Common Fossils in Pennsylvania

Dinosaurs?   Not common in Pennsylvania   Only found in Southeastern Part of the

state   Dinosaurs wondered near the lakes and

swamps and are preserved there dating from the Triassic Period (1st period of the Mesozoic Era

Where you can find the1st evidence of Life on Earth   Life has been found in rocks dating

back to 3.7 billion years ago.   These rocks were found in Africa &

Greenland.

1st Life in PA   The 1st evidence of life in Pa dates back

to 1.6 billion years ago.   This simple life was single celled algae.   The rocks that make up Pennsylvania

were created after life had already begun on earth.

What happens to life when it dies? 1.  Animal gets eaten by scavengers 2.  Life decays & disappears 3.  Under certain conditions life will fall to

the bottom of lakes, streams, oceans and will become buried by sediments and the natural process of decay will be stopped.

Preserving life   Fossil – any natural evidence of

prehistoric life that provides some idea of size shape or form of the organism.

  Doesnʼt need to be a whole specimen   Most fossils we find are only remains of

their hard parts. (bones, shells, teeth)

Rule of thumb   More common – organisms that had

inhabited marine environments are more likely to become preserved.

  Less common – organisms that had inhabited land.

Notable exceptions   During the Pennsylvanian Period many

plant fossils were preserved.   330 – 290 million years ago

Other ways of preserving   Animal or plant falls into a tar pond   Animal is covered in tree sap

(preserved in amber)   Animal is frozen (glacial activity, ice

ages)   Casts & molds

Casts & Molds Mold   Hard parts are commonly dissolved

after they are buried.   This leaves an empty space in the rock. Cast   If more of a sediment fills in this mold it

will take the shape of the mold Most fossils are considered to be casts &

molds.

What are your chances?   It is likely for about 1 of every million

living organism has a chance of being preserved

  Mainly b/c the natural processes quickly destroy them.

  It is likely that certain species were never preserved and therefore they will go unknown forever.

Uses of fossils Paleontology – the collecting & studying

of fossils 1.  Direct evidence of the types of life that

lived on earth 2.  We learn how these animals evolved

& developed 3.  Determine the climate, environment, &

position of landmasses & marine waters of the past.

Classification   2 part naming system Genus Species Homo sapien = human Canis familiaris = dog

  Names usually in Greek or Latin

Life you can find in PA   Corals   Bryozoans   Brachiopods   Mollusks   Arthropods   Echinoderms   Plants

Corals   Groups of animals (polyp) that build a

framework composed of calcium carbonate

  2 main types   Colonial   Solitary

Bryozoans

  Very small colonial animals that build a plant-like or moss-like calcareous skeletal framework.

Brachiopods   Among the most common fossils found

in Pa.   Have 2 shells   Differ in size & shape   Resemble a clam

Ways to tell a Brachiopod from a Bivalve

Mollusks   Grouped into 2 very common & well

known animals:   Bivalves (clams)   Gastropods (snails)

Bivalves   We know them as clams, scallops,

oysters   Have 2 shells   Muscular foot for moving & burrowing

Gastropods   We know them as snails & slugs   Live on the land & in the sea

Arthropods   Jointed legs & segmented bodies   4 main families of arthropods:

  Insecta (flies, mosquitoes)   Arachnoidea (spiders, scorpions)   Crustecea (crabs, lobsters)   Trilobita (extinct)

Trilobita   Lived during the Paleozoic Era   570 – 250 million years ago   Mass extinction killed off all trilobites   Had 3 main sections (cephalon, thorax,

pygidium)   Soft underbellies which included legs &

antennae   Grew by molting, shed off different

sections at different times.

Official State fossil of Pennsylvania   Phacops rana

Echinoderms   We know them as starfish, sea cucumbers,

sea urchins.   Contains Class Crinoidea   Sometimes called “sea lilies”   Are not plants   Have 3 sections:

  Stalk – attaches itself to the sea floor   Body – houses the soft fleshy body   Arms – gathers food

  Abundant fossil in Pa

Plants common in Pa   Very common in Anthracite &

Bituminous coal regions   Coal is made from decaying plants   What ever plants that didnʼt change into

coal were preserved

Common finds   Scale trees – grew to great sizes   Scouring rushes   Fossilized leaf whorls   Ferns & seed ferns   Trees that had wood probably look

much like our present day pine trees

How to obtain these fossils   Collect them from the rock in which they

had lived in.   If you are further interested in fossils go

to:  www.dcnr.state.pa.us

Anthracite Valley Section mountain and valley section

  The Anthracite Valley Section is a narrow to wide, canoe-shaped valley. It is enclosed by a steep-sloped mountains rim. The overall structure of the Valley is a broad, doubly plunging syncline with smaller folds. Elevations on range from 500 to 2,368 feet. The rocks are composed of sandstone, siltstone, conglomerate, and anthracite coal.

  Anthracite Valley Section occurs in northeastern Pennsylvania in parts of Columbia, Luzerne, Lackawanna, Wayne, and Susquehanna Counties. A good view of the Section can be seen from Interstate 81 and State Route 11.

  Some Outstanding Scenic Geological Features of the Section include Archbald Pothole, Campbell Ledge, Nay Aug Park Gorge, and Pinnacle Rock

Dinosaurs   Not commonly found in Pennsylvania.   Found in the southeastern parts of Pa   Triassic period

So how do dinosaurs become fossilized 1.  They die 2.  While they lie dead the meat and fleshy

parts of their bodies either decay or are eaten.

3.  If the creature had died near a stream bed, sediments will cover its body up.

4.  As it begins to age minerals dissolved in the water will fill in the pore spaces and harden the bones. Preserving them for years to come.

Set backs   Most of the bones are very brittle   A rain storm or wind can wear them

away once they are exposed.   Fossilized bones do not have a very

long shelf life when exposed to the elements.

Why is it so difficult to find a complete dinosaur?