene samples of C. erosa. The results indicate that, although the magnitude of intraspecific geographic variation is as great as interspecific temporal variation, the species are morphologically discrete groups. The direction of morphological variance is as important as its magnitude, and interpretations overlooking this point are at best equivocal.

The distributional patterns of reticulate sculptures, corresponding to those of the underlying epidermal cells, of two Baffinicythere species (Ostracoda, Crustacea) are discussed from a geometrical point of view to understand whether they are under some rule or not. Reticulation geometry has been quantified by applying the method of Dirichlet domains defined as convex polygons, each being demarcated by bisectors normal to the lines connecting neighboring pairs of points. Studies of the distributional patterns of reticulation during growth reveal that these polygons become closer to Dirichlet domains and are dominated by hexagonal or subcircular fossa outlines toward the adult stage, and ultimately reach an equilibrium and stable pattern at maturity.

A disk-shaped massive colony of Tetradium, from the Middle Ordovician Bobcaygeon Formation in southern Ontario, displays features of a coral microatoll. This is the first pre-Holocene coral microatoll yet described, indicating that some tabulate corals in level-bottom communities were growing as microatolls as do many modern colonial skeleton-secreting organisms.

The microatoll therefore is not strictly a Quaternary or even Cenozoic phenomenon, but has a fossil record that may span most of the Phanerozoic. This indicates that the special conditions necessary for microatoll growth have existed outside of reef environments, and were present before the advent of scleractinian coral reefs. It may be possible to use ancient microatolls to estimate absolute water depths at low tide, thereby providing a means for estimating maximum water depths on a local and regional scale.

Speocarcinus berglundi n. sp. is described from the Imperial Formation in Riverside County, California. Although the Imperial Formation spans late Miocene through late Pliocene time, the part of the unit that bears crabs has been radiometrically dated as late Miocene. The identification of a new species was based upon comparison with four extant species and represents the first documented fossil occurrence for the genus. The occurrence of this new species suggests that the genus may have originated in the Pacific and, during the Miocene, dispersed through the Isthmus of Panama to the Caribbean. Two of the specimens exhibit parasitism by Bopyridae (Isopoda).