Fossils/Fossil List

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This page contains information about all of the specimens you need to know for the event Fossils.


Of all the groups that you are responsible for knowing for this event, protists are the most under-represented. There are only two groups you need to know- the phylum Foraminifera and the class Bacillariophyta. You also need to know the Fusulinid family and the genus Nummulites.


The class Foraminifera, or as they are usually called, forams, are extremely basic fossils. They are single celled organisms, the oldest of which date back to the Permian.

An illustration of various forams
An illustration of various forams

The distinguishing feature of forams is their test, a shell that the animal secreted while it was alive. This test is made of CaCO3 (calcium carbonate) the majority of the time, but it is sometimes made of particles of sediment. Many forams lived benthically, but some were planktonic, and all were marine. They became much more common when coral reefs expanded, and would die off without them. They are useful indicators of past environments and can be good index fossils. The petroleum industry will analyze the foram content of the ground they want to drill in to determine whether or not to drill there.

You are responsible for knowing Fusulinids (usually the genus Fusulina) and the genus Nummulites.


A diagram of fusulinid morphology

Fusulinids are easily recognizable by their appearance- they appear to be grains of wheat. They lived from the late Mississippian to the Permian, and are excellent index fossils. Their presence indicates that the area was shallow, clear, and marine in the past. Morphologically, they are very complex. The test, as it grew, would twist into a spiral around the single cell, and would form chambers within itself. They are omnivorous, eating via reticulopodia (cell extensions), which projected through pores in the test to catch small creatures.

Classification: Protista (kingdom), Foraminifera (phylum), Granuloreticulosea (class), Foramiferida (order), Fusilinidae (family), Fusilinids (genus)



The name "nummulites" means "little coin" in Latin. The test of Nummulites is also spiraled, but does not form the same structure as that of the fusulinids. Its test takes the shape of a disc. They date from the Paleocene to the Ogliocene epochs, and are commonly found in the Middle East, North Africa, Europe, and Asia. Nummulitic limestone was what was used to build the pyramids. Extremely large for a foram, they can reach a diameter of six centimeters. This is an index fossil because it evolved quickly and was very widespread.

Classification: Protista (kingdom), Foraminifera (phylum), Granuloreticulosea (class), Foramiferida (order), Nummulitidae (family), Nummulites (genus)


Diatoms under a microscope

The name "diatom" means "cut in half". Diatoms have been around since the lower Cretaceous. The official name for their group is Bacillariophyta. They are a major group of one-celled algae. Their cell wall is made of silica, and is called the frustule. They are microscopic. Diatoms carry out photosynthesis, and can be found in both marine and fresh water environments. Their body is divided into two parts, the epitheca and the hypotheca. The epitheca overlaps the hypotheca like the lid of a Petri dish. Diatoms were present in such great numbers that their remains contributed greatly to ocean sediment. The term 'diatomaceous earth' refers to sediment that is overwhelmingly composed of fossil diatoms.

Classification: Protista (kingdom), Heterokontophyta (phylum), Bacillariophyceae (class), Centrale/Pennale (order)


Invertebrate Animals

The vast majority of fossils you will need to know for the event are invertebrates. This makes sense for two reasons- invertebrates are the most common fossils throughout North America, and they are inexpensive and cheap to use as samples during the event. They may seem boring at first, but they are just as important as anything else.


Porifera, or as they are usually known, sponges, are extremely ancient, extremely primitive organisms. They are first known from the Late Precambrian, and are still around today. Their bodies do not contain tissue, muscles, nerves, or organs. They pump water through the body to feed, and have one body orifice to serve for ingestion as well as excretion. They are benthic and sessile, and live in marine environments. Some are composed of silica spicules, and others of calcium carbonate. Sponges reached their greatest diversity during the Cretaceous period.

You need to know two sponge genera for the event.


Hydnoceras, a glass sponge

The genus Hydnoceras is considered a "glass sponge", which means it was composed of silica spicules, which provided structural support and deterred enemies. Glass sponges are extant, but are now found only in the deep ocean. In the past, they could be found at almost all depths. Hydnoceras lived from the Devonian to the Pennsylvanian in the eastern United States and Europe. It is the simplest form of multicellular life.

Classification: Animalia (kingdom), Porifera (phylum), Hexactinellida (class), Lyssakida (order), Dictyospongiidae (family), Hydnoceras (genus)


Astraeospongia, a calcareous sponge

Astraeospongia is referred to as a "basket sponge". It was a calcareous sponge- that is, it was composed mostly of calcium carbonate. It lived in marine environments, and lived from the Silurian to the Devonian. The spicules were the only part of the sponge that got fossilized, and there are star-shapes spicules all over the body (though they can be faint). The pores of the sponge are called ostium.

Classification: Animalia (kingdom), Porifera (phylum), Heteractinida (class), Octactinellida (order), Astraeospongiidae (family), Astraeospongium (genus)


Fossil bryozoans, with a penny for size reference

Bryozoans evolved in the Ordovician, and are still found today. The structure you see when you look at a bryozoan is actually a support structure composed of calcium carbonate. The animal itself lives in tiny holes in that structure, and is rarely larger than a millimeter. They appear very similar to corals, but are very,very different in biology. They are commonly found in Paleozoic rocks and indicate a shallow marine environment. Nowadays, they can also be found in fresh water. They attached to the bottom of the ocean, and were filter feeders. The produce a compound known as bryostatin 1, which is currently being tested as an anti-cancer drug. Bryozoans can reproduce both sexually and asexually. They are commonly known as "moss animals". Bryozoans come in three growth forms: massive (a mound with no planned shape), branching (where the structure forms intricate branches), and fenestrate (where in life the bryozoan would have large, soft appendages coming out from the skeleton).

You need to know two bryozoan genera for this event.


Archimedes, which looks like a screw

Archimedes lived during the Carboniferous period. It was a fenestrate bryozoan, that was much wider in life than it seems from the fossil. It was named for the Greek thinker Archimedes, who invented the water screw - Archimedes looks very much like a screw. It was a filter feeder, than was benthic and sessile in nature, living in shallow marine waters. Individual animals are called zooids. Archimedes prefer clear water because murky water clogs zooecium.

Classification: Animalia (kingdom), Bryozoa (phylum), Stenolaemata (class), Fenestrata (order), (family?), Archimedes (genus)


Rhombopora, a classic branching bryozoan

Rhombopora lived from the Carboniferous to the Permian. It was a branching bryozoan that lived as all of them did- sessile, benthic, and filter feeding.


The graptolites (phylum hemichordata) were around from the Cambrian to the end of the Carboniferous. Their fossils generally look like pencil marks on a rock. They are usually fossilized by means of carbonization in shale. They serve as excellent index fossils for the paleozoic. They consisted of colonies of microscopic organisms with a threefold body division.

Notice that they are Hemichordates. They are thought to be on the path that led to the vertebrates.

Graptolites, which do look very much like pencil marks


The cnidarian group contains jellyfish, sea anemones, and corals. They all use stinging cells knwon as nematocysts to capture prey, which is usually plankton. Corals are benthic, shallow marine, whereas jellyfish are planktonic. Modern corals have a symbiotic relationship with algae.


A fossil jellyfish.

Scyphozoans (jellyfish) are extremely rare as fossils, as their bodies are made mostly of water. Very, very unusual conditions are required to have fossils of jellyfish form. They have two life stages- the polyp and the medusa. As a polyp, they are sessiles, but they eventually mature into a medusa, which is planktonic. They use their nematocysts to capture and kill marine organisms. They have an internal support structure called the mesoglea, which serves as a skeleton.


Corals are divided into two groups for this event- horn corals and colonial corals.

Solitary horn coral

Horn corals are all members of the order Rugosa, which flourished from the middle of the Ordovician to the end of the Permian. All horn corals were solitary, and get their name from their body shape, which is horn-like. Their presence indicates that the area had been a shallow marine environment.

Colonial corals include tabulate, scleractinian, and some rugose coral. Scleractinian coral is the only variety found in today's waters. The colonial corals were and are the reef builders, each polyp being part of a large community of organisms. Keep in mind that the grouping of "colonial corals" is not natural. It divides up other groups of coral, and includes some that are more closely related to horn coral than to other colonial corals.

Heliophyllum, horn coral

Heliophyllum was a solitary horn coral that lived during the Devonian period. It was, of course, a member of the order Rugosa. It fed using its nematocysts to stun prey.

Favosites, colonial tabulate coral

Favosites was a colonial tabulate coral that lived from the Ordovician to the Devonian. A specimen can be anywhere from a few centimeters to tens of centimeters in all dimensions. It is commonly found in Silurian limestone, and is easily recognizable by the honeycomb-like appearance when viewed from above. They are found worldwide.

Hexagonara, a colonial rugose coral

Hexagonaria was a colonial rugose coral. It was very widely distributed around the earth. It is the state fossil of Michigan, known commonly as the Petoskey Stone.

Halysites, the "chain coral"

Halysites is commonly known as the "chain coral", due to its growth pattern, which resembles a chain. It was a tabulate coral and lived in warm, shallow waters (including ancient reefs) from the middle of the Ordovician to the late Silurian.

The only scleractinian coral on the list

Septastraea is the most recent coral on the list. It lived from the Miocene to the Pleistocene during the Neogene and Quaternary periods. Septastraea's morphology is variable, being able to grow into just about any shape. It was a scleractinian coral, the only variety found today. It lived in warm, shallow water reefs.


This is the phylum that contains the "creepy-crawlies" of today. Arachnids, insects, and the like are all arthropods. They have segmented bodies and many limbs.


This is the major class of arthropods you will be asked about.

The lobes that give trilobites their name. 1- Left pleural, 2-Axial, 3-Right pleural
The sections of a trilobite's body. 1- cephalon, 2-Throax, 3-pygidium

Trilobites are named for their bodies, which are divided into three lobes, which run longitudinally along the body. The trilobite's body is also divided into three sections. They were widespread from the Cambrian to the Permian, but fell victim to the huge mass extinction at the end of the Permian period. Most of them lived benthically, but some may have been planktonic. They were all marine. They are good index fossils, and were most diverse at the end of the Cambrian. After the Ordovician, they moved from shallow water to deep water. Most of them were detritus feeders, but some may have been active predators and scavengers. They had legs, which were probably made of chitin, and antennae. Neither of these are commonly fossilized, but some exceptional specimen do have these parts intact. Trilobites had spikelike structures on each side of the cephalon known as "free cheeks", which fell off during molting. There are four genera of Trilobite that you will be responsible for knowing.


Phacops is notable for its huge glabella. That is the distinguishing feature of this genus.

Phacops, a Devonian trilobite

It had eyes with fewer lenses than other trilobites, which may have meant that it had better vision than its counterparts. It lived in warm, shallow seas during the Devonian period (it is an index fossil). It is commonly found rolled up into a ball, which it was probably doing for self protection.


Isotelus was a trilobite that lived during the Ordovician period. It was the largest trilobite- three species of Isotelus grew to almost a meter long. It also possessed pits around the body that some think housed sensory hairs.


Cryptolithus was a small trilobite that lived during the Ordovician. It was almost completely blind, and probably just ate detritus on the bottom of the ocean. It is also known as the "lace collar trilobite", because the front edge of its cephalon looks somewhat like lace. It is easily identifiable by its long free cheeks, and its unbelievably squashed appearance.

Elrathia, a Cambrian trilobite

Elrathia is the oldest trilobite on the list. It is identifiable by its small head and well-defined axial lobe. It is divided into thirteen narrow segments, and dates back to the Cambrian period.


A systematic diagram of a eurypterid's anatomy

The eurypterids belonged to the same group that modern-day horseshoe crabs are classified in. Horseshoe crabs and eurypeterids both date back to the Ordovician. As arachnids, they are related to modern day spiders and scorpions. They are the largest-known arthropods ever to exist, the largest measuring in at 2.5 meters long. Most, however, were less than eight inches long. Although the earliest fossils of eurypterids date back to the Ordovician, the level of complexity already exhibited by the group indicates that these "sea scorpions" evolved in the Cambrian. They were another victim of the Permian extinction. When they were first discovered, paleontologists thought that they were ancient catfish- it was seven years later that they became identified as arthropods. Eurypterids were most diverse during the Devonian and Silurian periods. More detail is known about the external anatomy of eurypterids than any other group of fossils, and they are almost as well known as modern animals. The picture above lists and shows the body segments. Note that the prosoma is both the head and the body, and that the chelicerae are homologous not to the pincers of scorpions (which are the second appendage) but to the fangs of spiders.


A fossilized insect

Insects have been on Earth since the Devonian period. They are a group of terrestrial and freshwater arthropods. They are divided into three sections; the head, thorax, and abdomen. They have six legs attached to the thorax. Insects began as wingless organisms, but evolved wings in the Carboniferous. Many undergo metamorphosis in the change from one stage of life to another. The oldest true flies date from the Triassic. By the Jurassic butterflies had evolved, and by the Cretaceous all modern forms of insects had appeared. Insects were not visibly effected by the extinction of the dinosaurs at the end of the Cretaceous.


A fossilized crustacean

Crustaceans evolved in the Cambrian period. They are a group of aquatic, carnivorous arthropods. Their bodies and legs are encased in a shell made of chitin, a glucose derivative with the formula C8H13O5N. Their bodies are divided into segments, sometimes called the head, thorax, and abdomen, but sometimes referred to as the cephalothorax and abdomen. Every crustacean's head has two pairs of tactile antennae and three pairs of food-handling limbs. Their walking legs are divided into two, and may contain gills. Like in lobsters, the last appendage of the abdomen may be flattened.


Brachiopods are a diverse group of lophophorates that are externally very similar to clams and other bivalves. As lophophorates, their closest relatives are bryozoans. They are divided into two groups- inarticulate and articulate.


Inarticulate brachiopods evolved in the Cambrian and are still found in today's oceans. Although they were originally shallow marine organisms, today's brachiopods are only found in the deep ocean. Most inarticulate brachiopods are less than 1 cm in size. Their shells were composed of calcium phosphate, and they lived in benthic marine environments. They could be either epifaunal or infaunal in nature, depending on the species. They were filter feeders.


Lingula is a living fossil that evolved in the Ordovician. It is known for having a very long pedicle, which anchored it to the sea floor (thus, it was a sessile). It had a thin, tongue-shaped shell. It lived in vertical burrows in intertidal areas.







Ammonitoidea, Nautiloidea, and Coleoidea

goniatitic, ceratitic, ammonitic











Vertebrate Animals

















Aves (Crown-Aves/Neornithes)




Homo neanderthalensis