when did equus first appear in fossil record
1820s ~3.5 million years old about 3.5 mya
title: History of Earth text: before a reliable (fossil) record of life; it began with the formation of the planet and ended 4.0 billion years ago. The following Archean and Proterozoic eons produced the beginnings of life on Earth and its earliest evolution. The succeeding eon is the Phanerozoic, divided into three eras: the Palaeozoic, an era of arthropods, fishes, and the first life on land; the Mesozoic, which spanned the rise, reign, and climactic extinction of the non-avian dinosaurs; and the Cenozoic, which saw the rise of mammals. Recognizable humans emerged at most 2 million years ago, a vanishingly small period on the geological title: Australopithecus africanus text: Australopithecus africanus Australopithecus africanus is an extinct ("fossil") species of the australopithecines, the first of an early ape-form species to be classified as hominin (in 1924). Recently it was dated as living between 3.3 and 2.1 million years ago, or in the late Pliocene and early Pleistocene times; it is debated as being a direct ancestor of modern humans. "A. africanus" was of slender, or gracile, build and has been found only in southern Africa at four sites: Taung (1924), Sterkfontein (1935), Makapansgat (1948) and Gladysvale (1992). Raymond Dart, then the head of the department of anatomy at the University title: Equus (genus) text: The oldest material to date was found in Idaho, USA. The genus appears to have spread quickly into the Old World, with the similarly aged "E. livenzovensis" documented from western Europe and Russia. Molecular phylogenies indicate that the most recent common ancestor of all modern equines (members of the genus "Equus") lived ~5.6 (3.9-7.8) Mya. Direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse metapodial bone from Canada implies a more recent 4.07 Mya for the most recent common ancestor within the range of 4.0 to 4.5 Mya. Mitochondrial evidence supports the division of "Equus" species into noncaballoid (which includes title: Eoarchean text: Eoarchean The Eoarchean (; also spelled Eoarchaean) is the first era of the Archean Eon of the geologic record for which the Earth has a solid crust. It spans 400 million years from the end of the Hadean Eon 4 billion years ago (4000 Mya) to the start of the Paleoarchean Era 3600 Mya. The beginnings of life on Earth have been dated to this era and evidence of cyanobacteria date to 3500 Mya, just outside this era. At that time, the atmosphere was without oxygen and the pressure values ranged from 10 to 100 bar (around 10 to 100 title: Evolution of the horse text: years old from Idaho, USA. The genus appears to have spread quickly into the Old World, with the similarly aged "Equus livenzovensis" documented from western Europe and Russia. Molecular phylogenies indicate the most recent common ancestor of all modern equids (members of the genus "Equus") lived ~5.6 (3.9–7.8) mya. Direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse metapodial bone from Canada implies a more recent 4.07 Myr before present date for the most recent common ancestor (MRCA) within the range of 4.0 to 4.5 Myr BP. The oldest divergencies are the Asian hemiones (subgenus "E. (Asinus)", including the kulan,