Horses hooves’ evolution, new research


This video is a 2017 National Geographic documentary about horse evolution.

From the University of Bristol in England:

Is one toe really better than three? How horse’ legs evolved for travel rather than speed

April 17, 2019

Palaeobiologists from the University of Bristol and Howard University (USA) have uncovered new evidence that suggests that horses’ legs have adapted over time to be optimised for endurance travel, rather than speed.

The ancestors of horses (including asses and zebras) had three toes on each foot. Because only single-toed (monodactyl) forms survive today this anatomy has been perceived as a superior evolutionary outcome, enabling horses to outrun predators.

But our interpretation of equine evolution may be biased by our own history with horses: performance at the racetrack has been less important for human history than the endurance of horses at slower speeds, and such endurance may have been the critical factor in horse evolution.

The research team combined evidence from the fossil record with existing studies on horse locomotion and propose that the adaptive significance of single-toed limbs was for trotting during roaming for food and water, rather than for galloping to avoid carnivores.

The real evolutionary ‘step forward’ in horse foot anatomy was not the loss of additional toes, but the evolution of the ‘spring foot’.

This pogo-stick type of foot anatomy evolved in the three-toed distant ancestors of modern horses, which sported an enlarged central toe but retained small ‘side toes’, which likely prevented the foot from over-extending during extreme locomotor performance.

The ‘spring foot’ enables the storage of elastic energy in the limb tendons during locomotion, and its evolution coincided with the spread of grasslands around 20 million years ago in North America (the original home of horse evolution).

The spring-footed horses radiated extensively and were as diverse during their time as antelopes in Africa today.

By around 11-million-years ago they also spread into Eurasia and Africa, where they eventually included forms larger than a modern horse. But only the lineage leading to modern horses, one amongst many, showed any tendency to reduce the number of toes.

If being single-toed was evolutionary advantageous, why did the majority of horses retain the three-toed condition for most of their evolutionary history?

Professor Christine Janis, lead author from the University of Bristol’s School of Earth Sciences (and also affiliated with Brown University, USA) said: “Early members of the single-toed horse lineage were not only losing their side toes, but the bones of the remaining central toe showed evidence of the boosting-up of the ‘spring foot’ apparatus, implying that these horses were becoming more reliant on energy-efficient locomotion.

“But at the same time these horses’ backs were becoming shorter and stiffer, contraindicative of adaptation for the back-flexing fast galloping gait. Rather, the preferred locomotion was more likely the medium-speed trot.”

The authors propose that the early single-toed horses were changing their daily foraging behaviour to roam more widely in search of food, promoting energy-saving adaptations in their feet.

The loss of the side toes may simply have been a consequence of upgrading the anatomy of the main, central toe, and with the boosted-up ligament system their original function was no longer necessary.

Single-toed horses appeared in North America around 12-million-years ago. Over the next few million years they radiated alongside three-toed horses but remained pony-sized and were neither diverse nor numerous.

But at this time the climate in northern latitudes was becoming cooler and drier. An increase in roaming behaviour would promote selection for the energy-efficient single-toed foot.

At the time, the foraging behaviour of the single-toed horses would have been one adaptive strategy among an equine diversity, much as different kinds of antelope have different modes of foraging today.

But by around five million years ago the cooling and drying trend became more intense worldwide; the former great diversity of three-toed horses had dwindled, and the direct ancestor of modern horses (early species of the genus Equus) appeared. By a million years ago all lineages of three-toed horses were extinct.

Why were single-toed horses the only equine lineage to survive to the present day? It is unlikely that competition was involved between the differently-adapted equines, as the Old World three-toed horses started their decline several million years before Equus emigrated from North America to join them 2.5 million years ago. More likely, the climatic changes of the late Cenozoic favoured the evolutionary strategy of the single-toed horses.

Professor Ray Bernor, the co-author of the paper, from Howard University’s College of Medicine, notes that the single-toed horses really just got a lucky break due to changing climates.

He added: “The three-toed horses, especially the Old World hipparions, were an incredibly successful radiation, and their skeletons showed adaptations for leaping and springing as well as running. But they evolved for a world that was warmer and wetter than that of today, and like many other large mammals did not survive to the present day.”

Single-toed horses became the dominant equines across the world in the past couple of million years, and only went extinct in the Americas at the end of the Pleistocene, around 12,000 years ago.

Professor Janis added: “However, nobody could have foreseen this eventual success ten million years ago, when single-toed horses were merely a minor lineage among equines, confined to North America.

“Their foot anatomy was ultimately important for finding food, rather than for avoiding becoming food themselves.”

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Konik horses in Dutch Lauwersmeer national park


The number of konik horses in Dutch nature Oostvaardersveld had become too big. Therefore, In January forty horses were moved to Lauwersmeer national park. They are useful there in keeping the vegetation varied. The horses are doing well in their new environment, this 25 January 2019 says.

Florida, USA prehistoric horses did not travel far


This May 2018 video says about itself:

The modern day horse is the result of over 55 million years of evolution.

The fossilised remains of Eohippus, also known as the ‘Dawn Horse’ or ‘Hyracotherium‘, is considered to be where the horse, or ‘Equus’, as we know them today, originated from.

Eohippus not only developed into Equus, but it also led to a whole family tree of other equine species.

A TIMELINE OF HORSE EVOLUTION

1. Eohippus 55-50 MYA
2. Orohippus 50-40 MYA
3. Epihippus 47 MYA
4. Mesohippus 40-20 MYA
5. Miohippus 36-34 MYA
6. Merrychippus 20-11 MYA
7. Pliohippus 11-5 MYA
8. Dinohippus 5 MYA
9. Equus 2 MYA
10. Present-day horse 2MYA-Present

From the University of Cincinnati in the USA:

Some prehistoric horses were homebodies

Geochemical analysis of fossil teeth shows horses in Florida did not make epic migrations

December 19, 2018

Summary: A strontium analysis of fossilized horse teeth from Florida found that the animals did not travel far from where they were born. Researchers also found evidence that prehistoric horses fed along the coast like wild horses do today at places like Assateague Island National Seashore.

Unlike today’s zebras, prehistoric horses in parts of North America did not make epic migrations to find food or fresh water, according to a new study by the University of Cincinnati.

The findings suggest Florida was something of a horse paradise 5 million years ago, providing everything the animals could want in a relatively small area.

The study was published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

Plains zebras and Mongolian wild horses take on epic migrations each year to find water or green grass.

The Mongolian wild horse, also known as a Przewalski’s horse, travels as much as 13 miles per day. And Burchell’s zebras in southern Africa are known for their seasonal migrations that take them as far as 300 miles and back as they follow the rains to green grass.

But geologists in UC’s McMicken College of Arts and Sciences found that prehistoric horses in coastal Florida lived and died within a comparatively small area.

“It seems that these horses in Florida were relatively sedentary. They didn’t travel far distances,” said Jenelle Wallace, a UC graduate and lead author of the study.

The study was the basis of Wallace’s master’s thesis. Today, she works as an engineering geologist for the New York State Department of Environmental Conservation.

“My third spoken word after mom and dad was horse,” Wallace said. “I’ve loved them ever since I was little.”

The world’s first horses originated in North America. They lived there for 55 million years before spreading to Asia and Africa while going extinct on their home continent about 12,000 years ago.

The small three-toed animals lived like antelope, browsing leaves in deep forests. But during the Miocene Period between 23 million and 8 million years ago, horse evolution exploded into 15 different families. Horses developed bigger bodies, longer legs and hard hooves in place of toes to help them cover more ground.

Their teeth also changed, becoming bigger and longer for cropping coarse grass covered in abrasive silica dust instead of plucking soft leaves. It’s these teeth that helped UC researchers study how extinct horses lived.

UC’s geologists compared strontium isotopes found in fossilized horse teeth to the strontium in bedrock in different parts of the American Southeast to track the horses’ wanderings. Plants such as grass absorb strontium from the earth and the horses, in turn, absorb that strontium while grazing. In this way, strontium serves as a geographic marker.

UC geology professors and study co-authors Brooke Crowley and Joshua Miller have used this technique to track the movements of other animals, both living and prehistoric. Crowley used bones collected from the nests of secretive goshawks to map the birds’ travels in Madagascar. She and Miller also are studying the movement of Ice Age mastodons in North America.

“There is a lot of opportunity for expanding the use of strontium to look at a variety of animal groups, time periods and locations,” Crowley said.

The study examined seven species of horse along with two known leaf-eaters: a prehistoric tapir and a distant relative of elephants called a gomphothere.

The results were surprising, researchers said.

Of all the animals studied, the tapir seemed to have the widest geographic range based on the high variability of strontium found in its teeth. But given that modern tapirs have relatively modest home ranges, researchers said it’s more likely that prehistoric tapirs consumed river plants that absorbed nutrients carried far downstream.

Among the horses, the researchers found little variation in the size of their ranges. But the strontium showed a connection between horses and the sea. Like modern horses today in places such as Assateague Island National Seashore, prehistoric horses might have fed along the coast. Researchers suggested the vegetation horses consumed was influenced by marine-derived strontium from seaspray, precipitation or saltwater intrusion into groundwater.

The study was funded by grants from the UC Geology Department, Sigma Xi, the Geological Society of America and the American Society of Mammalogists along with the Association for Women Geoscientists Winifred Goldring Award.

“The study suggests we’re not the only couch potatoes. If animals don’t have to move, they won’t,” Miller said.

Migrating is dangerous business, Miller said. Animals face injury, illness and starvation when they travel great distances. And in the Miocene Period, horses had to outwit plenty of big predators such as saber-toothed cats.

“The energetic costs of moving are high,” Miller said.

Crowley, who also teaches in UC’s Department of Anthropology, said studies like this shed light on the habitat needs of animals long before they were influenced by human activities.

“Having a deep perspective is really important for understanding a species’ needs in conservation and management,” Crowley said. “If we just look at a narrow window of time — like 50 or 100 years — we don’t get a good picture of a species when it’s not in crisis.”

Using the geologic record, researchers can piece together how animals interacted, what allowed them to thrive and what ultimately caused them to perish, she said.

“By using this technique, we can answer questions in a way we couldn’t otherwise,” Crowley said. “That’s the cool thing about geochemistry. You can unlock secrets in teeth and bones.”

Young Ice Age horse discovery in Siberia


This video says about itself:

12 August 2018

A 40,000-year-old baby horse has been found almost perfectly preserved in Siberia.

The foal has been kept in such good condition by the region’s permafrost, it still has its hair, tail, mane and many of its internal organs. “There are no visible wounds on its body”, reports The Siberian Times.

The discovery was made in the Yakutia region – long-known for fossils of woolly mammoths – by a joint expedition of scientists and archaeologists from Russia and Japan.

It is estimated the animal was just three months old when it died – although it has no visible wounds to suggest why.

“The extra value of the unique find is that scientists also obtained samples of soil layers where it was preserved, which means they will be able to restore a picture of the foal’s environment.

The find recovered from a depth of about 30 meters, in a vast crater known as the Batagai depression, was located by scientists from the North-Eastern Federal University in Yakutsk and Kindai University in Osaka, Japan.

Wild horses and flamingos in France


This 19 August 2018 video from the Camargue in France says about itself:

Wild Horses Run into Flamingos Feeding | BBC Earth

The peace for the pink flamingos is disrupted when a group of wild horses run into the river in this beautiful slow motion video.

Featuring common cranes as well.

Prehistoric horses in North America


This 14 August 2018 video from the USA says about itself:

How Horses Took Over North America (Twice)

The ancestors of modern horses became so successful that they spread all over the world, to Europe, Asia, South America, and Africa. But in their native range of North America, they’ll vanish for 10,000 years. Until another strange mammal brings them back.

The illustration of Equus simplicidens–also known as the Hagerman Horse–is by Roger Hall. You can check out more of Roger’s work here.