Larvae of sea urchins, brittle stars, and allies are common, ecologically important, and diverse members of marine ecosystems in all of the world's oceans today. In contrast to modern representatives, the fossil record of echinoderm larvae is poorly known. This study reports the first ophiopluteus skeleton from Cretaceous sediments worldwide, obtained from chalky sediment of the Isle of Wolin, NW Poland. The evidence presented here, that it is possible to isolate fossil echinoderm larval skeletons from rocks, indicates a hidden diversity of such fragile fossils and thus the possibility of direct geological recording.

The end-Ordovician mass extinction, linked to a major glaciation, led to deep changes in Hirnantian–Rhuddanian biotas. The Hirnantia Fauna, the first of two Hirnantian survival brachiopod-dominated communities, characterizes the lower–mid Hirnantian deposits globally, and its distribution is essential to understand how the extinction took place. In this paper, we describe, illustrate, and discuss the first macrofossiliferous Hirnantia Fauna assemblage from Belgium, occurring in the Tihange Member of the Fosses Formation at Tihange (Huy), within the Central Condroz Inlier. Six fossiliferous beds have yielded a low-diversity, brachiopod-dominated association. In addition to the brachiopods (Eostropheodonta hirnantensis, Plectothyrella crassicosta, Hirnantia sp., and Trucizetina? sp.), one trilobite (Mucronaspis sp.), four pelmatozoans (Xenocrinus sp., Cyclocharax [col.] paucicrenulatus, Conspectocrinus [col.] celticus, and Pentagonocyclicus [col.] sp.), three graptolites (Cystograptus ancestralis, Normalograptus normalis, and ?Metabolograptus sp.), together with indeterminate machaeridians and bryozoans were identified. The graptolite assemblage, from the Akidograptus ascensus-Parakidograptus acuminatus Biozone, indicates an early Rhuddanian (Silurian) age, and thus, an unexpectedly late occurrence of a typical Hirnantia Fauna. This Belgian association may represent an additional example of relict Hirnantia Fauna in the Silurian, sharing characteristics with the only other known from Rhuddanian rocks at Yewdale Beck (Lake District, England), although reworking has not been completely ruled out. The survival of these Hirnantian taxa into the Silurian might be linked to delayed post-glacial effects of rising temperature and sea-level, which may have favored the establishment of refugia in these two particular regions that were paleogeographically close during the Late Ordovician–early Silurian.

The genus and species Johnognathus huddlei Mashkova, 1977, is synonymized with Distomodus staurognathoides (Walliser, 1964) on the basis of common occurrence, similar morphology, and the discovery of a complete S element of D. staurognathoides with a posterior process developed into a platform that is identical in morphology to specimens referred to J. huddlei.

Among hyoliths from the Givetian Kersadiou Formation in northwestern France one form is assigned to Hyolithes triliratus Hall, 1879, which is used as the basis for Brittanella new genus. The occurrence of this species in France supports affinity for fauna in that region to the Eastern Americas Realm. Other hyoliths from this unit include one species of Hyolithes Eichwald, which is left in open nomenclature, and one conch and one platyclaviculate operculum that cannot be identified to genus. The occurrence of these fossils in concretions in an oxygen-stressed dark gray shale supports the notion that this environment served as a refuge for taxa that were less efficient competitors with other normal marine benthos in the Devonian.

Spirodentalium Walcott, 1890, was originally described as a scaphopod. A reinterpretation of the type lot suggests that its overall shape is that of an open-coiled gastropod. If so, this is probably the earliest known open-coiled form and it is sinistral in coiling direction.

A new species of Brissus is described from the lower Oligocene (Rupelian–Vicksburgian) Bridgeboro limestone of southwestern Georgia. Brissus bridgeboroensis n. sp. most closely resembles the Recent Brissus unicolor (Leske) of the West Indies and the Gulf of Mexico, but it differs primarily in features of the posterior paired petals. Brissus bridgeboroensis is the oldest known member of the genus from continental North America.

Five new species of Early Permian (late Sakmarian to Kungurian) colonial corals from eastern Nevada and southeastern California, one assigned to a new genus, are described and illustrated. These include Heintzella playfordi n. sp. from the Arcturus Formation in Nevada and the Darwin Canyon Formation in California, Paraheritschioides fergusonensis n. sp. from the Ferguson Mountain and Bird Spring formations in Nevada, and Wendoverella arca n. gen. and n. sp., Permastraea nevadensis n. sp., and Pararachnastraea moormanensis n. sp. from the Pequop Formation in eastern Nevada. These new taxa are distinct from all previously described species, but most are related to other species in the North American miogeocline. Wendoverella arca n. sp., however, is unlike any other species described from North America but is quite similar to a Russian species, indicating faunal communication between the Ural Mountains and the Cordilleran miogeocline at least into Artinskian time.

Phosphatized and phosphatic small shelly fossils are a major source of information concerning the evolution of animals during the early Cambrian. Although progress has been made in understanding some of these fossils, many remain enigmatic, both with regard to their phylogenetic affinities and the overall morphology of the animal from which isolated sclerites came. Two unusual fossils from the upper lower Cambrian (Qiongzhusian or Atdabanian) Xihaoping Member of the Dengying Formation from Xiaowan, Xixiang County, southeastern Shaanxi Province, China are described herein. The first of these is a cap-shaped fossil we describe as Cambroskiadeion xiaowanense new genus and species. On its concave surface it bears a spine, the base of which is covered with numerous hemispherical verruculae. The long spine indicates that this was a sclerite rather than a univalved shell, although it remains unclear from what sort of animal it came. Similar fossils have been hypothesized to be halkieriid valves; although the rarity of halkieriid sclerites in the present samples argues against this view, it is possible these fossils are part of a similar multi-element skeleton. The second fossil is Acidocharacus longiconus Qin and Ding, 1988; it is known only from the Xihaoping Member and consists of a tall spine, often bearing barbs or bumps, attached to a rounded conical base. The base is covered with verruculae similar to those found on Cambroskiadeion. The function of these elements, and whether they were internal or external, remains unknown.

A new helminthomorph millipede, Sinosoma luopingense new genus new species, from the Triassic Luoping biota of China, has 39 body segments, metazonites with lateral swellings that bear a pair of posterolateral pits (?insertion pits for spine bases), and sternites that are unfused to the pleurotergites. This millipede shares a number of characters with nematophoran diplopods, but lacks the prominent dorsal suture characteristic of that order. Other “millipede” material from the biota is more problematic. Millipedes are a rare part of the Luoping biota, which is composed mainly of marine and near-shore organisms. Occurrences of fossil millipedes are exceedingly rare in Triassic rocks worldwide, comprising specimens from Europe, Asia, and Africa, and consisting of juliform millipedes and millipedes that are either nematophorans or forms very similar to nematophorans.

Recently developed analytical procedures for meshwork fenestrate and pinnate bryozoans made it possible to recognize two Russian species in the Toroweap Formation of southern Nevada. This analysis separates zoarial and zooecial features and emphasizes the three-dimensional form and size of the zooecial chamber as well as accessory features. In this investigation, these analytical procedures are successful even when specimens are fragmented and embedded in a hard rock matrix.

The bryozoans in the Toroweap Formation in this study were found to be more similar to Permian species of the Russian platform than to species described in earlier North American Permian studies. Five species of fenestrate bryozoans are present in the Toroweap Formation. Wjatkella permiana Morozova, 1970, and Polypora sargaensis Trizna, 1948, originally described in Russia, are recognized in the Toroweap. Three new species, Penniretepora oppositus n. sp., Septopora bilateralis n. sp., and Reteporidra anaphora n. sp., are present and, along with the Russian species, are described in this paper.

The local range zones of the five species of fenestrates were identified in three measured sections. Penniretepora oppositus and Septopora bilateralis are present throughout the three sections; Reteporidra anaphora is present in the lower two-thirds of the three sections; Wjatkella permiana is present in the middle parts of the three sections; and Polypora sargaensis is present in the upper parts of the three sections. Concurrent range zones, based on ramose bryozoans, were previously identified in two of the three sections and, using the distribution of the fenestrates in these two sections, four of the five concurrent range zones were recognized in the third section.

Bocchino (1964) described and figured a new genus and species, Propygidium primaevus, and assigned it to the siluriform family Trichomycteridae (=Pygidiidae). After examination of the holotype, the only referred specimen, the authors conclude that it does not correspond to a catfish, but to an acanthopterygian. Since it was considered the only fossil record of trichomycteridae, and having been used to support speculations on the “center of origin” of this Neotropical family (see Ringuelet, 1975), it is appropriate to correct the former assignment.

Reticuloceras (Swintoceras) n. subgen. unites an early group of the mid-Carboniferous goniatite family Reticulocertidae, in which reticulate sculpture is weakly developed or lacking and the typically reticuloceratid suture has slightly expanded ventral prongs. The type species, Reticuloceras (S.) spiraloides (Bisat and Hudson, 1943), is a rare, poorly known species from the British Namurian. Two additional species, R. (S.) wainwrighti (Quinn, 1966) and R. (S.) tiro (Gordon, 1969), are common in the basal type Morrowan Series, Lower Pennsylvanian, of Arkansas. Swintoceras occurs with two distinctive, late forms of the ammonoid, Hudsonoceras: Hd. ornatum (Foord and Crick, 1897) in Britain and Hd. moorei Quinn and Saunders, 1968, in Arkansas. The cooccurrence of these taxa correlates the basal Morrowan in its type region with the Namurian Reticuloceras nodosum (R1b) Zone of Britain and thereby also dates the close of the Mid-Carboniferous Eustatic Event in the North American Midcontinent.

Karlsorus n. gen. is proposed in this study as a large, smooth-shelled pentameride brachiopod of the family Pentameridae, based on Pentamerus gothlandicus Lebedev, 1892, from the Wenlock (Silurian) Slite beds of Gotland, Sweden. This species is transferred from Pentamerus to the new genus because of the combination of a Pentamerus-like shell shape and the development of a brachiophorium through fusion of the outer hinge plates in the middle portion, like a dorso-ventrally inversed cruralium. The first appearance of brachiophorium in pentamerids is in the late Wenlock, known also in Brooksina, Pentamerifera, and other related pentamerid genera, marking a significant stage in morphological transformation of dorsal internal structures, as part of the Silurian pentameride diversification in both level-bottom and reefal depositional environments.

Specimens of the Late Mississippian productoid genera Inflatia and Keokukia from northeastern Oklahoma and northwestern Arkansas, collected from the Boone and “Moorefield” Formations, Hindsville Limestone, and Fayetteville Shale, display morphologic similarities and differences that delineate species and determine their biostratigraphic ranges. Generic assignments are based primarily on internal characters. Systematic descriptions include seven species of Inflatia Muir-Wood and Cooper: Productus inflatus McChesney (the type species), P. cherokeensis Drake, P. clydensis Girty (figured herein for the first time and for which a lectotype is designated), four new species of Inflatia (I. cooperi, I. gracilis, I. pusilla, and I.? succincta), and one species of Keokukia (the type species for the genus, K. sulcata Carter). Also proposed and described is a new genus, Adairia, with its type species Productus (Marginifera) adairensis Drake. All these species of Inflatia, Keokukia, and Adairia have biostratigraphically restricted ranges within the Meramecian and Chesterian sequence in the Ozark region.

The genus Cribrella Lipina, 1989, with type species Cribrella mstaensis Lipina, was described from the Lower Carboniferous (middle Visean) of the southern Urals, and placed in the family Lituotubellidae (Lipina, 1989, p. 40, PL II, figs. 1–4). As the generic name is preoccupied by Cribrella Agassiz, 1835, an echinoderm, Cribrella Schmid, 1892, a sponge, Cribrella Cossman, 1906, a bryozoan, and Cribrella Gawor-Biedowa, 1987, a foraminifer, the new name Cribroaperturata is herein proposed for Cribrella Lipina. The type species of the genus thus becomes Cribroaperturata mstaensis (Lipina).

Cyphaspis wessmani new species is a morphologically aberrant taxon from the Ludlow Henryhouse Formation of south-central Oklahoma. Its long, scoop-shaped cephalic border is without close comparison in the family Aulacopleuridae, but its possession of eleven thoracic segments with an axial spine on the sixth, an inflated glabella with tiny L1 and dorsal tuberculate sculpture, a prominently expressed bilobate eye socle, and a micropygous pygidium all support assignment to Cyphaspis. The genus is common in Silurian rocks from most parts of the world, but C. wessmani is the first published record from southern Laurentia.

The genus Merychippus was erected by Leidy (1857), who named as the type species Merychippus insignis. The type specimen of M. insignis is an immature and incomplete maxilla containing a broken dp2 and a dp3. The type comes from the Bijou Hills of South Dakota, probably from the Barstovian (middle Miocene) Fort Randall Formation of South Bijou Hill in Charles Mix County (Skinner and Taylor, 1967), but possibly from the overlying undifferentiated Ogallala Formation, or possibly from North Bijou Hill in Brule County. Despite this enigmatic type, the species M. insignis has frequently been identified in the fossil record, and the genus Merychippus has grown to include all mesodont horses (Stirton, 1940). Conceptually, the taxon Merychippus is considered a horizontal grade rather than a vertical clade (Simpson, 1945, p. 18). As a horizontal concept, the genus Merychippus derived importance as the ancestral group for the many Mio-Pliocene lineages of hypsodont horses. Today, as horse classification is remodeled along cladistic lines, the taxon Merychippus derives importance from its early naming. Several distinctive horse clades extend upward from a middle Miocene radiation (Stirton, 1940; Quinn, 1955). If M. insignis can be placed within one of these clades, then it is likely that the clade will bear the generic nomen Merychippus because of the antiquity of the name.

A series of well-preserved specimens of the little-known Palaeogene species Biselenaria placentula (Reuss, 1867) warrant the designation of a new family of free-living cheilostome bryozoans, Biselenariidae n. fam. In contrast to the structural organization of all other free-living, lunulitiform cheilostomes, all zooids are enclosed almost completely by cuticular, exterior walls. Yet, like other lunulitiforms, the colony must be regarded as a highly integrated functional unit, as revealed through the unique, highly complex interior architecture. In creating the new monotypic family, the type species Biselenaria placentula is described in detail, while the ambiguous taxonomic status of the only other taxon, B. offa Gregory, 1893, is discussed.

UUID: http://zoobank.org/6ad8a795-c45e-4619-b2bb-46916585fbd9

Ptychites is among the most widely distributed ammonoid genera of the Triassic and is namesake of a family and superfamily. However, representatives of the genus mostly show low-level phenotypic disparity. Furthermore, a large number of taxa are based on only a few poorly preserved specimens, creating challenges to determine ptychitid taxonomy. Consequently, a novel approach is needed to improve ptychitid diversity studies. Here, we investigate Ptychites spp. from the middle and late Anisian of Nevada. The species recorded include Ptychites embreei n. sp., which is distinguished by an average conch diameter that is much smaller and shows a more evolute coiling than most of its relatives. The new species ranges from the Gymnotoceras mimetus to the Gymnotoceras rotelliformis zones, which makes it the longest-ranging species of the genus. For the first time, the ontogenetic development of Ptychites was obtained from cross sections where possible. Cross-sectioning highlights unique ontogenetic trajectories in ptychitids. This demonstrates that, despite showing little phenotypic disparity, Ptychites was highly ontogenetically differentiated, and thus the high taxonomic diversity at the species level is justified for the species investigated.

UUID: http://zoobank.org/5abe2487-8a00-4b48-adc7-ec7db7a097f7