Fossils/Fossil List

Protists
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.

Foraminifera
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. 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.

Fusulinid
Fusulinids are easily recognizable by their appearance- they appear to be grains of rice (this has been asked on the national exam- I kid you not). They lived from the 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.

Nummulites
The test of Nummulites is also spiraled, but does not form the same structure as that of the fusulinids. It's test takes the shape of a disc. They date only from the Eocene Epoch, and are commonly found in the Middle East and North Africa. Nummulitic limestone was what was used to build the pyramids (this is also commonly asked). Extremely large for a foram, they can reach a diameter of six centimeters.

Its name means "little coin" in Latin- can you see why?

Diatoms
Diatoms have been around since the Jurassic period. 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. Ever hear of diatomaceous earth? That's the term used to describe sediment that is overwhelmingly composed of fossil diatoms.

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
Porifera, or as they are usually known, sponges, are extremely ancient, extremely primitive organisms. They are first known from the Late Precambrian, and are (obviously) 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 were benthic and sessile, and lived in marine environments. Some were composed of silica spicules, and the others were composed of calcium carbonate. Sponges reached their greatest diversity during the Cretaceous period.

You need to know two sponge genera for the event.

Hydnoceras
The genus Hydnoceras is considered a "glass sponge", which means it was composed of silica spicules. 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 Carboniferous (not sure whether it lived to the Mississippian or Pennsylvanian- could someone check?).

Astreaospongia
Astraeospongia was a calcareous sponge- that is, it was composed mostly of calcium carbonate. It lived in marine environments, and lived from the Silurian (possibly the Ordovician) to the Devonian.

Bryozoa
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, and it 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
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.

Rhombopora
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.

Hemichordata
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.

Cnidaria
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.

Scyphozoa
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
Corals are divided into two groups for this event- horn corals and colonial corals. 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
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
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
Hexagonara (which I believe is actually spelled "Hexagonaria", but appears as Hexagonara on the list) was a colonial rugose coral. It was very widely distributed around the earth