Museum Report

Harlan’s Ground Sloth

They comprised mammals whose bones and teeth configurations were similar to the present tree sloths, though, they were much larger. They date back as early as 11 million years ago and went into extinction about 12000 years ago. Paleontological studies suggest their origin is South America and migrated to the North America about 3 million years ago. Their fossils have been found in many western states of the US. 

Like the other giant ground slots, Harlan’s had huge jaws, and fore limbs were shorter than hind limbs. They had strong limbs and three wide triangular claws on their fore limbs used for digging roots and tubers. Their locomotion was either bipedal or on their four feet. They lacked incisors just like the other giant ground sloths. All their teeth were molar-like, presumably for grazing on grass. Their teeth were highly crowned and this could easily be associated with burrowing, which added grit to their diet. Additionally, they had small bone plates on their skins known as dermal ossicles, which protected them from potential predators. 

Various studies have interpreted these sloths as browsers, grazers, or mixed feeders. However, dentine isotopic studies carried out classified them as mixed feeders with a large portion of their diet being grass. Additional isotopic studies conducted at Rancho La Brea concluded Paramylodon harlani to have been strict herbivores. Their habitats were open grasslands and close to water bodies such as lakes. Paleontological studies have found their fossils next to mammoth fossil, a clear indication that they lived in almost similar habitats. However, the way they avoided competition on similar plant food sources remains poorly understood.

Antique Bison

They originated from Asia but later migrated to North America about 0.2 million years ago. They are the ancestors of the North American Bison. Some Researches link their extinction to climatic changes and overhunting. Their common predators included the saber-toothed tigers, lions, and the dire wolves. They were heavy grazers and could at times browse. They were the most common herbivores in North America. They became extinct about 4000- 5000 years ago. They were about 15.6 feet long and about 7.5 feet tall. Generally, they were much larger than the present bison. Their horns were about 4.2 feet long which were used for protection from prospective predators. In addition, they had a large layer of deep fur on their upper body, which insulated them during cold seasons. The males were also larger than female.

They lived in open woodlands and the savannah where the present bison resides. They were also found in many parts of Central and South America and went all the way to Mexico and Canada. They shared same habitats with mammoths, ground sloths, camels, and horses. Their biggest threats were the humans who hunted them down for various reasons. They were food sources for humans, their skins helped in producing cloths during the ice age. In addition, their bones and horns were used as tools. They had some behavioral adaptations, which were useful for survival. These included their movement in herds whereby they would migrate from place to place in search of vegetation for grazing. A majority of their herd gave birth during warm seasons. This was vital for a survival of the calves. A majority of calves born during winter did not survive the cold weather. Furthermore, vegetation remained limited during winter. A study regarding disease pathology indicated fungal infections as result of Coccidiosis similar to those evident in modern cattle. Other diseases which affected them comprised osteoarthritis.

Columbian Mammoth

Studies suggest that they lived about 1.1 million years ago in North America and became extinct about 13000 years ago. They were the largest mammoths according to archeological studies. At Anza-Borrego State Park in California, their fossils have been found alongside Steppe mammoth suggesting that the latter would have been their ancestors. They originated from Asia and Europe and later entered N. America.

Their habitats in the Channel Island is said to have been destroyed during the end of the ice age, which raised the sea level. They had variable habitats ranging from sea levels to mountains of Colorado plateau. They were also found in grasslands and riparian. They have similarity to the modern elephants. They weighed about 5.5-11 tons and 4-4.5 m in body length. They have been found to have 26 teeth and had six sets of teeth in a lifetime. 

The sets of teeth marked different stages in their lifetime. The male’s tusks are larger and stronger in comparison to those of the females, which is also similar to modern elephants. Due to their huge sizes, they had no predators even though saber-toothed cats preyed on their calves. The mammoth is said to have been swimming their way to the Pleistocene Channel Island, which had open grasslands.

Research has indicated that they were browsers and grazers depending on food resources available on a seasonal basis. Some undisputed recent studies claim that they became extinct as a result of comet impact alongside other ice age animals. However, most of the mammoths of their time are said to have become extinct because of human hunting activities and climatic changes. Isotopic dentine studies reveal that they lived 55-70 years.

Dire Wolves

They were similar to the present gray wolves. They first existed in Central America before migrating to North America and northern South America where they existed between 0.3 million to 12000 years ago. They lived in the same habitat with the gray wolves, which exists in the North America up-to-date. Numerous fossils have been found in La Brea asphalt in California and could suggest they lived in groups. Their habitats varied from sea levels, mountain regions, grasslands, and forests. Fossils have been collected in southern California, which has Pleistocene climate. They were similar to modern wolves though they were larger in size and had larger skulls. They had massive jaws and studies on their teeth, which revealed they were bone crushers similar to the modern wolf. The pulp cavity studies indicate that they lived about 6-8 years of age. Their physical attributes are almost similar to the large gray wolves of Alaska and the spotted hyenas. However, their flatter skull suggests that they were not heavy bone crushers as the modern hyenas.

Their fossils have been found in same places with many types of carnivorous wolves such as the timber wolves, domestic dogs, and coyotes suggesting they lived in the same habitats. The earlier dire wolves teeth had more fractures and breakage compared to the recent dire wolves. It is an indication that they broke fewer bones of their prey compared to the earlier species. Furthermore, competition for prey may have slowed down and could, therefore, make many kills. It made them unable to finish their kills. They had stronger canines than the modern gray wolves with which they used to subdue their kill. They did not have a specialized diet and could feed on any mega fauna they came across. The fact that they lived in packs was more advantageous as they could kill a large animal such as a bison. A bone study on their health indicates no variation from the modern gray wolves.

Juvenile Mastodon

They lived 3.7 to 13000 million years ago. They lived in many parts of North America, Mexico, and Alaska. They were smaller than mammoths and slightly larger than the modern elephants. They were found in North and Central America, as well as Greece. Males were about 10 feet tall with the females averaging 7 feet. Adults weighed about 6 tons and their bodied curved slightly backward. They were tallest at the shoulder on side viewing. They were about 4.5m long. The saber-toothed cats heavily preyed on these animals, and numerous fossils have been found in dens.

They had larger tusks compared to the modern elephants. Male mastodon had a pair of small tusks in their lower jaws, which were lost as they matured. They were herbivores. A clear difference between them and mammoths exist in their molars. They had cusped molars unlike for mammoths, which were flat with ridges. Their variation in tooth structure suggests a difference in feeding habits. The mastodon used their cusped molars to hold and crush trees and shrubs. Mammoths in the other hand used their teeth to graze.

They were larger than females, and their tusks were larger stronger. Scientists attribute the difference in sizes and structure to have developed as they tried to dominate each other over mate partners. They had two layers of hair comprising the undercoat and the outer layer, which insulated the animals during the winters. They used their trunks to dig for water and salt, as well as, debarking of trees. They were also used for protection purposes. They are believed to have gone extinct due to overhunting and climatic changes. The fact that they were highly hunted by the saber-toothed cats may have also contributed to them been wiped from the food chain. 

Summary

Harlan’s Ground Sloth

(Paramylodon Harlan)

• Lived in open grassland; sea level to high lands.
• Similar but much larger than modern tree sloths. They were more than 6ft tall.
• Fed on grasses and bushy plants.
• Predated by saber-toothed cats, bear, and American lion.
• Had strong limbs and three wide triangular claws on their fore limbs.

Ancient Bison

(Bison antiquus)

• Found in  North America, mainly south  western U.S. also in Canada, Mexico and Central America
• Lived in Open woodlands or savanna
• Had fur and large horns of about 1m.  Larger that modern American bison.
• Dentine isotope suggests they grazed and browsed on small herbs.
• Predators: American lions, saber-toothed cats and dire wolves.

Columbian Mammoth

(Mammuthus columbi)

• Found in North America, Canada and central Mexico
• Lived in Sea level to mountainous regions, riparian and grasslands.
• Were grazers and browsers
• Locomotion and social behaviors similar to modern elephants
• Weighed about 5,000-10,000 kg.
•   Twenty six teeth and six sets of teeth in a lifetime.
• molars had 5- 8 enamel plates per 10 cm.

Dire Wolf

(Canis dirus)

• Found in North America into northern South America
• Lived in variable habitats; forested mountains to open grasslands and plains; sea level to plateaus. 
• Weighed 34-67kg, 62cm long tail and about 80cm shoulder height.
• They similarly associated with to modern gray wolves and predated on small and large mammals such as bison, giant ground sloths and mammoth calves.

Juvenile Mastodon

• Lived in many parts of North America, Mexico and Alaska.
• Almost similar in size to modern elephants.
• Lived in Sea level to mountainous regions, riparian and grasslands.
• Isotopic dentine studies show they were browsers.
• Head not domed as in mammoths and modern elephants 
• 2 layers of hair; undercoat, outer layer hair.
• Trunks and ears  not known 
• Tusks up to 2.5 m ; usually much shorter; curved; and  thicker than modern elephants 
• Molar teeth were cusped; unlike any mammoths or modern elephants