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Ice Age Mammals
| || Ice Age Mammals || |
During the last Ice Age, there were many large, interesting mammals, like the saber-toothed cats, giant ground sloths, mastodons, and mammoths. These animals have long since gone extinct and are known mostly from fossils, from frozen, mummified carcasses, and even from ancient cave drawings.
The Last Ice Age
The last Ice Age started about 70,000 years ago and ended about 10,000 years ago (during the Pleistocene epoch). The Earth was much colder than it is now; snow accumulated on much of the land, glaciers and ice sheets extended over large areas and the sea levels were lower. These phenomena changed the surface of the earth, forming lakes, changing the paths of rivers, eroding land, and depositing sand, gravel, and rocks along the glaciers' paths.
What Is a Mammal?
Mammals are animals that have hair, are warm-blooded, and nourish their young with milk. Mammals evolved during the Triassic period, about the same time that the first dinosaurs appeared. Some modern-day mammals include people, apes, cats, dogs, mice, elephants, whales, and horses. Mammals are advanced synapsids, animals distinguished by having extra openings in the skull behind the eyes; this opening gave the synapsids stronger jaw muscles and jaws (the jaw muscles were anchored to the skull opening). Synapsids include the mammals, and their ancestors, the pelycosaurs, therapsids, and cynodonts. The pelycosaurs (like Dimetrodon and Edaphosaurus) were early synapsids, they were mammal-like reptiles. Later synapsids include the therapsids and the cynodonts (with multicusped post-canine teeth; they lived from the late Permian through the Triassic period). The cynodonts led to the true mammals. Over time, the synapsid gait became more upright and tail length decreased.
Mammals From the Pleistocene Epoch (and Some Important Ancestors)
(1.8 million years ago to 10,000 years ago)
(pronounced ANN-drew-SARK-us) Andrewsarchus (named for paleontologist Roy Chapman Andrews, who led the expedition on which it was found) was a primitive, carnivorous mammal that lived during the early Eocene Epoch, roughly 45 million years ago. This giant creodont was heavily-built and wolf-like. It was about 13 feet (4 m) long and had a skull over three feet (1 m) long; it was the largest creodont. It walked on four short legs and had a long body, a long tail, and a long snout. It had large, sharp teeth and clawed feet. Flat cheek teeth were perhaps used to crush bones. Fossils have been found in Mongolia; they were first found in 1923 by Kan Chuen Pao. Andrewsarchus may be an ancestor of the whales.
Baluchitherium (now called Indricotherium) is a large, extinct, hornless rhinoceros. It was one of the largest land mammals. Adults were about 26 feet (8 m) long, 18 feet (5.5 m) tall, and weighed about 17 - 18 tons (16 tonnes). The skull was 4.25 feet (1.3 m) long. This herbivore ate leaves and twigs from the tops of trees. It had four teeth; two tusk-like front teeth in the top jaw, pointing down and two on the bottom pointing forwards. This extinct ungulate (hoofed mammal) had three toes on each foot and lived from the Oligocene to the early Miocene in central Asia (Pakistan). Classification: Order Perissodactyla (odd-toed ungulates), Family Hyrachyidae (odd-toed ungulates between tapirs and rhinos).
The cave lion (Panthera leo spelaea) was probably the biggest lion that ever lived. It was 25 percent bigger than lions today and was up to about 11.5 ft (3.5 m) long. This subspecies of lion lived in Europe (as far north as Denmark) until historical times; the last of these huge mammals lived until about 2,000 years ago in the Balkans (southeastern Europe). There are cave drawing of this huge feline. It probably hunted in a manner similar to that of today's lions.
Chalicotherium was an early, herbivorous mammal from the Miocene. This forest browser was an ungulate with large, clawed feet (instead of hooves). It may have been able to rear up on its hind legs to eat leaves high up in trees. Fossils have been found in Europe (Kazakhstan). Classification: Suborder Ancylopoda, Family Chalicotheriidae.
Coelodonta, the woolly rhino, is from the Pleistocene epoch and survived the last ice age. It belongs to the family Rhinocerotids, which includes modern-day rhinos. This plant-eater was about 11 feet (3.5 m) long. It had two horns on its snout, the lower one larger than the one between its eyes (about 3 feet (1 m) long). It had long hair, small ears, short, thick legs, and a stocky body. Its fossils have been found in Europe (Britain) and Asia (eastern Siberia). Its shape is known from prehistoric cave drawings! Family Rhinocerotidae.
Dinictis was a small, primitive cat from the Oligocene (about 40 million years ago). This extinct, sabertooth cat had a sleek body, short legs, powerfully-muscular jaws, a small brain (in a 7 in), large canine teeth, and a long tail. Dinictis was plantigrade, walking in a flat-footed manner (unlike modern cats, which are probably much faster, digitigrade, walking on their toes). Dinictis, like modern cats, had three eyelids, the third one being a nictitating membrane (or haw). Dinictis evolved into pseudailurus, which was more like modern-day cats. Dinictis was very similar to Hoplophoneus (the ancestor of smilodon) except the canine teeth were less exaggerated. Dinictis may have preyed upon Indricotherium. Classification: Family Felidae, Subfamily Machairodontinae, Genus Dinictis.
Dinohyus (meaning "terrible pig") was a large, warthog-like hoofed mammal that lived during the early Miocene, roughly 24 million years ago. This herbivore (it ate plants, including roots) had a long skull (over 1 m = 3 feet long), a small braincase, a pair of knob-like protrusions on the back of the lower jaw (in the cheek area), blunt incisors, and wide, strong canine teeth. Its long legs probably made it a fast runner. The neck was short and stout and there was a hump on the shoulders formed by spines along the backbone. It was about 6 feet (2 m) tall at the shoulders and was the biggest and among the last of the Entelodonts. Fossils have been found in western North America (including Battle Creek, South Dakota, USA). Classification: Class Mammalia (mammals), Order Artiodactyla (even-toed ungulates), Family Entelodontidae (large, pig-like mammals from the Oligocene to early Miocene, including Archaeotherium, Megachoerus, Dinohyus, Entelodon and Eoentelodon), Genus Dinohyus.
Doedicurus (family glyptodontidae) was an ancient armadillo that lived during the Pleistocene. This extinct, armored mammal had four short legs, powerful jaws, with no teeth in the front and grinding teeth farther back in the jaws. This glyptodont had a long tail with a mace at the end. Doedicurus was 13 feet (4 m) long and 5 feet (1.5 m) tall. Fossils have been found in Patagonia, South America. These herbivores (plant-eaters) may have been preyed upon by saber-toothed cats and borhyaenids.
Elasmotherium was a rhinoceros-like mammal that lived in the steppes of Eurasia during the Pleistocene.
Indricotherium is an extinct, hornless rhinoceros with relatively long legs. (It used to be known as Baluchitherium since fossils were found in Baluchistan province, Pakistan). Adults were about 26 feet (8 m) long, 18 feet (5.5 m) tall, and weighed about 17 - 18 tons (16 tonnes). The skull was 4.25 feet (1.3 m) long. It was one of the biggest land animal ever to live on Earth (Paraceratherium was even bigger). This herbivore ate leaves and twigs from the tops of trees. It had four teeth; two tusk-like front teeth in the top jaw pointed downwards and two on the bottom pointed forwards. This extinct ungulate (hoofed mammal) had three toes on each foot and lived from the Oligocene to the early Miocene (toughly 40-26 million years ago). Fossils have been found in Asia. Two of its enemies were the carnivores Hyaenodon and Dinictis. Classification: Order Perissodactyla (odd-toed ungulates), Family Hyrachyidae (odd-toed ungulates between tapirs and rhinos).
Mammoths (scientific name Mammuthus) are extinct herbivorous mammals that had long, dense hair and underfur, very long tusks, a long proboscis (nose), large ears and lived throughout the world. They lived from about 2 million years ago to 9,000 years ago, millions of years after the dinosaurs went extinct. They are closely related to modern-day Indian elephants (they have common ancestor). Some tusks were straight, some were curved; the longest were up to 13 feet (4 m) long. The tusks were used in mating rituals, for protection, and for digging in the snow for food. Much of our knowledge of mammoths is from cave drawings and from mummified mammoths found in Siberian ice! Mammoths had longer tusks than Mastodons, a wider head, a sloping back, flat, chewing teeth, a trunk with two finger-like projections, and were mostly taller.
(pronounced MEG-ah-THEER-ee-um) Megatherium was the largest giant ground sloth; its name means "great beast." Megatherium was a huge, bulky, slow-moving herbivore (plant-eater) with peg-like teeth, powerful jaws, and a thick, short tail. This ice-age mammal had three hook-like claws on each hand. It was primarily a quadruped (walked on four legs). It may have eaten leaves from the tops of trees while standing upright on its hind legs, using its tail to balance. Megatherium was the size of an elephant. It lived during the Pleistocene epoch in what is now South America, going extinct about 11,000 years ago. It was about 20 feet (6 m) long and weighed roughly 3-4 tons. Megatherium was named by R. Owen in 1856; the first Megatherium fossil was found in Brazil in 1789. (Cohort (many grouped orders) Edentata, Family Megatheriidae, Genus Megatherium)
Megistotherium was a huge Hyaenodont (not a dinosaur, but an early, hyena-like mammal, a creodont) from the Miocene Epoch (about 24 million years ago). This meat-eater may have been a scavenger and/or an active hunter. Its skull was over 3 ft (1 m) long. Fossils have been found in northern Africa (Egypt and Libya). Megistotherium was named by Robert J. G. Savage in 1973. Classification: Superorder Ferae, Order Creodonta, Family Hyaenodont.
These extinct cats are notable for 2 huge canine teeth among other sharp teeth in powerful jaws. They also had very strong jaw and neck muscles that let them stab prey with their deadly teeth. They ate mammoth, rhinoceros, and other thick-skinned animals. Examples include: Smilodon (the largest and most powerful, from North America), Hoplophoneus (with short teeth, from the Oligocene), Eusmilus (leopard-sized with very long teeth, from the Oligocene), and Machairodus (lion-sized and common; from the Paleocene). Fossils have been found in Pliocene to early Pleistocene rocks from both North and South America and other Northern continents.
Smilodon, the largest saber-toothed cat (or saber-toothed tiger), was a fierce predator about 4-5 feet (1.2-1.5 m) long. Its one foot (30 cm) long skull had 2 huge canine teeth (they were serrated and oval in cross-section) in powerful jaws that opened to an angle of about 120°. It also had very strong jaw and neck muscles that let smilodon stab prey with its deadly teeth. It had a short, bobbed tail. It may have eaten thick-skinned prey like mastodons (hairy, extinct elephants) and bison. Thousands of fossils have been found in late Pleistocene tar pits and rocks from both North America (S. californicus in California) and South America (S. neogaeus in Argentina). Classification: family Nimravidae (early cats).
(pronounced you-IN-tah-THEER-ee-um) Uintatherium was a huge, rhinoceros-like mammal (not a dinosaur) from the Eocene in North America; it has no living descendants. Uintatherium was 13 feet (4 m) long and weighed about 2.25 tons (2 tonnes). It had 3 pairs of bony knobs protruding from its snout and a very small brain. Males had large, downwards-pointing canine teeth. It walked on 4 thick legs and had elephant-like feet. This herbivore lived in forests and ate leaves and soft plants. It was preyed upon by packs of the dog-like Synoplotherium.
Woolly Mammoths (scientific name Mammuthus primigenius) are extinct herbivorous mammals that had long, dense, dark black hair and underfur, long, curved tusks, a fatty hump, a long proboscis (nose), and large ears. They lived in the tundras of Asia, Europe, and North America. They lived from the Pleistocene to the early Holocene epoch (about 10,000 years ago), millions of years after the dinosaurs went extinct. They are closely related to modern-day Indian elephants. They were about 11.5 feet (3.5 m) long, 9.5 feet (2.9 m) tall at the shoulder and weighed about 3 tons (2.75 tonnes). The tusks were used for protection, in interspecies dominance, and for digging in the snow of the ice ages for grass and other food. Much of our knowledge of mammoths is from cave drawings found in France and Spain and from mummified mammoths found in Siberian ice! (Classification: Family Elephantidae)
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