Re-Evaluating Hypertragulid Diversity in the John Day Basin, Oregon, USA

Despite their relative abundance, members of the family Hypertragulidae (Artiodactyla, Mammalia) have proved a conundrum regarding species diversity in the Turtle Cove Member (Oligocene) of the John Day Formation, located in central and eastern Oregon. Three species and two separate genera are described in the area, but previous research lacks statistical support for this level of variation. We use coefficients of variation (V) on measurements of dentition and astragali of hypertragulid specimens designated Hypertragulus hesperius, Hypertragulus minutus, and Nanotragulus planiceps as a metric for determining whether there were multiple species present in the population. Asymptotic and modified signed-likelihood ratio V equality tests show that V values of anterior-posterior molar length and transverse molar width vary significantly when comparing single species of modern ecological analogs (Muntiacus muntjak, Muntiacus reevesi, and Tragulus javanicus) to groupings of a combined population. However, the V equality tests on dental and postcranial measurements yield almost no significant results when comparing variation in the extinct John Day hypertragulids to an extant population comprised of a single species. Similar comparisons between astragali measurements of hypertragulids and T. javanicus express no significant difference in the level of variation from the combined population to a modern single species. The low level of variation in the hypertragulids and the lack of differentiation between dental characters of individuals does not statistically support the hypothesis that there were multiple species present in the population, suggesting either that cryptic species may be present but impossible to identify without soft tissue remains, or there may have been taxonomic over-splitting of a single hypertragulid species in the John Day region

Microtomography of an enigmatic fossil egg clutch from the Oligocene John Day Formation, Oregon, USA, reveals an exquisitely preserved 29-million-year-old fossil grasshopper ootheca

Eggs are one of the least understood life stages of insects, and are poorly represented in the fossil record. Using microtomography, we studied an enigmatic fossil egg clutch of a presumed entomological affinity from the Oligocene Turtle Cove Member, John Day Formation, from the National Park Service-administered lands of John Day Fossil Beds National Monument, Oregon. A highly organized egg mass comprising a large clutch size of approximately 50 slightly curved ellipsoidal eggs arranged radially in several planes is preserved, enclosed in a disc-shaped layer of cemented and compacted soil particles. Based on the morphology of the overall structure and the eggs, we conclude that the specimen represents a fossilized underground ootheca of the grasshoppers and locusts (Orthoptera: Caelifera), also known as an egg pod. This likely represents the oldest and the first unambiguous fossil evidence of a grasshopper egg pod. We describe Subterroothecichnus radialis igen. et isp. nov. and Curvellipsoentomoolithus laddi oogen. et oosp. nov., representing the egg pod and the eggs, respectively. We advocate for adopting ootaxonomy in studying fossil eggs of entomological affinities, as widely practiced with fossil amniotic eggs. An additional 26 individual and clustered C. laddi collected throughout the A–H subunits of the Turtle Cove Member suggest the stable presence of grasshoppers in the Turtle Cove fauna, and we discuss the paleoecological implications. Oothecae have convergently evolved several times in several insect groups; this ovipositional strategy likely contributed to the fossilization of this lesser-known ontogenetic stage, enriching our understanding of past insect life

Paleobiology of a Large Mammal Community From the Late Pleistocene of Sonora, Mexico

A paleontological deposit near San Clemente de Térapa represents one of the very few Rancholabrean North American Land Mammal Age sites within Sonora, Mexico. During that time, grasslands were common, and the climate included cooler and drier summers and wetter winters than currently experienced in northern Mexico. Here, we demonstrate restructuring in the mammalian community associated with environmental change over the past 40,000 years at Térapa. The fossil community has a similar number of carnivores and herbivores whereas the modern community consists mostly of carnivores. There was also a 97% decrease in mean body size (from 289 kg to 9 kg) because of the loss of megafauna. We further provide an updated review of ungulates and carnivores, recognizing two distinct morphotypes of Equus, including E. scotti and a slighter species; as well as Platygonus compressus; Camelops hesternus; Canis dirus; and Lynx rufus; and the first regional records of Palaeolama mirifica, Procyon lotor, and Smilodon cf. S. fatalis. The Térapa mammals presented here provide a more comprehensive understanding of the faunal community restructuring that occurred in northern Mexico from the late Pleistocene to present day, indicating further potential biodiversity loss with continued warming and drying of the region

A Comparison of the Clarendonian Equid Assemblages from the Mission Pit, South Dakota and Ashfall Fossil Beds, Nebraska

The Mission Pit locality (SDSM V5314), near Mission, South Dakota, has produced a large collection of equid teeth obtained from the Miocene Ash Hollow (=Thin Elk) Formation. Ashfall Fossil Beds (UNSM Ap-116), near Royal, Nebraska, has yielded an extensive collection of equid cranial elements and teeth derived from the Cap Rock Member, Ash Hollow Formation. The two sites are interpreted to be Clarendonian in age [12.5 to 9.0 Ma], but may contain faunal assemblages from differing Clarendonian subages. The two sites exhibit a notably similar composition of equid genera, including the tribes Equini (Pliohippus, Calippus, and Protohippus), and Hipparionini (Cormohipparion, Neohipparion, and Pseudhipparion). Both sites share the same proportion of the equid tribes Hipparionini and Equini. Approximately seventy-five percent of the equids at both sites are members of the Hipparionini tribe, whereas twenty-five percent are of the Equini tribe. The comparative composition within the Equini tribe between the two sites is nearly identical with differences in the absence of Calippus at Ashfall and a larger proportion of Protohippus at Mission. Only slight differences are observed in the composition of genera within the Hipparionini tribe between the two sites, with the Mission Pit containing a higher percentage of Neohipparion. The striking taxonomic similarity between the two sites is not only unique but also rare, suggesting a correlative relationship within the early to medial Clarendonian (Cl1 or Cl2). This similarity also suggests unique paleoecological relationships among equids and has a potential for insight into plant ecology and equid niche partitioning during this time interval. Includes Appendix A & Appendix B

Data from: Statistical analysis of dental variation in the Oligocene equid Miohippus (Mammalia, Perissodactyla) of Oregon

As many as eight species of the “anchitherine” equid Miohippus have been identified from the John Day Formation of Oregon, but no statistical analysis of variation in these horses has yet been conducted to determine if that level of diversity is warranted. Variation of the anterior-posterior length and transverse width of upper and lower teeth of Turtle Cove Member Miohippus was compared to that of M. equinanus, Mesohippus bairdii, Equus quagga, and Tapirus terrestris using t tests of their coefficients of variation (V). None of the t tests are significant, indicating that the variation seen in Turtle Cove Miohippus is not significantly different from any of the populations of other perissodactyls examined in this study. Data also indicate that Mesohippus is present in the Turtle Cove Member. Additionally, hypostyle condition, used to diagnose all species of Miohippus, was found to be related to stage of wear using an ordered logistic regression. Only two species of equid, one Miohippus and one Mesohippus, in the Turtle Cove Member can be identified, therefore only Miohippus annectens, the genotype and first species described from the region, can be recognized as the sole Miohippus species known from the Turtle Cove assemblage. There are insufficient data to determine which species of Mesohippus is present. The dependence of hypostyle condition on crown height in Miohippus implies that wear stage must also be considered in investigations of dental morphology in the “Anchitheriinae.

On the relationship between enamel band complexity and occlusal surface area in Equids (Mammalia, Perissodactyla)

Enamel patterns on the occlusal surfaces of equid teeth are asserted to have tribal-level differences. The most notable example compares the Equini and Hipparionini, where Equini have higher crowned teeth with less enamel-band complexity and less total occlusal enamel than Hipparionini. Whereas previous work has successfully quantified differences in enamel band shape by dividing the length of enamel band by the square root of the occlusal surface area (Occlusal Enamel Index, OEI), it was clear that OEI only partially removes the effect of body size. Because enamel band length scales allometrically, body size still has an influence on OEI, with larger individuals having relatively longer enamel bands than smaller individuals. Fractal dimensionality (D) can be scaled to any level, so we have used it to quantify occlusal enamel complexity in a way that allows us to get at an accurate representation of the relationship between complexity and body size. To test the hypothesis of tribal-level complexity differences between Equini and Hipparionini, we digitally traced a sample of 98 teeth, one tooth per individual; 31 Hipparionini and 67 Equini. We restricted our sampling to the P3-M2 to reduce the effect of tooth position. After calculating the D of these teeth with the fractal box method which uses the number of boxes of various sizes to calculate the D of a line, we performed a t-test on the individual values of D for each specimen, comparing the means between the two tribes, and a phylogenetically informed generalized least squares regression (PGLS) for each tribe with occlusal surface area as the independent variable and D as the dependent variable. The slopes of both PGLS analyses were compared using a t-test to determine if the same linear relationship existed between the two tribes. The t-test between tribes was significant (p < 0.0001), suggesting different D populations for each lineage. The PGLS for Hipparionini was a positive but not significant (p = 0.4912) relationship between D and occlusal surface area, but the relationship for Equini was significantly negative (p = 0.0177). λ was 0 for both tests, indicating no important phylogenetic signal is present in the relationship between these two characters, thus the PGLS collapses down to a non-phylogenetic generalized least squares (GLS) model. The t-test comparing the slopes of the regressions was not significant, indicating that the two lineages could have the same relationship between D and occlusal surface area. Our results suggest that the two tribes have the same negative relationship between D and occlusal surface area but the Hipparionini are offset to higher values than the Equini. This offset reflects the divergence between the two lineages since their last common ancestor and may have constrained their ability to respond to environmental change over the Neogene, leading to the differential survival of the Equini

Palaeogale von Meyer 1846

Genus Palaeogale von Meyer, 1846 Bunaelurus Cope, 1873: 8. — Type species: B. lagophagus. TYPE SPECIES. — Palaeogale minuta Gervais, 1848 (synonym of Mustela) by original designation. GENUS DIAGNOSIS. — “An early mustelid with cheek tooth formula 1.4/1-3.2-1/2. P1 and M2 vestigial or absent. P4 with small protocone, directed forward, large, somewhat recumbent main blade separated by a deep cleft from the strong metastylar blade. M1 strongly transverse, short and wide, triangular, with sharply projecting parastyle, small, simple protocone, not expanded anteroposteriorly and without cingulum. P2 procumbent, with long, shearing heel. M1 compressed, without metaconid, heel unbasined, with longitudinal shearing crest. M2 small but functional, elongate oval in outline, with weak longitudinal crest, without metaconid or basined talonid but with three vague cusps in series. No postorbital processes. No ossified auditory meatus. Palate ending at level of M1. Pterygoid crests converging posteriorly. Cerebellar region long and bounded externally by a distinct groove posterior to the cerebral region. Stylomastoid foramen lateral, near porus. Foramen ovale posterior to level of postglenoid processes. Carotid foramen small and nearly confluent with posterior lacerate foramen. Sagittal crest single throughout. Paroccipital process free, small.” (Simpson 1946: 12)Published as part of Famoso, Nicholas A. & Orcutt, John D., 2022, First occurrences of Palaeogale von Meyer, 1846 in the Pacific Northwest, United States, pp. 427-436 in Geodiversitas 44 (14) on page 430, DOI: 10.5252/geodiversitas2022v44a14, http://zenodo.org/record/644863

Palaeogale dorothiae MacDonald 1963

Palaeogale dorothiae MacDonald, 1963 (Fig. 3; Table 2) REFERRED SPECIMENS. — JODA 6177 left fragmentary dentary with p4-m1. JODA 5893 right fragmentary dentary with p2 and p4. OCCURRENCE. — JDNM-140, Lonerock, Gilliam County, Oregon, USA. Kimberly Member, John Day Formation. Precise locality information available to qualified researchers upon request. AGE. — Late Oligocene in the Late Arikareean (Ar3) NALMA, between the Tin Roof Tuff (25.3 Ma) and the UNSM JD-BC-3 tuff (23.5-23.8 Ma) (Fremd & Whistler 2009). SPECIES DIAGNOSIS. — The p4 is without a posterior accessory cusp and the protoconid of the m1 is not expanded laterally (MacDonald 1963). DESCRIPTION JODA 5893 has no posterior accessory cusp on p4; however, there is a small enamel anomaly on the posterior edge. There is an alveolus for p3. The p2 crown is stretched forward with an upturned posterior heel. JODA 6177 is broken behind the c, and there is no p2 alveoli. There is no p4 accessory cusp. The m1 protoconid is not expanded laterally. See Table 2 for measurements of both specimens. COMPARISON Both specimens match the species diagnosis in the absence of the p4 accessory cusp. They are both too large to be P. minuta. In JODA 5893, the morphology of the p4 is similar to P. sectoria (Lange-Badre & Dashzeveg 1989; Wang & Zhang 2015). The size of JODA 6177 is comparable to P. sectoria from Mongolia but the protoconid of the m1 is not expanded (Lange-Badre & Dashzeveg 1989; Wang & Zhang 2015). The type specimen is from the Sharps Formation of South Dakota which is 30-28.6 Ma (MacDonald 1963; McConnell & DiBenedetto 2012). Swisher (1982) states that this species is also known from the Brown Siltstone Beds or Whitney Member of the Brule Formation (c. 31-30 Ma) and the Unit B Member of the Gering Formation (28.26-28.11 Ma) both of Nebraska (Tedford et al. 1996, 2004). This makes the Lonerock specimens, which are between 25.3 and 23.8 Ma, the latest known occurrences of this species.Published as part of Famoso, Nicholas A. & Orcutt, John D., 2022, First occurrences of Palaeogale von Meyer, 1846 in the Pacific Northwest, United States, pp. 427-436 in Geodiversitas 44 (14) on page 432, DOI: 10.5252/geodiversitas2022v44a14, http://zenodo.org/record/644863

Palaeogale undetermined

Palaeogale sp. (Fig. 2; Table 1) REFERRED SPECIMEN. — JODA 13221, Skull; Braincase broken on both sides, exposing endocase. Posterior sagittal crest absent. Zygomatic arches absent. Incisors and left premolar absent. Tympanic bulla broken exposing endocast. LOCALITY. — JDNM-7B, North Foree, Grant County, Oregon, USA. Unit E2, Turtle Cove Member, John Day Formation. Precise locality information available to qualified researchers upon request. AGE. — Middle Oligocene in the Early Arikareean (Ar1) NALMA, between A/B tuff (30.0 Ma) and Blue Basin Tuff (28.9 Ma) (Albright et al. 2008). DESCRIPTION JODA 13221 is a mostly complete skull. The braincase is broken on both sides, exposing endocase. Posterior sagittal crest is broken, and the zygomatic arches are broken. The tympanic bulla is broken, exposing the endocast. All Incisors are broken in the alveoli.The canines are missing but the alveoli are present and filled with matrix. Both P1s are missing and some matrix and dentine are present in the alveoli. The left P2 is broken at the roots which are lodged in the alveoli. The crown of the left P4 is damaged as is that of the left M1. The protocone of both the left and right M1s are present but are heavily worn. Dentition In the P4, the protocone is small and rounded. In the M1, the protocone is small but is worn so other characters are unknown. However, the M1 is triangular, transverse, short and wide, with a sharply projecting parastyle. Alveoli are present for both right and left P1. M2 is absent. See Table 1 for measurements. Cranium The skull is elongate (total length of 50.63 mm; max skull height of 14.76 mm) while the muzzle is short (14.50 mm from the naris to the orbit) making up about 29% of the total skull length.Tympanic bullae are elongate and rounded. The sagittal and occipital crests are damaged. COMPARISON There are no species level characters that are identified on the skull making a species level diagnosis impossible. Inference based on size is possible, but it lacks the rigor to justify a species-level diagnosis. It is likely that this specimen belongs to P. sectoria based on the size (Wang & Zhang 2015), but it also overlaps in size with P. minuta (Hayes 2000). This specimen could be attributed to P. sectoria because of the presence of the P1s, but it is on the smaller end of the body size distribution. However, the presence of the P1s has been shown to be a plastic character in this genus (Simpson 1946). Additionally, P. sectoria is traditionally known from the Oligocene while P. minuta is known from the Miocene (de Bonis 1981) further suggesting this specimen could be P. sectoria. However, this is called into question by the presence of P. sectoria in the Miocene of South Dakota (Harksen & MacDonald 1967) and reference to specimens of this species from the Eocene (Baskin & Tedford 1996; Boyd & Welsh 2014). The morphology of JODA 13221 also closely resembles a skull from the Oligocene White River Badlands of South Dakota (BADL 18581/SDSM 7118) which has also not been assigned to a specific species of Palaeogale (Benton et al. 2015). The teeth of JODA 13221 are not robust or large enough to be P. hyaenoides (Fejfar et al. 2003), or P. praehyaenoides (Morlo 1996). The skull clearly cannot belong to Cryptailurus, the other genus putatively in the Palaeogalidae, because the muzzle is narrow, P4 protocone is less developed, and the bullae are inflated and less flattened ventrally (Martin & Lim 2001).Published as part of Famoso, Nicholas A. & Orcutt, John D., 2022, First occurrences of Palaeogale von Meyer, 1846 in the Pacific Northwest, United States, pp. 427-436 in Geodiversitas 44 (14) on pages 430-431, DOI: 10.5252/geodiversitas2022v44a14, http://zenodo.org/record/644863

Occlusal Enamel Complexity in Middle Miocene to Holocene Equids (Equidae: Perissodactyla) of North America

<div><p>Four groups of equids, “Anchitheriinae,” Merychippine-grade Equinae, Hipparionini, and Equini, coexisted in the middle Miocene, but only the Equini remains after 16 Myr of evolution and extinction. Each group is distinct in its occlusal enamel pattern. These patterns have been compared qualitatively but rarely quantitatively. The processes influencing the evolution of these occlusal patterns have not been thoroughly investigated with respect to phylogeny, tooth position, and climate through geologic time. We investigated Occlusal Enamel Index, a quantitative method for the analysis of the complexity of occlusal patterns. We used analyses of variance and an analysis of co-variance to test whether equid teeth increase resistive cutting area for food processing during mastication, as expressed in occlusal enamel complexity, in response to increased abrasion in their diet. Results suggest that occlusal enamel complexity was influenced by climate, phylogeny, and tooth position through time. Occlusal enamel complexity in middle Miocene to Modern horses increased as the animals experienced increased tooth abrasion and a cooling climate.</p></div