Paleopathologies and tooth marks observed on bones have long been used for behavioral interpretations of extinct organisms, including non-avian dinosaurs. However, our understanding of this behavior is limited by the rarity of large-scale surveys of recovered material. Here, we present a systematic survey of tooth marks across 148 hadrosaurid jugals from various Late Cretaceous formations of Alberta, Canada. Across 20 of the elements (13.6%), we observed 48 tooth marks, restricted to the lateral surface, 40% of which were located on the middle jugal body and showed no preferred orientation of the mark long axis. Across taphonomic modes, tooth marks are most common on isolated specimens, followed by bonebed specimens, with few articulated/semi-articulated/associated specimens showing marks. The proportion of tooth-marked to non-tooth-marked jugals is comparable to tooth-marking frequencies observed for modern mammalian carnivores. Although tooth marks were likely produced postmortem during feeding, it is unclear whether tooth marks were produced when the jugal was removed to access underlying adductor musculature or during the removal of extraoral tissues or a combination of these behaviors. Future large-scale surveys of hadrosaurid cranial elements could help clarify which of these explanations is more likely and elucidate Cretaceous carnivore carcass-processing behaviors. Our survey also identified an additional two specimens showing elongate healed marks extending anteroposteriorly across the lateral surface of the jugal body that are of unknown, but potentially the same, origin. Further specimens with similar paleopathologies could help decipher a likely mechanism of injury.

Shelf-edge-derived boulders in debris-flow conglomerates of the Shallow Bay Formation of western Newfoundland are relicts of a Cambrian–Lower Ordovician margin of Laurentia that was largely obliterated during the Taconic Orogeny. As such, they are an important archive of trilobite faunas from the edge of the continent. In this paper, we document Cambrian trilobites from the mid-Steptoean Stage (upper Paibian of global nomenclature) in the Downes Point Member. Most of the species are from three boulders assigned to the agnostid Acmarhachis kindlei Fauna and include Dunderbergia Walcott, 1924, Pterocephalops Rasetti, 1944, Quebecaspis Rasetti, 1944, Bathyholcus Rasetti, 1961, Glyptometopsis Rasetti, 1961, and Tholifrons Palmer, 1968. These trilobites are assigned to a new biostratigraphical unit, the Quebecaspis conifrons Fauna, which can also be identified in shelf-margin-derived facies in Quebec, Vermont, and Maryland. Comparison with the shelf interior is more difficult because of ecological and biogeographical differences, but the Q. conifrons Fauna most likely correlates into the Dunderbergia Zone of the traditional Laurentian trilobite zonation. New species are Bathyholcus punctatus, Bellaspidella crocalae, Dunderbergia astropletha, D. bovicephala, D. magnatubercula, “Eugonocare” arquatum, Glyptometopsis parilimba, Onchopeltis anconis, and Tholifrons maritima.

UUID: http://zoobank.org/9c381131-a457-45d1-bbab-1b839c6b2812

A number of echinoderm groups lack representation in the Silurian fossil record, which becomes especially clear when considering the echinoderm fossil record of the Ordovician and Devonian. This paucity constrains our ability to resolve echinoderm evolutionary dynamics and biogeographic pathways during the Silurian, thereby underscoring the significance of newly discovered species. Herein, we describe a new species of blastozoan diploporan echinoderm, Eucystis charlotteae new species, from the Silurian of Missouri, USA, representing the first example of this genus described from Laurentia, which now makes this one of the most broadly distributed genera within diploporans. Within this paper, we compare and contrast this new species to other known species within Eucystis Angelin, 1878. Eucystis charlotteae n. sp. is characterized by having five ambulacral grooves that branch three times into unequal lengths and each end in large, tumid facetal scars. Eucystis charlotteae n. sp. is also relatively large when compared to other named species of the genus, which could lend insight into body size trends of diploporan echinoderms in the early Paleozoic. This new occurrence also lends insight into the biogeographic dynamics of diploporan taxa across the early Paleozoic.

UUID: http://zoobank.org/4e64fd0d-f7f5-4f0e-a310-438bad08f046

The presence and spatial distribution of intraspecific variation impact the evolvability of a species. Understanding this variation may shed light on the natural history and ecological breadth, realized and potential, of specific taxa. Insights from the paleontological record can provide additional information on potential phenotypic variation for species that have adapted to past and present environments. Here, we use the American mink, Neogale vison (Schreber, 1777), as a case study to understand the extent and pattern of mandibular shape variation among extant populations (n = 290) and fossil assemblages (n = 13). We use these data to examine whether the role of N. vison has changed in response to environmental conditions or through time. We found that some fossil N. vison mandibles lie outside the morphospace occupied by extant N. vison and are distinct from modern mink. Fossils from Conard Fissure, Arkansas (n = 8), represent a unique morphotype that likely had higher bite forces than modern N. vison. This morphotype may have allowed N. vison at this site to take advantage of larger or different prey. These results demonstrate both the adaptive potential of N. vison and the fossil record’s ability to reveal unique variation in a lineage.

Keimeliopteridae n. fam., a new family of stem-group paraneopteran insects containing two species, Keimelioptera solensis n. gen. n. sp. and K. rara n. gen. n. sp., is described from the Upper Triassic (Norian) Cow Branch Formation of the Solite deposit in Virginia and North Carolina, USA. A phylogenetic analysis using 16 terminal taxa and 68 morphological characters recovered Keimeliopteridae outside of crown Paraneoptera (bark lice, true lice, thrips, and hemipterans), as sister to Hypoperlidae + Paraneoptera sensu stricto. Keimeliopteridae can be definitively placed near Paraneoptera on the basis of the fusion of veins R + M + CuA into a common stem, the presence of an arched cua-cup crossvein, a simple CuP vein, and a two-branched CuA vein forming an areola postica. However, the plesiomorphic retention of pentamerous maxillary palpi, pentamerous tarsi, and probable cerci exclude Keimeliopteridae from crown Paraneoptera and necessitate the creation of this new family. Similar taxa are unknown from elsewhere during the late Paleozoic and early Mesozoic, which may be expected given the general rarity of shared taxa between Solite and coeval deposits. Keimeliopteridae is particularly significant due to the sparse Mesozoic record of Paraneoptera from the New World, and its discovery further demonstrates the significance of the Solite deposit as a window into the evolutionary history of insects following the End Permian Mass Extinction.

UUID: http://zoobank.org/bb0e9f2f-dcb2-48ad-bd14-37f6f89fea0e

Bromidocycloides sprinklei new genus new species (Echinodermata) from the Upper Ordovician, Bromide Formation, Oklahoma, is a cyclocystoid distinguished by having a thin dome-shaped stereomic plate covering each epispire on the aboral surface of the central disk. The tube foot basin side walls are distinctively straight, intersecting at angles of 25–35°, all forming a unique zigzag pattern in lateral view. Also described are new specimens of Moroccodiscus smithi Reich et al., 2017 from the Middle Ordovician Taddrist Formation, Morocco, revealing how floor plates and the associated water vascular system developed sequentially according to the Ocular Plate Rule. These findings support the view that cyclocystoids had an upward facing central disk composed of perforate extraxial plates housing epispires and a peripheral ring of stout ambulacral plates bearing tube feet that projected downward toward the substratum.

UUID: https://zoobank.org/35fcd4b8-49c8-41b2-9058-1ed56251c2c2

Mesozoic calcareous nannofossils of the family Eoconusphaeraceae have traditionally been interpreted as nannoliths of uncertain biological affinity. However, their morphology, crystallographic organization, and occurrence in articulated coccospheres strongly suggest that they represent coccoliths produced by haptophyte algae. This study re-examines the genera Eoconusphaera Jafar, 1983 and Conusphaera Trejo, 1969 using light and scanning electron microscopy from an Upper Triassic section of the Northern Calcareous Alps and published Jurassic material. Particular attention is given to coccolith ultrastructure, coccosphere organization, and the effects of diagenetic alteration on the morphology of the genus Eoconusphaera. Newly documented articulated coccospheres of Eoconusphaera zlambachensis (Moshkovitz, 1982) Jafar, 1983 demonstrate that this species formed monomorphic coccospheres composed of conical coccoliths arranged around a central cell cavity. Morphological observations further indicate a protolith-type rim structure and biologically controlled crystallographic organization comparable to those observed in other early coccolithophores. Variations in preservation reveal five successive stages of dissolution-related alteration that progressively obscure primary ultrastructural features. The results highlight that the Eoconusphaeraceae represent true coccoliths rather than nannoliths and support their interpretation as early calcihaptophytes. Similar morphologies observed in Triassic and Jurassic conical coccoliths might have resulted from repeated morphological evolution, although the possibility of phylogenetic relationships between some taxa remains open.

The fossil record of freshwater crayfishes (Astacoidea and Parastacoidea) is globally scarce and dominated largely by trace fossils and bio-gastroliths, particularly in Gondwana. In South America, Mesozoic records have been restricted to ichnofossils, with unequivocal body remains known only from the Paleogene. Here we describe isolated mandible cephalic molar fields attributable to Parastacidae from the Maastrichtian Los Alamitos Formation of northern Patagonia, Argentina. These specimens, recovered from historical collections of the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” and previously misidentified as vertebrate teeth, represent the oldest confirmed parastacid body fossils from South America and the second Cretaceous record of the clade in the Southern Hemisphere. The material consists of five incompletely preserved molariform structures, including one nearly complete cephalic molar field, exhibiting a distinctive combination of features such as a subrectangular outline, prominent lateral cusps, a longitudinal central depression, and a thick enamel-like apatite coating. Comparative analysis indicates that these remains cannot be referred to any extant South American genus and likely represent a distinct, unnamed parastacid lineage, possibly showing closer affinities to Malagasy taxa. The Patagonian record reported here fills a critical temporal gap between Early Cretaceous parastacids from Australia and Paleogene records from South America and Australasia, supporting a widespread Gondwanan distribution of parastacids during the Late Cretaceous and reinforcing hypotheses of early high-latitude diversification followed by subsequent dispersal.

The regular echinoid Arbacia Gray, 1835 is a key model in evolutionary, ecological, and biogeographic research, yet its fossil diversity and paleobiogeographic history in the western Atlantic remain understudied. We present a comprehensive revision of Plio-Pleistocene Arbacia from the southeastern United States and Caribbean based on examination of > 400 specimen lots from institutional collections, including preserved material retaining spines. Our results resolve longstanding taxonomic confusion by (1) recognizing and designating a neotype for Arbacia improcera (Conrad, 1843) as encompassing Arbacia sloani (W.B. Clark in W.B. Clark and Twitchell, 1915) and Arbacia crenulata Kier, 1963; (2) confirming the distinctiveness of Arbacia waccamaw Cooke, 1941 and Arbacia rivuli Cooke, 1941; and (3) describing Arbacia percaribbeana new species, from Venezuela, the Caribbean, and southern Florida. The revised taxonomy establishes a coherent regional succession: Arbacia improcera in the Late Pliocene, Arbacia waccamaw and Arbacia rivuli at the Pliocene-Pleistocene transition, and Arbacia punctulata persisting from the Late Pleistocene to the present. These species occur in well-dated formations and provide useful biostratigraphic markers. The absence of Arbacia from Miocene deposits of the eastern USA aligns with molecular estimates suggesting a Pliocene origin of modern Atlantic lineages. Morphological comparisons reveal a previously unrecognized biogeographic structure. Four western Atlantic species share a distinctive trait combination separating them from extant Pacific taxa, whereas Arbacia percaribbeana n. sp. exhibits stronger Pacific affinities. This pattern suggests a North Atlantic lineage and a lineage with Pacific relationship, possibly reflecting transisthmian exchanges during the progressive closure of the Central American Seaway. Together, these results establish Arbacia as a robust model for investigating macroevolutionary dynamics in Neogene western Atlantic echinoids.

UUID: http://zoobank.org/4a9e9e9e-e101-49b0-aa34-bc247b10fe0a

The origin of dinosaurs represents one of the most intriguing evolutionary events of the Mesozoic. Although dinosaurs ultimately came to dominate terrestrial ecosystems worldwide, their earliest evolutionary history unfolded within complex Triassic ecosystems dominated by synapsids and crocodile-line archosaurs. In this context, South America, particularly southern Brazil, preserves a critical fossil record documenting the emergence of dinosauromorphs and the initial radiation of Dinosauria. This contribution reviews recent discoveries of Triassic dinosauromorphs from the Santa Maria Supersequence of Rio Grande do Sul, Brazil, and discusses their implications for understanding early avemetatarsalian evolution, dinosaur origins, and the initial diversification of Dinosauria. The Brazilian record documents a nearly continuous presence of avemetatarsalians from the Middle (Ladinian) to Late Triassic (Norian), encompassing lagerpetids, silesaurids, herrerasaurids, theropods, and sauropodomorphs. These fossils provide key insights into major evolutionary transitions, including the rise and extinction of herrerasaurids as the earliest apex predatory dinosaurs, and the transformation of early sauropodomorphs from small-bodied carnivores into larger, herbivorous forms. Exceptional preservation in several Brazilian specimens, including articulated skulls and nearly complete skeletons, has substantially advanced our understanding of the anatomy, morphological disparity, and paleoecology during the early evolutionary history of dinosaurs. Despite remaining uncertainties in stratigraphic dating and phylogenetic relationships, the Triassic fossil record of southern Brazil stands as one of the most informative worldwide regarding the initial evolution of dinosauromorphs. Continued discoveries and refined stratigraphic frameworks promise to further clarify the tempo, mode, and ecological context of dinosaur origins.

Understanding how ecological communities respond to environmental change over long timescales is essential for predicting modern ecosystem dynamics. Here, we reconstructed functional community composition and trophic network structure of seven mammal communities from the eastern region of Oregon. We focused on fossil localities that span the past 32 million years. We used diet and body mass to reconstruct community functional diversity and evaluated community differences using correspondence analysis and Fisher’s exact tests. To understand whether there were changes in community trophic structure through time, we also reconstructed potential trophic-species food webs using trait- and body-mass-derived dietary interactions and calculated network metrics that have been linked to ecosystem differences. Overall, functional diversity patterns mirror previously described North American continental trends, including the decline of browsing herbivores and small-bodied omnivores after the mid-Miocene Climatic Optimum. Immigration of novel taxa from the Eurasian continent did influence the functional diversity of these assemblages. Functional diversity also changed because of the late Cenozoic extinction of large-bodied taxa. The reconstructed food-web structure adds further resolution to these patterns. For example, reconstructed food webs for the Oligocene-aged lower Turtle Cove assemblage exhibit high connectance, long trophic chains, and a rich omnivore guild, features consistent with a structurally complex habitat. The Oregon fossil record suggests that as climate shifts, certain mammalian functional groups decrease in diversity, which can impact trophic network structure and overall community structure. These findings highlight how combining trait-based and network-based approaches deepens our understanding of ancient ecosystem change.

Turtles provide an important link between terrestrial and aquatic ecosystems, acting as both predators and prey, while also being an important host for a range of parasites. The dermal armor that characterizes the group ensures their abundance in the vertebrate fossil record and preserves evidence of biotic interactions. We evaluated the ichnofauna and body size distributions of turtles from the early Paleocene Tiupampa Fauna (Santa Lucía Formation), Bolivia, to reconstruct aspects of the Tiupampan ecosystem. We observed bite traces in several specimens of Lapparentemys vilavilensis from the ichnogenera Brutalichnus, Linichnus, Machichnus, and Nihilichnus, which are consistent with predation or scavenging by crocodyliforms, including sebecids and possibly dyrosaurids. The carapaces and plastra also include evidence of invertebrate activity (Karethraichnus and cf. Thatchtelithichnus), interpreted to represent parasitism, possibly by leeches or trematodes. Evidence of fungal or bacterial infection, through records of ichnogenera such as Gunnellichnus or Violinichnus, is rare, but may suggest host–parasite specialization was present shortly after the Cretaceous–Paleogene boundary. The rarity of these features and the general stability of the population, assessed through body size distributions, possibly suggests that the turtles of Tiupampa were not experiencing particularly high levels of environmental stress.

Direct evidence of trophic interactions in the fossil record (e.g., feeding traces, stomach contents) are key to understanding predator–prey relationships between extinct species and reconstructing ancient ecosystems. Recently discovered associated cranial material of an immature Albertosaurus sarcophagus from the Upper Cretaceous (uppermost Campanian–Maastrichtian) Horseshoe Canyon Formation (Alberta, Canada) represents the smallest associated Albertosaurus skull discovered to date. Osteohistological analysis of an associated limb element indicates the individual was at least eight years old at time of death. The specimen preserves two sets of unhealed tooth marks on the mandible. Tooth and denticle mark spacings were studied to identify the potential trace maker. We apply a new method to account for rake angle in tooth and denticle marks to improve the estimation of inter- and intra-mark spacing. Our results reveal that the tooth marks are most consistent with those produced by dromaeosaurids. Given that the tooth marks display no signs of healing, they represent the first documented evidence of a dromaeosaurid feeding/scavenging on tyrannosaurids. Dromaeosaurs and immature tyrannosaurids likely participated in reciprocal predation/scavenging within the carnivorous dinosaur guild. The Albertosaurus specimen and its preserved traces expand our understanding of dromaeosaurid diet and interspecific interactions and provide insight into the skull morphology of young Albertosaurus individuals.

During the Early to Middle Devonian, southwestern Gondwana was characterized by a highly endemic marine fauna defining the Malvinoxhosan (= Malvinokaffric) Realm, a major austral paleobiogeographic domain encompassing South America (except Colombia and Venezuela), Antarctica, and South Africa. Several clades that were diverse elsewhere during this interval were extremely rare or absent in this realm, including conodonts, graptolites, and stromatoporoids. The scarcity of biostratigraphic marker groups has historically complicated stratigraphic correlations across Malvinoxhosan basins. Ammonoids are among these rare groups, previously reported only from a few localities in Argentina and Bolivia. Here, we report a new ammonoid assemblage from the Middle Devonian of the northernmost Precordillera Basin (Sierra de Las Minitas, La Rioja Province, Argentina). 15 specimens, housed in the Museo de Antropología y Ciencias Naturales de la Universidad Nacional de La Rioja, allowed the identification of three species: Epitornoceras baldisi (Leanza), previously known from the Chigua Formation type locality, and two new species assigned to Trimaenioceras Bockwinkel and Korn: Trimaenioceras ivanae n. sp. and Trimaenioceras alegria n. sp. Epitornoceras and Trimaenioceras are known to co-occur exclusively within the uppermost middle Givetian ammonoid biozone (Pharciceras aff. P. amplexum zone), based on data from Morocco. The Argentine fossil-bearing strata are therefore assigned to this interval, providing one of the most precise biostratigraphic correlations for the Devonian of SW Gondwana. This biozone corresponds to the upper part of the Taghanic Crisis interval (end-Middle Devonian), suggesting an incursion of ammonoids into the cold-water basins of the Malvinoxhosan Realm during that time.

UUID: http://zoobank.org/2e549c39-c6cc-402d-867a-d297ce3ed364

Helmetiida is a major group of Trilobitomorpha and Artiopoda known from Cambrian Burgess Shale-type Lagerstätten. Phylogenetic studies have suggested that they are closely related to trilobites as their possible sister taxon. With seven genera and eight species, Helmetiida has only been found in the Burgess Shale and the Chengjiang biota. Here we describe a new helmetiid, Dianhaia heptacantha n. gen. n. sp., from the early Cambrian Chengjiang biota (Cambrian Series 2, Stage 3), Yunnan Province, South China. Dianhaia heptacantha n. gen. n. sp. possesses an anterior sclerite that is diagnostic of Helmetiida. The semicircular cephalon bears a pair of short genal spines. The thorax consists of seven tergites, each having a pair of long pleural spines and showing edge-to-edge articulation. The pygidium carries one short terminal spine and three pairs of long lateral spines. Dianhaia heptacantha n. gen. n. sp. is distinguished from other helmetiids by different numbers of thoracic tergites and pygidial spines. Computed microtomography shows that D. heptacantha n. gen. n. sp. has a pair of antennae and 13 pairs of homonomous biramous appendages. Each biramous appendage consists of a gnathobasic protopodite, seven-podomerous endopodite, and a lobate exopodite with lamellae. Phylogenetic analysis of Artiopoda resolved Dianhaia n. gen. as the sister taxon of Haifengella within Helmetiida. The discovery of this new helmetiid enriches the taxonomic diversity and appendicular morphoanatomy of Cambrian trilobitomorphs from the Chengjiang biota.

UUID: http://zoobank.org/1e9c8dcc-b4e2-4c3e-a2e3-9945692e0c68

Dental adaptations to abrasive wear include increased tooth crown height and complexity of occlusal enamel folds. These trends have been studied extensively in ungulates, and some other mammal groups with hypsodont dentition. Beavers (family Castoridae) represent diverse lineages that occupied different ecological niches through time, including the fossorial beavers of the Oligocene and the semiaquatic beavers that diversified in the Miocene. As an adaptation to the high volume of abrasive grit entering their mouths from digging with their incisors, we hypothesized that the cheek teeth of fossorial beavers had increased occlusal enamel complexity compared to semiaquatic beavers. We chose John Day Fossil Beds National Monument (JDFB) in eastern and central Oregon for this study because of its extensive time range and exceptional preservation of castorid fossils. We took scaled photographs of the occlusal surface of 43 beaver specimens (N = 84 teeth) from six genera (Capacikala MacDonald, 1963; Castor Linnaeus, 1758; Dipoides Schlosser, 1902; Microtheriomys Korth and Samuels, 2015; Monosaulax Stirton, 1935; and Palaeocastor Leidy, 1869) from previously collected JDFB specimens. Each tooth was measured using ImageJ to calculate occlusal enamel index (OEI). We performed an analysis of variance on linear models using residual randomization permutation procedure to test the dependence of enamel complexity on taxonomy, dentition, time, geology, and ecology. Results indicate that genus, epoch, ecology, geologic formation, and geologic formations with combined units of the John Day Formation were significant, however, post-hoc pairwise comparisons resulted in no differences between groups. This suggests that enamel complexity in JDFB beavers does not significantly differ between fossorial and semiaquatic lifestyles.

The 121 Ma Jiufotang Formation in northeastern China contains the greatest avifaunal diversity of any known Mesozoic deposit. Enantiornithine birds dominate this formation with hundreds of exceptionally preserved specimens often bearing soft tissues such as feather traces. Of the described enantiornithines from these deposits, Longipteryx is the most abundant, easily identified by its elongate rostrum and distally restricted, proportionally large teeth. Although numerous specimens of this taxon have been described, data concerning its plumage is surprisingly lacking. Here, we qualitatively describe two new Longipteryx chaoyangensis specimens preserving feathers across the body, including the best evidence of wing feather (remex) morphology thus far for this taxon. The folded wing of Longipteryx has a predominantly linear trailing margin and primary feathers nearly twice the length of the secondaries. Based on remex lengths and the preserved position of the forelimbs, the outstretched wings of Longipteryx may have been intermediate (i.e., a wing profile between the broad morphology inferred for some enantiornithines and the elongate shape reconstructed for Confuciusornis), superficially resembling extant bird species whose wing profiles are associated with bounding, continuous-flapping, and flap-gliding flight. These flight strategies have been previously predicted for some enantiornithines based also on remex and skeletal morphometrics. Additionally, all known Longipteryx specimens lack traces or impressions of tail feathers (rectrices) altogether. Most enantiornithines with preserved rectrices have a pair of elongate ornamental feathers. It is thus unusual and notable that these appear to be absent in both sexes in Longipteryx.

Bioerosion (the biological removal, abrasion, or dissolution of hard substrata) has produced a rich and behaviorally informative trace fossil record spanning the Archean to the Recent. We here present a comprehensive review of the fossil record of bioerosion based on an exhaustive survey of the ichnological literature through August 2026. Building on earlier syntheses, we compile and critically evaluate all currently valid bioerosional ichnogenera and ichnospecies, documenting their original authorship, substratum preference, inferred trace makers, architectural design, ichnofamilial assignment, and stratigraphic ranges resolved to, where possible, the stage level. The resulting database recognizes 151 valid bioerosional ichnogenera and 419 ichnospecies. Analyses of ichnodiversity and ichnodisparity of the bioerosion record shows that the most fundamental architectural designs of bioerosion were established by the end of the Great Ordovician Biodiversification Event (GOBE), with relatively limited innovation thereafter. Ichnogenus diversity increased overall through the Phanerozoic, punctuated by major diversification pulses in the Late Ordovician, Late Triassic, Jurassic, and especially the Cretaceous. In contrast to body fossil patterns, most mass extinctions, including the end-Permian event, are weakly expressed in the bioerosional ichnogenus record, whereas the Cretaceous-Paleogene boundary shows the most pronounced decline. These patterns underscore the resilience and recurrence of bioerosional behaviors through deep time.

The John Day Formation offers a remarkably complete terrestrial record of Eocene-, Oligocene-, and Miocene-aged mammalian faunas in central Oregon. Sites in the John Day Formation have yielded numerous mammalian species spanning across many taxonomic orders, offering a unique opportunity to closely examine changes in mammalian diversity and disparity across a geographically constrained region. However, a comprehensive review of the full diversity and disparity of John Day Formation faunas has not yet been undertaken. In this study, we examine species richness (i.e., taxonomic diversity) alongside morphological disparity in sites in the John Day Formation to assess how these measures vary with each other and with stratigraphy and sampling effort. We did this by gathering a broad dataset of mammalian occurrences across nine sites in the John Day Formation and collected first-molar area for each occurrence, followed by coverage-based rarefaction analyses to assess sampling completeness and calculations of Chao and shareholder quorum subsampling (SQS) richness. We found that sampling appears to have a stronger relationship with taxonomic diversity than with morphological disparity, and that diversity and disparity patterns do not appear to be strongly correlated. We assess these diversity and disparity patterns and discuss implications for the effects of taphonomic and collection biases on calculations of diversity and disparity in fossil assemblages.

Since their first appearance in the fossil record (Cambrian Stage 3, ~520 Ma), echinoderms were already relatively diverse (classes Edrioasteroidea, Eocrinoidea, Helicoplacoidea) and cosmopolitan. Herein, we describe the gogiid Atlaseocrinus new genus—the oldest echinoderm known so far from the African continent (Issafen Formation, Cambrian Series 2, Stage 3; Morocco). The discovery of the oldest articulated specimens from the Iberian Chains (northeastern Spain) clarifies the systematic position of ‘Rhopalocystis’ mesonesensis (Clausen, 2004), which is assigned to the new genus Atlaseocrinus. Atlaseocrinus issafenensis new genus new species has a weakly differentiated stem composed of small, irregularly arranged circular plates. The theca is made of a mosaic of irregularly polygonal plates in five regular circlets, each ornamented with fine granulation and numerous respiratory structures (epispires). The aboral end consists of a single basal plate, which is a trait unique among gogiids. The brachioles comprise two series of alternating floor plates and two series of alternating cover plates. These long appendages branch as bundles of generally three from elevated spouts around the oral frame. Atlaseocrinus mesonesensis new combination from Spain, is included in the new genus based on a single cup-shaped basal plate. Its basal plate has a single through-going canal leading from theca to stem.

UUID: http://zoobank.org/c86c40de-8733-4cfa-b1e3-1593a409f6b5