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Paleontology

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What is Paleontology

Paleontology is the study of past life. It is considered to include all the history of life on Earth from about 3.5 billion years ago to nearly the present. The study of past human civilizations and their immediate precursors, which are covered by the related science of archaeology.

The study of Palaeontology includes the study of fossils, the places they occur, how things become fossils, the relationship of one fossil with other fossils and living species, and the environment they lived in. It also involves the piecing together past organisms from their remains as living organisms.

Most paleontologists need to have some knowledge of geology, anatomy, ecology, and other fields of science depending on their specialty.

Paleontology is usually classed as a branch of geology, but because it studies past life, it is heavily reliant on the biological sciences as well. In universities and museums paleontologists, and some paleontology programs, are included as part of biology departments instead of or in addition to their relationships with geology departments.

Among the sub disciplines of paleontology are the following:

• Invertebrate paleontology - the study of fossil invertebrates.
• Molecular Paleontology - the recovery of DNA from ancient remains.
• Paleoanthropology - the study of human evolution (this comes closest to archaeology).
• Paleoautecology - the study of an individual fossil in relation to the ancient habitat where it occurred.
• Paleobotany - the study of fossil plants.
• Paleoecology - the study of ancient ecosystems as a whole, not just the individual species that occurred.
• Paleosynecology - the study of fossil assemblages.
• Paleornithology - the study of fossil birds.
• Ichnology - the study of tracks, burrows etc. considered to be trace fossils.
• Taphonomy - the study of process of dying and the processes that occur after an organisms death).
• Vertebrate paleontology - the study of fossil vertebrates.
• Micropaleontology - the study of microscopic fossils.
• Palynology - the study of fossil pollen.

Geologic Time

Geologic time is the term used by geologists, paleontologists, and other Earth scientists to relate the relationships and timing of events in the history of Earth. The Geologic Time Scale is the representation of geologic time, listing the different groupings.

Originally in the study of Earth history, it was not possible to give specific dates to when things happened in the past. Even the total age of the Earth was debated. It is now known that the Earth is about 4.5 billion years old.

Because of that vast span of time, and the nature of the preservation of events in geology, we can't use a regular calendar. It's impossible to say, for instance, that a particular fossil fish died on February 12, 29,000,000 years ago. Using the geologic time scale allows us to group things together as to when they happened. Sometimes this grouping can be fairly precise, but even two fossils laying next to each other may not mean the organisms died together, or even within the same century. But we can say, probably, that they both lived (and died) in the Miocene Epoch (5.3-1.8 million years ago). It's a coarse system, but it allows us to follow the history of the Earth fairly well.

Modern dating techniques have given us better ideas regarding the timing of events over the course of the planet's history, and further refinements are being worked on all the time.

About the Geologic Time Scale

The geologic time scale is governed by international agreement among scientists by the International Commission on Stratigraphy. The commission periodically releases updates and corrections as new information becomes available and accepted as accurate.

The time scale is divided into three Times, the earliest being Hadean Time which is the time before life evolved, one is Precambrian Time which was originally part of Hadean Time until fossils from it were found, the third has no name and includes everything since the Precambrian. Not the

The Times may be divided into Eras. The Eras may be divided into Periods. The Periods may be divided into Epochs. Not every division on the scale has subdivisions.

As you look over the scale below, note that the length of each section is not equal. The boundaries of each is set by some major geological event. In the case, for instance, of the Mesozoic Era, the ending is considered to be the extinction of the last of the non-avian dinosaurs about 65 million years ago.

The scale is presented from most recent to earliest. The earliest

One further note. The Anthropocene Epoch (1945 to present) is newly added to the time scale. This is the time of major human impact on the Earth. The timing of it's start is still widely debated. Some argue for it to have begun with wide-scaled agriculture abut 12,000 years ago, others place it beginning with the explosion of the first atomic bomb. Most scientists seem to currently favor the latter, so that is the date given here.

The Geologic Time Scale

• Cenozoic Era (65 million years ago to present)
  • Quaternary Period (1.8 million years ago to 1945)
    • Anthropocene Epoch (1945 to present)
    • Holocene Epoch (8,000 years ago to present)
    • Pleistocene Epoch (1.8 million to 8,000 years ago)
  • Tertiary Period (65 to 1.8 million years ago)
    • Pliocene Epoch (5.3 to 1.8 million years ago)
    • Miocene Epoch (23.8 to 5.3 million years ago)
    • Oligocene Epoch (33.7 to 23.8 million years ago)
    • Eocene Epoch (55.5 to 33.7 million years ago)
    • Paleocene Epoch (65 to 55.5 million years ago)
• Mesozoic Era (248 to 65 million years ago)
  • Cretaceous Period (145 to 65 million years ago)
  • Jurassic Period (213 to 145 million years ago)
  • Triassic Period (248 to 213 million years ago)
• Paleozoic Era (544 to 248 million years ago)
  • Permian Period (286 to 248 million years ago)
  • Carboniferous Period (360 to 286 million years ago)
  • Pennsylvanian Period (325 to 286 million years ago)
  • Mississippian Period (360 to 325 million years ago)
  • Devonian Period (410 to 360 million years ago)
  • Silurian Period (440 to 410 million years ago)
  • Ordovician Period (505 to 440 million years ago)
  • Cambrian Period (544 to 505 million years ago)
• Precambrian Time (4500 to 544 million years ago)
  • Proterozoic Era (2500 to 544 million years ago)
    • Vendian Period (544 to 650 million years ago)
  • Archaean Era (3800 to 2500 million years ago)
• Hadean Time (4500 to 3800 million years ago)

A Geologic clock showing the scale of various periods of geologic history.

External Links

• International Commission on Stratigraphy
• Geologic Time Scale Foundation
• The Anthropocene at Wikipedia

Vertebrate Fossils

Nearly all vertebrate fossils are represented by the bones of the deceased specimen. These can be in the form of partial or complete skeletal remains, but for many species individual bones are all that has been found. This partial evidence of a species may lead to disputes as to its classification and many are classed as Nomen dubium, indicaring that their relationship with other species is not known. Sometimes direct impressions such as skin, feathers or scales are left behind, usually because the sediment is fine and the fossil hasn't undergone any major changes such as compression. Other times trace fossils are left, in the form of coprolite (feces), footprints, burrows and the like.

Paleoecology

Paleoecology uses fossils and sub fossils to recreate the ecosystems and environments in the past. It involves the study of prehistoric fossils of organisms and remains that have been fossilized. The goal is to be able to recreate the fossils paleoenvironments, life cycle, living interactions, and the death and burial of the fossil. It is then that scientists will be able to see the ecosystems of prehistoric organisms and their environs.

Field Techniques

Paleontology involves outdoor and indoor activities.

Finding, removing, and packaging fossils for transport are the major component of fieldwork done by paleontologists. The field work, however begins with preparatory work in the office or laboratory.

Finding a Location

Finding locations where you might find fossils begins by relying on previously recorded data. It may begin with conversations with or field notes from other paleontologists or geologists. This information can help you find places where fossils have previously been found. If you don't have access to unpublished field notes, or people who have worked in the area you want to dig, you can work with a geological map.

A geological map is a map covering the kind of rock or other material that underlies the landscape. A paleontologist wants to find places with sediment or sedimentary rock of the age the fossils you are interested could be located, and formed in the environment (freshwater, marine, or land sediments) where the organisms you're interested in might have been found.

In the U.S.A., State and Federal geological agencies (e.g. the United States Geological Survey) produce these maps. There are similar bodies in many countries, and international organizations that cover the geology of most of the world.

Is Your Location Accessible?

Before you head to a promising site, you should find out if it is accessible. Is the location covered by forest? Is it covered by houses? Consultation of a map or online mapping service can help you with this (see external links).

You also need to know whether or not you can dig there. You need to find out the ownership of the land. In almost every location around the world, all land is owned by someone - whether an individual, company, or government. Whether you can dig for fossils there depends on the ownership and the laws governing fossil digging.

For instance, in the U.S.A., property owners legally control all activity on their land, including digging for fossils. Trespassing, going on to private land without permission, is a crime. State and Federal entities that own land have varying rules about whether fossil collecting is permitted.

Whenever you plan on going fossil hunting, you should work to get permission from the owner in writing, along with any restrictions (e.g. "put any soil back where it was" or "pack out your trash"). On State or Federal land you may need a permit, which acts as your permission to dig, and lays out the rules for collecting.

Finding Fossils on Location

Students searching for fossils.

Not all fossils found are under sediment, in fact most of them aren't. Most are broken or chipped material that have weathered and eroded out of the surrounding sediment or rock. It makes little sense to move to a location and simply start digging in a random spot. Some rare finds may be made by randomly digging in a backyard, but these are few and far between.

Most fossils are initially found by simply walking around an area and seeing what's there to be seen. Places that are fruitful to look initially include the bases of any hill or cliff sides where material may have weathered out and fallen to the bottom. If you find something there, you can follow up by looking above where you find the fossil for others that have not yet been fully released from their resting place.

Excavating Fossils

Once you find a potential location, by having found weathered out fossils, you will need to excavate any fossils that are still in the rock, only very rarely would you be able to remove fossils by hand, so you'll need tools to do that.

Depending on the size and difficulty of removing the fossils from their matrix (the rock or soil it's in), the tools you may need may be large or small. They may include shovels or even jackhammers to remove the rock surrounding the fossil. Smaller jobs may only require rock hammers or small drills. For working close to the fossil and final field preparation, brushes and dental picks may be used.

The idea in the field is to get the fossil out as completely as possible, so generally a fair amount of the surrounding rock is included in the material taken back to the laboratory.

Field Preparation

Sometimes crumbling fossils need to be glued together in order not to break the fossil. Either as excavation progresses, or some time before transport, a fossil may need to be held together. Sometimes a reversible glue is used (see below for link).

The next step is to cover the excavated parts of the fossil with wet paper towels (or toilet paper, which is preferred by many paleontologists) over the specimen and it's surrounding rock. This protects the fossil specimen from the next covering layers.

Those covering layers consist of plaster coated burlap strips. If you have access to plaster impregnated bandages, usually used for making casts for broken bones, these are an excellent alternative. The plaster dries into a hard shell or jacket that protects the fossil during transport and storage until it can be worked on in the laboratory.

With some fossils, wrapping may be started before excavation is complete to protect the specimen. With others this is not necessary.

The final step is to label the jacket with the date, time, and specimen number. It is then ready to be transported back to the lab. With large fossils, the resulting package may be very heavy and may require a truck or helicopter if it is really heavy. Before beginning any excavation, you should make sure you have the means to protect and transport it from the field. Otherwise it should be left where it is for future excavation by you or someone else.

Field Notes

Field notes can be useful for recording geologic details.

Field notes are an essential part of paleontology field work. Usually notes are recorded on site, at the time events are happening. Your memory should not be relied upon. Most professionals record their notes in a bound volume so pages can't easily been lost.

Essential notes include date, name/s of the people involved, location, and what you see. You should include anything you find relevant or interesting.

Useful notes include things like a general description of the location is important (is it hilly? flat? is the rock exposed or under soil?). Specific notes about any specimens you find should also be included. Did you find it at the bottom of a cliff? What color is it? Add a short description or sketch of any fossil you find.

If you take photographs, make notes on how to find those photographs. You might, for instance, take an additional picture of you field notebook at a specific location before you move to another, so you can figure out which in a series of similar looking pictures are the ones you're talking about.

Field Numbers

Each specimen you find should be given a separate field number. Each person has their own numbering system. Whatever numbering you use, continue it from one fossil location to another. If you start your first fossil find with "1", your next fossil location should not restart the numbers at "1", but continue on, so that each and every fossil you find is given a unique field number.

In your field notes, record the field number alongside information about any specimen you collect, so you can refer back and forth, and can eventually label your specimen in the lab with the information about where you found it and other information from your field notes.

Back in the Laboratory

All the information you gather and care you take in the field is immensely valuable once you return to the laboratory to prepare your fossil for study and/or display.

External Links

• United States Geological Survey
• Google Maps, an online mapping service that can help find out whether an area has exposed rock.
• Adhesives and Consolidants from the American Museum of Natural History
• Field Techniques from the American Museum of Natural History

Careers in Paleontology

After doing specialization work in paleontology, you work in university, museum, oil and gas industry, nuclear power, scientific magazines and TV production companies.