Unpack the Past - Fossils
Part 1: What is a Fossil?
What is a
fossil? They are the remains of plants
and animals that lived long ago. Remains
have to be a minimum of 10,000 years old (!) to be considered a fossil. Sometimes, it is the hard part of the animal,
like shell, teeth, or bone, that is preserved.
It can be wood, seeds, or insects, too.
Footprints, leaves, eggs or burrows (a tunnel) can be fossils as
well. In order for something to become
fossilized, it must be buried quickly, usually by mud or sand.
Southern
Indiana, along the Ohio River, is an excellent place to look for fossils. The area was a warm sea during the Paleozoic
Era (544-528 million years ago). It was
filled with plants and small marine animals.
During the
Mesozoic Era (248-65 m.y.a.), or the “Age of Reptiles”, there were reptiles
along with plants and marine life. No
dinosaur remains have ever been found in Southern Indiana. There was a massive
land mass shift and evidence of most life during this time was lost.
The Cenozoic
Era (65 m.y.a.) was called “The Age of Mammals”. During this time, mammals became the biggest
population of large land animals. Birds appeared as well. Again, erosion during climate upheavals make
fossils from this era scarce.
During the
“Ice Age”, or Pleistocene Epoch (1.8 m.y.a.- 8,000 years ago), many of the huge
land mammals became extinct. Ice Age
glaciers destroyed or buried remains further north. Most of the recent fossils discovered have
been in caves, swamps, bogs, and washed out river beds. Almost all of the fossils we recover from
this time period are of sea life and are easy to find.
Part 2: Fossils in Indiana
Some fossils
you may find:
Crinoids
They look like flowers but are really animals anchored to the sea floor by a
segmented stem and root structure. It is
common to find the stem portion in fossil form.
Arthropods
Animals that
include insects, spiders, horseshoe crabs, centipedes, millipedes, pill bugs
(roly poly’s), lobsters, crayfish, and the extinct trilobite. Horseshoe crabs are the closest living
relative to a trilobite. They ranged
from an inch or two long to nearly two feet and existed for nearly 300 million
years.
Coelenterates (see len ter ates)
Include
jellies, sea anemones, and corals. The
presence of fossil coral in Indiana proves that the seas that covered Indiana
during the Paleozoic era were at times shallow and tropical.
Bryozoans
Bryozoans
built colonies that were either attached to the sea floor branching out like
antlers, or grew over the shells of other ocean animals. Their lifestyle was very similar to corals.
Brachiopods
Brachiopod
shells are probably the most commonly collected fossils in Southern Indiana.
Brachiopods are a type of marine invertebrate (lacking a backbone) animal.
Their shells have two valves attached along a hinge, similar to clams.
Part 3: Mammoth
These
fossils were found here in Madison at the foot of Hanging Rock Hill (Cragmont
Street) in 1919 by W.O. Wycroft. A
letter from Mr. Wycroft states that he was a 14-year-old boy when he found the
artifacts. The fossils were “quite
crumbly” so his father shellacked them (a type of glue) so they wouldn’t fall
apart. We believe they are the remains
of a mastodon, as there have been other similar fossils found in
Scottsburg. These items were donated the
Historical Society in 1988.
This snail
shell is NOT a fossil. It hasn’t been
buried in the mud and was probably recently occupied.
These are fish bones, and they are not
fossils, either. They are most likely
the remains of a bird’s dinner.
Other
treasures you may find along the rivers and streams in Indiana:
Native
American artifacts from the various local tribes such as arrowheads, hatchet or
axe heads, fishing hooks.
You may find
geodes, which have beautiful crystals inside when broken open.
If you look along the river down by Ferry
Street, you may be lucky enough to find mussel shells, which have had buttons
punched out of them. The Pearl Button
Factory dredged the Ohio River for mussels, which had clothing buttons punched
from them. Women would sew the buttons
onto cards for extra spending money.
Most of the shells have quite a bit of erosion on them, but you can
still see where the holes were punched. We have an excellent exhibit on mussel
shells in the museum.
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