Paleontologists base their classifications on the forms which fossil remains display, and by observing similarities and differences between related fossil organisms. For example, they simply match limb bone to limb bone, skull with skull, and tooth with tooth in an attempt to find enough specific characteristics to assign the plant or animal within a biological group of evolutionarily cousins or to relate it logically to an overall evolutionary scheme. The animal's unique organic structures play a critical role in this science.

Of course, the "tree" at the right is really over-simplified. In reality, an evolutionary tree would have a near-infinite number of branches leading to both dead ends that became extinct in the geological past, and to lifeforms living today, the current chapters in this history of life.

As the organism's changes are observed over geologic time, the process of evolution, each anatomical variable must be compared with similar structures of animals in similar evolutionary stages. Any modern biological classification is based on the evolutionary relationship of the parent's offspring to the offspring's progeny, and on the common ancestry of those animals which possess similar anatomical characteristics. Patterns thus determined constitute the roots of paleontology, or the biological history of fossil life. And what a trip down memory lane it is, because we are classified too, that is "racially profiled" in a zoological sense.


for example

So, you're holding a fossil in your hand. The tooth of some terrestrial vertebrate creature that seems to be adapted to capturing another large animal, slicing it into bite-size pieces and not doing much grinding on the flesh. Try talk about it, or even to think clearly about it, unless it has been given a name, either a common or scientific one. You'll soon realize that it's equally impossible to examine the relationship or its place among the incredibly vast number of complex biological phenomena or to treat it in a universally accepted scientific manner, without the formality of a scientific name. The science of arranging the members of the animal kingdom is called taxonomy. Taxonomy, then, is the most elementary as well as the most inclusive part of animal-life studies; the most elementary because animals cannot be discussed without it; and the most inclusive because taxonomy eventually gathers together, utilizes, summarizes, and implements all that is known about the animal and plant kingdoms. As an avocational fossil collector, you really don't have to memorize all these long Latin names all at once, or even at all, but you will eventually find yourself talking to your fellow fossil collectors in the language of science soon enough, and better yet, understand it when they talk to you.

The fossil collector must be familiar with the various invertebrate groups so the fossils found can be identified and appreciated to their fullest extent. One of the most rewarding parts of fossil collecting is the uncertainty of what one may find over the next hill or down in the next arroyo. Collectors also enjoy the investigative work often needed to identify and understand what a fossil is and how it got where it was.

The Classification of animals:

Animal Kingdom can be split up into main groups, vertebrates (with a backbone) and invertebrates (without a backbone). Looking at a chart like the one on the right is a good way to start understanding the evolutionary processes. I know it's an over-simplification of a very complex series of events over time that enable one kind or organism to slowly transform into an entirely different species, but knowing the principle is vital if you're to see the fossil you've found as having a history.


Assuming that you have a handle on taxonomy after reading this page, now you're faced with having a real fossil, maybe only a fragment of one, and the questions somehow comes up, "What it it?"

Having a stack of good reference books is one of the best cures for the "What is its."

Good reference books just feel good and are so important
There are two books I can't live with out. For the fossil plants I find, get a copy of Common Fossil Plants of Western North America William D. Tidwell, 1998. ISBN 1-56098783-9 (cloth), 1-56098-758-8 (paper). Second edition, 299 pp. Smithsonian Institution Press, 470 L'Enfant Plaza, Suite 7100, Washington, D.C. 20560. - "Bill Tidwell hits the nail on the head on the very first page of his book when explaining one of the driving forces behind paleobotanical fieldwork: Collecting fossils is like opening Christmas packages. For a collector, the thrill of breaking or splitting a rock and finding fossilized remains of plants that have been extinct for millions of years is very rewarding."


When I was thirteen years old, my brother Rich gave me a copy of INDEX FOSSILS OF NORTH AMERICA (Index Fossils of North America by HW Shimer and RR Shrock; MIT Press, 1944.) I suspect that there's probably equivalent kind of references for Europe or Asia, but this is Arizona. There are other great reference books on both invertebrate and vertebrate fossils, and you home paleontology library should have a few. Also, if you specialize in fossils from one geographical area,or one kind of fossil, there are lots of technical scientific papers. Write to the authors, usually they are happy to assist you by sending you a free reprint.


When you think of an animal, you usually think of something like a cat, a dog, a mouse, or a tiger. All told, around 800,000 species have been identified in the Animal Kingdom -- most of them in the Arthropod phylum.

In fact, some scientists believe that if we were to identify all species in the tropical rain forests the ranks of Arthropoda would swell to over 10 million species! Most people do not normally think of a clam, a jellyfish, or an earthworm as an animal. Yet all of them belong to the kingdom of animals. The science of classifying organisms is called taxonomy.

In order to study living things, scientists classify each organism according to its:

KINGDOM To date there are five kingdoms: Animalia, which is made up of animals; Plantae, which is made up of plants; Protista, which is made up of protists (single-celled creatures invisible to the human eye); Fungi, which is made up of mushrooms, mold, yeast, lichen, etc; and Monera, which is made up of the three types of bacteria.
PHYLUM The next category is the Phylum. There are several phyla within each kingdom. The phyla start to break the animals (or plants, fungi, etc) into smaller and more recognizable groups. The best known phylum is Chordata, which contains all animals with backbones (fish, birds, mammals, reptiles, amphibians). There is also Arthropoda (insects, spiders, crustaceans); Mollusca (snails, squid, clam); Annelida (segmented worms); Echinodermata (starfish, sea urchins) and many, many more
CLASS The next category that makes up the phyla is the Class. The class breaks up animals into even more familiar groups. For example, the phylum Chordata is broken down into several classes, including Aves (birds), Reptilia (reptiles), Amphibia (amphibians), Mammalia (mammals) and several othe
ORDER The next category is the Order. Each class is made up of one or more orders. Mammalia can be broken down into Rodentia (mice, rats), Primates (Old- and New-World monkeys), Chiroptera (bats), Insectivora (shrews, moles), Carnivora (dogs, cats, weasels), Perissodactyla (horses, zebras), Artiodactyla (cows), Proboscidea (elephants) and many more.
FAMILY Orders can then be broken down into Families. The order Carnivora can be broken down into Canidae (dogs), Felidae (cats), Ursidae (bears), Hyaenidae (hyaenas, aardwolves), Mustelidae (weasels, wolverines), and many more.
GENUS The next category is the Genus. The family Felidae, for example, can be broken down into Acinonyx (cheetah), Panthera (lion, tiger), Neofelis (clouded leopard) and Felis (domestic cats).
SPECIES Finally, the genus is broken down into the Species. The genus Panthera can be broken down to include Panthera leo (lion) and Panthera tigris (tiger). Note that the genus is placed in front of the species. Usually, a species is called by its genus name (capitalized) followed by its species name (lower case), so a human being is called Homo sapiens. In Latin that means "wise man."