Abstract The “butter shale” Lagerstätten of the Cincinnati Arch region is renowned for its well-preserved fossil records, documenting the dynamics of the Late Ordovician “Richmondian Invasion,” during which faunal migration from multiple source basins into the region led to a drastic increase in diversity. Among the diverse fossil groups, ostracods, an important component in marine benthic communities, have been substantially neglected, despite their great potential for paleobiogeographical, paleoecological, and macroevolutionary reconstructions. Here we systematically document ostracods from the butter shale for the first time, with 29 species of 24 genera being described. Two new species, Milleratia binodosa n. sp. and Daleiella ? cincinnatiensis n. sp., are examined in detail. Analyses on faunal composition indicate that ostracods also participated in the process of the invasion during the early and main stages, as evidenced by the presence of both native and migrated taxa from other paleobasins in Laurentia. The studied ostracod fauna, characterized by the dominance of the suborder Binodicopina with relatively low diversity but high abundance, is associated with siliciclastic depositional environments and is consistent with the interpreted depositional setting of the butter shales. We also found strong biogeographical connections of the butter shale ostracod fauna with those within Laurentia as well as with faunas from adjacent paleocontinents, especially Baltica and Avalonia. UUID: http://zoobank.org/1718afb4-a453-4b6a-b5d8-3c36dad835fd
The John Day Formation of central Oregon preserves a diversity of Oligo-Miocene caniform carnivorans, many of which were first described from the formation. However, many historically important specimens lack detailed locality or stratigraphic information, complicating any analysis of faunal change through time. Here, we describe 16 new specimens of caniforms from the John Day Formation, most with precise stratigraphic information. We report multiple specimens of the amphicyonids Daphoenus Leidy, 1853, Paradaphoenus cuspigerus (Cope, 1878), and Temnocyon altigenis (Cope, 1878), all previously known from the formation. We also report the first definitive occurrence of the hesperocyonine canid Osbornodon Wang, 1994 from the John Day Formation and the first occurrence of the borophagine canid Otarocyon Wang, Tedford, and Taylor, 1999 from west of the Rocky Mountains. Two isolated postcranial elements are consistent in size and morphology with large amphicyonines but we cannot confidently assign them to this subfamily. Biostratigraphic trends in these taxa parallel those seen elsewhere in North America, although the turnover in large carnivorans observed at the Oligocene-Miocene boundary on the Great Plains might begin somewhat earlier in Oregon. The possible presence of a large amphicyonine would, however, mark a major temporal range extension for the subfamily and would be the oldest occurrence of this Eurasian taxon in North America.
Estimates of the stratigraphical and paleogeographical ranges of fossil taxa depend on sample sizes, with the limiting case being a sample consisting of a single known specimen. The cnidarian order Conulariida Miller and Gurley, 1896 in the subphylum Medusozoa Petersen, 1979 comprises multiple genera that are represented by < 50 reposited specimens, in some cases from a single locality and stratum. The present note deals with two such genera, Galliconularia Van Iten and Lefebvre, 2020 and Glyptoconularia Sinclair, 1952. The former genus previously was known from the Lower Ordovician of the southern Montagne Noire in France; the latter was known from the Middle Ordovician of the central Moroccan Anti-Atlas (Van Iten et al., 2022) and from the Upper Ordovician of cratonic North America (Van Iten, 1994; Van Iten et al., 2022). Glyptoconularia was represented by < 12 reposited specimens, and Galliconularia was based on a total of 32 specimens.
Abstract Conodonts with conical elements that closely resemble Paleozoic species reappeared in the Early Triassic. The phylogeny, evolution, and paleoecology of these conodonts are poorly known. In this study, we describe a new species of Neostrachanognathus , N. koikei n. sp., one of the conical conodonts, and reconstruct the conodont apparatus of this species according to natural assemblages from the “Toishi-type” siliceous claystone of Japan. The apparatus of N. koikei consists of 15 elements, including two pairs of P, one pair of M, and four pairs of S elements, and a single S 0 element. Notable features include conical P 1 and P 2 elements and nine S elements that are similar in morphology to each other. The S elements of N. koikei are identified as belonging to the form species “ Neohindeodella aequiramosa ” Kozur and Mostler, 1970, specifically to the morphology occurring from the Spathian to the Anisian. Furthermore, S elements of the type species of Neostrachanognathus , N. tahoensis Koike, 1998, appear to correspond to “ Neohindeodella benderi ” (Kozur and Mostler, 1970). Therefore, from these S-element morphologies, we conclude that Neostrachanognathus belongs to the family Ellisoniidae. These conodonts with simplified elements flourished and were widely distributed throughout the world, from continental shelves to the open ocean, during the Early Triassic to the early Middle Triassic. UUID: http://zoobank.org/5e21971a-aac9-432c-8413-1994293867ab
A suite of Miaolingian to Furongian (i.e., traditional middle-upper Cambrian) trilobites are reported from the Abrigo Formation at exposures along Nugget Canyon and adjacent Peppersauce Canyon, Santa Catalina Mountains, Arizona, USA. These fossils are uncommon in the region because the unit predominantly comprises coarser-grained siliciclastic facies deposited near shoreface settings where fossils are not often preserved. Trilobites include Agnostidae gen. indet. sp. indet. and the ptychoparioids Ehmaniella sp. indet.; Neoblairella sp. indet.; Altiocculus sp. indet.; Arapahoia ransomei (Stoyanow, 1936); Bolaspidella sp. indet.; Bolaspididae gen. indet. sp. indet.; Brachyaspidion sp. indet.; Cedaria sp. indet.; Crepicephalus sp. indet.; Elburgia sp. indet.; Eldoradia linnarssoni (Walcott, 1884); Eldoradia prospectensis (Walcott, 1884); Iddingsia sp. indet.; Modocia centralis (Whitfield, 1877); Modocia cf. M. crassimarginata Rasetti, 1965b; Modocia oweni? (Meek and Hayden, 1861); Strigambitus cf. S. transversus Palmer, 1965; and Tricrepicephalus texanus (Shumard, 1861). The type specimens of Arapahoia ransomei and Arapahoia butleri (Stoyanow, 1936) are refigured and considered synonymous. This fauna spans the Ehmaniella to Crepicephalus biozones and the Dunderbergia Biozone; the last has not been previously reported from the Abrigo Formation. This biostratigraphy is calibrated by correlation with regional strata constrained by detrital zircon U-Pb geochronology, which provides ages that are consistent with the observed biozones. Considered together, these data help correlate the Abrigo Formation to more fossiliferous and offshore successions elsewhere in Arizona, Sonora, New Mexico, Texas, USA, and beyond.
We evaluate the systematic position of Shundeagrion cheni Huang, Lia, and Nel, 2024 and transfer it to the odonate suborder Cephalozygoptera and family Dysagrionidae.
The early Maastrichtian kossmaticeratid ammonite Gunnarites serves as an important biostratigraphic index fossil for correlating between localities within the James Ross Basin (JRB), Antarctica. The JRB is the highest southern paleolatitude marine sedimentary outcrop record of the Upper Cretaceous. Gunnarites is abundant within a relatively narrow stratigraphic interval in the JRB, and its presence in outcrops is used to recognize this specific interval, which is coeval with environmental disturbances including cooling temperatures and local sea level regression. Early taxonomic work on the genus (e.g., Spath, 1953) qualitatively described morphological differences between Gunnarites specimens from different locations within the JRB; if real, these location-based differences could have important implications for the utility of Gunnarites for biostratigraphy in the JRB and could contribute to our understanding of controls (e.g., environmental or temporal) on ammonite morphology.To test whether JRB Gunnarites specimens exhibit location-based morphological differences, we collected morphometric measurements (conch morphology and ribbing parameters) from multiple ontogenetic stages on 118 specimens from seven distinct localities within the JRB. We used linear mixed models and generalized additive mixed models to quantitatively evaluate mean differences in morphological variables by location, while accounting for variation in specimen size (i.e., characterizing scaling relationships between size and shape). Every morphological variable except whorl radius expansion rate exhibited significant location-based differences, although patterns of variation across sites differed by morphological variable. These location effects on Gunnarites morphology may be a result of phenotypic variation along an environmental gradient (e.g., depth), a result of temporal effects (e.g., evolution), or a combination of both. Large magnitude morphological differences between nearby locations may also be due, in part, to the influence of stratigraphic repetitions produced by previously hypothesized structural features in the JRB such as faults or folds, which could disrupt spatial or temporal gradients in the basin. Untangling the exact mechanisms behind location-based morphological differences in Gunnarites must await more precise, independent, age-dating of each outcrop.
This study considers Glomalveolina subtilis Hottinger, 1960, to be a distinct species within the genus Glomalveolina, previously grouped with G. lepidula (Schwager, 1883). This species is distinguished by unique morphological and biometrical features, setting it apart from closely related species and establishing it as a significant biostratigraphic marker for the early Ypresian (SBZ6-7) in the central Neo-Tethys. Although first reported from the Iranian platform, it expands the paleobiogeographic distribution of G. subtilis, with earlier records from the western Neo-Tethys (Mediterranean and North African basins) during the early Ilerdian (SBZ5-SBZ6) and from the eastern Neo-Tethys (China) in the middle Ilerdian (SBZ7-SBZ8). The Alveolina biostratigraphy is correlated with the calcareous nannofossil biostratigraphy, placing it in the middle part of the NP10 Zone. This discovery highlights the broader distribution of G. subtilis and its significance in refining biostratigraphic correlations and understanding foraminiferal evolution during the Paleocene-Eocene transition.
Increased dietary specialization has been considered a significant predictor for risk of extinction within the fossil record. However, these interpretations typically come from species-level morphological assessment of diets aggregated across a broad geographic extent. Using the exceptional fossil record of the John Day Formation, we reconstructed dietary niche breadth for the regional community of canids via morphological tooth traits and dental microwear textures to assess how measures of dietary behavior and plasticity might influence species durations. We found that signals of dietary behavior, as inferred from dietary niche breadth estimated via dental microwear textures, showed a stronger relationship with lineage durations than did morphological tooth traits. Specifically, dietary niche breadth was negatively associated with increased species durations. These results suggest the relationship between overall dental morphology and dietary behaviors is more nuanced than previously expected and that the contribution of dietary flexibility irrespective of tooth morphology to extinction risk deserves further attention.
Canids increased in cursoriality through the Cenozoic, as environments transitioned from closed-canopy forest to open grassland and steppe. Canids have evolved through a series of radiations since their origin in the Eocene, but it is unclear if cursorial adaptations appeared in the earliest of these radiations. In the middle Oligocene, the basal hesperocyonines ecologically diversified, and the coyote-sized Mesocyon coryphaeus exemplified the transition from smaller, omnivorous canids to larger, hypercarnivorous forms. M. coryphaeus is exclusively known from the John Day Formation of North America. Although M. coryphaeus is a relatively common fossil in this formation, first recognized in the late 19th century, no postcranial material from this species has ever been formally described. Here, we present a near-complete skeleton of M. coryphaeus, JODA 3366, which includes a complete cranium, near-complete presacral spine, all long bones, elements of both the manus and pes, and a baculum. The short, robust limbs, mobile elbow joint, and tarsal morphology of M. coryphaeus indicate that this species retained a plantigrade to semidigitigrade posture, similar to the earliest canid Hesperocyon, and lacked the cursorial adaptations found in more derived canids. Based on this morphology, we interpret M. coryphaeus as a terrestrial ambush predator, more similar to large mustelids than extant canids, likely hunting small prey like hypertragulids. Although the habitat of M. coryphaeus would have been cooler and more open than the dense closed-canopy forests of the Eocene, enough vegetation cover was still present in the Oligocene for ambush hunting to remain a successful strategy.
Trilobites collected from six locations of the Madison Group (middle to late Tournaisian) of Montana consist of 17 taxa and 11 new species. New species include Proetides raymondi new species, Brachymetopus swimmingwomanensis new species, Liobolina montanaensis new species, Belgibole complanata new species, Belgibole? madisonensis new species, Phillibole? acutis new species, Piltonia sandoi new species, Piltonia douglassi new species, Perexigupyge angusticapitalis new species, and Thigriffides? andersoni new species. Eoameura kollari new genus new species is also recognized, and neotypes are designated for Phillipsia peroccidens (Hall and Whitfield, 1877) and Perexigupyge loganensis (Hall and Whitfield, 1877). The overall taxonomic makeup of the trilobite faunas from the Madison Group is markedly different from that of contemporary strata of the central and eastern United States in that it appears to have a distinctly European generic composition. The lowest unit of the Madison Group (Lodgepole Formation) appears to exhibit a distinct upsectional change from deep- to shallow-water paleobathymetric characteristics that translate into a paleoecological gradient of trilobite species consistent with those seen in contemporary units of western Europe.UUID: http://zoobank.org/22821775-6c6a-4ac5-8fe6-2a34a26db9ab
Three new species of small (similar to 25-200 g) tribosphenic marsupials, including a new genus, are described from the Early Miocene deposits of the Riversleigh World Heritage Area. Phantasmodon travouilloni, Phantasmodon minuferox, and Keeunidae gen. and sp. indet. share dental apomorphies with the late Oligocene marsupials Keeuna woodburnei and Ankotarinja tirarensis (currently Australidelphia incertae sedis), and with Australia's oldest and most plesiomorphic marsupial, the early Eocene Djarthia murgonensis. Parsimony analyses recover these taxa as a distinct clade, warranting recognition of a new marsupial order, Keeunamorphia. In contrast, Bayesian analyses do not support the inclusion of D. murgonensis in this group, instead placing it as a stem australidelphian or stem marsupial. When early Eocene South American and European metatherians are excluded, Keeunamorphia new order appears to be the most basal (parsimony analysis) or one of the most basal (Bayesian analysis) lineages of Australidelphia. However, when these taxa are included in parsimony analysis, Keeunamorphia weakly links to South American sternbergiids and European herpetotheriids, whereas Bayesian analysis suggests keeunamorphians (excluding D. murgonensis) are more closely related to dasyuromorphians than to peramelemorphians, microbiotherians, D. murgonensis, and non-australidelphian metatherians. Keeunamorphia n. ord. may represent some of Australia's earliest marsupials, with possible origins in Gondwana and a record spanning more than 35 million years before its apparent extinction in the Middle Miocene.
