Studying the Evolution of the Horse's Spine

Modern horses are expert runners. They reach top speeds using a special running gait in which they hold their back stiff as they move. A new study published today reveals that tiny fossil ancestors of modern horses may have moved quite differently to their living counterparts.

"Horses provide a perfect case-study on the evolution of running because they have such an amazing fossil record", explains author Dr. Katrina Jones, a post-doctoral researcher in Harvard's Museum of Comparative Zoology. Dating back over 50 million years, the oldest horse ancestors were no bigger than a house cat. From those ancient horse ancestors, some lineages evolved larger sizes, grazing habit and limbs that were specialized for running. This new study suggests that the stiff-backed gait of modern horses likely evolved to save energy while running as horses got bigger through their evolution.

"For over a century, researchers studied the feet of fossil horses to explain how they evolved features specialized for running," explains Jones, "but very little is known about how the backbone might be involved in this famous transition." Four-legged mammals tend to move their lower back during running to help increase speed and regulate breathing. But horses are unusual because they restrict the motion of their lumbar spine to a single joint near their rump. Jones wanted to find out if this unusual pattern was shared by extinct horses, and how increasing size in horse evolution may have affected their back mobility and running style.

To understand the evolution of the back in fossil horses, Jones first examined the anatomy and mobility of the spine in modern domestic horses. The shape of the vertebral joints--bony connections between the vertebrae--help determine how much motion occurs at each joint. Armed with this information, Jones then measured the shape of vertebral joints in 16 species of fossil horses spanning their full size and age range.

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Late Pleistocene Quaternary Horses in Mexico had a Very Adaptable Diet, More Than Modern Horses

Dietary adaptability of Late Pleistocene Equus from West Central Mexico

Authors:

Marín-Leyva et al

Abstract:

Most of the Pleistocene species of Equus from Mexico have been considered to be grazers and highly specialized on the basis of their craniodental features, and therefore analogous to their modern relatives from an ecological point of view. Here we rely on dental wear analyses of three different species of Rancholabrean Equus that exhibit differences in limb proportions and body mass and occurred in two different habitats in order to test whether species exhibited more heterogeneous dietary capabilities compared to modern horses. Overall, and although our analyses show grazer lifestyles, there is a significant degree of dietary variability among taxa according to the site, apparently as a response to differences in climate and environmental conditions, with intermediate feeding preferences on the basis of the last items consumed during the last days prior to death in some cases. Accordingly, fossil Equus might have been more sensitive to different environments and diverse in terms of dietary preferences, thus incorporating a higher proportion of browse vegetation if necessary, than their modern relatives. These results highlight the dietary plasticity of certain fossil species, and evidence the caution that should be paid when reconstructing the ecology of fossil species using their modern relatives as analogs.

Hominins From Lower Paleolithic Schöningen Spear Site Competed With Sabre Tooth Cats and ate a lot of Horse

Bone taphonomy of the Schöningen “Spear Horizon South” and its implications for site formation and hominin meat provisioning

Authors:

Starkovich et al

Abstract:

This paper presents the faunal remains from the new excavation area at the Lower Paleolithic site of Schöningen. The focus of the study is on the southern extension of the main find horizon (Spear Horizon South), which includes the layer that yielded the famous Schöningen spears (13 II-4). Taxonomic data corroborate previous studies, that hominins primarily hunted Equus mosbachensis, a large Pleistocene horse. Equid body part representation at the site suggests that the animals were hunted and butchered locally. There is no evidence for density-mediated attrition in the assemblage. Weathering damage is uncommon, though there is ample evidence that carnivores had access to the bone. Carnivore bite sizes were measured and compared to experimental data provided by previous authors. Based on relationships between bite size and carnivore behavior and body size, we conclude that the primary modifying agents were large carnivores (i.e., wolves or saber-toothed cats). Previous studies show that carnivores often had secondary access to the remains, after hominins. Cut marks are commonly arranged haphazardly on the bones. This may indicate that multiple hominins participated in the butchery of horse skeletons, or that they were butchered over the course of hours or days. Cut marks on axial elements are more “orderly,” which probably reflects the physical logistics of orienting one's body in relation to a large carcass. These data differ from sites formed by Middle and Upper Paleolithic hominins, which might suggest that in later times, a system of organized meat provisioning was already in place. Taken together, the faunal evidence from the Spear Horizon South indicates that late Lower Paleolithic hominins using the site understood the behaviors of different prey species, hunted socially to take down large game, and successfully competed with large carnivores on the landscape for primary access to ungulate remains.

Hominins From Lower Paleolithic Schöningen Spear Site ate a lot of Horse

The larger mammal fauna from the Lower Paleolithic Schöningen Spear site and its contribution to hominin subsistence

Authors:

van Kolfschoten et al

Abstract:

The locality Schöningen (Germany) is an important source of knowledge about Lower Paleolithic hominin subsistence. The locality includes a series of sites dated to the late Middle Pleistocene with a Holsteinian (MIS 11) and Reinsdorf Interglacial (MIS 9) age. One of the youngest sites is Schöningen 13 II-4, the Spear Horizon site also known as the Horse Butchery site. The organic remains excavated here are exceptionally well-preserved as they were embedded in anaerobic, waterlogged sediments in an area where the groundwater is rich in calcium carbonate. The fossil assemblage is ideal for the study of patterns in hominin interference with the mammalian species encountered at the site.

The vertebrate record is extensive and very diverse. The fossil larger carnivore guild of the Spear Horizon faunal assemblage includes saber-toothed cat, fox, and wolf. Herbivores are represented by an elephant species, two equid species, two rhinoceros species, two cervid species, and two large bovid species.

Evidence of hominin interference presents itself as either marks on skeletal remains related to the use of bones as knapping tools or hammers, or as marks that indicate butchering activities such as skinning, dismembering, defleshing, filleting, and marrow extraction. The humerus of the saber-toothed cat clearly shows that the bone has been used as a knapping tool. The fossil remains of the other larger carnivores do not show any signs of hominin interference or exploitation. This also applies to the limited number of elephant and rhinoceros remains found at the site. The large horse Equus mosbachensis dominates the larger mammal record and played a major role in hominin subsistence. Marks on the horse bones indicate that a large number of carcasses have been butchered. Traces on the fossil remains of both red deer (Cervus elaphus) and the large bovids also indicate exploitation by Lower Paleolithic hominins.

Eocene Paleogene Eohippus Found With Fossil Fetus

Description of a Well Preserved Fetus of the European Eocene Equoid Eurohippus messelensis

Authors:

Lorenz Franzen et al

Abstract:

The early Middle Eocene locality of Grube Messel, near Darmstadt (Germany), is famous for its complete vertebrate skeletons. The degree of preservation of soft tissues, such as body silhouettes, internal organs and gut contents, is frequently remarkable. The present specimen was analyzed for remnants of the reproductive system. Classic anatomy and osteology and high-resolution micro-x-ray were applied to describe the fetus of the European Eocene equoid Eurohippus messelensis. Scanning electronic microscopy (SEM) was used for determination of soft tissue remnants. The fetus is the earliest and best-preserved fossil specimen of its kind. The postcranial fetal skeleton is almost complete and largely articulated, allowing the conclusion that the pregnant mare was in late gestation. The apparent intrauterine position of the fetus is normal for the phase of pregnancy. Death of mare and fetus were probably not related to problems associated with parturition. Soft tissue interpreted as the uteroplacenta and a broad uterine ligament are preserved due to bacterial activity and allow considerations on the evolutionary development of the structures.

Evolutionary Genomics and Conservation of the Endangered Przewalski’s Horse

Evolutionary Genomics and Conservation of the Endangered Przewalski’s Horse

Authors:

Der Sarkissian et al

Abstract:

Przewalski’s horses (PHs, Equus ferus ssp. przewalskii) were discovered in the Asian steppes in the 1870s and represent the last remaining true wild horses. PHs became extinct in the wild in the 1960s but survived in captivity, thanks to major conservation efforts. The current population is still endangered, with just 2,109 individuals, one-quarter of which are in Chinese and Mongolian reintroduction reserves [ 1 ]. These horses descend from a founding population of 12 wild-caught PHs and possibly up to four domesticated individuals [ 2–4 ]. With a stocky build, an erect mane, and stripped and short legs, they are phenotypically and behaviorally distinct from domesticated horses (DHs, Equus caballus). Here, we sequenced the complete genomes of 11 PHs, representing all founding lineages, and five historical specimens dated to 1878–1929 CE, including the Holotype. These were compared to the hitherto-most-extensive genome dataset characterized for horses, comprising 21 new genomes. We found that loci showing the most genetic differentiation with DHs were enriched in genes involved in metabolism, cardiac disorders, muscle contraction, reproduction, behavior, and signaling pathways. We also show that DH and PH populations split ∼45,000 years ago and have remained connected by gene-flow thereafter. Finally, we monitor the genomic impact of ∼110 years of captivity, revealing reduced heterozygosity, increased inbreeding, and variable introgression of domestic alleles, ranging from non-detectable to as much as 31.1%. This, together with the identification of ancestry informative markers and corrections to the International Studbook, establishes a framework for evaluating the persistence of genetic variation in future reintroduced populations.

New Fossil From Darriwilian Ordovician Winneshiek Lagerstätte in Iowa Sheds Light on Sea Scorpion, Horseshoe Crab Relationship

A new Ordovician arthropod from the Winneshiek Lagerstätte of Iowa (USA) reveals the ground plan of eurypterids and chasmataspidids

Authors:

Lamsdell et al

Abstract:

Euchelicerates were a major component of Palaeozoic faunas, but their basal relationships are uncertain: it has been suggested that Xiphosura—xiphosurids (horseshoe crabs) and similar Palaeozoic forms, the synziphosurines—may not represent a natural group. Basal euchelicerates are rare in the fossil record, however, particularly during the initial Ordovician radiation of the group. Here, we describe Winneshiekia youngae gen. et sp. nov., a euchelicerate from the Middle Ordovician (Darriwilian) Winneshiek Lagerstätte of Iowa, USA. Winneshiekia shares features with both xiphosurans (a large, semicircular carapace and ophthalmic ridges) and dekatriatan euchelicerates such as chasmataspidids and eurypterids (an opisthosoma of 13 tergites). Phylogenetic analysis resolves Winneshiekia at the base of Dekatriata, as sister taxon to a clade comprising chasmataspidids, eurypterids, arachnids, and Houia. Winneshiekia provides further support for the polyphyly of synziphosurines, traditionally considered the stem lineage to xiphosurid horseshoe crabs, and by extension the paraphyly of Xiphosura. The new taxon reveals the ground pattern of Dekatriata and provides evidence of character polarity in chasmataspidids and eurypterids. The Winneshiek Lagerstätte thus represents an important palaeontological window into early chelicerate evolution.

The Equid Diets From Miocene Climatic Optimum Oregon

Dietary niche stability of equids across the mid-Miocene Climatic Optimum in Oregon, USA

Author:

Maguire

Abstract:

During the middle Miocene in North America, hypsodont equids became more diverse and more abundant than brachydont equids. This pattern is evident in middle Miocene deposits of Oregon in which the brachydont taxa became extinct while the hypsodont equids flourished. This turnover, associated with morphological tooth differences, is hypothesized to be a result of dietary differences between taxa, with hypsodont species exploiting the increasing grassland landscape and demise of the brachydont species a result of less vegetation suitable for browsers. Here this hypothesis is tested and the dietary niches of four equid genera are examined using stable carbon and oxygen isotopes. Dietary niche partitioning is evident based on δ13C and δ18O values and tooth morphology: Archaeohippus, a small brachydont equid, had a narrow dietary niche most likely consuming crown leaf vegetation in the clearings of a woodland habitat; Parahipppus and Desmatippus, medium sized brachydont to incipiently hypsodont equids, ate C3 vegetation in a relatively open environment; and aff. Acritohippus, a larger hypsodont equid, had a broad dietary niche eating C3 grasses in a relatively open environment. The dietary niches of these four genera did not change through time or across the mid-Miocene Climatic Optimum. Local extinction of the browsing genera, especially Archaeohippus with its narrow niche breadth, was most likely due to the opening of habitats as C3 grasses spread after the mid-Miocene Climatic Optimum. There is no evidence of C4 vegetation in the diet of aff. Acritohippus consistent with the idea that C4 grasses did not invade the Pacific Northwest during the middle Miocene, in contrast to other regions of North America during that time.

15 Sites are Considered Undisputed Examples of Clovis Era Human Predation of Megafauna

Revisiting Paleoindian Exploitation of Extinct North American Mammals

Authors:

Grayson et al

Abstract:

In 2002, we assessed all sites known to us that had been suggested to provide evidence for the association of Clovis-era archaeological material with the remains of extinct Pleistocene mammals in North America. We concluded that, of the 76 sites we assessed, 14 provided compelling evidence for human involvement in the death and/or dismemberment of such mammals. Of these sites, 12 involved mammoth (Mammuthus), the remaining two mastodon (Mammut). Here, we update that assessment. We examine Clovis-era, and earlier, sites reported since 2002, as well as sites examined previously but for which additional information has become available. Our assessment leads us to exclude Hebior (Wisconsin) from the list of accepted sites, and to add El Fin del Mundo (Sonora) and Wally’s Beach (Alberta). There are now 15 sites on our list, providing what we find to be compelling evidence for human involvement in the death and/or dismemberment of five genera of now-extinct late Pleistocene mammals: Equus, Camelops, Cuvieronius, Mammut, and Mammuthus. As in 2002, however, we note this is a small fraction of the 37 genera that disappeared at the end of the Pleistocene, and for this and other reasons we remain highly skeptical that human overkill was responsible for their extinction.

The PaleoGenetics of Horse Domestication

Prehistoric genomes reveal the genetic foundation and cost of horse domestication

Authors:

Schubert et al

Abstract:

The domestication of the horse ∼5.5 kya and the emergence of mounted riding, chariotry, and cavalry dramatically transformed human civilization. However, the genetics underlying horse domestication are difficult to reconstruct, given the near extinction of wild horses. We therefore sequenced two ancient horse genomes from Taymyr, Russia (at 7.4- and 24.3-fold coverage), both predating the earliest archeological evidence of domestication. We compared these genomes with genomes of domesticated horses and the wild Przewalski’s horse and found genetic structure within Eurasia in the Late Pleistocene, with the ancient population contributing significantly to the genetic variation of domesticated breeds. We furthermore identified a conservative set of 125 potential domestication targets using four complementary scans for genes that have undergone positive selection. One group of genes is involved in muscular and limb development, articular junctions, and the cardiac system, and may represent physiological adaptations to human utilization. A second group consists of genes with cognitive functions, including social behavior, learning capabilities, fear response, and agreeableness, which may have been key for taming horses. We also found that domestication is associated with inbreeding and an excess of deleterious mutations. This genetic load is in line with the “cost of domestication” hypothesis also reported for rice, tomatoes, and dogs, and it is generally attributed to the relaxation of purifying selection resulting from the strong demographic bottlenecks accompanying domestication. Our work demonstrates the power of ancient genomes to reconstruct the complex genetic changes that transformed wild animals into their domesticated forms, and the population context in which this process took place.

Horses, Equids Have a Complicated Evolutionary History

Speciation with gene flow in equids despite extensive chromosomal plasticity

Authors:

Jónsson et al

Abstract:

Horses, asses, and zebras belong to a single genus, Equus, which emerged 4.0–4.5 Mya. Although the equine fossil record represents a textbook example of evolution, the succession of events that gave rise to the diversity of species existing today remains unclear. Here we present six genomes from each living species of asses and zebras. This completes the set of genomes available for all extant species in the genus, which was hitherto represented only by the horse and the domestic donkey. In addition, we used a museum specimen to characterize the genome of the quagga zebra, which was driven to extinction in the early 1900s. We scan the genomes for lineage-specific adaptations and identify 48 genes that have evolved under positive selection and are involved in olfaction, immune response, development, locomotion, and behavior. Our extensive genome dataset reveals a highly dynamic demographic history with synchronous expansions and collapses on different continents during the last 400 ky after major climatic events. We show that the earliest speciation occurred with gene flow in Northern America, and that the ancestor of present-day asses and zebras dispersed into the Old World 2.1–3.4 Mya. Strikingly, we also find evidence for gene flow involving three contemporary equine species despite chromosomal numbers varying from 16 pairs to 31 pairs. These findings challenge the claim that the accumulation of chromosomal rearrangements drive complete reproductive isolation, and promote equids as a fundamental model for understanding the interplay between chromosomal structure, gene flow, and, ultimately, speciation.

Evidence of Seasonal Change in Eocene Paleogene Paleoclimate

Stable isotope patterns found in early Eocene equid tooth rows of North America: Implications for reproductive behavior and paleoclimate

Authors:

D'Ambrosia et al

Abstract:

Reproductive behaviors of early Eocene equids were likely different from their modern-day counterparts as a result of their small body size and warmer global temperatures. To better understand the paleoenvironment and ecology of these early horses, teeth of Protorohippus montanum jaws from a single stratigraphic locality in early Eocene sedimentary deposits of Wyoming were sampled for oxygen and carbon isotope analysis. These enamel data along with an inferred body mass of ~ 7.5 kg suggests that adult teeth formed over a matter of months, with the final tooth erupting at ~ 1.3 years of age. Thus, average isotopic values from each tooth likely represent environmental conditions from a single season. Results indicate two isotopic patterns. In the case of isotopic “pattern A,” the second forming molars (m/2s) have significantly lower isotopic ratios compared to other teeth within the jaw. This suggests the first forming molars (m/1s) formed during a cooling fall season, followed by formation of the m/2s during the cooler winter. In the case of isotopic “pattern B,” results suggest that m/1s formed during a warming spring season, while the m/2s formed during the following warmer summer season. Isotopic ratios of m/1s may represent an individual's birth season (or in utero season, depending on timing of initial formation), implying that early equids experienced at least two birth seasons per year. These results suggest that temperatures and reduced seasonality of the early Eocene played a strong role in early equid birth cycles. Lastly, the mean and variance in carbon and oxygen isotope ratios was not significantly different across tooth positions of all jaws when all individuals were grouped together, regardless of their pattern assignment. Such results indicate that isotopic data from fourth premolars, first molars, second molars, and third molars can be combined for purposes of temporal reconstructions of paleoclimate, thus increasing the potential sample sizes for these types of studies.

Hipparion phlegrae: a new Species of Miocene Neogene Horse From Greece

Hipparion phlegrae, sp. nov. (Mammalia, Perissodactyla): a new species from the Turolian locality of Kryopigi (Kassandra, Chalkidiki, Greece)

Authors:

Lazaridis et al

Abstract:

A new hipparion species, Hipparion phlegrae, sp. nov., is described on the basis of both morphological characters and metrical data as a member of Hipparion s.s. It is compared with H. dietrichi, H. prostylum, and similar forms of the Greco-Iranian province. The age of the Kryopigi fauna is discussed as Turolian on the basis of the hipparion assemblage, whereas the coexistence of a small Cremohipparion referred here as C. matthewi/nikosi indicates that H. phlegrae, sp. nov., is probably a derived species in respect to H. prostylum. The decreased size of the H. phlegrae and the short and wide muzzle are discussed for Hipparion s.s. during the Turolian period. Phylogenetic relationships of the new species and related taxa are reconstructed and also considered.

A new Species of Hipparion Horse Found in Miocene Neogene Greece

Hipparion phlegrae, sp. nov. (Mammalia, Perissodactyla): a new species from the Turolian locality of Kryopigi (Kassandra, Chalkidiki, Greece)

Authors:

Lazaridis et al

Abstract:

A new hipparion species, Hipparion phlegrae, sp. nov., is described on the basis of both morphological characters and metrical data as a member of Hipparion s.s. It is compared with H. dietrichi, H. prostylum, and similar forms of the Greco-Iranian province. The age of the Kryopigi fauna is discussed as Turolian on the basis of the hipparion assemblage, whereas the coexistence of a small Cremohipparion referred here as C. matthewi/nikosi indicates that H. phlegrae, sp. nov., is probably a derived species in respect to H. prostylum. The decreased size of the H. phlegrae and the short and wide muzzle are discussed for Hipparion s.s. during the Turolian period. Phylogenetic relationships of the new species and related taxa are reconstructed and also considered.

Eurygnathohippus woldegabrieli: A New Horse Species From Pliocene Neogene Ethiopia

A new species of fossil horse from 4.4 million-year-old fossil-rich deposits in Ethiopia,
Eurygnathohippus woldegabrieli, was about the size of a small zebra, Eurygnathohippus woldegabrieli, had three-toed hooves and grazed the grasslands and shrubby woods in the Afar Region, according to its naming in the Journal of Vertebrate Paleontology.

The horse fills a gap in the evolutionary history of horses but is also important for documenting how old a fossil locality is and in reconstructing habitats of human forebears of the time, said Scott Simpson, professor of anatomy at Case Western Reserve's School of Medicine, and co-author of the research. "This horse is one piece of a very complex puzzle that has many, many pieces."

The researchers found the first E. woldegabrieli teeth and bones in 2001, in the Gona area of the Afar Region. This fossil horse was among the diverse array of animals that lived in the same areas as the ancient human ancestor Ardipithecus ramidus, commonly called Ardi.

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Earliest Old World Hypsodont Equids Were Opportunistic Feeders

Opportunistic Feeding Strategy for the Earliest Old World Hypsodont Equids: Evidence from Stable Isotope and Dental Wear Proxies

Authors:

1. Thomas Tütken (a)

2. Thomas M. Kaiser,

3. Torsten Vennemann,

4. Gildas Merceron

Affiliations:

a. Steinmann-Institut für Geologie, Mineralogie und Paläontologie, University of Bonn, Bonn, Germany

b. University Hamburg, Biozentrum Grindel, Hamburg, Germany

c. Institut de Géochimie, Université de Lausanne, Lausanne, Switzerland

d. iPHEP UMR 7262 CNRS, Université de Poitiers, Poitiers, France

Abstract:

Background

The equid Hippotherium primigenium, with moderately hypsodont cheek teeth, rapidly dispersed through Eurasia in the early late Miocene. This dispersal of hipparions into the Old World represents a major faunal event during the Neogene. The reasons for this fast dispersal of H. primigenium within Europe are still unclear. Based on its hypsodonty, a high specialization in grazing is assumed although the feeding ecology of the earliest European hipparionines within a pure C3 plant ecosystem remains to be investigated.

Methodology/Principal Findings

A multi-proxy approach, combining carbon and oxygen isotopes from enamel as well as dental meso- and microwear analyses of cheek teeth, was used to characterize the diet of the earliest European H. primigenium populations from four early Late Miocene localities in Germany (Eppelsheim, Höwenegg), Switzerland (Charmoille), and France (Soblay). Enamel δ13C values indicate a pure C3 plant diet with small (<1 .4="" a="" abrasion="" all="" and="" are="" br="" browse-dominated="" by="" carbon="" compatible="" compositions="" contrast="" data="" dental="" diet.="" dietary="" differences.="" except="" food="" for="" four="" from="" h.="" h="" high="" hipparionines="" indicate="" isotope="" low="" mesowear="" microwear="" of="" patterns="" populations.="" populations="" primigenium="" range="" resources.="" seasonal="" spectrum="" suggesting="" the="" to="" tooth="" variations="" wear="" wenegg="" wide="" with=""> Conclusions/Significance

Combined dental wear and stable isotope analysis enables refined palaeodietary reconstructions in C3 ecosystems. Different H. primigenium populations in Europe had a large spectrum of feeding habits with a high browsing component. The combination of specialized phenotypes such as hypsodont cheek teeth with a wide spectrum of diet illustrates a new example of the Liem’s paradox. This dietary flexibility associated with the capability to exploit abrasive food such as grasses probably contributed to the rapid dispersal of hipparionines from North America into Eurasia and the fast replacement of the brachydont equid Anchitherium by the hypsodont H. primigenium in Europe.

7000,000 Year Old Horse Genome Sequenced

It is nothing short of a world record in DNA research that scientists at the Centre for GeoGenetics at the Natural History Museum of Denmark (University of Copenhagen) have hit. They have sequenced the so far oldest genome from a prehistoric creature. They have done so by sequencing and analyzing short pieces of DNA molecules preserved in bone-remnants from a horse that had been kept frozen for the last 700.000 years in the permafrost of Yukon, Canada. By tracking the genomic changes that transformed prehistoric wild horses into domestic breeds, the researchers have revealed the genetic make-up of modern horses with unprecedented details. The spectacular results are now published in the international scientific journal Nature.

DNA molecules can survive in fossils well after an organism dies. Not as whole chromosomes, but as short pieces that could be assembled back together, like a puzzle. Sometimes enough molecules survive so that the full genome sequence of extinct species could be resurrected and over the last years, the full genome sequence of a few ancient humans and archaic hominins has been characterized. But so far, none dated back to before 70,000 years.

Now Dr. Ludovic Orlando and Professor Eske Willerslev from the Centre for GeoGenetics have beaten this DNA-record by about 10 times. Thereby the two researchers – in collaboration with Danish and international colleagues – have been able to track major genomic changes over the last 700.000 years of evolution of the horse lineage.

First, by comparing the genome in the 700,000 year old horse with the genome of a 43,000 year old horse, six present day horses and the donkey the researchers could estimate how fast mutations accumulate through time and calibrate a genome-wide mutation rate. This revealed that the last common ancestor of all modern equids was living about 4.0-4.5 million years ago. Therefore, the evolutionary radiation underlying the origin of horses, donkeys and zebras reaches back in time twice as long as previously thought. Additionally, this new clock revealed multiple episodes of severe demographic fluctuation in horse history, in phase with major climatic changes such as the Last Glacial Maximum, some 20,000 years ago.

De-extinction!  De-Extinction!  This one seems like an easy do!  

Some Surprising Bits About Horse Evolution from Ancient DNA

Ancient DNA retrieved from extinct horse species from around the world has challenged one of the textbook examples of evolution – the fossil record of the horse family Equidae over the past 55 million years.

The study, published today in the Proceedings of the National Academy of Sciences, involved an international team of researchers and the Australian Centre for Ancient DNA (ACAD) based at the University of Adelaide.

Only the modern horse, zebras, wild asses and donkey survive today, but many other lineages have become extinct over the last 50,000 years.

ACAD Director Professor Alan Cooper says despite an excellent fossil record of the Equidae, there are still many gaps in our evolutionary knowledge. "Our results change both the basic picture of recent equid evolution, and ideas about the number and nature of extinct species."

The study used bones from caves to identify new horse species in Eurasia and South America, and reveal that the Cape zebra, an extinct giant species from South Africa, were simply large variants of the modern Plains zebra. The Cape zebra weighed up to 400 kilograms and stood up to 150 centimetres at the shoulder blades.

"The Plains zebra group once included the famous extinct quagga, so our results confirm that this group was highly variable in both coat colour and size."

Lead author of the paper, Dr Ludovic Orlando from the University of Lyon, says the group discovered a new species of the distinct, small hippidion horse in South America.

"Previous fossil records suggested this group was part of an ancient lineage from North America but the DNA showed these unusual forms were part of the modern radiation of equid species," Dr Orlando says.

A new species of ass was also detected on the Russian Plains and appears to be related to European fossils dating back more than 1.5 million years. Carbon dates on the bones reveal that this species was alive as recently as 50,000 years ago.

"Overall, the new genetic results suggest that we have under-estimated how much a single species can vary over time and space, and mistakenly assumed more diversity among extinct species of megafauna," Professor Cooper says.

"This has important implications for our understanding of human evolution, where a large number of species are currently recognised from a relatively fragmentary fossil record.

"It also implies that the loss of species diversity that occurred during the megafaunal extinctions at the end of the last Ice Age may not have been as extensive as previously thought.

Paper is located here.

Browsing Horse Found in Panama Canal Zone

Rushing to salvage fossils from the Panama Canal earthworks, Aldo Rincon, paleontology intern at the Smithsonian Tropical Research Institute, unearthed a set of fossil teeth. Bruce J. MacFadden, curator of vertebrate paleontology at the Florida Museum of Natural History, University of Florida in Gainesville, describes the fossil as Anchitherium clarencei, a three-toed browsing horse, in the May 2009 issue of the Journal of Paleontology.

By far the most complete fossil of a horse collected at the site in excavations spanning the last century, characteristics such as the shape of the teeth confirm the identity of two earlier finds and indicate that this horse was primarily a forest-dwelling browser living in the area between 15 and 18 million years ago. This evidence supports MacFadden's earlier proposal that the habitat was probably a mosaic of relatively dense forest and open woodlands. The presence of this browsing horse in Panama significantly extends the southern tip of its range from previous finds from roughly the same period in Florida, Nebraska and South Dakota.

No time to comment.

Oldest Domesticated Horses Found

An international team of archaeologists has uncovered the earliest known evidence of horses being domesticated by humans. The discovery suggests that horses were both ridden and milked. The findings could point to the very beginnings of horse domestication and the origins of the horse breeds we know today. Led by the Universities of Exeter and Bristol (UK), the research is published on Friday 6 March 2009 in leading academic journal Science.

The researchers have traced the origins of horse domestication back to the Botai Culture of Kazakhstan circa 5,500 years ago. This is about 1,000 years earlier than thought and about 2,000 years earlier than domestic horses are known to have been in Europe. Their findings strongly suggest that horses were originally domesticated, not just for riding, but also to provide food, including milk.

Through extensive archaeological fieldwork and subsequent analysis, using new techniques, the team developed three independent lines of evidence for early horse domestication. Their findings show that in the fourth millennium BC horses in Kazakhstan were being selectively bred for domestic use. They also show horses were being harnessed, possibly for riding, and that people were consuming horse milk.

Analysis of ancient bone remains showed that the horses were similar in shape to Bronze Age domestic horses and different from wild horses from the same region. This suggests that people were selecting wild horses for their physical attributes, which were then exaggerated through breeding.

The team used a new technique to search for 'bit damage' caused by horses being harnessed or bridled. The results showed that horses had indeed been harnessed, suggesting they could have been ridden.

Using a novel method of lipid residue analysis, the researchers also analysed Botai pottery and found traces of fats from horse milk. Mare's milk is still drunk in Kazakhstan, a country in which horse traditions run deep, and is usually fermented into a slightly alcoholic drink called 'koumiss'. While it was known that koumiss had been produced for centuries, this study shows the practice dates back to the very earliest horse herders.

Lead author Dr Alan Outram of the University of Exeter said: "The domestication of horses is known to have had immense social and economic significance, advancing communications, transport, food production and warfare. Our findings indicate that horses were being domesticated about 1,000 years earlier than previously thought. This is significant because it changes our understanding of how these early societies developed."

Ridden and milked. It makes me wonder if there were not multiple independent attempts at domesticating animals based on what was locally available. Horses, goats, cattle, etc all in different places and then trade, as people came in contact with one another, spread the varieties around. It'd be interesting if there were some way to test, genetically, if those horses are related to our horses. Or if it was an separate attempt from the lineage that survives today.