Part I. Questions - Jay Patton online...Phylum Brachiopoda – Brachiopods: These are Bivalved (two...

GEO 2: Historical Geology with Lab Lab 6: Fossils and Time

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Name: ______________________________ Date: ___________

Part I. Questions

Reference Material:

What is meant by Phylogeny or Phylogenesis? How is this related to evolution? “The central ideas of evolution are that life has a history—it has changed over time—and that different species share common ancestors.” University of California Museum of Paleontology http://evolution.berkeley.edu/evolibrary/article/evo_01

The common taxonomic subdivisions in descending order (Kingdom, Phylum, Class, Order, Family, Genus, and Species).

There are five kingdoms of organisms:

1. Animalia (animals) 2. Plantae (plants) 3. Monera (bacteria and blue‐green algae) – Includes Stromatolites 4. Fungi (mushrooms, fungus) 5. Protista (included in Rhizaria): single‐celled organisms, – Includes Foraminifera/Fusulinids,

Diatoms, Radiolaria

The Animal Kingdom animals can be grouped into the invertebrates (animals without backbones) and the vertebrates. There are more than 20 invertebrate Phyla, but the chief ones that are preserved as fossils include:

1. Phylum Porifera ‐ the sponges (may include Archeocyathids, or in a separate Phylum) 2. Phylum Cnidaria (formerly Coelenterata) ‐ the corals and jellyfish 3. Phylum Bryozoa ‐ the colonial moss animals 4. Phylum Brachiopoda ‐ the brachiopods or lamp shells 5. Phylum Arthropoda ‐ the insects, crabs, shrimp, lobsters, trilobites and eurypterids 6. Phylum Mollusca ‐ the clams (Bivalves), snails (Gastropods), octopus, squid, nautilus, and

ammonites (Cephallopods) 7. Phylum Echinodermata ‐ the starfish, sand dollars, sea urchins, crinoids, and blastoids

The vertebrates belong to Phylum Chordata (referring to the nerve chord that extends down the center of the spine).

Our goal with lab is to be able to identify the following common fossils and provide a general age range:

Porifera (sponges), Trilobites, Brachiopods, Bryozoans, Cnidaria (corral), Mollusca – including bivalves, ammonites, gastropods, Echinoderms – including crinoids, blastoids

1. Provide a short definition of a fossil


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2. Describe how the following processes of fossil preservation differ: Permineralization compared to Replacement

3. Briefly describe what is meant by a “trace fossil”

4. List the seven common taxonomic subdivisions (start with Kingdom)

5. What is meant by Phylogeny or phylogenesis? How is this related to evolution?

From Poort and Carlson (Historical Geology Interpretations and Applications):

Fossil animals and, less commonly fossil plants are used to determine the relative geologic age of a sediment; the nature of the paleoenvironments, and the characteristics of an ancient area. Certain fossils are especially useful for age determination. These fossils are known as Index Fossils. Index Fossils must fulfill the following conditions:

1. Organisms should have lived during a relatively short period of geologic time and should have been abundant.

2. Organisms should have had a wide geographical distribution that was not strongly influenced by facies changes

3. Organisms should have distinctive appearance to be easily recognized.

6. Consider the following collections of fossils. Use the age ranges of these fossils to answer the following questions.

Specimen 1 – Ordovician‐Permian

Specimen 2 – Silurian‐Mississippian

Specimen 3 – Cambrian‐Triassic

Specimen 4 – Devonian‐Eocene

Specimen 5 – Ordovician‐Jurassic

Specimen 6 – Mississippian‐Recent

a. Which is the best index fossil? b. Which is the poorest index fossil? c. What combination of fossils is the most definitive?


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7. All of the fossils named in the column below are trilobites. The columns have been correlated based on rock type and fossils.

Use the age ranges of the trilobite species to determine the geologic time interval corresponding to the Cherty Limestone.


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Lab Activities

Part 1 – Shape and Symmetry. Getting to know the common fossils

Use the attached drawings (as well as other lab books) to analyze the specimens provided in the lab.

Match each specimen letter to one of the descriptions below. List the distinctive characteristics of the Phylum/Class.

Specimen Letter

Symmetry/characteristics Taxonomic Group (Phyla and/or Class)

Phylum Bryozoa

Phylum Cnidaria, Class Anthozoa ‐ colonial

Phylum Porifera

Phylum Echinodermata – Class Crinoidea

Phylum Echinodermata – Class Echinoidea

Phylum Mollusca ‐ Class Cephalopoda, Subclass Ammonoidea

Phylum Mollusca, Class Bivalvia

Phylum Brachiopoda

Phylum Mollusca, Class Gastropoda

Phylum Mollusca, Class Cephalopoda, Order Belemnitida (non‐coiled, no sutures)

Phylum Arthropoda, Class Trilobita

Phylum Cnidaria, Class Anthozoa, non‐colonial – solitary Rugose (Order)

Kingdom Monera, Cyanobacteria ‐ Stromatolite

Kingdom Protista, Foraminifera

Phylum Porifera/Archaeocyathid


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Part 2 – Identify the fossil specimens provided to phylum using the enclosed key and resources.

List the class for Cnidarians (Class Anthozoa), Mollusca (Classes: Bivalvia, Gastropoda, Cephalopoda), Arthropoda (Class Trilobita, Class Crustacea), and Echinodermata (Classes: Crinoidea, Blastoidea, Asteroidea, Echinoidea). List Archaeocyathids as Phylum Porifera. A.

B.

C.

D.

E.

F.

G.

H.

I.

J.

K.

L.

M.


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Part 3 – Use the enclosed geologic range charts and Phyla information to answer the following questions.

Be specific about class if different classes of phyla span different age ranges.

1. Which taxonomic group(s) were present during the Precambrian?

2. Which taxonomic groups were present during the Paleozoic Era?

3. Which taxonomic groups were abundant during the Mesozoic Era and which groups were either absent or had declined compared to the Paleozoic Era?

4. Which taxonomic groups were abundant during the Cenozoic Era and which groups were either absent or had declined compared to the Mesozoic Era?

5. Major extinctions occurred several times in the geologic past. What times of extinction are suggested by the geologic range information provide? Remember that not all members of a phylum go extinct during one of these events, but the total number of species may decline.

6. If you found a rock containing both Scleractinian corals and ammonoids, to which geologic periods might it belong?


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Part 4 – Assign the following fossil assemblages to geologic age range (as specific as possible).

Trilobites, Brachiopods, straight shelled Cephalopods, Archaeocyathids

Rugose Coral, Crinoids, Blastoids

Bivalvia, Echinoids, Gastropods

Belemnites, Ammonites, Asteroids

Part 5

Examine each of the samples (or sets of samples) provided and indicate:

a. Fossil identified – to Phylum and/or Class b. The approximate time interval represented. Indicate the portion of the Era (or Period) for the

Paleozoic Era.

1. Specimen Group 5A

2. Specimen Group 5B

3. Specimen Group 5C


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Phylum Porifera – sponges: Globular, cylindrical, conical or irregular shape. Basic structure is vase‐like with pores and canals. Interior may be hollow or filled with branching canals. Solitary or colonial. Skeletal elements are called spicules, and they may be separate or joined. Composition may be calcareous, siliceous or organic material called spongin. The Cambrian Archaeocyatha is sometimes grouped with sponges or put into a separate phylum

A. Diagram of an Archaeocyathid. B. is a transverse section >>>>

(a) Rugose (b) Tabulate (c) Scleractinian

Phylum Cnidaria – Corals and Jellyfish: Many living cnidarians are soft‐bodied (such as jellyfish and sea anemones), but only those cnidarians which are able to form hard skeletal structures (such as corals) are readily preservable as fossils. Corals have a hard calcareous skeleton, and may be solitary or colonial.

Colonies are composed of many polyps living together. The "cup," in which an individual coral polyp sits, is called the Theca. Each theca is small (several millimeters to several centimeters in diameter), and roughly circular or hexagonal in shape. The theca is divided internally by vertical partitions called septae, arranged in a radial pattern.

Types of corals are distinguished by presence or absence, and number of septae:

The Paleozoic Rugose corals (or tetracorals) have septae arranged in multiples of four.

The Mesozoic and Cenozoic Scleractinian corals (or hexacorals) have septae arranged in multiples of six.

The Paleozoic Tabulate corals lack septae. Instead, they have horizontal plates within the theca called tabulae. Tabulae are one of the main features of the tabulate corals.

Phylum Bryozoa ‐ Colonial (many microscopic individuals living physically united adjacent to one another). The individuals are called zooids, and they are housed in a hard "capsule" called a zooecium. The colony is called a zoarium. Individual zooecia (plural of zooecium) are very tiny (about the size of a pin‐hole, a millimeter or less in diameter). They are just large enough to be seen with the unaided eye. The bryozoan colony may resemble lace or a tiny net, may be delicately branching, finger‐like, circular or dome‐shaped.

Bryozoans may be distinguished from corals because of the apertures in the skeleton are much smaller.


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Phylum Brachiopoda – Brachiopods: These are Bivalved (two shells), each with bilateral symmetry. The plane of symmetry passes through the center of each shell or valve. The two valves differ in size and shape in most. Sometimes the larger valve will have an opening near the hinge line through which the pedicle extended in life. Lower Cambrian to Recent. Very abundant during the Paleozoic. A few species (belonging to only three families) remain today. Primitive brachiopods called inarticulate brachiopods do not have a hinge. Brachiopods with calcareous valves attached together with a hinge are called articulate brachiopods. Note: this is a separate phylum than Mollusks

Phylum Mollusca – Bivalvia (includes

clams): Skeleton consists of two calcareous

valves connected by a hinge. Bilateral

symmetry; plane of symmetry passes

between the two valves. Note: this is the

difference between bivalves and

brachiopods. Early Cambrian to Recent,

but common in the Cenozoic

Phylum Mollusca – Gastropods (snails and slugs): The “snails” have an asymmetrical, spiral‐coiled calcareous shell. These differ from ammonites because the spiral is not in a flat plain.

Phylum Mollusca – Class Cephalopoda: Nautiloid Cephalopods have smoothly curved septa, which produce simple, straight or curved sutures. Geologic range: Cambrian to Recent. Ammonoid Cephalopods have complex, wrinkled or crenulated septa, which produce angular or dendritic sutures.

a. Goniatite or goniatitic (septae have relatively simple, zig‐zag undulations)

b. Ceratite or ceratitic (septae have smooth "hills" alternating with saw‐toothed "valleys")

c. Ammonite or ammonitic (septae are complexly branching and tree‐like or dendritic)

Ammonoidea ranges from Devonian to Cretaceous.

Belemnoid Cephalopods have an internal calcareous shell (which resembles a cigar in size, shape, and color) called a rostrum. The front part of this shell is chambered, as in the nautiloids and ammonoids.


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Phylum Echinodermata (Crinoid, Sand Dollar, Blastoids, Sea Stars and others): Calcite skeleton with five‐part symmetry, superimposed on primitive bilateral symmetry. Sand Dollars and Starfish are echinoderms with five‐part symmetry. Important echinoderms in the fossil record are Crinoids, Blastoids, and Echinoids

<<< Crinoids are animals which resemble flowers ‐ they consist of a calyx with arms, atop a stem of calcite disks called columnals. The disk look like little rings or washers. A column often looks like a bolt.

Blastoids are extinct animals with an armless bud‐like calyx on a stem. >>>

Echinoids (includes sand dollars) are disk‐shaped, biscuit‐shaped, or globular. Viewed from above, they may be circular or somewhat irregular in shape, but with a five‐part symmetry. >>>

Phylum Arthropoda (Includes: Insects, spiders, shrimp, crabs, lobsters, barnacles, ostracodes, and trilobites): Segmented body with a hard exterior skeleton composed of chitin (organic material). Paired, jointed legs. Highly developed nervous system and sensory organs.

Subphylum Trilobita (Cambrian to Permian ‐ all extinct.): Body has a three‐lobed

appearance; two long grooves running from the head to the tail divide the body into three lobes: Body is divided into three segments:

a. Rigid head segment (cephalon), often with compound eyes. b. Jointed, flexible middle section (thorax). c. Rigid tail piece (pygidium).

Subphylum Crustacea includes Crabs, Lobsters, and Barnacles as well as microscopic organisms called Ostracodes, which are common in limestone and dolostone.

Other important organisms in the fossil record (not part of the Animal Kingdom)

Kingdom Monera (bacteria and blue‐green algae) – Includes Stromatolites: Unicellular organisms with a prokaryotic cell organization – lack membrane and a bound nucleus. Stromatolites are layered structures formed by the prokaryotic, cyanobacteria, composed of Prokaryotic cells. They range from the PreCambrian (as old as 3.5 billion) to the present.

Kingdom Protista (included in Rhizaria) – Eukaryotic microorganisms. Eukaryotic cells (1.8 billion): contain a true nucleus, sexual reproduction. Most are unicellular.


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Phylum Sarcodinia, includes Foraminifera (including Fusulinids) and Radiolaria.

Foraminifera (“forams”) are single‐celled protists with shells. This group includes Fusulinids. In some systems, Foraminifera is a Phylum. This are typically microscopic. They range in age from earliest Cambrian to the present day. >>>

<<< Fusulinids have rice‐grain shaped tests and evolved into numerous widespread species during the Permian but went extinct at the end of that

period. They ranged from Silurian to the end of the Permian.

Radiolaria: These single celled organisms have silica‐shells (called tests) that accumulate in the deep ocean to form silica‐ooze and eventually chert. The first occurrence of radiolarian is latest Precambrian. Deep‐water Radiolaria developed in the Silurian. >>>

<<< Phylum: Bacillariophyta, Class: Diatomatae (Diatoms) ‐ photosynthesizing algae: they have a siliceous skeleton and are found in almost every aquatic environment. The oldest “certain” fossil diatoms are Lower Cretaceous in age. Most diatom fossils known are from Eocene and Miocene rocks, but they are still exist.

<<< Cnidaria ‐ Coral

Tabulate Coral (colonial) – middle Ordovician to Permian; become extinct at the end of the Paleozoic

Rugose Coral (coarse outer ridges, includes “horn coral”) – middle Ordovician to Permian

Scleractinian Corals (mostly colonial) – modern coral. First appear in the Triassic

Brachiopods – abundant in Ordovician‐Devonian >>>

Reduced after Devonian extinctions. Sustained major extinctions at the end of the Paleozoic. Only two modern Orders survive to the present.


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Mollusca>>>

Bivalves are abundant in Mesozoic and Cenozoic. They replaced many Brachiopod habitats after the Permian extinction.

Gastropods (snails) become abundant in the Ordovician.

Cephalopods – early Paleozoic cephalopods were mostly straight shelled. Later ones are coiled (like coiled ammonites). Many cephalopods are defined by suture patterns (Nautiloid, Goniatite, Ceratite, and Ammonite).

Ammonites first appear in the Devonian and become extinct at the end of the Mesozoic.

Belemnites (cigar shaped) – age range Carboniferous to Cretaceous‐Paleogene boundary. Common Jurassic‐Cretaceous.

Arthropoda – Class: Trilobita >>>

Abundant in the early Paleozoic, but became extinct at the end of the Paleozoic.

Echinodermata – five‐fold symmetry >>>

Crinoids, Cystoids, and Blastoids were most common in the Paleozoic. The Cystoids went extinct at the end of the Devonian. The Blastoids went extinct at the end of the Permian.

Echinoids – includes sea urchins and sand dollars. Ordovician to recent.

Asteroids – includes sea stars. Ordovician to recent.


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Geologic ranges and relative abundances of frequently fossilized categories of invertebrate animals. Width of range bands indicates relative abundance.

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Part I. Questions - Jay Patton online...Phylum Brachiopoda – Brachiopods: These are Bivalved (two...

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