A creek’s gift

Discovered in a Yorktown, Virginia creek

32 years ago: a mastodon’s large molar,

part of its lower jaw, some foot bones and

a few rib fragments.

D.C.

DEL.

MD.

VIRGINIA

Richmond

Yorktown

0

50

MILES

The M3 molar

 

A heavily worn back molar still bears the marks of a severe abscess, which might have played a role in the animal’s death. A deep cavity in the root matches up with an infection scar found in a portion of the lower right jaw.

A less-worn molar would be capped with a

series of pointed cones.

7”

Cavity

American mastodons became extinct about 12,000 years ago, after living in North America for nearly 4 million years. The animals stood as tall as 10 feet and weighed as much as six tons. They lived in herds in forested regions, browsing on vegetation, which they ground to a pulp with huge jagged molars.

Final resting place

 

The mastodon’s last stand was on ancient sediment that had been exposed by the local creek. Known as the Yorktown Formation, the sediment contains fossils of shells and other marine organisms deposited in warmer, higher seas about 5 million years ago.

Scavengers may have spread out the mastodon’s remains as they feasted on the carcass.

Preservation

Bones eventually became covered by silt and soil. The bed of shells provided an alkaline soil environment, which protected the bones from the erosive effects of naturally acidic rainwater.

Discovery

After thousands of years, the creek finally cut into the bank of soil holding the remains, exposing some of the mastodon fossils, which were discovered by a brick mason in 1983.

Recovery

Ground-penetrating radar has pinpointed the location of some larger bones. After an excavation machine removes the top layers of soil, scientists will begin the delicate job of unearthing the

mastodon’s remains.

Where have all the megafauna gone?

Some scientists believe that climate change exterminated most of North America’s megafauna before prehistoric humans spread across the continent. Only the bones of mammoths and mastodons reveal the marks of butchering.

10 feet

8

6

4

2

American camel

 

Giant sloth

 

 

American lion

 

Teratorn

 

 

10

8

6

4

2

American mastodon

 

Southern

mammoth

 

Giant beaver

 

A creek’s gift

Discovered in a Yorktown, Virginia creek 32 years ago:

a mastodon’s large molar, part of its lower jaw, some

foot bones and a few rib fragments.

D.C.

DEL.

MD.

VIRGINIA

Richmond

Yorktown

0

50

MILES

A less-worn molar would

be capped with a series

of pointed cones.

7”

Cavity

The M3 molar

 

A heavily worn back molar still bears the marks of a severe abscess, which might have played a role in the animal’s death. A deep cavity in the root matches up with an infection scar found in a portion of the lower right jaw.

 

The mastodon’s last stand was on ancient sediment that had been exposed by the local creek. Known as the Yorktown Formation, the sediment contains fossils of shells and other marine organisms deposited in warmer, higher seas about 5 million years ago.

Final resting place

 

American mastodons became extinct about 12,000 years ago, after living in North America for nearly 4 million years. The animals stood as tall as 10 feet and weighed as much as six tons. They lived in herds in forested regions, browsing on vegetation, which they ground to a pulp with huge jagged molars.

An unlikely fossil

East of the Blue Ridge, conditions haven’t been favorable for preservation of mastodon fossils, although a few fragments have been recovered. However, one of the animals died in a spot that was unusually protective of its bones, the discovery of which may lead to Virginia’s first full mastodon.

Death

Preservation

Discovery

Recovery

The animal died on top of a bed of fossil shells that had been exposed by a creek. Scavengers may have spread out the remains as they feasted on the carcass.

Bones eventually became covered by silt and soil. The bed of shells provided an alkaline soil environment, which protected the bones from the erosive effects of naturally acidic rainwater.

After thousands of years, the creek finally cut into the bank of soil holding the remains, exposing some of the mastodon fossils, which were discovered by a brick mason in 1983.

Ground-penetrating radar has pinpointed the location of some larger bones. After an excavation machine removes the top layers of soil, scientists will begin the delicate job of unearthing the mastodon’s remains.

Where have all the megafauna gone?

Some scientists believe that climate change exterminated most of North America’s megafauna before prehistoric humans spread across the continent. Only the bones of mammoths and mastodons reveal the marks of butchering.

10 feet

8

6

4

2

Teratorn

 

 

American camel

 

American mastodon

 

Giant beaver

 

American lion

 

Southern

mammoth

 

Giant sloth

 

 

SOURCE: Jackson Landers, Illinois State Museum, Science.