Late Pleistocene Horse Research Articles

Determining the gait of Miocene, Pliocene, and Pleistocene horses from fossilized trackways

Abstract. Much work has been done on the study of vertebrate gaits over the past several decades and efforts undertaken to apply this to fossil tracks, especially dinosaurs and mammals such as cats, dogs, camels, and horses. This work seeks to expand upon such studies and in particular to study footprints laid down in sand by modern horses and apply such studies to determine the gaits of fossil horse trackways. It thus builds upon the work of Renders (1984a, b) and Kienapfel et al. (2014) and suggests additional measurements that can be taken on horse footprints. In this study the footprints left in the sand by 15 horses of various breeds with various gaits were videotaped, photographed, described, and measured in order to determine characteristics useful in distinguishing gaits. These results were then applied to two new sets of fossil footprints, those of the middle Miocene merychippine horse Scaphohippus intermontanus that I personally examined and measured and those from the late Pleistocene horse Equus conversidens, previously illustrated and described in the literature (McNeil et al., 2007). The latter horse exhibits a fast gallop of around 9.4 m/s, but it is the former whose footprints are quite unique. The quantitative and visual features of these prints are suggestive of a medium-fast gait involving apparent “understepping” of diagonal couplets and hind feet that overlap the centerline. The gait that most closely matches the footprints of Scaphohippus is the “artificial” gait of a slow rack or tölt, or pace, around 1.9 m/s, though an atypical trot of a horse with major conformation issues or which is weaving (swaying) from side to side is a less likely possibility. This intimates, along with the earlier study of Renders (1984a, b), who found the artificial gait of the running walk displayed by Pliocene hipparionine horses, that ancient horses possessed a much greater variety of gaits than modern horses and that over time they lost these abilities with the exception of certain gaited breeds.

Feeding and environmental studies on late Pleistocene horses in mid-latitudes of South America (northern Uruguay)

The first analyses of carbon and oxygen stable isotopes (δ13C, δ18O) on horses of late Pleistocene beds, between 50 and 30 kyr B.P., at mid-latitudes of South America (northern Uruguay), are reported here. Isotopic analyses on Equus neogeus and Hippidion principale were made on tooth enamel, considering the Suess Effect. Isotopic values have been used as indicators of diets and environmental conditions, alongside with Hypsodonty Index, to pinpoint specific feeding strategies as grazer or browser. E. neogeus was a mixed-grazer that fed mostly on C3 grass in open wooded areas and grasslands with a variable proportion of C4 grass in the diet. H. principale was a mixed feeder with preference for open canopy wooded floor C3 grass and plants. These results could explain the co-occurrence of both taxa that evolved a combination of feeding and habitat preferences that resulted in niche differentiation. The isotopic data supports the diversity of habitats previously proposed by other authors and corroborate the environmental context associated to the mammal assemblage in late Pleistocene at these latitudes of South America. Juveniles show δ13C depletion and δ18O enrichment related to adults. This shift could be explained by maternal effect, owing to gestation and lactation (depleted δ13C and enriched δ18O). The later because breast milk is significantly enriched in δ18O in comparison to drinking water and also is not fractionated in the same way as plant-derived carbon.

Species Diversity and Paleoecology of Late Pleistocene Horses From Southern Mexico

Equids are among the most common mammals found in faunal assemblages of Late Pleistocene age in Mexico. Much of what is known about the Equus species is the result of studies conducted in central and northern Mexico; much less is known about species in lower latitudes of Mexico. Here we describe three species that inhabited Oaxaca and Chiapas states. The fossil localities are in northwestern and central Oaxaca, as well as the central part of Chiapas. In Oaxaca, the largest species, Equus mexicanus, and the medium-sized Equus conversidens are represented by mandibles, skulls, diverse isolated teeth and some postcranial bones, while the smallest species, Haringtonhippus francisci is represented by a skull fragment and few isolated teeth. In Chiapas, E. mexicanus is represented by a mandible and several isolated teeth, E. conversidens by several mandibles and diverse isolated teeth, and H. francisci by isolated teeth and two mandibles. AMS radiocarbon and uranium dating of some of the equid localities in Oaxaca and Chiapas indicate that they were at least present since approximately 44,000 Cal BP years, they were common around 30,000 Cal BP years, and were still present at the end of the Pleistocene, around 12,000 years ago. The record of H. francisci from Chiapas is the youngest in North America. A cluster analysis of extended mesowear data and a discriminant analysis showed that Equus conversidens from Chiapas was obligate grazer, whilst the rest of the equids were variable grazers. Geographic distribution of localities in southern Mexico indicates that during the Pleistocene the equid species moved across the Transvolcanic Belt-Sierra Madre del Sur temperate biogeographic corridor and the Tamaulipas-Central America Gulf Lowlands tropical corridor.

Enamel hypoplasia and dental wear of North American late Pleistocene horses and bison: an assessment of nutritionally based extinction models – ERRATUM

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Enamel hypoplasia and dental wear of North American late Pleistocene horses and bison: an assessment of nutritionally based extinction models

AbstractApproximately 50,000–11,000 years ago many species around the world became extinct or were extirpated at a continental scale. The causes of the late Pleistocene extinctions have been extensively debated and continue to be poorly understood. Several extinction models have been proposed, including two nutritionally based extinction models: the coevolutionary disequilibrium and mosaic-nutrient models. These models draw upon the individualistic response of plant species to climate change to present a plausible scenario in which nutritional stress is considered one of the primary causes for the late Pleistocene extinctions.In this study, we tested predictions of the coevolutionary disequilibrium and mosaic-nutrient extinction models through the study of dental wear and enamel hypoplasia ofEquusandBisonfrom various North American localities. The analysis of the dental wear (microwear and mesowear) of the samples yielded results that are consistent with predictions established for the coevolutionary disequilibrium model, but not for the mosaic-nutrient model. These ungulate species show statistically different dental wear patterns (suggesting dietary resource partitioning) during preglacial and full-glacial time intervals, but not during the postglacial in accordance with predictions of the coevolutionary disequilibrium model. In addition to changes in diet, these ungulates, specifically the equid species, show increased levels of enamel hypoplasia during the postglacial, indicating higher levels of systemic stress, a result that is consistent with the models tested and with other climate-based extinction models. The extent to which the increase in systemic stress was detrimental to equid populations remains to be further investigated, but suggests that environmental changes during the late Pleistocene significantly impacted North American equids.

Cheek tooth morphology and ancient mitochondrial DNA of late Pleistocene horses from the western interior of North America: Implications for the taxonomy of North American Late Pleistocene Equus.

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. Notably the separation into caballine and non-caballine species was observed in the Bayesian phylogenetic analysis of ancient mtDNA as well as in the geometric morphometric analyses of the upper and lower premolars. Teeth morphologically identified as E. conversidens that yielded ancient mtDNA fall within the New World stilt-legged clade recognized in previous studies and this is the name we apply to this group. Geographic variation in morphology in the caballine species is indicated by statistically different occlusal enamel patterns in the specimens from Bluefish Caves, Yukon Territory, relative to the specimens from the other geographic regions. Whether this represents ecomorphological variation and/or a certain degree of geographic and genetic isolation of these Arctic populations requires further study.

Late Pleistocene horse Equus (Equus) ferus (Perissodactyla, Equidae) from the Cis-Baikal and Transbaikalia

The paper presents morphological examination of caballoid horse remains (Equus (Equus)) from the Baikal region. The study area stretches from Angara river basin up to western Transbaikalia. Fossil material was dated to the second half of the Late Pleistocene, from Kargin Interstadial to the Late Glacial. In all 18 upper and lower jaws, 34 isolated teeth, 37 metacarpal and 56 metatarsal bones were measured. Comparative analysis of horse remains from the Cis-Baikal area, Transbaikalia, and contemporaneous material from the south of Eastern Europe, the Ural Mountains, Western and North-Eastern Siberia revealed marked intraspecific variation in the Late Pleistocene horses. Observed size variation in skeletal elements reflects temporal and regional variation in horse body size. Multivariate analysis showed that despite the significant size variation between local populations, fossil horses were homogeneous in their morphology. Relative proportions of metacarpal and metatarsal bones remained constant through the Late Pleistocene. Horse remains from the Cis-Baikal area and Transbaikalia were attributed to Equus ferus – a circumpolar species in the Late Pleistocene. Przewalski’s horse (Equus przewalskii) differs from fossil horses by the relative proportions of the limb bones. Based on morphometric analysis we can conclude that E. przewalskii did not inhabit the Baikal region during the Late Pleistocene.

ДОМЕСТИКАЦИЯ ЛОШАДИ В ЮГО-ЗАПАДНОЙ АЗИИ

This compilation of faunal data has allowed the development of a chronology of the dispersal of domesticated horses from the Eurasian steppe into Southwest Asia. During the late Pleistocene horses were widespread throughout much of the Near East, however increasing aridifi cation led to their extinction from the region. Their presence within the archaeological record of the Late Holocene therefore suggests their spread as a human-controlled domesticate. Early domesticated horses are found at Botai, Kazakhstan, although faunal data indicates that Anatolia, Iran and the southern Levant contained surviving populations of wild horses during the mid-Holocene. If these remains from the Levant, western Iran and Anatolia do not belong to native wild progenitors, their presence in Late Chalcolithic deposits indicate an introduction of domesticated horses to this region much earlier than previously assumed. The Buhen horse is the oldest dated domesticated horse in Egypt and was assumed to be anachronistic given the lack of contemporaneous Levantine specimens. However horses were present in the Levant prior to and contemporary with the Buhen horse, illustrating a steady southward distribution from the Eurasian steppe over two millennia dating from the Late Chalcolithic to the Late Bronze Age; a spread likely hastened by the widespread adoption of chariot warfare in the early second millennium BCE.

Late Pleistocene horse and camel hunting at the southern margin of the ice-free corridor: Reassessing the age of Wally’s Beach, Canada

The only certain evidence for prehistoric human hunting of horse and camel in North America occurs at the Wally's Beach site, Canada. Here, the butchered remains of seven horses and one camel are associated with 29 nondiagnostic lithic artifacts. Twenty-seven new radiocarbon ages on the bones of these animals revise the age of these kill and butchering localities to 13,300 calibrated y B.P. The tight chronological clustering of the eight kill localities at Wally's Beach indicates these animals were killed over a short period. Human hunting of horse and camel in Canada, coupled with mammoth, mastodon, sloth, and gomphothere hunting documented at other sites from 14,800-12,700 calibrated y B.P., show that 6 of the 36 genera of megafauna that went extinct by approximately 12,700 calibrated y B.P. were hunted by humans. This study shows the importance of accurate geochronology, without which significant discoveries will go unrecognized and the empirical data used to build models explaining the peopling of the Americas and Pleistocene extinctions will be in error.

Recalibrating Equus evolution using the genome sequence of an early Middle Pleistocene horse.

The rich fossil record of equids has made them a model for evolutionary processes. Here we present a 1.12-times coverage draft genome from a horse bone recovered from permafrost dated to approximately 560-780 thousand years before present (kyr BP). Our data represent the oldest full genome sequence determined so far by almost an order of magnitude. For comparison, we sequenced the genome of a Late Pleistocene horse (43 kyr BP), and modern genomes of five domestic horse breeds (Equus ferus caballus), a Przewalski's horse (E. f. przewalskii) and a donkey (E. asinus). Our analyses suggest that the Equus lineage giving rise to all contemporary horses, zebras and donkeys originated 4.0-4.5 million years before present (Myr BP), twice the conventionally accepted time to the most recent common ancestor of the genus Equus. We also find that horse population size fluctuated multiple times over the past 2 Myr, particularly during periods of severe climatic changes. We estimate that the Przewalski's and domestic horse populations diverged 38-72 kyr BP, and find no evidence of recent admixture between the domestic horse breeds and the Przewalski's horse investigated. This supports the contention that Przewalski's horses represent the last surviving wild horse population. We find similar levels of genetic variation among Przewalski's and domestic populations, indicating that the former are genetically viable and worthy of conservation efforts. We also find evidence for continuous selection on the immune system and olfaction throughout horse evolution. Finally, we identify 29 genomic regions among horse breeds that deviate from neutrality and show low levels of genetic variation compared to the Przewalski's horse. Such regions could correspond to loci selected early during domestication.

Towards a million-year-old genome

The sequencing of a complete horse genome from a bone dating to around 700,000 years ago sheds light on equine evolution and dramatically extends the known limit of DNA survival. See Letter p.74 A low-coverage draft genome sequence has been obtained from a horse bone recovered from a permafrost site in the Yukon Territory, Canada, dated to around 560,000–780,000 years before present. This is by far the earliest genome sequence so far determined. The data were compared to draft genome sequences for a Late Pleistocene horse, those of five contemporary domestic horse breeds, a Przewalski's horse and a donkey. Comparative genomics suggest that the Equus lineage that gave rise to all contemporary horses, zebras and donkeys originated about 4.0–4.5 million years ago — much earlier than previously suspected. The data support the contention that Przewalski's horses — an endangered subspecies native to the Mongolian steppes — represent the last surviving wild horse population.

Origin and History of Mitochondrial DNA Lineages in Domestic Horses

Domestic horses represent a genetic paradox: although they have the greatest number of maternal lineages (mtDNA) of all domestic species, their paternal lineages are extremely homogeneous on the Y-chromosome. In order to address their huge mtDNA variation and the origin and history of maternal lineages in domestic horses, we analyzed 1961 partial d-loop sequences from 207 ancient remains and 1754 modern horses. The sample set ranged from Alaska and North East Siberia to the Iberian Peninsula and from the Late Pleistocene to modern times. We found a panmictic Late Pleistocene horse population ranging from Alaska to the Pyrenees. Later, during the Early Holocene and the Copper Age, more or less separated sub-populations are indicated for the Eurasian steppe region and Iberia. Our data suggest multiple domestications and introgressions of females especially during the Iron Age. Although all Eurasian regions contributed to the genetic pedigree of modern breeds, most haplotypes had their roots in Eastern Europe and Siberia. We found 87 ancient haplotypes (Pleistocene to Mediaeval Times); 56 of these haplotypes were also observed in domestic horses, although thus far only 39 haplotypes have been confirmed to survive in modern breeds. Thus, at least seventeen haplotypes of early domestic horses have become extinct during the last 5,500 years. It is concluded that the large diversity of mtDNA lineages is not a product of animal breeding but, in fact, represents ancestral variability.

Horses Through The Ages

Honoring a renowned specialist in studies of ancient horses, Equids in Time and Space: Papers in Honour of Vera Eisenmann edited by Marjan Mashkour includes 18 chapters by 22 international paleontologists, archaeologists, anatomists, historians, and other experts on living and extinct Equus and related horse relatives. There is also an introduction providing a brief review of Dr. Eisenmann’s life and career. The volume is not without some substantial flaws, but remains a useful acquisition for anyone interested in the history and prehistory of these important animals. The book is hardcover and oversize. Typeface is generally clean and sharp; figures are grayscale and of varying quality, depending upon the author(s). The volume is divided into five more or less equally-weighted sections: geographic distribution, Paleolithic horses, domestication, methodology, and anthropozoology. Equids earlier than the latest Tertiary and Quaternary are not discussed in any detail, reflecting Dr. Eisenmann’s focus on more geologically recent horses. The investigative approaches employed are extremely diverse, including historic and paleontologic literature reviews, interpretations of old and new metric indices, uniand multivariate statistical analyses, and assessments of stable isotope chemistry in fossil equid teeth. The four papers comprising the geographic distribution portion of the volume demonstrate the diversity of investigative methods employed. Deng reviews late Pleistocene Przewalski’s horses from China, using carbon isotopes from dental enamel to suggest that Przewalski’s horses, as arid-adapted animals, can be used to track the waxing and waning of the East Asian monsoon through time. Foronova examines numerous late Pleistocene sites in southern Siberia, determining through dental morphology and morphometric analyses of metapodials that caballine and hemionine horses were all present in the region, but in varying abundance through time depending upon local climate. Pichardo reviews the published literature on late Pleistocene horses from North and South America; this study is unfortunately hampered by an unfocused presentation and an incomplete selection of reference works [several important J Mammal Evol (2008) 15:147–149 DOI 10.1007/s10914-007-9063-5

Late Pleistocene Horse Hunting at the Wally's Beach Site (DhPg-8), Canada

Evidence from the Wally's Beach site in southwestern Alberta indicates Pleistocene horses were hunted by Clovis age peoples. A number of artifacts are associated with a horse skeleton, including a cut-marked hyoid indicative of butchering and a flake projecting below one of the vertebrae that establishes the archaeological material is not intrusive. A large unmodified cobble apparently was used to mark the kill or anchor the cache. Six other finds of horse remains also have associated lithic artifacts. Horse behavior is explored to speculate on hunting strategy. It is concluded that humans and climate change probably contributed to the late Pleistocene extinction of North American horses.

Late Pleistocene Horses of Dry Cave, Eddy County, New Mexico

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 recognized as E. scotti are identified as E. niobrarensis . Cluster analysis of measurements of single elements, acting on matrices of taxonomic distances, appears to allow assignment of intermingled elements to species more successfully than do traditional comparative methods. Cluster analysis based on correlation matrices of limb proportions indicates close similarity of E. niobrarensis to E. przewalskii Poliakoff. Dental characters and cluster analysis suggest that E. conversidens belongs to the subgenus Hemionus or was derived from that subgenus.