Page 35

things, gave the name Megalonyx to these giant ground sloths. It was later given the name Megalonyx jeffersonii in his honor. It was a bear-sized ground sloth that sometimes grew more than six feet tall. It lived in North Dakota about 12,000 years ago and was widespread in North America during that...

Full description

Bibliographic Details
Language:unknown
Subjects:
Online Access:http://cdm16921.contentdm.oclc.org/cdm/ref/collection/ndbb/id/13444
Description
Summary:things, gave the name Megalonyx to these giant ground sloths. It was later given the name Megalonyx jeffersonii in his honor. It was a bear-sized ground sloth that sometimes grew more than six feet tall. It lived in North Dakota about 12,000 years ago and was widespread in North America during that time. It became extinct with many of the other large Ice Age mammals at the end of the Pleistocene Epoch. The Ice Age horse was very similar to the modern horse, and like today's is called Equus. Contrary to what many people believe, horses lived in North America, including North Dakota, before they were brought to North America by the Spaniards. Horses first evolved here and have lived in North Dakota since the Eocene Epoch, about 50 million years ago, as documented by fossils of "Hyracotherium" that were recovered from the Golden Valley Formation. Fossils of the ancient sheep-sized three-toed horse, Mesohippus, have been collected from 30-million-year-old rocks in North Dakota. Remains of Equus have also been found in North Dakota from 50,000-year-old and younger Pleistocene deposits. Like today's horse, the Ice Age horse had one toe on each foot and high-crowned teeth adapted for eating grasses. Horses were wide ranging during the Pleistocene in North America, but became extinct on this continent at about the same time as many of the other large Pleistocene mammals. It is not known why they became extinct in North America and not in the Old World. Spanish conquistadors did have horses with them when they arrived in the southwestern part of what is now the United States in the 1500s, but most scholars believe that Native People in the southwest probably did not have extensive access to horses until the 1600s. Apparently the Mandan Indians in North Dakota acquired horses by about 1750. The importance of the horse to the Plains Indians cannot be overstated. Some scholars refer to the period from the time Native People obtained horses until the near extermination of the bison about 1880 as the "Horse Culture Period." The importance of the horse on the Great Plains extends to the days of pioneers and settlers and is important today in cowboy culture. Unfortunately, fossils of the large Pleistocene Epoch carnivores, like the famous sabertoothed cat, Smilodon fatalis, or the dire wolf, Canis dims, have yet to be found in North Dakota. After about 20,000 years ago, the last glacial maximum in North Dakota, glaciers began to melt as a result of climate warming. Spruce-aspen forests then began to become established in North Dakota, south of the glacial ice. The climate was still cool and moist, and ponds and bogs existed in these forests. Fossils found in 11,000-year-old bog sediments indicate that cold-adapted frogs, fish, insects, crustaceans, mollusks, plants, and small mammals, including beavers and muskrats, inhabited the area. At the end of the Ice Age great volumes of meltwater entered the drainage systems creating large channels across North Dakota. Glacial Lake Agassiz formed in what is now the Red River Valley as the ice margin retreated into Canada. At its maximum, this lake near Fargo was about 300 feet deep, and more than 100 Chapter One - History of Ancient Life in North Dakota 35