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.

Zokors (Myospalacinae) continue to be the center of systematics discussions. Phylogenetic schemes based on molecular data do not always agree with each other, nor can phylogenetic schemes based on paleontological material be complete due to the only-partial description of West Siberian zokors. This paper tries to fill this gap and presents a description of the West Siberian lineage from the late early Pleistocene to the present, together with an analysis of molar development in other zokor lineages. We describe two new species and one subspecies (Myospalax myospalax krukoveri n. ssp., Myospalax convexus n. sp., Prosiphneus razdoleanensis n. sp.) ancestral to the extant Myospalax myospalax Laxmann, 1769. We also reveal differences in the ontogeny of molars of modern species that were not previously detailed. These differences, together with paleontological data, indicate that in the West Siberian lineage, peramorphosis occurred in the structure of the chewing surface (with the exception of the lower m1), whereas in all other zokor lineages, there was pedomorphosis. On the basis of these results, we suggest a new view on the systematics of Myospalacinae.

UUID: http://zoobank.org/b06d6c99-1648-454b-9b95-4d869bfe8bdc

A highly diverse fauna of dromioid brachyurans from the Serraduy Formation (lower Eocene) in the western Pyrenees (Huesca, Spain) is described and illustrated. Recorded taxa are Mclaynotopus longispinosus new genus new species, Torodromia elongata n. gen. n. sp., Basidromilites glaessneri n. gen. n. sp., ?Basidromilites sp., Sierradromia gladiator n. gen. n. sp., Kromtitis isabenensis n. sp., and ?Basinotopus sp. Other European outcrops have yielded dromioids in association with specific environments, likely coral and sponge reef and siliciclastic soft bottoms; but the present material constitutes the most diverse dromioid assemblage from the lower Eocene worldwide. These dromioids co-occurred with a rich invertebrate fauna and lived near coral–algal reef mounds. Sedimentological data suggest that most of the fauna accumulated in fore reef settings as a result of storm activity. The present material greatly increases the diversity of known dromioid crabs associated with Eocene reef environments.

UUID: http://zoobank.org/aed8cafa-7c64-4e70-bd45-9f357fc37a28

Paromomyidae are one of several families of plesiadapiforms that flourished during the Paleocene in North America soon after the extinction of non-avian dinosaurs some 66 million years ago. Although they are often among the best-represented plesiadapiforms in mammalian faunas in both North America and Europe, the early history of paromomyids is poorly understood, and their fossil record at higher latitudes is comparatively depauperate. We report here on the discovery of two new species of paromomyids from Paleocene deposits in southwestern Alberta: Edworthia greggi new species is the second known species of the basal paromomyid Edworthia Fox, Scott, and Rankin, 2010 whereas Ignacius glenbowensis new species is among the most abundantly represented species of Ignacius Matthew and Granger, 1921. These new discoveries document, for the first time, parts of the upper dentition of Edworthia, and the new species of Ignacius represents the first new, pre-Clarkforkian species of the genus to be described in nearly 100 years. A comprehensive phylogenetic analysis of nearly all known paromomyid taxa (including the new species described herein) recovered both species of Edworthia near the base of the paromomyid tree in a polytomy with Paromomys depressidens Gidley, 1923 and a paraphyletic Ignacius. The new paromomyids from Alberta not only increase the known taxonomic diversity of Edworthia and Ignacius but also add significantly to knowledge of the dental anatomy of these poorly known genera and further add to a uniquely Canadian complement of Paleocene plesiadapiforms.

UUID: http://zoobank.org/a2f31cfe-09b9-4168-b09f-9d0c3d0af342

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 Miocene Solemyidae of Chile are revised. The holotype of Solemya antarctica Philippi, 1887, originally described as Solenomya, is lost. Due to the lack of information on internal characters, its systematic position is considered as uncertain. A new species, Solemya lucifuga n. sp., is described from the lower Miocene Ranquil Formation of south-central Chile. Its dense radial external ornamentation shows that it is clearly different from S. antarctica. It is currently the only confirmed and described Miocene solemyid bivalve from the Southern Hemisphere.

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The Cretaceous chaetetid sponge Acanthochaetetes huauclillensis Sánchez-Beristain and García-Barrera is reported for the first time from the Aptian–Cenomanian Khalsi Formation, Ladakh Himalaya, India. Its low- to high-domical growth form could suggest an adaptation to either an environment with constant sedimentation rates, or to an irregular substrate. However, these growth forms also may indicate an absence of important environmental/sedimentological changes during the lifespan of the sponges. In addition, the growth form of this species suggests a calm, non-turbulent, reef-like microenvironment. Along with the other faunal assemblages, such as the rudists, corals, and the gastropod Nerinea, A. huauclillensis indicates a tropical to subtropical shallow marine carbonate platform setting. This new finding extends its stratigraphic range from the upper Hauterivian to the Aptian–Cenomanian interval in the eastern Tethyan realm.

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.

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 Lochkovian, Pragian, and basal part of the Emsian, which represent the post-Kwangsian Orogeny strata in the South China Block, are mainly composed of siliciclastic rocks. This lithological composition impedes investigation of Pragian and Lochkovian conodont biostratigraphy in the South China Block, which results in a persistent controversy on the age of relevant lithological units. The present study provides new evidence by reporting for the first time Lochkovian conodonts obtained from the South China Block, specifically the Gaoling Member of the Nahkaoling Formation at the Lingli section, central Guangxi. The conodont fauna, consisting of Pandorinellina exigua lingliensis Lu n. subsp., Pandorinellina exigua exigua, Zieglerodina? tuojiangensis Lu n. sp., Amydrotaxis praejohnsoni, and Eognathodus cf. E. irregularis, places the studied interval of the Gaoling Member in the lower or middle Lochkovian (contingent upon varying definitions for the base of the middle Lochkovian) to lower Pragian. Moreover, Amydrotaxis praejohnsoni, which was reported previously only in North America and eastern Australia, is herein also recorded in the South China Block, and thus may play an important role in intercontinental biostratigraphical correlation. By shedding light on the age of the upper limit of the underlying Lianhuashan Formation at the Lingli section, the present study indicates that the Kwangsian Orogeny ended before the late Lochkovian. This date is slightly earlier than the previously estimated late Lochkovian based on studies of fossil plants from the siliciclastic rocks deposited after the Kwangsian Orogeny.

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Modular coral-like fossils occur in thrombolitic reefal beds at two stratigraphic levels within the Lower Ordovician (Floian) Barbace Cove Member of the Boat Harbour Formation, in the St. George Group of western Newfoundland. They are here assigned to Reptamsassia n. gen.; R. divergens n. gen. n. sp. is present at both levels, whereas a comparatively small-module species, R. minuta n. gen. n. sp., is confined to the upper level. Reptamsassia n. gen. resembles the Ordovician genus Amsassia in its phacelocerioid structure, back-to-back walls of adjoining modules, module increase by longitudinal fission involving infoldings of the wall, tabula-like structures that are continuous with the vertical module wall, and calices with concave-up bottoms. The new genus is differentiated by its encrusting habit, modules with highly variable growth directions and shapes throughout skeletal growth, and modules that may separate slightly or diverge from one another following fission. Together, Amsassia and Reptamsassia n. gen. are considered to represent a distinct group of calcareous algae, the Amsassiaceae n. fam., which possibly belongs to the green algae. The Early Ordovician origination of Amsassia followed by Reptamsassia n. gen. contributed to the beginning of the rise in diversity on a global scale and in reefal settings during the Great Ordovician Biodiversification Event. Reptamsassia minuta n. gen. n. sp. was an obligate symbiont that colonized living areas on its host, R. divergens n. gen. n. sp., with isolated modules of R. divergens n. gen. n. sp. able to persist in the resulting intergrowth with R. minuta n. gen. n. sp. This is the earliest known symbiotic intergrowth of macroscopic modular species, exemplifying the development of ecologic specialization and ecosystem complexity in Early Ordovician reefs.

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.

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.

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 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

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.

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.

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.

The new invertebrate trace fossil from paleosols of the Bijori Formation, Palliedaphichnium gondwanicum new ichnogenus new ichnospecies, which belongs to an upper Permian Gondwana sequence of India, makes a significant contribution to the meager records of invertebrate trace fossils from Permian and Indian paleosols. This trace fossil attributed to Diplopoda and composed of tunnels and chambers filled with pellets is also an important addition to the scarce record of Permian millipedes. The abundance of plant remains in the same paleosol indicates that these millipedes probably fed on leaf litter as other fossil and extant representatives. Chambers and abundant pellets in burrows indicate adverse conditions on the surface, at least seasonally. This finding contributes to the emerging scenario of invertebrate ichnofaunas from paleosols and points to a successive dominance of millipedes during the Paleozoic, crayfishes and earthworms in the Mesozoic, and insects in the Cenozoic.

UUID: http://zoobank.org/4378c739-9bd1-4382-b084-e2176045e209