The small horse from Valley Wells, San Bernardino County, California

Journal of Mammalogy, 1980

Ninety-eight relatively complete metapodials (29 metacarpals and 69 metatarsals) of Equus were recovered from late Pleistocene terrace and valley fill deposits along the Nueces River in western Nueces and San Patricio counties, Texas. Sixteen measurements were taken on each metapodial. Three species of Equus were determined to be present using discriminant functions and bivariate and multivariate plots of the data.

Journal of Mammalian Evolution, 2006

Anewgenus of hypsodont equid, Scaphohippus, is recognized from the Green Hills Division (Ba1), Second Division (Ba1), and Barstow Faunas (Ba2) of the medial Miocene Barstow Formation, as well as fromBa1 andBa2 faunas in the Punchbowl Formation ofCalifornia, the Tesuque Formation of NewMexico, the Pawnee Creek Formation of Colorado, and the Olcott Formation of Nebraska. The genus includes two species, Scaphohippus sumani n. sp. and Scaphohippus intermontanus n. sp. Scaphohippus is a member of the “protohippine” clade, but is differentiated from its more derived sister taxon, Protohippus, by an arc-shaped incisor battery, a shorter I3-P1 diastema, and a more rounded protocone. The upper cheek teeth of S. sumani n. sp. have an unworn crown height of 40 mm. The protocone remains isolated until as much as 60% of wear, and the enamel fossettes are more complex than those of S. intermontanus n. sp. S. intermontanus n. sp. has an unworn crown height of 48–50 mm, the protocone opens by 30% of wear, and the enamel fossettes are simpler than those of S. sumani n. sp. Phyletic analysis shows S. sumani n. sp. to be the more primitive species. Similar facial and dental characteristics reveal a likely common ancestorwith Merychippus insignis. The wider geographic and temporal range of S. sumani n. sp. reported here allows for useful phyletic and biogeographic interpretations. S. sumani n. sp. and M. insignis diverged during the late Hemingfordian (He2) of the Great Plains and both taxa dispersed throughout the western United States. S. intermontanus n. sp. is only recognized from the Barstow Formation, where it was likely directly descended from S. sumani n. sp.

The Texas Journal of Science

For more than a century many paleontologists, biologists, paleoecologists, and archaeologists have contended that Equus species (American horse) became extinct on the North American continent by about 13,000 calibrated years BP – all part of the Late Pleistocene (Ice Age) extinction event. The paleontological project presented here that focuses on Equus from Rancho Carabanchel, San Luis Potosí, México became chronologically intriguing to us in having the horse consistently radiometrically dating into the Holocene, well beyond the presumed extinction event. Our approach to this observation was to conduct successive radiocarbon dates (n=19) tied as closely as possible to fossil remains and to stratigraphic units. The remains of the extant horse, Equus caballus, were recovered only in the upper-most Unit I while the extinct Equus cf. mexicanus, E. cf. conversidens, and E. cf. tau were recovered from the underlying Units II – VI of the late Holocene to approximately 45,000 calibrated ye...

2000

Equus conversidens Owen, E. niobrarensis Hay, E. occidentalis Leidy referred, E. scotti Gidley referred, and a small zebrine horse are recognized from late Pleistocene deposits of Dry Cave, southeastern New Mexico. Equus midlandensis Quinn is synonymized with E. niobrarensis; New Mexican specimens previously rec- ognized as E. scotti are identified asE. niobrarensis. Cluster analysis of measurements of single elements, acting

Ninety-eight relatively complete metapodials (29 metacarpals and 69 metatarsals) of Equus were recovered from late Pleistocene terrace and valley fill deposits along the Nueces River in western Nueces and San Patricio counties, Texas. Sixteen measurements were taken on each metapodial. Three species of Equus were determined to be present using discriminant functions and bivariate and multivariate plots of the data. Equus cf. conlversidens, the most abundant species, is a small- to average-sized horse with normal length metapodials. It is similar to members of the E. alaskae group. The second species, represented by 24 metapodials, is assigned to E. cf. scotti. These are larger horses with robust limbs that resemble members of the E. scotti and E. laurentius groups. The third, represented by six specimens, is a stilt-legged horse of the E. francisci group.

The extinct New World stilt-legged, or NWSL, equids constitute a perplexing group of Pleistocene horses endemic to North America. Their slender distal limb bones resemble those of Asiatic asses, such as the Persian onager. Previous palaeogenetic studies, however, have suggested a closer relationship to caballine horses than to Asiatic asses. Here, we report complete mitochondrial and partial nuclear genomes from NWSL equids from across their geographic range. Although multiple NWSL equid species have been named, our palaeogenomic and morphometric analyses support the idea that there was only a single species of middle to late Pleistocene NWSL equid, and demonstrate that it falls outside of crown group Equus. We therefore propose a new genus, Haringtonhippus, for the sole species H. francisci. Our combined genomic and phenomic approach to resolving the systematics of extinct megafauna will allow for an improved understanding of the full extent of the terminal Pleistocene extinction e...

PloS one, 2017

Horses were a dominant component of North American Pleistocene land mammal communities and their remains are well represented in the fossil record. Despite the abundant material available for study, there is still considerable disagreement over the number of species of Equus that inhabited the different regions of the continent and on their taxonomic nomenclature. In this study, we investigated cheek tooth morphology and ancient mtDNA of late Pleistocene Equus specimens from the Western Interior of North America, with the objective of clarifying the species that lived in this region prior to the end-Pleistocene extinction. Based on the morphological and molecular data analyzed, a caballine (Equus ferus) and a non-caballine (E. conversidens) species were identified from different localities across most of the Western Interior. A second non-caballine species (E. cedralensis) was recognized from southern localities based exclusively on the morphological analyses of the cheek teeth. Not...