Evolution

Evolution

Anastasia Kellogg

Evolution

• According to Darwin’s Theory of Evolution, changes in animals are caused by natural selection and/or mutation

• Those with favorable characteristics will survive to breed: this is natural selection

• The evolution of the horse is the best known example among mammals because it has the most documented fossil record

The Five Main Evolutionary Stages

• Eohippus

• Mesohippus

• Merychippus

• Pliohippus

• Equus

Eohippus: The Dawn Horse

• Nicknamed the Dawn Horse

• Also called Hyracotherium

• First appeared during the first epoch, or Eocene Epoch, of the Cenozoic Era (60 to 70 million years ago)

• 12 to 14 inches at the withers (the size of a small dog)

Eohippus:The Dawn Horse

• 4 toes on each front foot, 3 toes on each hind foot (14 toes total)

• Arched back, rounded body

• Lived in forests and ate soft plants

Mesohippus

• First appeared during the Oligocene Epoch of the Cenozoic Era (at least 38 million years ago)

• 18 to 22 inches at the withers (the size of a sheep)

• 3 toes on each foot (12 toes total)

• Lived in forests and ate soft plants

• Name means “middle horse”

Merychippus

• Sometimes called the Primitive Plains Horse

• First appeared during the Miocene Epoch of the Cenozoic Era

• Pony sized• 3 toes on each foot, but

walked on a dominant middle toe

• Lived on the plains and used its modified teeth to eat grass

Merychippus

• Name means “rudimentary horse”

Pliohippus

• First appeared during the Pliocene Epoch of the Cenozoic Era

• First one toed horse• Lived on plains and

ate grass• Name means “more

horse”

Pliohippus

• Although early equine ancestors were plentiful in the Americas, and Eohippus is sometimes said to have originated in North America, pliohippus died out completely in first North and then South America

• Different types developed into modern horse (Equus caballus) as well as donkeys, zebras, and onagers

Equus and the Primitive Types

• From Pliohippus came Equus caballus, the modern horse, as well as donkeys, zebras, and onagers

• The four early types of the horse included– Primitive Type I which

included both the Celtic pony and the European forest horse

– Prezwalski’s Horse (Primitive Type II)

– The Wild Horse of Central Asia (Primitive Type III)

Equus and the Primitive Types

• The Caspian pony, as well as the Tarpan (Primitive Type IV)

• The European Forest Horse was the ancestor of the draft breeds

• Prezwalski’s Horse still exists as a subspecies

• Primitive Type III became the Akhal-Teke

Equus and the Primitive Types

• The Caspian pony still exists as well, although centuries of domestication have surely changed it somewhat

• Primitive Type IV, crossed with Type III, eventually produced the Arabian

Zoological Classification of the Modern Horse

Kingdom Animalia

Subkingdom Vertebrata

Phylum Chordata

Class Mammalia

Cohort Ferungulata

Order Perissodactyla

Family Equidae

Genus Equus

Species Equus caballus

Subspecies Equus caballus caballus (domestic horse)

Early Domestication

• Anthropologists have evidence that horses were hunted for food during the “Old Stone Age” (Paleoithic Era) 25,000 years ago

• Horses are thought to have been domesticated after oxen, sheep, goats, donkeys, and camels

• Credit for domesticating the horse is given to nomadic tribes in Persia around 3000 B.C.

Early Domestication

• The Sumerians of Persia invented the wheel, and used onagers (the wild ass) to conquer Babylon around 2000 B.C.

• The horse entered Egypt in 1680 B.C.

• By 1000 B.C., the Greeks were using horses in battle

• The Greeks invented the snaffle bit

Early Domestication

• Xenophon wrote the first book on horsemanship, and his opinion are still valued today

• Chariot races were added to the 25th Olympic Games in 750 B.C.

• The Romans invented the curb bit

• Julius Caesar invaded Britain in 55 B.C., bringing the horses that centuries later contributed to the thoroughbred

Early Domestication

• According to legend, the prophet Mohammed identified the five mares from which the modern Arabian descends in 600 A.D.