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Common Fossils
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Western New York
CAROL A. HEUBUSCH
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BUFFALO MUSEUM OF SCIENCE
BUFFALO, NEW YORK
EARTH
SCIENCES
GIFT
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Common Fossils of Western New York
r* i A LJ L L SCIENCES
Carol A. Heubusch LIBRARY
Geologist, Buffalo Museum of Science
Introduction
There are many people who find a fossil and want to know something
about it. This article has been prepared to aid these amateur collectors.
Descriptions are limited to the common invertebrate fossils of Western New
York although some primitive plants and fishes are found. Many kinds of
fossils are not discussed for various reasons: few or no representatives are
present locally; there is difficulty in recognizing and identifying some
groups; space is lacking to provide necessary detailed descriptions of the
numerous classifications.
What is a Fossil?
A fossil is some evidence of the existence of a plant or animal which is
found preserved in the rocks. To insure preservation, it is necessary that
organisms be embedded soon after death in some protective material. Hard
parts must be present since soft parts of organisms are rarely preserved.
Some sort of alteration of the resistant parts usually occurs, either mineral
infiltration of pore spaces or substitution of the original material by mineral
matter. The resulting composition of the fossil is often calcium carbonate,
the same substance of which the hard parts may be originally composed.
Some fossils are composed of silica while others are of chitin, a complex
organic substance. Fossils are sometimes preserved as black carbonaceous
films on rock.
Besides the actual remains of animals and plants, any evidences of their
former existence are counted among the fossils. Objects indicating the
former presence of organisms include casts and molds, trails, tracks, imprints,
and burrows.
Fossils are often not perfectly preserved. They may be crushed or
distorted and they are frequently fragmentary. Many fossils can be identified
from fragments.
Fossils are found in almost all the sedimentary rocks of Western New
York. The essentially flat-lying layered rocks are composed of sediments
once deposited in warm shallow seas covering this area. This occurred
mainly during the geologic times of the earth's history called the Devonian
and Silurian periods over 300 million years ago. There was a great abund-
ance and variety of life in these seas. A small percentage of the animals
was preserved in the soft sediments. The sediments consolidated forming
rock, the finer grained forming shale and the coarser grained, sandstone.
Calcium carbonate was precipitated from the sea water; it settled to the
bottom and became limestone.
Irregularly rounded rocks of various sizes are often mistaken for fossils.
These rocks may be concretions which have been formed inorganically by
the collection of mineral matter around some nucleus. They may resemble
animal bones. Rocks divided into segments by cracks which have been filled
with a different rock may be mistaken for fossil turtle shells.
422
What are the Characteristic Fossil Groups?
Porifera
The sponges or Porifera comprise the simplest group of multiceliea
animals. They typically are attached forms of marine environment. Sponges
are of greatly varied shape, being globular, cylindrical, conical, or irregular.
The soft body of a sponge is generally supported by an internal skeleton
composed of organic fibers or spicules. The most commonly found fossil
representatives of sponges in Western New York are spicules. Sprcuies
show considerable range in shape, size, composition, and structure. They
consist fundamentally of simple spines or of spines radiating from a point.
Size of these spicules is small, averaging less than one-fourth of an irwrh
in length.
In many extinct sponges the spicules were the most prominent hard
parts. They frequently became thickened and united to form a solid trellis
or framework which retained the form of the sponge during fossilization.
Fossil sponges include isolated spicules of calcium carbonate or silica, frag-
mentary or whole skeletons, and, rarely, the distorted outlines of complete
bodies. Sponge fossils are usually poorly preserved and difficult to recognize.
Coelenterates
Corals are bottom-dwelling marine coelenterates which have an exten-
sive fossil record and are still abundant in warm shallow seas. These
animals secrete calcium carbonate skeletons about the sides and base of
their barrel-shaped bodies. This encases the lower part of the coral in a
conical or cylindrical tube or forms a flattish basal expansion. Radiating
calcareous vertical partitions called septa are built by infolded parts of the
body covering. These partitions help to strengthen the animal. The animal
lives in the depression at the top of the coral. As it grows, the skeleton
is built upward; earlier parts are abandoned, and new supporting structures
are built beneath itself. These horizontal plates are termed tabulae and
together with septa are often significant features of fossil corals.
Corals may live singly but many kinds are of a colonial nature, hundreds
of individuals being attached to each other by their outer skeletal walls.
The corals that form isolated fossils are called cup corals or horn corals.
They range from almost microscopic in size to two feet or more in length
and over twenty inches in width. These conical-shaped fossils often display
the radiating septa at the top. The outer surface of the walls varies. It
may be wrinkled and irregular with encircling growth lines, or may show
vertical septa when the outer wall is worn away.
A cup coral common in Western New York is Heliophyllum halli. It
averages three to four inches in length. The major radiating septa extend
CUP CORAL Heliophyllum halli
CoLdxiAL CORALS Favosites
,%
to the center of the coral like the spokes of a wheel and are strengthened
by small crossbars. The outer surface of the coral is strongly wrinkled.
In colonial forms the skeleton may be branching or closely packed
and massive. Colonial corals were very numerous in the Devonian and
Silurian seas once covering Western New York. Favosites is an abundantly
found fossil whose massive colony may be a few feet in diameter. The
colony is made up of numerous prismatic shaped individual tubes a fraction
of an inch in diameter. They have no vertical septa but characteristically
possess many horizontal partitions or tabulae. The vertical walls of the
individual animals are perforated by small pores. Favosites is often called
honeycomb coral.
Pleurodictyum is a colonial coral of a depressed and disc-like shape.
A concentrically wrinkled covering is found over the lower surface. The
individual corals average one-fourth of an inch or less in diameter and
are prismatic and funnel-shaped. The colony averages a few inches in
diameter. Pleurodictyum is sometimes mistaken for a fossil turtle shell
because of its convex mosaic-like surface.
Bryozoans
Most bryozoans are tiny, colonial marine animals. The calcareous
skeletons formed by the colony of animals are often preserved as fossils.
Some fossils consist of a simple chainlike series of tubes usually found
encrusting foreign surfaces such as brachiopod shells. Others form thin
leaflike expansions, rounded branches, massive bodies, or lacy fans. The tiny
holes seen perforating the fossils are the openings where each animal of the
colony lived.
Bryozoans are common local fossils; they are found in a great variety
of shapes and sizes. One of the commonest Western New York bryozoan
fossils is Fenestrellina (often called Fenestella) which is a fan or funnel-
shaped, lacelike colony. The individual animals lived in the almost micro-
scopic double row of holes along the radiating branches.
Brachiopods
Brachiopods are common fossils of Western New York because they
were among the dominant forms of the ancient life which existed here and
possessed the necessary hard parts to be preserved as fossils. The hard parts
consist of an external shell of two parts called valves. In this respect they
bear a superficial resemblance to clams. However, the valves of brachiopods
differ from those of clams because they are of unequal size and shape. If the
brachiopod were to be cut so that two equal valves resulted, the cut would
pass through the middle of each valve, while in a clam it would pass
between the valves.
BRYOZOAX Fenestrellina BRACHIOPODS Mucrospirijer mucronatus, Atrypa reticularis
Brachiopod fossils vary greatly in size, from less than one-fourth of
an inch to several inches. They are of calcium carbonate or chitino-
phosphatic composition. Many of the shells have variously shaped structures
or platforms which supported soft parts of the animal; they are found on
the inside of the valves.
Shells of brachiopods are characterized by a wide diversity of appear-
ance. Some are circular or elliptical in outline while others are irregular.
Some shells have two very convex valves; some have one convex and one
almost flat valve; others may have one convex and one concave valve.
Where the halves of the shell are joined, one valve typically has a
pointed beak. At this end of the fossil is the hinge line, an area which
varies greatly in different kinds of brachiopods. When the hinge line is
short, the shell shape is pointed at that end.
A shell with a wide hinge line may possess greater width than length.
An example is Mucrospirijer mucronatus. This species is characterized by
lines radiating from the center of the hinge line and by a prominent center
fold in one valve and corresponding depression in the other.
Some brachiopod shells are smooth; others, such as the common Atrypa
reticularis, display prominent ridges and grooves radiating out from the
hinge of the shells plus growth lines concentrically arranged.
Mollusks
Gastropods
Snails, or gastropods, are mollusks possessing a single shell which is
usually coiled into a spiral, although it may be conical or saucer-shaped.
The animal lives in the entire shell which is not partitioned into chambers.
Growth lines are often present encircling the shell. Ornamentation of
various types may occur including ridges, folds, and spines.
Although gastropods were abundant in the ancient seas the gastropod
shells were quite easily destroyed because they were mainly composed of
a relatively soluble mineral called aragonite. Many gastropod fossils may
be merely fillings of the shell interior. They are internal molds which do
not indicate the outer form of the shells and therefore are difficult to
identify.
Some gastropod fossils may be recognized because of characteristic
coiled or conical forms. Others, such as Platyceras, possess horn-shaped
shells of irregular growth reflecting irregularities in the object to which the
shell was fixed during life.
Peiecypods
Clams, or pelecypods, have calcium carbonate shells composed of two
valves typically equal in size and shape, each half being the mirror image
of the other. Each valve is often asymmetrical in outline. These features
are the most evident means of differentiating pelecypods from the more
commonly found brachiopod fossils which also possess two valves but of
unequal size and shape.
Concentrically arranged growth lines are commonly present as are
various types of ornamentation such as radiating ribs. Fossils may consist
of the shell or of internal fillings or external molds. They generally range
in size from a fraction of an inch to a few inches in length and width.
Cephalopods
Cephalopods are among the most highly developed mollusks. Squids,
octopuses, cuttlefish, and the pearly nautilus are living representatives of
this class which are abundantly represented as fossils. The calcium carbonate
shell possessed by ancient forms has essentially the form of a slender cone
which may be straight, curved, or coiled. Whether loosely to tightly coiled,
it is almost always in a flat spiral.
The animal occupied only the end portion of the fossil shell. It sealed
this "living chamber" off from the rest of the shell by transverse partitions
called septa. The line of junction of the septa with the inner surface of
the shell wall is called the suture. In most fossil cephalopods the outer shell
has been eroded away, exposing the characteristic kinds of sutures. These
suture lines and the presence of a small tube running through the septa
connecting the chambers are distinguishing features of cephalopods.
Straight and coiled shelled cephalopod fossils are found in the shales
and limestones of Western New York. The cover portrays a restoration
of the nautiloid cephalopod Nephritic eras. Its shell can be found locally.
Annelids
Annelid worms are represented by fossils of various forms including
tooth-bearing jaw parts, trails, castings, and tubes. The worm jaws, called
scolecodonts, show considerable range in shape, size, structure, and number.
These microscopic or near-microscopic fossils are usually composed of chitin
and are recognized by their black, glossy, opaque appearance.
Fossil worm tubes are minute straight or coiled snail-like forms which
can be found cemented to the surface of other fossils. The tubes are often
ornamented with ridges, spines, and nodes.
Fossil worm borings or trails are occasionally found but are generally
difficult to recognize. Arthrophycus, a fossil found in the rocks of the
Niagara Gorge, is believed by some paleontologists to be worm tubes; others
consider it a primitive plant.
Conodonts
Conodonts are minute, toothlike, transparent, or translucent fossils.
Conodonts can be distiguished from fossil worm jaws or scolecodonts by
their smaller size, calcium phosphate composition, translucent nature, and
pale amber to dark brown color.
I
CONODONT
EURYPTERID Eurypterus lacustris
These fossils are of unknown origin. Because of great diversity in size
and shape, the conodonts have at various times been called worm teeth,
fish teeth, parts of arthropods, gastropods, and cephalopods.
Arthropods
Eurypterids
Eurypterids are extinct representatives of a group of animals which
include the spiders and scorpions. Up to nine feet in length, these arthro-
pods were scorpion-like in appearance. They possessed a thin, chitinous,
segmented shell and a tail which was either long and pointed or flat.
Jointed legs are found fossilized. Many eurypterids had large compound
eyes on the dorsal (upper) surface.
Western New York is very well known for the eurypterids obtained
from its Silurian rocks. However, it is no longer possible to collect specimens
because the principal collecting locality, which was in the quarry behind
Bennett High School, is no longer accessible. Eurypterus lacustris is an
eurypterid known from specimens found locally. It averaged about a foot
in length and is characterized by large eyes and a pointed tail.
The seal of the Buffalo Society of Natural Sciences depicts an
eurypterid.
TRILOBITE Dalmanites
Trilobites
Trilobites are an extinct group of insect-like animals which have left
abundant and varied fossils. Most are less than two inches in length
although they vary from less than one fourth of an inch to thirty inches.
The animals were well protected on the dorsal surface by a hard
shield which was differentiated into three parts: a head (cephalon) some-
times possessing large compound eyes; a thorax often of numerous jointed
segments; and a spiny or rounded tail (pygidium). The body is character-
ized by an elevated ridge longitudinally along the center.
Trilobites molted as they grew, casting off their old exoskeletons much
the same as insects do today. Many fossils are the castoff immature shells.
While the animals possessed a hard dorsal covering, their lower surface
was not similarly protected. To protect themselves from enemies the trilo-
bites curled up into balls. Fossils may be found of curled up trilobites.
Trilobite fossils are often fragmentary because the trilobite shell is
so differentiated and the sections easily separated. A commonly found
trilobite in the rocks of Western New York is Phacops rana. It is charac-
terized by large popping eyes and an oval-shaped body of many segments
Dalmanites is a trilobite with a thorax of eleven segments and a tail which
is often large and pointed.
Ostracodes
Ostracodes are usually microscopic or almost microscopic crustaceans,
the same class of animals that includes lobsters and crabs. The oval or
bean-shaped shells of ostracods are composed of two valves hinged at the
top. The shells may be smooth and rounded or marked by various structures
such as lobes, pits, spines, or nodes.
Fossil ostracodes are common in some of the rock formations of
Western New York but may be difficult to find because of their small size.
Echinoderms
Echinoderms include animals well known today, such as the star-fishes,
as well as forms known only as fossils. The echinoderm shell is in the form of
calcium carbonate plates which form mosaic patterns covering the body.
Many fossil echinoderms were attached to some foreign object or to the
sea bottom by a flexible jointed stem.
Cystoids
Cystoids, the most primitive echinoderms, possess a body of irregularly
arranged plates which result in a fossil of saclike indefinite form. The body
plates in most cystoids are five-sided or polygonal in shape and are per-
forated by pores or fissures.
A cystoid found in Western New York is the oval shaped Caryocrinites
ornatus. It is characterized by pores radiating from the center of the indi-
vidual plates. These pores form rhombic-shaped designs covering the fossil.
Blasfoids
Blastoids are extinct echinoderms with a symmetrical, often bud-like,
body usually less than an inch in diameter. Their bodies are encased in
shells composed of thirteen principal plates firmly knit in definite positions.
There are five food grooves running downward from the top of the blastoid.
A representative Western New York blastoid, Nucleocrinus, is of about
the size and shape of a small olive. The five food grooves are very narrow
in this particular species.
TRILOBITE Phacops rana BLASTOID Nucleocrinus CRINOID STEMS
Crinoids
The crinoids, sometimes called sea-lilies, are animals of a plant-like
appearance. Their globular or cup-shaped bodies with radiating jointed
arms are generally supported by a stem or stalk. Their total length may
be from a fraction of an inch to over sixty feet. Plates cover the body in a
symmetrical fashion, usually in arrangements of five.
The crinoid stem consists of numerous button-like discs stacked in a
column. Through the center of the stem is typically found a rounded or a
star-like opening. Crinoids lived in great numbers in the shallow Devonian
and Silurian seas. Very rarely is the whole animal preserved; upon the
death of the animal its calcium carbonate plates fell apart. Disc-shaped
sections of crinoid stems are among the commonest fossils in many local
rocks, at places making up a large percentage of the rock itself.
Graptolites
Graptolites are extinct, colonial organisms which usually appear fos-
silized as flattened films of carbon on rocks. They possessed a protecting
and supporting skeleton; the individual animals lived in cups or pits along
the chitinous stalk. In some forms the stem was attached to a round float
and in others two, three, or four stems might be attached together. Most
graptolites floated free in the oceans and were scattered throughout jhe
world.
During fossilization the skeletons became carbonized so that they
resemble black shiny lines with irregular edges. Inocaulis is a graptolite
which can be found in the rocks of Western New York.
References
Goldring, W. F. 1950. Handbook of Paleontology for Beginners and
Amateurs: Part I, The Fossils. Second Edition. New York State
Museum Handbook 9.
Grabau, A. W. 1899. The Paleontology of Eighteen Mile Creek and the
Lake Shore Sections of Erie County., New York. Buffalo Society of
Natural Sciences Scientific Bulletin 6.
Grabau, A. W. 1901. Guide to the Geology and Paleontology of Niagara
Falls and Vicinity. New York State Museum Bulletin 45. pp. 130-252.
Moore, R. C. (ed.) 1955-. Treatise on Invertebrate Paleontology. Univer-
sity of Kansas Press and Geology Society of America. Parts in process
of publication.
Shimer, W. H. and Shrock, R. R. 1944. Index Fossils of North America.
New York: John Wiley and Sons, Inc.
Shrock, R. R. and Twenhofel, W. H. 1953. Principles of Invertebrate
Paleontology. Second Edition. New York: McGraw-Hill, Inc.
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