Eight new species of the conodont Neogondolella are described from the Anisian (Middle Triassic) of northeastern British Columbia. The subtlety of morphological variation in this conodont genus has hampered biostratigraphical correlation, but large, often independently dated collections have enabled the description of N. cuneiforme, N. curva, N. hastata, N. dilacerata, N. indicta, N. panlaurentia, N. tenera, and N. vellicata n. spp. Several of these species are widespread, as specimens of N. curva, N. hastata, N. indicta, N. panlaurentia, N. tenera, and N. vellicata are found in contemporary collections from Nevada, whereas N. panlaurentia has also been recovered from the Canadian Arctic. This distribution promises to significantly improve correlation among Anisian sections in North America.

Three new species of the new genus Phyllonaspis are described from Early Devonian localities in the western United States. Phyllonaspis laevis, P. serratus, and P. taphensis are broad, flattened cyathaspids with lateral brims and fine dermal ornament, that show a close relationship to the cyathaspids Boothiaspis and Alainaspis from the late Silurian and Early Devonian of the Canadian Arctic. These taxa are here accommodated within the new subfamily Boothiaspidinae within the family Cyathaspididae. This relationship supports previous evidence of faunal connection between these two areas and indicates dispersal around the Old Red Sandstone Continent from a center in the Canadian Arctic. Isolated oral plates allow a reconstruction of the oral cover and increase our knowledge of the range of oral structures in this family.

Recently discovered specimens of the marsupial Herpetotherium merriami (Stock and Furlong, 1922) from the John Day Formation, Oregon, are described. The species was previously known only from a single (type) specimen. These additional specimens have allowed for a revised diagnosis of the species based on the presence of an additional stylar cusp on the upper molars, as well as the relative size of the stylar cusps. This new material also allows for an examination of the variability within the species and establishes a time range for the species, which extends through most of the Arikareean (late Oligocene: Ar1–Ar3: late Rupelian-Aquitanian). Herpetotherium merriami is distinct within the genus because it is among the larger of the species, but one of the latest occurring, whereas the general pattern of the genus is a reduction in size through time.

We diagnose a new species of Brontotheriidae from a middle Eocene locality, the Clarno Nut Beds, from the Clarno Formation, John Day Basin, Central Oregon. Though renowned for its richness in fossil flora, fossil vertebrates are rare in the Clarno Nut Beds and this new species is the most abundantly represented mammal. Radiometric dating constrains the age of the Nut Beds fauna to about 43.76 Ma within the Uintan North American Land Mammal Age. This new taxon, represented by numerous cranial, mandibular, and dental specimens, is comparatively small for a brontothere and notable for its cranio-caudally shorted nasal incision, a trait shared with three larger-bodied middle Eocene species, Metatelmatherium ultimum, Wickia brevirhinus, and Sthenodectes incisivum. Phylogenetic analysis suggests the sister taxon of the Nut Beds brontothere could be one of two species—Wickia brevirhinus from the Sand Wash Basin of Colorado and Washakie Formation of Wyoming, or Metatelmatherium ultimum, a pan-Beringian species known from the Uintan Formation of Utah (and other Uintan age deposits) and the “Irdin Manha” Formation of Inner Mongolia, China. Phylogenetic results also indicate that the Nut Beds brontothere is a dwarf taxon. Though brontotheres are renowned for having evolved very large body sizes, this new brontothere is one of several discovered in recent decades that suggest evolutionary reductions in body size may have been relatively common in Brontotheriidae.