The Pleistocene- Vertebrate Fossils from Mississippi Gravel Bars Dr. Nina L. Baghai-Riding. The Pleistocene Epoch lasted from about 1.65 million until 10,000 years ago. Much of northern North America was covered by a large ice sheet.
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The Pleistocene- Vertebrate Fossils from Mississippi Gravel Bars
Dr. Nina L. Baghai-Riding
Extent of ice sheets during the coolest glacial
period, Cutchins and Johnston, 2000).
Compare the various vegetational zones 18.000 years ago to the present
The world of the ice ages is much more familiar to us than any other geological time – Pleistocene epoch
Bering Land Bridge in orange connected Alaska to Siberia. This area is currently under water.
Mammoth localities - common in areas that were covered by savannas, grasslands, or tundra during the last Ice Age. http://www.museum.state.il.us/exhibits/larson/mammuthus.html
About 50% of the new genera immigrated from South America and 27% from Asia during the Irvingtonian--
Great Animal Interchange (Cutchins and Johnston 2000).
Other mammals that first appeared ~ 1.9 ma
1. Sabertoothed cat (Smilodon)
2. hares (Lepus)
4. shrub oxen (Euceratherium)
119 genera of Irvingtonian mammals (Savage and Russell, 1983).
North America was known for the American mastodons (Mammut americanum)
Preying on the herbivores were:
Rancholabrean – 300,000 – 10,000 years ago marks the climax of the Ice Age Mammal assemblage in North America.
Numerous large mammals occurred in the Midwestern United States below the ice sheet
Date between 40,000 and 10,000 years ago (the last Ice Age).
Most of these animals no longer live in the United States and are extinct.
Sites older than 40,000 years old are less common than younger sites.
Glyptodont – from Fossil
Treasures of Florida-com
Ground sloth had blunt teeth (Specimen from Danny West collection).
Huge claws and powerful arms were used to break and bend branches
The Lower Mississippi River region served as an important ecological resource for many land-dwelling and freshwater animals.
Grassland habitats and forests prevailed - dominant presence of large grazing animals (bison, mammoth, horse, and stag moose).
Tapirs (cow-sized) could swim, wallow in mud, and hide in dense vegetation.
Giant Ice Age Beaver
Stag moose – the name implies that it is cross between an elk and a moose. Actually it was a large deer.
- Had a larger head and bigger teeth than any past or present member of the wolf family
- Hunted in packs
- A crushed skull was found on the Rosedale Gravel Bar.
Great Short-faced bear
- Regarded as the most powerful predator in North America during the Pleistocene.
- Stood 8-10 ft (2.4 – 3 m) tall on its hind legs.
- Canine teeth were suited for puncturing tough hide
- Large, jagged molars were exceptional for gnawing, tearing, and slicing meat.
A lower jaw was found on ‘The Bar’ in Desha Country, Arkansas.
Range of Great short-faced (http://www.museum.state.il.us/exhibits/larson/arctodus.html)
The Great short-faced bear was believed to become 13,400 years ago as the result of competition with invading brown bears (including the grizzly bear) that are also predatory in nature.
Manatee – Unusual find
Why was gigantism so widespread among Pleistocene mammals?