\u3ci\u3eMylanodon rosei\u3c/i\u3e, a New Metacheiromyid (Mammalia: Palaeanodonta) from the Late Tiffanian (Late Paleocene) of Northwestern Wyoming

Mylanodon rosei is a new genus and species of late Paleocene metacheiromyid palaeanodont from a new late Tiffanian locality, Y2K Quarry, in the Clarks Fork Basin, Wyoming. The type is an adult dentary with P4 and a molariform double-rooted M1. This provides the first evidence that molariform teeth were retained in early Metacheiromyidae. A second specimen is a juvenile dentary with a partial P3 and an unerupted P4. This is the first juvenile dentition known for a Paleocene metacheiromyid. The new specimens enable determination of dental homologies. Reduction of teeth in early metacheiromyids took place from back to front, opening the characteristic posterior diastema. Both Mylanodon and Propalaeanodon, a slightly older metacheiromyid, are intermediate morphologically and temporally between the older Tiffanian epoicotheriid Amelotabes and the younger Clarkforkian and Wasatchian metacheiromyid Palaeanodon. Propalaeanodon has a single-rooted M1, a derived characteristic not found in Mylanodon, suggesting that two lineages are involved and Propalaeanodon was not ancestral to Mylanodon

Statistics of Solar Wind Electron Breakpoint Energies Using Machine Learning Techniques

Solar wind electron velocity distributions at 1 au consist of a thermal "core" population and two suprathermal populations: "halo" and "strahl". The core and halo are quasi-isotropic, whereas the strahl typically travels radially outwards along the parallel and/or anti-parallel direction with respect to the interplanetary magnetic field. With Cluster-PEACE data, we analyse energy and pitch angle distributions and use machine learning techniques to provide robust classifications of these solar wind populations. Initially, we use unsupervised algorithms to classify halo and strahl differential energy flux distributions to allow us to calculate relative number densities, which are of the same order as previous results. Subsequently, we apply unsupervised algorithms to phase space density distributions over ten years to study the variation of halo and strahl breakpoint energies with solar wind parameters. In our statistical study, we find both halo and strahl suprathermal breakpoint energies display a significant increase with core temperature, with the halo exhibiting a more positive correlation than the strahl. We conclude low energy strahl electrons are scattering into the core at perpendicular pitch angles. This increases the number of Coulomb collisions and extends the perpendicular core population to higher energies, resulting in a larger difference between halo and strahl breakpoint energies at higher core temperatures. Statistically, the locations of both suprathermal breakpoint energies decrease with increasing solar wind speed. In the case of halo breakpoint energy, we observe two distinct profiles above and below 500 km/s. We relate this to the difference in origin of fast and slow solar wind.Comment: Published in Astronomy & Astrophysics, 11 pages, 10 figure

Carpolestes simpsoni, New Species (Mammalia, Proprimates) from the Late Paleocene of the Clark's Fork Basin, Wyoming

131-162http://deepblue.lib.umich.edu/bitstream/2027.42/48654/2/ID521.pd

Oldest Skeleton of a Plesiadapiform provides additional evidence for an exclusively arboreal radiation of stem Primates in the Palaeocene

Palaechthonid plesiadapiforms from the Palaeocene of western North America have long been recognized as among the oldest and most primitive euarchontan mammals, a group that includes extant primates, colugos and treeshrews. Despite their relatively sparse fossil record, palaechthonids have played an important role in discussions surrounding adaptive scenarios for primate origins for nearly a half-century. Likewise, palaechthonids have been considered important for understanding relationships among plesiadapiforms, with members of the group proposed as plausible ancestors of Paromomyidae and Microsyopidae. Here, we describe a dentally associated partial skeleton of Torrejonia wilsoni from the early Palaeocene (approx. 62Ma) of New Mexico, which is the oldest known plesiadapiform skeleton and the first Palaechthonid plesiadapiforms from the Palaeocene of western North America have long been recognized as among the oldest and most primitive euarchontan mammals, a group that includes extant primates, colugos and treeshrews. Despite their relatively sparse fossil record, palaechthonids have played an important role in discussions surrounding adaptive scenarios for primate origins for nearly a half-century. Likewise, palaechthonids have been considered important for understanding relationships among plesiadapiforms, with members of the group proposed as plausible ancestors of Paromomyidae and Microsyopidae. Here, we describe a dentally associated partial skeleton of Torrejonia wilsoni from the early Palaeocene (approx. 62Ma) of New Mexico, which is the oldest known plesiadapiform skeleton and the firs

Mylanodon rosei, a new metacheiromyid (Mammalia, Palaeanodonta) from the late Tiffinian (late Paleocene) of northwestern Wyoming

385-399http://deepblue.lib.umich.edu/bitstream/2027.42/48666/2/ID533.pd

Systematics and Phylogeny of Late Paleocene and Early Eocene Palaeoryctinae (Mammalia, Insectivora) from the Clarks Fork and Bighorn Basins, Wyoming

p. 119-154http://deepblue.lib.umich.edu/bitstream/2027.42/41252/1/C31-5.pd

New Primates (Mammalia) From The Early and Middle Eocene Of Pakistan And Their Paleobiogeographical Implications

http://deepblue.lib.umich.edu/bitstream/2027.42/61363/1/GunnellContributions32 no1.pd

New species of Macrocranion (Mammalia, Lipotyphla) from the earliest Eocene of North America and its biogeographic implications

373-384http://deepblue.lib.umich.edu/bitstream/2027.42/48665/2/ID532.pd

Evolution and Allometry of Calcaneal Elongation in Living and Extinct Primates

Specialized acrobatic leaping has been recognized as a key adaptive trait tied to the origin and subsequent radiation of euprimates based on its observed frequency in extant primates and inferred frequency in extinct early euprimates. Hypothesized skeletal correlates include elongated tarsal elements, which would be expected to aid leaping by allowing for increased rates and durations of propulsive acceleration at takeoff. Alternatively, authors of a recent study argued that pronounced distal calcaneal elongation of euprimates (compared to other mammalian taxa) was related primarily to specialized pedal grasping. Testing for correlations between calcaneal elongation and leaping versus grasping is complicated by body size differences and associated allometric affects. We re-assess allometric constraints on, and the functional significance of, calcaneal elongation using phylogenetic comparative methods, and present an evolutionary hypothesis for the evolution of calcaneal elongation in primates using a Bayesian approach to ancestral state reconstruction (ASR). Results show that among all primates, logged ratios of distal calcaneal length to total calcaneal length are inversely correlated with logged body mass proxies derived from the area of the calcaneal facet for the cuboid. Results from phylogenetic ANOVA on residuals from this allometric line suggest that deviations are explained by degree of leaping specialization in prosimians, but not anthropoids. Results from ASR suggest that non-allometric increases in calcaneal elongation began in the primate stem lineage and continued independently in haplorhines and strepsirrhines. Anthropoid and lorisid lineages show stasis and decreasing elongation, respectively. Initial increases in calcaneal elongation in primate evolution may be related to either development of hallucal-grasping or a combination of grasping and more specialized leaping behaviors. As has been previously suggested, subsequent increases in calcaneal elongation are likely adaptations for more effective acrobatic leaping, highlighting the importance of this behavior in early euprimate evolution