Class Hyolitha Marek, 1963 encompassing the Order Hyolithida Sysoev, 1957 (Early Cambrian to Upper Permian) and Order Orthothecida Marek, 1966 (Early Cambrian to Early Devonian) consists of a group of conical, calcareous-shelled invertebrates of controversial affinity. One opponent view holds that hyoliths may be reasonably accommodated under the Phylum Mollusca (Malinky and Yochelson, 2007 and references therein), whereas another supports separate phylum status under the name Hyolitha (Pojeta, 1987 and references therein). Hyolith abundance and diversity attain a maximum in the Cambrian, followed by a progressive decline up to their Permian extinction (Fisher, 1962; Wills, 1993). Their demise was part of the extinction event of the Late PermianlEarly Triassic. The cause(s) of this event remains controversial (Erwin et al., 2002), and no imprint remains in the geologic record of the specific circumstances surrounding the disappearance of the hyoliths, though it is highly probable that reduced population size was a contributing factor. Given the overall rarity of Late Paleozoic hyoliths, every occurrence is worthy of note to better understand patterns of hyolith diversity and abundance in the Late Paleozoic, the geographic and stratigraphic distribution of hyolith taxa and circumstances related to their extinction. The species from the Upper Permian described herein is among the youngest, if not the youngest, members of class Hyolitha.

Extinct Hydrochoerinae traditionally included within ‘Cardiomyinae’ (Cavioidea, Caviidae) are caviomorph rodents well represented in the late Miocene to late Pliocene of Argentina, but their paleobiology has received little scientific attention. The postcranium of these rodents is poorly known and has not been considered in morphofunctional or systematic studies. Here, we provide the first description of the postcranium of the basal hydrochoerine Cardiomys Ameghino, 1885, based on a well-preserved specimen from the late Miocene of Central Argentina, and evaluate its paleobiological and systematic implications. A morphofunctional study and a character mapping analysis were performed. We concluded that most of its postcranial features are neither adaptations to a specialized cursoriality, as in some extant cavioids, nor major modifications associated with swimming, as in extant capybaras. Cardiomys exhibits several features (high humeral distal articular surface, perforated olecranon fossa, proximal portion of radius cranially located with respect to the ulna, subrectangular-shaped radial head with flattened ulnar facet, calcaneocuboid joint distally located with respect to the astragalonavicular joint) that allow us to interpret it as an ambulatory caviid. Among cavioids, some features of Cardiomys are more similar to those of Hydrochoerus Brisson, 1762 (lateral coronoid process reduced, humeral capitular tail well differentiated, capitular tail facet of the radial head well developed and relatively short craniodistally, plantar process of the navicular massive and short). Other postcranial features (relatively longer and more gracile third metatarsal and phalanges, straight caudal border of the ulna) suggest that Cardiomys would have been a generalized hydrochoerine, as also indicated by its dental and cranial characters.

Four rare Pennsylvanian (Stark Shale: Pennsylvanian, Missourian [=Kasimovian]) coleoids from Nebraska and Iowa, which are preserved as flattened partial phragmocones and body chambers associated with three-dimensionally fossilized ink sacs, are herein described as Pabianiconus starkensis new genus new species, Nebraskaconus whitei new genus new species, and Starkites compressus new genus new species. One specimen that is missing most of the phragmocone, is provisionally assigned to Donovaniconus. The fossils are assigned to the Coleoidea because of the presence of ink-filled sacs in the body chamber region of the conch. Additionally, eight fragmented and flattened phragmocones and body-chamber clusters with similar morphologies, including some with ink fragments and arm hooks, are assigned to the Coleoidea, but are not named because of their fragmentary condition. On most of the eight specimens, the shell material is associated with other unidentified finely macerated material, which suggests these fossils are probably either ejectoid masses or coprolites from coleoid predators and/or scavengers. However, the new genera named above appear to have been deposited as complete animals, based on the presence of the ink-filled sacs that are in the body chambers. With their body chamber and phragmocone morphologies, these rare coleoid taxa provide valuable information about conch variability within the Carboniferous evolutionary radiation of coleoids.

A new species of the Paleozoic bryozoan genus Ptilotrypa of the order Cryptostomata is described from the lower part of the Yong Limestone Formation, Katian, Upper Ordovician of the Kumaun Tethys Himalaya: Ptilotrypa bajpaii new species. The presence of the genus Ptilotrypa in the Tethyan Himalaya suggests paleogeographic connections to the Upper Ordovician of North America and, consequently, Upper Ordovician age for the lower part of the Yong Limestone Formation. This species displays a reticulate colony shape, which suggests an efficient filtering capacity in an environment with a high primary production. Morphological peculiarities and systematic assignment of the genus Ptilotrypa are discussed.

UUID: http://zoobank.org/898276c8-2924-4da2-ae96-3392cb2ebbc3

Misidentified fossils are common in paleontology, but Platylithophycus has undergone a particularly problematic series of descriptions. The holotype of P. cretaceus comes from the Upper Cretaceous Niobrara Chalk of Kansas, and was first described as a calcareous green alga, based on the surface texture of the specimen. Later, Platylithophycus was re-identified as a sepiid cephalopod, based partly on a comparison of microstructure between P. cretaceus and the pen of modern squids. Platylithophycus then became part of the University of Nebraska teaching collection, where, according to paleontological legend, an undergraduate student suggested that the fossil’s tessellated surface looked a lot like shark cartilage. However, that interpretation has not been formally proposed until now. This work re-describes the holotype of Platylithophycus cretaceus as part of the branchial endoskeleton of an elasmobranch, based on both gross morphology and ultrastructure, including recognizable tessellated cartilage with intertesseral pores and joints.

Colonial rugose corals ranging in age from Carboniferous to Late Triassic and Early Permian (Cisuralian) fusulinids have been recovered from cobbles in a conglomerate in the Upper Triassic Brisbois Member of the Vester Formation in the Izee terrane in central Oregon. Early Permian (late Sakmarian or early Artinskian) fusulinids typical of those present in the Coyote Butte Limestone in the nearby Grindstone terrane (part of the allochthonous McCloud Belt) include Eoparafusulina, Pseudofusulinella, Chalaroschwagerina, and Schwagerina. The presence of these fusulinid genera and the Pennsylvanian coral Heritschioides?, which is mostly restricted to the McCloud Belt, suggest these particular cobbles were derived from limestone in that belt. The Early Permian fusulinids Changmeia bostwicki new species and Changmeia bigflatensis new species, and the Early Permian corals Yokoyamaella? oregonensis new species and Yokoyamaella? sp. 1, all of which have Tethyan affinities, occur rarely in other cobbles. The presence of definitive fossils from the two different realms in a conglomerate associated with beds containing Late Triassic ammonoids indicates that by Late Triassic time a fragment of a Tethyan terrane was close to or had been amalgamated with a terrane belonging to the McCloud Belt.

Pupae of the nonbiting midge Chaoborus are reported from the middle Eocene (Claibornian) Tallahatta Formation in Benton County, Mississippi. These pupae are placed within the genus Chaoborus because the shape of the respiratory organs, length of the abdomen, and shape of the anal paddles closely resemble other species of this extant genus. This occurrence represents the oldest record of Chaoborus pupae and the first record of fossil Chaoborus from North America. The flora and fauna found associated with the fossil pupae along with the known habitats of extant Chaoborus pupae indicate a lentic environment. This interpretation corresponds to the depositional environment of similar Eocene-aged clay deposits in western Tennessee.

Twelve specimens of Eumorphocystis Branson and Peck, 1940 provide the basis for new findings and a more informed assessment of whether this blastozoan (a group including eocrinoids, blastoids, diploporites, rhombiferans) constitutes the sister taxon to crinoids, as has been recently proposed. Both Eumorphocystis and earliest-known crinoid feeding appendages express longitudinal canals, a demonstrable trait exclusive to these taxa. However, the specimen series studied here shows that Eumorphocystis canals constrict proximally and travel within ambulacrals above the thecal cavity. This relationship is congruent with a documented blastozoan pattern but very unlike earliest crinoid topology. Earliest crinoid arm cavities lie fully beneath floor plates; these expand and merge directly with the main thecal coelomic cavity at thecal shoulders. Other associated anatomical features echo this contrasting comparison. Feeding appendages of Eumorphocystis lack two-tiered cover plates, podial basins/pores, and lateral arm plating, all features of earliest crinoid ‘true arms.’ Eumorphocystis feeding appendages are buttressed by solid block-like plates added during ontogeny at a generative zone below floor plates, a pattern with no known parallel among crinoids. Eumorphocystis feeding appendages express brachioles, erect extensions of floor plates, also unknown among crinoids. These several distinctions point to nonhomology of most feeding appendage anatomy, including longitudinal canals, removing Eumorphocystis and other blastozoans from exclusive relationship with crinoids. Eumorphocystis further differs from crinoids in that thecal plates express diplopores, respiratory structures not present among crinoids, but ubiquitous among certain groups of blastozoans. Phylogenetic analysis places Eumorphocystis as a crownward blastozoan, far removed from crinoids.

Small round pits and holes in fossil skeletal material are found in a wide variety of invertebrate substrates from diverse environmental settings. They are associated with parasitism, predation and commensal attachment. Four ichnogenera have been proposed for these trace fossils: Sedilichnus Müller, Oichnus Bromley, Tremichnus Brett and Fossichnus Nielsen, Nielsen and Bromley. Previous authors have established that Tremichnus is a junior synonym of Oichnus. Herein we show that Oichnus and Fossichnus are junior synonyms of Sedilichnus.

Sedilichnus, as defined herein, includes 10 ichnospecies. Sedilichnus spongiophilus, S. simplex, S. paraboloides, S. ovalis, S. coronatus, S. gradatus, S. halo, S. asperus, S. excavatus and S. solus. Consistent with previous work Sedilichnus ichnospecies are defined solely by morphological criteria and not by a priori assumptions regarding depositional environment or tracemaker. Thus, this ichnotaxon is recognized in both marine and continental settings on a wide variety of invertebrate skeletal tests. As is true with many ichnotaxa, Sedilichnus ichnospecies represent end-members in morphological spectra, however each ichnospecies is clearly differentiable from the others.

Sedilichnus spongiophilus are circular, non-penetrative pits in shells. Sedilichnus paraboloides are penetrative holes with spherical paraboloid forms and typically have larger external openings and smaller internal openings. Sedilichnus simplex are simple cylindrical borings that have both penetrative and non-penetrative forms. Sedilichnus coronatus differ from other forms by the presence of an etched or granular halo surrounding the boring. Sedilichnus gradatus have two concentric parts, an outer boring and an inner shelf of smaller diameter. Sedilichnus ovalis and S. asperus are both oval in outline differing in the presence of tapering paraboloid margins in S. ovalis and margins perpendicular to the substrate in S. asperus. Sedilichnus excavatus and S. solus are primarily non-penetrative and differ from other Sedilichnus by the presence of central, raised bosses or platforms. These two ichnospecies differ in the shapes of their external walls and the proportional thickness of the bounding groove.

The Leptarctinae are an enigmatic subfamily of mustelids present in North America and Eurasia during the Miocene (Arikareean to Hemphillian North American Land Mammal Ages). Their diet and ecology have been particularly controversial. Some workers have suggested they were similar to koalas, whereas others suggested they were crushing omnivores analogous to raccoons. Leptarctus oregonensis Stock, 1930, a poorly known leptarctine from the early Barstovian, is represented by fragmented cranial elements and isolated teeth from the Mascall Formation of Oregon, and some fairly complete but undescribed material from the Olcott Formation of western Nebraska. Herein, we describe the first well-preserved skull of L. oregonensis from the type formation. Based on this new specimen, we confirm that L. oregonensis is a distinct species from L. primus Leidy, 1856 and L. ancipidens White, 1941 that is characterized by a distinct morphology of its tympanic projections and first upper molars. We are also able to describe intraspecific variation within L. oregonensis coinciding with the geographic distribution of the specimens (Oregon and Nebraska). The most variable characters are concentrated in the morphology of the frontals and the upper fourth premolar. Additional specimens will be needed to settle the debate over sexual dimorphism in this species, but this new specimen suggests that Leptarctus oregonensis, despite being one of the smallest members of the Leptarctinae, was an animal-dominated omnivore with considerable crushing ability.

A latest Paleocene charophyte flora collected from the South Gobi area in the Junggar Basin, western China, includes the geographically widespread taxa Peckichara torulosa var. varians (Dollfus and Fritel, 1919) Sanjuan, Vicente, and Eaton, 2020, Lychnothmanus vectensis (Groves, 1926) Soulié-Märsche, 1989, and Gyrogona lemani capitata Grambast and Grambast-Fessard, 1981. Lychnothmanus vectensis (as Lychnothmanus aff. L. vectensis) is known from the Cretaceous–Paleocene transition in eastern China and the latest Paleocene in western China, with likely additional records from the United States (Utah). The earliest European records of L. vectensis are from the late Eocene to early Oligocene in Spain, France, and England. Similarly, the oldest record of G. lemani capitata is from the latest Paleocene in the South Gobi area, with younger records from the middle Eocene of France. These latest Paleocene gyrogonite assemblages demonstrate the origin of these charophyte lineages in Asia. The dispersal of these charophytes from Asia to Europe in the middle to late Eocene appears to have occurred before the retreat of the Turgai Strait in both the Tarim area and the Siberian Basin by the end of the late Eocene and before the “Grande Coupure” in Europe and the Mongolian Remodelling in Asia during the Eocene–Oligocene transition. We hypothesize that waterbirds may have facilitated this intercontinental dispersal, and that idea is supported by the shared occurrence of avian groups in Central Asia and Europe in the middle and late Eocene.

The spider crabs Willinachoides santanai n. gen. n. sp. from the early-middle Miocene of north Brazil and Paradasygyius rodriguezi n. sp. from the late Miocene of Venezuela are described and illustrated. Additionally, Eoinachoides senni Van Straelen, 1933, from the late Oligocene–early Miocene of Venezuela, is redescribed based on photographs of the holotype, and the diagnosis of Eoinachoides latispinosus Carriol, Muizon, and Secretan, 1987, from the late Miocene of Peru, is emended also on the basis of photographs of the holotype. The past distribution points to a Tethyan background for the current amphi-American Inachoididae, with the oldest fossil species known from the early Eocene Tethyan regions (Pakistan and Italy), and from the late Eocene–late Pliocene of the Americas. The high number of monotypic genera in Inachoididae could be the result of rapid dispersion followed by diversification during the Neogene of the tropical America, facilitated by global and regional events (e.g., eustatic sea level changes, the Mi-1 Oligocene-Miocene boundary global cooling, the global warming period of the Middle Miocene Climate maximum, closure of the Panama Isthmus, and marine incursions into the Amazon Basin). The shoaling and final closure of the Central American Seaway are thought to have critically affected the evolution of the inachoidids and shaped their current distribution patterns.

UUID: http://zoobank.org/6275fdc4-4bfa-4873-9320-3143d4915172.

Species of the megaorder Poromyata, although common and relatively diverse in Albian–lower Cenomanian Comanchean strata in Texas and northern Mexico, have been neglected as biostratigraphic markers and paleoecological indicators. Since 1852, more than a dozen species have been identified as Homomya Agassiz, order Pholadomyida, superfamily Pholadomyoidea or Pleuromya Agassiz, order Pholadida, superfamily Pleuromyoidea. Because valve morphologies of the two genera are similar in many ways, casts are difficult to separate. Statistical analysis of key morphological properties objectively defines species concepts and assesses synonymies. Eight species are retained in Homomya; four are synonymized with these. Two species are provisionally retained in “Homomya” although they differ significantly. One species is reassigned to Liopistha (Sergipemya) alta (Roemer, 1852). Pleuromya henselli (Hill, 1893) is reassigned to Panopea.

Homomyid species range from upper Aptian to lower Cenomanian of the Comanchean Series in Texas and Mexico. Their ranges vary in duration from one million years up to eight million years. These infaunal suspension feeders occupied calcareous mud and carbonate shelf substrates. Two sets of species are distinct morphotypes: a smaller-sized set of H. knowltoni Hill, 1895; H. tarrantensis Perkins, 1961; H. tlahualiloensis Perkins, 1961; and H. kellumi Perkins, 1961 and a larger-sized set of H. cymbiformis Perkins, 1961; H. austinensis Shattuck, 1903; H. vulgaris Shattuck, 1903; H. budaensis Whitney, 1911; and H. auroraensis Perkins, 1961. Two end-member morphotypes are represented by the “streamlined” Homomya knowltoni, which is an elongate, slightly inflated form with a relatively high umbo, and the cylindrical Homomya budaensis, which is a very elongate, tubular, inflated form with a very low umbo.

Stratigraphic distribution of two key brachiopod species in the Ramp Creek Formation and Harrodsburg Limestone (middle Mississippian) in south-central Indiana suggests the boundary between the Osagean and Meramecian Series lies in the lower part of the Ramp Creek Formation. Marginirugus magnus (Meek and Worthen), an Osagean index fossil, ranges into the lower part of the Ramp Creek Formation. Warsawia lateralis (Hall), a Meramecian index fossil, also occurs in the lower part of the Ramp Creek Formation and in the lower part of the Harrodsburg Limestone. Thus, the upper part of the Edwardsville Formation and lower part of the Ramp Creek Formation in Indiana are temporally equivalent to the lower half of the Warsaw Formation in the Mississippi Valley. The upper part of the Ramp Creek Formation and the lower part of the Harrodsburg Limestone are temporally equivalent to the upper half of the Warsaw Formation.

In the past 25 years, I have regularly observed floating shells at various localities in the Dutch Wadden Sea. Such shells start to float with the incoming tide and with their concave side up. Bivalve shells float like a boat and are transported in this way over short distances (meters to tens of meters) towards the high tide line. In order to study this phenomenon in more detail, I selected a tidal flat bordering the southern part of Texel, the westernmost barrier island of the Wadden Sea. I visited this tidal flat daily during incoming tides from 8 to 18 October 1992. Presence or absence of floating shells on the incoming floodwater was noted over a stretch of about 250 m.

An unusual occurrence of a colony of microcrinoids from shale within a fragment of a large orthoconic nautiloid body chamber is described from the Imo Formation (Mississippian, Chesterian) near Elba, Arkansas. The colony, about 70 individuals, consists principally of immature specimens that lack facets for the arms, and a few mature specimens with four or five arm facets. The crinoids are interpreted as record of a census population that was engulfed suddenly by mud. The crinoids are assigned to Allagecrinus coronarius Gutschick, 1968. The body chamber may have been broken during predation by other large cephalopods, or sharks, known from the Imo, or by post-mortem transport. The shell served as a firm substrate on which the microcrinoid larvae could settle and the convex sides may have provided some protection from currents.

The coral-inhabiting archaeobalanid barnacle genus Eoceratoconcha Newman and Ladd, 1974, previously known only from the middle Miocene of Trinidad and questionably from the lower Miocene of Jamaica, is represented by a new species, E. weisbordi, in the coral Solenastrea bournoni Milne-Edwards and Haime from the upper Pliocene Pinecrest beds of Sarasota County, Florida. The new species differs from Miocene species of Eoceratoconcha in its larger overall size and more subdued wall plate ribbing, and is further distinguished from the type species, E. kugleri Newman and Ladd, in having a well-developed scutal adductor ridge and conspicuous tergal depressor muscle crests. The opercular morphology of E. weisbordi further supports the proposal of Newman and Ladd (1974) that Eoceratoconcha is ancestral to the pyrgomatid genus Ceratoconcha Kramberger-Gorjanovic.

While preparing materials for the pentameroid portion of the Treatise on Invertebrate Paleontology revision of the brachiopod volumes, problems were encountered with four enigmatic genera: Rugolepyros Lenz, 1989; Aenigmastrophia Boucot, 1971; Spondylostrophia Kulkov, 1967; and Stricklandistrophia Sapelnikov and Rukavishnikova, 1975.

Camptocrinus alabamensis Strimple and Moore, from the Gasperian (Mississippian: Chesterian) part of the Monteagle Limestone and overlying Bangor Limestone in northern Alabama, is the only species of Camptocrinus known to have more than 10 arms. Camptocrinus alabamensis exhibits morphological features (basals that are taller on their posterior ends than on their anterior ends, flattened primanal, shorter posteriormost secundibrachs on C ray and D ray) indicative of a tightly coiled life position, with most of the stem lying along the sediment. Unlike other coiled crinoids, Camptocrinus alabamensis had a double-folded stem and more than 10 arms, which we interpret to have been compromise solutions to the problems of protection from high current energy and predation pressure coupled with the need to lift the animal into a feeding posture. In addition, C. alabamensis is the only dichocrinid exhibiting highly modified pinnules, which may have been used as rheo/chemosensory organs. Camptocrinus alabamensis was a leeward passive suspension feeder that, in times of danger, could fold in its arms and coil tightly against the sediment.

Camptocrinus alabamensis is removed from synonymy with C. cirrifer and the diagnosis of Camptocrinus is modified. Species of the genera Camptocrinus and Neocamptocrinus should be used only for specimens in which calyces are known; therefore, the plethora of stem-species erected over the years should all be assigned to stem genera unless adequate calyx descriptions are available.

A new strophalosiid, Megalosia chuluensis n. gen. and sp., from the Nisal Member, Senja Formation, in the Manang district north of Mt. Annapurna, north-central Nepal, is of early Dorashamian or Changhsingian (Late Permian) age. Wyndhamia circularis Chang, from slightly older faunas of south Tibet, might be congeneric.