Common Fossils in Pennsylvania

Transcription

1 Common Fossils in Pennsylvania

2 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 (1 st period of the Mesozoic Era

3 Where you can find the 1 st 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.

4 1 st Life in PA The 1 st 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.

5 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.

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7 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)

8 Rule of thumb More common organisms that had inhabited marine environments are more likely to become preserved. Less common organisms that had inhabited land.

9 Notable exceptions During the Pennsylvanian Period many plant fossils were preserved million years ago

10 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

11 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.

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13 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.

14 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.

15 Classification 2 part naming system Genus Species Homo sapien = human Canis familiaris = dog Names usually in Greek or Latin

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

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38 Corals Groups of animals (polyp) that build a framework composed of calcium carbonate 2 main types Colonial Solitary

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

40 Brachiopods Among the most common fossils found in Pa. Have 2 shells Differ in size & shape Resemble a clam

41 Ways to tell a Brachiopod from a Bivalve

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43 Mollusks Grouped into 2 very common & well known animals: Bivalves (clams) Gastropods (snails)

44 Bivalves We know them as clams, scallops, oysters Have 2 shells Muscular foot for moving & burrowing

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

46 Arthropods Jointed legs & segmented bodies 4 main families of arthropods: Insecta (flies, mosquitoes) Arachnoidea (spiders, scorpions) Crustecea (crabs, lobsters) Trilobita (extinct)

47 Trilobita Lived during the Paleozoic Era 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.

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49 Official State fossil of Pennsylvania Phacops rana

50 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

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52 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

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54 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

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56 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:

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59 Anthracite Valley Section mountain and valley section

60 The Anthracite Valley Section is a narrow to wide, canoe-shaped valley. It is enclosed by a steepsloped 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

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

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63 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.

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65 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.

66 Why is it so difficult to find a complete dinosaur?

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