Fossils in Southwestern
The rocks in southwestern Pennsylvania contain a wide variety
of invertebrate, vertebrate, plant, and trace fossils.
The following is a systematic overview of the types of fossils
that may be found. It is by no means meant to be inclusive.
|Phylum Cnideria (corals):
Only one genus of coral is found in the marine rocks in
southwestern Pennsylvania: Figure from Moore and others (1952).
Only two genera of bryazoa are commonly found in the marine
rocks of southwestern Pennsylvania. Figure from Wagner and others (1970).
A wide variety of brachiopods are found in the marine rocks.
Figures from Moore and others (1952) and Wagner and others (1970).
|Strophomenid articulate brachiopods
Chonetes (6a-c, top figure)
Derbyia (1a-d, 4a-b, bottom figure)
Dictyoclostus (4a-e, top figure)
Juresania (11a-b, 14a-b, top figure)
Linoproductus (9a-b, top figure)
Meekella (3a-c, bottom figure)
|Spiriferid articulate brachiopods
Composita (middle figure)
Crurithyris (5a-c bottom figure)
Hustedia (5a-c top figure)
Neospirifer (1a-c, 2a-b bottom figure)
Punctospirifer (4a-b top figure)
|Rhynchonellid articulate brachiopods
|Orthid articulate brachiopods
Rhipidomella (2a-b, 4a-b)
|Lingulid inarticulate brachiopods
A wide variety of mollusca from three subphyla are found in
both the marine and non-marine rocks. Figures from Moore and others (1952), Harper (1990), and
Wagner and others (1970).
Amphicpha (1a-c, top figure)
Antracopupa (2, top figure)
Bellerophon (8a-c, top
Cymtospira (3a-c, top
Euomphalus (15a-c, top figure)
Euphemites (not shown)
Leptozyga (10, bottom figure)
Meekospira (5, top
Pharkidontus (4a-b, top
Phymatopleura (7, bottom
Shansiella (9, top
Soleniscus (9, bottom figure)
Trepospira (12, bottom figure)
Worthenia (14a-b, bottom figure)
Acanthopecten (23, top figure)
Astartella (not shown)
Aviculopecten (14a-b, top figure; 12, bottom
Chaenomya (15a-b, top figure)
Clinopistha (12a-b, top figure)
Dunbarella (not shown)
Edmondia (9a-b, top figure)
Lima (7, top figure)
Nucolopsis (6a-b, top figure)
Nuculana (4a-b, botom figure)
Orthomyalina (24, top figure)
Palaeolima (not shown)
Palaeoneila (1, top figure)
Parallelodon (10, top figure)
Phestia (not shown)
Pseudomonotis (8, bottom figure)
Schizodus (5, bottom figure)
Septimyalina (not shown)
Solemya (not shown)
Wilkingia (not shown)
Echinoderms may be found in the marine rocks in the area. Figures from Harper (1990).
Uncommon trilobites may be found in the marine limestone
units such as the Pine Creek and Woods Run. Top figure (from d'Invilliers
and Lyman, 1895).
Fragments of insects may be found in the nonmarine shales,
particularly the roof shales of coals (Harper, 1990) (top two figures,
from d'Invilliers and Lyman (1895). Look particularly at:
- The shales of the Bakerstown coal.
- Shales above the Duquesne limestone.
- Shales above the Waynesburgh coal.
- Roof shales of a thin coal seam below the Brush Creek
Ostracodes are common to abundant in nearly all of the non-marine limestones. They are very
small however, generally less than 1-2 mm
across. Bottom two figures (from Moore and others, 1952).
For a good summary of ostracodes visit:
bones, and scales
The teeming life in the shallow seawater and the fresh-
brackish water lakes is evidenced by common teeth, spines, and scales. These are
generally quite small (less than 1 cm) but large teeth (up to 2-3 cm) may be
found. Top figure from Harper (1990). Bottom two figures from d'Invilliers
and Lyman (1895).
Occasional fish bones may be found, particularly in the
non-marine Duquesne limestone, which has yielded bones of lungfish
Monongahela and Sagenodus (Harper, 1990)
Other remains, such as bones of amphibians and reptiles, are
very uncommon by may be found with careful searching. Although nearly any
non marine formation may yield vertebrate fossils, places to begin to look
include (based on Harper, 1990):
- The Pittsburgh Red Beds, particularly in the Turtle
Creek Valley near Pitcairn (finback mammal-like reptile Edaphosaurus
and the large amphibian Eryops).
- The gray limestones just below the Pittsburgh coal
(amphibians Sagendus and Orthocanthus).
- The freshwater limestones of the Monongahela and
VERY IMPORTANT: If you should be fortunate enough to find
vertebrate fossils, please contact The Carnegie Natural History Museum as
they may be extremely important from a scientific standpoint.
|Tracks, Trails, and Burrows
Trace fossils (ichnofossils) record the motion of animals on
or through sediment. They are formed as the animal feeds, walks, slithers,
burrows, or rests. The type of creature that makes the trace fossils is
generally not known, and can be a source of interesting speculation (see
note on Casselman Formation footprints below). The following are some common
trace fossils to look for
Planolites is a simple meandering burrow oriented horizontal or
oblique to bedding; it is typically distinguished from Palaeophycus
by its lack of a burrow lining. Planolites is interpreted as a
feeding burrow made by a worm-like animal. (Information and figure taken
Trace Fossil Image Database).
Zoophycos is a horizontally to obliquely oriented burrow that shows a
helical structure as a result of overlapping U-shaped burrows that have
spreite between the U's. Zoophycos is interpreted as a systematic
feeding burrow where the animal probed into the sediment in a U-shape swath,
then repeated the same type of swath adjacent to the previous swath, moving
in a clockwise or counterclockwise direction. (Information and figure taken
Trace Fossil Image Database).
Spirorbis sp. is a small worm in a calcareous tube (1 - 2 mms) with a
spiral form. It is always attached to some surface, in this case to a little
trunk. It was living under water and affixed itself to leaves or branches
lying in the water. (Information and image from
Aulichnites are Gastropod grazing traces. These traces are locally
There are many other trace fossils in the rocks including
Clionolithes, Concotrema, and Zapfella which are tiny
boring found in fossil shells.
Although most trace fossils in the area were formed by
invertebrate, some footprints have been linked to amphibians or early
A fossil trackway was recently found in a ripple-marked
sandstone surface in the Casselman Formation of northern Cambria County, PA.
Marks and others (1999) interpret the tracks to have been made by a giant
myriapod (similar to a present-day millipede).
Sir Charles Lyell, in a trip through the Pittsburgh area in
1845, reported (Lyell, 1849) seeing rock slabs showing 'air-breathing
reptile' footprints on a slab of rock shown to him in Greensburg. The
fossils came from a 'stone quarry in Union Township six miles southeast of
Greensburg on a farm belonging to Mr. Gallagher.' See photos to the right.
If these footprint slabs still exist today is uncertain.
Fossil plants in the area include trunks, and stems,
branches, leaves, fruit or cones, seeds, and roots of many different
varieties. Top two figures from Harper (1990).
As pointed out by Harper (1990), Although different fossils
may bear different names, they commonly represent parts of the same plant.
For example, the scale tree Lepidodendron is recognizable by the
diamond-shaped pattern on its trunk surface. Other parts of the tree
include: Lepidophylloides (the leaves), Stigmaria (the roots),
Lepidostrobus (the cone), and Lepidostrobophyllum (the scales
of the cone).
Other plant fossils that can be found include Sigillaria
(scale tree), Cordaites, Calamites (scouring rush),
Sphenophyllum (small scouring rush), Psaronius (a true fern,
leaves are Pecopteris), Medullosa (a seed fern, leaves are
Neuropteris, Alethopteris), and others.
The images to the right show the major plants that can be
found as fossils in the area, what they looked like, and their basic parts.
Figures are from Edmunds and Koppe (1968) and Gillespie and others (1978).
For a great site showing a wide variety of the plant fossils
found in the Pennsylvanian and Permian rocks go to:
Plant fossils may be found in nearly all non-marine shales and
sandstones. However, Harper (1990) gives several suggestions as to where to look:
- Gray shales in the Glenshaw Formation.
- Shales associated with the Monongahela Group coals.
However, where the rock is coarse, sandy, and full of mica, the abundance
of plant fossils decreases dramatically.
- Occasionally, the shales above the Pittsburgh Coal
contain a wide variety of flora. Look especially in the Burgettstown and
Where to Look for Fossils
Fossils will not occur in all rocks. Fossils that occur in a
rock section in one place, may be absent in the same rock section elsewhere. It
all depends on the environments the plants and animals lived, and whether or not
the remained were preserved. As a help in finding fossils, Cross and Schemel
(1956) presented a very concise type stratigraphic section for the
Pennsylvanian-Permian rocks in the central Appalachians. It illustrates the
types of rock layers found and their outcrop relationships. It also shows the
kinds of fossils that may be found in each kind of rock layer. Cross and
Schemel's chart is available in the thumbnail below as a jpeg file (nearly 1Mb)
or as a
file. It would be very useful to take a copy with you into the field.
When you examine the fossils that occur together in a
particular rock unit, you are really examining the remains of a community or
organisms that lived together when the rocks were deposited. At any particular
time, there are different communities of animals living in different
environments. For example, think about the animals that live in a forest, a salt
marsh, and in shallow sea water. Each area will have a different community of
organisms that is controlled by the environmental conditions. The study of
animals in relation to each other and to their environments is known as ecology.
When we study fossil organisms, we study paleoecology. The following
illustrations from McKerrow (1978) show how the fossil organisms found in a rock
may be used to reconstruct the environment of deposition. The environments shown
are similar to, but not exactly the same, as those for some of the rock units in
southwestern Pennsylvania. Communities present in the Pennsylvanian Ames marine
limestone are summarized by Brezinski (1983) and Saltsman (1986).
Non-marine bivalve community. Inhabited shallow waters which
spread over extensive areas after the flooding of coal forests. Brackish water.
Mud community. Inhabited shallow marine waters with a moderate
Composita community. Inhabited marine water with
calcite mud deposition.
References (used and other helpful sources of
Unfortunately, most of these resources are
out-of-print. I would suggest looking for used copies through the the
Advanced Book Exchange,
For additional references of paleontological
studies see page 162 of Schultz (1999).
Bartlow, J. A., editor, 1975, Proceedings of the First I. C.
White Memorial Symposium "The Age of the Dunkard," West Virginia Geological
Survey, 352 p.
Brezinski, D. K., 1983, Developmental Model for the Appalachian Basin marine
Incursion: Northeastern Geology, v. 5, p. 92-99.
Burns, J., 1991, Fossil Collecting in the Mid-Atlantic
States, Johns Hopkins Press, Baltimore, 201 p.
Cross, A. T., and Schemel, M. P., 1956, Geology and Economic
Resources of the Ohio River Valley in West Virginia, Part I: Geology of the Ohio
River Valley in West Virginia, West Virginia Geological Survey, Volume XXII, 149
d'Invilliers, E. V., and Lyman, B. S., 1895, A Summary
Description of the Geology of Pennsylvania, Volume III Part II Describing the
Bituminous Coal Fields and the New Red of Bucks and Montgomery Counties,
Pennsylvania Geological Survey, p. 2153 - 2588.
Edmunds, W. E., and Koppe, E. F., 1968, Coal in Pennsylvania,
Pennsylvania Geological Survey Educational Series No. 7, 29 p.
Gillespie, W. H., Clendening, J. A., and Pfefferkorn, H. W., 1978, Plant
Fossils of West Virginia, West Virginia Geological Survey Educational Series
Harper, J. A., 1990, Fossil Collecting in the Pittsburgh Area,
Pittsburgh Geological Society Guidebook, 50 p.
Hoskins, D. M., 1969, Fossil Collecting in Pennsylvania,
Pennsylvania Geological Survey Bulletin G 40.
Hoskins, D. M., 1999, Common Fossils of Pennsylvania,
Pennsylvania Geological Survey Educational Series 2, 19 p.
LaRocque, A., and Marple, M. F., 1965, Ohio Fossils, Ohio
Geological Survey Bulletin 54, 152 p.
Leighton, H. 1945, The Geology of Pittsburgh and its Environs: A Popular
Account of the General Geological Features of the Region: Carnegie Institute
Press, 2nd edition, Pittsburgh, PA , 80p.
Lyell, C., 1849, A Second Visit to the United States of North America, John
Murray, London, 2 volumes, 368 and 385 p.
Marks, W. J., Marks, R. I., and Pompa, A. M., 1999, Problematic Tracks in the
Casselman Formation of Cambria County, Pennsylvania Geological Survey
Pennsylvania Geology v. 29, n. 2/3, p. 2-6.
McKerrow, W. S., 1978, The Ecology of Fossils, M.I.T. Press,
Cambridge, Massachusetts, 384 p.
Moore, R. C., Lalicker, C. G., and Fischer, A. G., 1952,
Invertebrate Fossils, McGraw-Hill Book Company, Inc., New York, 766 p.
Read, C. B., and Mamay, S. H., 1964, Upper Paleozoic Floral
Zones and Floral Provinces of the United States. United States Geological Survey
Professional Paper 454-K, 30 p.
Saltsman, A. L., 1986, Paleoenvironment of the Upper Pennsylvanian Ames
Limestone and associated rocks near Pittsburgh, Pennsylvania: Geological Society
of America Bulletin, v. 97, p. 222-231.
Schultz, C. H., editor, 1999, The Geology of Pennsylvania,
Pennsylvania Geological Survey Special Publication 1, 888p.
Shimer, H. W., and Shrock, R. R., 1944, Index Fossils of North
America, The M.I.T. Press, Cambridge, Massachusetts, 837 p.
Wagner, W. R., and others, 1970, Geology of the Pittsburgh Area: Pennsylvania
Geological Survey General Geology Report G 59, 145p.