The Pleistocene Megafauna

The Pleistocene Megafauna Jarðsaga 2 Ólafur Ingólfsson Háskóli Íslands Unstable Pleistocene climate controls development of life Life adapts to seasonality and glaciations... http://www.bbc.co.uk/beasts/changing/pleistocene/currents.shtml Adaptations include: • Migrations to cope with seasonal temperature and precipitation changes • Physiological changes to cope with harsch climates (body size, growing/sheding a fur) • Generalization with regard to food to cope with seasonal availabilty • Activity levels adopted to seasons (winter sleep) Pleistocene fauna; general characteristics... • The Pleistocene animals and plants were basi- cally modern species. • There were many giant mammals - the so called megafauna - which evolved and lived on all the worlds continents. In Australia there were giant kangaroos and wombats; in Europe the mammoth and woolly rhinos, in America the mastodon, camels, and dire wolves, in South America elephant-sized ground sloths and giant glyptodonts. La Brea tarpits of LA The La Brea tar pits contain one of the richest, best preserved, and best studied assemblages of Pleistocene vertebrates, including at least 59 species of mammal and over 135 species of bird. The tar pit fossils bear eloquent witness to life in southern California from 40-8 ka BP; aside from vertebrates, they include plants, mollusks, and insects -- over 660 species of organisms in all. Natural sepage of tar... ...Animals get stuck in the sticky tar Animals get stuck in the tar Microfossils tell us a lot about the environments The asphalt has preserved plants, insects, freshwater shells and small rodent bones. The microfossils give a complete look at the Ice Age environment of the Los Angeles area. Although > million invertebrates have been recovered from the asphalt deposits, only two species are extinct. Invertebrates that have been identified include grasshoppers, termites, flies, and scorpions. Birds of Rancho La Brea Bird fossils are very rare because their bones are hollow and quite fragile. At Rancho La Brea the preservative effect of the asphalt has resulted in one of the largest collection of fossil birds in the world. The >100,000 bird fossils found at Rancho La Brea include different kinds of birds of prey, waterfowl and songbirds. The Columbian Mammoth Huge, about 4 m and weighing 8-10 tons, the Columbian mammoth could consume about 250 kg of vegetation a day. The life span for a Columbian mammoth was 60 to 80 years The Columbian Mammoth The Columbian Mamm- oth was a descendent of Mammuthus meri- dionalis, an ancestral mammoth that entered North America via the Bering Land Bridge 1- 1.5 MYago. In Eurasia, this same ancestor evolved separately into the woolly mammoth A gigant elephant The Columbian mammoth was one of the largest elephants to have walked the Earth. It had spiral- led tusks which measured up to 4.9 m long, longest tusks ever amongst the elephant family. Mammuts and Mastodonts American Mastodon Mammut americanum The mastodons at Rancho La Brea were roughly half the size of the mammoths. The Mastodont even went South... Ground sloths from S America Ground sloths, originally from S America, made their way into N America after the closing of the Panama seaway. Harlan's ground sloth was the largest and most common of the ground sloths found at Rancho La Brea. It stood over 2 m tall and weighed almost 1100 kg. This animal had flat grinding teeth that suggest a diet of grasses, but may have also fed on leaves, tree roots, and twigs. Western Horse (Equus occidentalis) With over 200 individuals of western horse recovered from Rancho La Brea, paleontologists have determined that this species had a strong resemblance to the modern East African zebra. It went extinct by the end of the Pleistocene. Horses were later introduced to the Americas by the Spanish conquistadores... Yukon Wild Ass Equus lambei - These small horses were one of the most common herbivores in N America during the Ice Age. They were very similar to the living wild asses of Asia and stood about 1.3 m high. The species occupied dry, shrub-covered grasslands. Only the fastest predators, such as the American lion and dire wolf, were able to kill them. Wild asses survived in the Yukon until about 13,000 years ago. Decline of horses in North America Western Camel The western camel was similar to the living two-humped camel, but slightly taller (>2.5 m at the shoulder). It was an opportunistic herbivore, like its modern day relatives. The western camel was more closely related to the llama than to living camels. Other herbivores Animals like the tapir and the llama are some of the more notable rare large mammal herbivores at Rancho La Brea and are mainly represented by just a few bones. The three-toed tapir is a distant relative of modern horses. Living tapirs are found in South Asia and South America. Dire Wolve Dire (“skelfilegur”) wolves were quite common in the Rancho La Brea area. More dire wolf fossils have been found during excavations than those of any other mammal species. The large number suggests that these fierce animals hunted in packs and may have been caught in the asphalt together while trying to feed upon other animals. Short faced bear The short-faced bear's size in comparison to the modern day grizzly (front) and polar bear (middle). The short-faced bear was the largest and most powerful carnivore found at Rancho La Brea. It stood over 1.6 m tall at the shoulder, making it larger than the modern grizzly, brown, and polar bears. When standing upright, the short- faced bear was over 3.5 m tall. Its teeth suggest that this bear, like the modern grizzly or brown bears, was an omni- vore with a diet dependent on food that was available. American Lion Closely related to the modern African lion, the American lion was the largest member of the cat family found in the asphalt deposits. Roamed the Americas between 70-20 ka BP The Sabretoothed Cat The sabertoothed cat had strong limbs and a heavy muscular build, making it much more bulky than other cats, whichtendtobeagileandnimble. Thesabertoothedcat had a short tail and research suggests that it relied on its powerful muscles to ambush and pounce upon prey, instead of chasing it in a manner similar to lions and other cats. Saabretoothedcatswereaboutthesizeof a lion. They specialized in killing young mammoths and probably other slow, thick-skinned prey such as mastodons and ground sloths. Sabretoothed cats survived in North America until the close of the last glaciation, about 10 ka BP. La Brea: Fossil ecosystem The fossil deposits at Rancho La Brea are an entire pre- historic ecosystem that existed in Los Angeles 40-12 ka BP preserved, from the smallest plant fragments to the largest mammals. Museum of LA County: http://www.tarpits.org/education/guide/index.html Giant Beaver The giant beaver (Castoroides ohioensis) was one of the largest rodents ever known. It reached a length of ca. 2.5 m and weighed up to an estimated 218 kg. Unlike modern beavers (Castor canadensis), giant beavers had ridged cutting teeth, deep skulls, and probably roundish, muskrat-like tails. Eurasian Pleistocene Megafauna The very dry tundra plains of northern Eurasia meant animals had to adapt to survive. Others migrated south to milder valleys in the winter. Woolly Rhino: Weight: 2 to 3 tons; height: 2 m tall at shoulder; length: 3-4 m Woolly Rhino, 500-10 ka ago Woolly Rhino remains have been found all across Europe and Asia, although they apparently did not make it across to N America. The horns of the woolly rhino have been found as fossils, and frozen carcasses have occasionally been found in Siberia. They also occur in cave paintings. Copy of a rhinoceros cave painting from cave of Font-de-Gaume, Dordogne, France. Elephant Family Tree The Woolly Mammoth 135-11 ka BP Males: 3 m tall, Females: 2.75 m tall Mammuthus primigenius, from the old Russian word mammut - meaning "earth mole" - as the animals were believed to live underground and die on contact with the light (explain- ing why they were always found dead and half-buried). Mammuthus Mammuthus primigenius - primigenius Woolly mammoths are the best known mammals of the Ice Age, because carcasses have been found preserved in frozen ground in Siberia, and pictures by stone-age artists can be seen in Euro- pean caves. Woolly mammoths grew to about the size of present-day Asiatic elephants, had warm coats consisting of long, brown guard hairs and soft under- wool, large curved ivory tusks, and knob-like heads. Pleistocene Mammals in the Russian Paleontological Institute Many of the most famous Pleistocene mammals remains are from Russia, including frozen mammoths that still contain stomach contents, hair, DNA, and muscle. European Lion - 900-10 ka ago Lions have been around in Africa for at least 3.5 MY, but 900 ka ago they first appeared in Europe, and from then on became reasonably common. The European lions were larger than their cousins in Africa, which probably helped them hunt some of the larger herbivores on the great European plains, such as bison. Cave paintings of European lions show no mane or tuft at the end of the tail, although it could be that the paintings are of females. European Cave Lion Lions were very wide-spread in Europe and Asia untill late Pleistocene The Pleistocene Cave Bear Ursus spelaeus (late Pleistocene, ca. 300 ka BP-10 ka BP). This bear is notable for its habit of inhabiting caves, where its remains are frequently preserved; in European cave deposits, the remains of more than 100,000 cave bears have been found.

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