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Paleontology is the study of the history of life on Earth. It focuses on fossils. A fossil is the remains of a long-dead animal or plant.
There are mainly two kinds of fossils. In one case, animal, or plant matter is replaced by rock over time. The remains still keep their shape. In the other case, the fossil is actually an impression. It can be a footprint, for example. Or it can be the outline of a body pressed into mud. Over time, the earth and mud turn to rock. Yet, the impression remains.
Paleontologists study all species, or kinds of animals and plants. They study species that still exist. They also study extinct species. Extinct species are ones that have died out. Dinosaurs are one example.
Fossils show how living things evolved, or changed, over time. They also show how one species evolved out of another. For example, paleontologists believe whales evolved from land animals. They think this because of the fossils of certain extinct animals. These animals are closely related to whales. Like whales, they lived in the ocean. Yet, they still had legs. Over time, those legs disappeared. Then, whales developed.
Subdisciplines of Paleontology
There are several different kinds of paleontology, called subdisciplines. Each looks at a different kind of fossil.
Vertebrate Paleontology
Vertebrate paleontology is one kind of paleontology. It is the study of fossils of animals with backbones. Vertebrate paleontologists have dug up the fossilized skeletons of many ancient animals. For example, they have found many kinds of dinosaurs.
Invertebrate Paleontology
Invertebrate paleontology is the study of the fossils of animals without backbones. Such animals are called invertebrates. They include things like crabs, shrimp, sponges, and worms. Invertebrates do not have bones. They do leave things like shells behind, though. Or, they leave an impression of their soft bodies.
Paleobotany
Paleobotany is the study of fossils of ancient plants. These can be impressions of plants left on rocks. Or, they can be parts of plants preserved in rock. Such fossils show how plants have evolved.
Micropaleontology
Micropaleontology is the study of fossils of microscopic organisms. These living things are very, very tiny. Most are so small they cannot be seen with the eye alone. They can only be seen with microscopes.
History of Paleontology
People around the world have been finding fossils for thousands of years. They did not always understand what they were, though.
Paleontology as we know it began in the 1700s. At that point, scientists were carefully studying fossils for the first time.
Scientist Charles Darwin changed paleontology greatly. In the 1850s, he showed that new species evolve over time. Over millions of years, one species can change and become a new species. Animals living today are related to species from the distant past. This can be true even when they look very different.
After Darwin, paleontologists saw fossils in a new way. They began to make connections between fossils and living animals. These connections helped show how ancient animals lived. They also showed how one kind of animal evolved into another.
Take the example of the Archaeopteryx. The Archaeopteryx lived many millions of years ago. Paleontologists discovered it had wings like a bird. Yet, it also had teeth like a dinosaur. That made paleontologists decide the Archaeopteryx was a very early kind of bird. Over time, dinosaurs evolved into birds. The Archaeopteryx was a first step in that direction.
In the late 1800s, scientists discovered radioactivity. Radioactive objects send out a certain amount of energy over time. By measuring how much radioactive material a fossil has, scientists can guess the fossil's age. This is called radiometric dating.
Paleontology Today
Today, paleontologists use many advanced tools. They study the smallest fossils with microscopes. They use x-ray machines to look inside fossils. Computers help them figure out how extinct animals looked and moved.
Paleontologists still make important discoveries with simple tools, too. They still use pickaxes and brooms. Around the world, many are still digging away. Each is hoping to learn more about the history of life on Earth.

Paleontologists dig deep.
Photograph by Robert Sisson
abundant
Adjective
in large amounts.
Age of Enlightenment
Noun
(1700s) period in European history where science and reason were promoted as ideals of good citizens and society.
algae
Plural Noun
(singular: alga) diverse group of aquatic organisms, the largest of which are seaweeds.
amber
Noun
translucent, yellow-orange material made of the resin of ancient trees. Amber is sometimes considered a gemstone.
animal
Noun
organisms that have a well-defined shape and limited growth, can move voluntarily, acquire food and digest it internally, and can respond rapidly to stimuli.
appendage
Noun
part of something that extends out from the main body, such as an arm or leg.
aquatic
Adjective
having to do with water.
Archaeopteryx
Noun
extinct reptilian bird that lived about 150 million years ago.
arthropod
Noun
invertebrate animal with a segmented body, exoskeleton, and jointed appendages.
aspect
Noun
view or interpretation.
atmospheric changes
Noun
alterations in the layer of air surrounding the Earth, such as an increase of pollution or humidity.
atom
Noun
the basic unit of an element, composed of three major parts: electrons, protons, and neutrons.
Plural Noun
(singular: bacterium) single-celled organisms found in every ecosystem on Earth.
biblical
Adjective
having to do with the Bible, the holy book of Christianity.
biologist
Noun
scientist who studies living organisms.
biostratigraphy
Noun
study of the dating of rock layers.
catastrophe
Noun
disaster or sudden, violent change.
cell
Noun
smallest working part of a living organism.
Charles Lyell
Noun
(1797-1875) English geologist.
chemistry
Noun
study of the atoms and molecules that make up different substances.
classify
Verb
to identify or arrange by specific type or characteristic.
climate
Noun
all weather conditions for a given location over a period of time.
coal ball
Noun
spherical structure of fossilized plant matter found in and around coal deposits.
colleague
Noun
a coworker or partner.
connective tissue
Noun
material that surrounds or links different organs or other parts of an organism.
crustacean
Noun
type of animal (an arthropod) with a hard shell and segmented body that usually lives in the water.
CT scanner
Noun
(computerized tomography scanner) device combining X-ray and computerized equipment to provide cross-sectional images of internal body structures. Also called a CAT scanner.
curative
Adjective
able to cure or treat a disease or illness.
cyanobacteria
Noun
type of aquatic bacteria that can photosynthesize light to create energy. Also called blue-green algae (even though it is not algae) and (in freshwater habitats) pond scum.
data
Plural Noun
(singular: datum) information collected during a scientific study.
debris
Noun
remains of something broken or destroyed; waste, or garbage.
decompose
Verb
to decay or break down.
deduce
Verb
to reach a conclusion based on clues or evidence.
Noun
area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.
dig site
Noun
place where paleontologists, archaeologists, or other scientists are digging into the Earth to find artifacts or fossils. Also called an excavation.
disprove
Verb
to prove wrong.
DNA
Noun
(deoxyribonucleic acid) molecule in every living organism that contains specific genetic information on that organism.
echinoderm
Noun
phylum of marine invertebrate including sea stars and sea urchins.
electron microscope
Noun
powerful device that uses electrons, not light, to magnify an image.
element
Noun
chemical that cannot be separated into simpler substances.
Emerging Explorer
Noun
an adventurer, scientist, innovator, or storyteller recognized by National Geographic for their visionary work while still early in their careers.
emit
Verb
to give off or send out.
environment
Noun
conditions that surround and influence an organism or community.
establish
Verb
to form or officially organize.
evolution
Noun
change in heritable traits of a population over time.
evolve
Verb
to develop new characteristics based on adaptation and natural selection.
excavation
Noun
area that has been dug up or exposed for study.
exoskeleton
Noun
the hard external shell or covering of some animals.
extinct
Adjective
no longer existing.
flipper
Noun
large, flat limb used by marine mammals for swimming.
forest
Noun
ecosystem filled with trees and underbrush.
formulate
Verb
to develop or create.
fossil fuel
Noun
coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals.
fungi
Plural Noun
(singular: fungus) organisms that survive by decomposing and absorbing nutrients in organic material such as soil or dead organisms.
genetic
Adjective
having to do with genes, inherited characteristics or heredity.
Genyornis
Noun
extinct large, flightless bird indigenous to Australia.
geologist
Noun
person who studies the physical formations of the Earth.
Georges Cuvier
Noun
(1769-1832) French paleontologist and biologist.
Gobi Desert
Noun
large desert in China and Mongolia.
hadrosaur
Noun
duck-billed dinosaur.
herd
Noun
group of animals.
hypothesis
Noun
statement or suggestion that explains certain questions about certain facts. A hypothesis is tested to determine if it is accurate.
ice age
Noun
long period of cold climate where glaciers cover large parts of the Earth. The last ice age peaked about 20,000 years ago. Also called glacial age.
indicator
Noun
sign or signal.
invertebrate
Noun
animal without a spine.
invertebrate paleontology
Noun
study of the fossils of animals without spines, such as corals, sponges, and insects.
isolate
Verb
to set one thing or organism apart from others.
lung
Noun
organ in an animal that is necessary for breathing.
mammal
Noun
animal with hair that gives birth to live offspring. Female mammals produce milk to feed their offspring.
mammoth
Noun
one of many extinct species of large animals related to elephants, with long, curved tusks. The last mammoths became extinct about 5,000 years ago.
marine
Adjective
having to do with the ocean.
microfossil
Noun
fossil that can only be seen and analyzed with a microscope, such as a grain of pollen or a single bacterium.
microorganism
Noun
very tiny living thing.
micropaleontology
Noun
study of fossils of microorganisms.
Middle Ages
Noun
(500-1500) period in European history between the Roman Empire and the Renaissance.
mold
Noun
type of fungi that forms on the surface of materials.
mollusk
Noun
large phylum of invertebrate animal, all possessing a mantle with a significant cavity used for breathing and excretion, a radula (except for bivalves), and the structure of the nervous system.
myth
Noun
legend or traditional story.
National Geographic Society
Noun
(1888) organization whose mission is "Inspiring people to care about the planet."
nest
Noun
protected area built by birds to hatch their eggs and raise their young.
Noah's flood
Noun
story in the Bible, a catastrophe that eliminated almost all life on Earth.
oyster
Noun
type of marine animal (mollusk).
paleobotany
Noun
study of the fossils of ancient plants.
paleoecology
Noun
study of prehistoric environments and habitats.
paleontologist
Noun
person who studies fossils and life from early geologic periods.
Patagonia
Noun
large plateau in southern South America, stretching from the Andes Mountains to the Atlantic Ocean.
petrify
Verb
to turn to stone.
pioneer
Noun
person who is among the first to do something.
plant
Noun
organism that produces its own food through photosynthesis and whose cells have walls.
pollen
Noun
powdery material produced by plants, each grain of which contains a male gamete capable of fertilizing a female ovule.
prehistoric
Adjective
period of time that occurred before the invention of written records.
prior
Adjective
before or ahead of.
protist
Noun
type of microscopic organism (not an animal, plant, or fungus).
pterosaur
Noun
extinct order of flying reptiles that flourished from 220 million-65 million years ago.
Quetzalcoatlus
Noun
flying reptile that lived about 70 million years ago, native to North America.
radioactive
Adjective
having unstable atomic nuclei and emitting subatomic particles and radiation.
radiometric dating
Noun
method of dating material such as rocks that compares the amount of a naturally occuring isotope of an atom and its decay rates. Also called radioactive dating.
resin
Noun
clear, sticky substance produced by some plants.
revolutionize
Verb
to completely change a process or way of doing something.
root
Noun
part of a plant that secures it in the soil, obtains water and nutrients, and often stores food made by leaves.
scholar
Noun
educated person.
seafloor
Noun
surface layer of the bottom of the ocean.
sequence
Verb
to put in order.
Shen Kuo
Noun
(1031-1095) Chinese scientist, politician, and poet.
Siberia
Noun
region of land stretching across Russia from the Ural Mountains to the Pacific Ocean.
skeleton
Noun
bones of a body.
soft tissue
Noun
connective tissue of an organism, such as blood, muscle, and skin.
specimen
Noun
individual organism that is a typical example of its classification.
sponge
Noun
simple type of marine animal permanently attached to something in the water.
stromatolite
Noun
fossil of ancient cyanobacteria that forms a rounded or column-like structure.
subdiscipline
Noun
field of study within a larger area of research.
suffocate
Verb
to be unable to breathe.
sustain
Verb
to support.
technology
Noun
the science of using tools and complex machines to make human life easier or more profitable.
theropod
Noun
type of dinosaur that walked on two legs and was usually carnivorous.
T. rex
Noun
(Tyrannosaurus rex) large carnivorous or scavenger dinosaur.
unearth
Verb
to dig up.
vertebrate
Noun
organism with a backbone or spine.
vertebrate paleontology
Noun
study of the fossils of animals with spines, such as dinosaurs.
volcanic eruption
Noun
activity that includes a discharge of gas, ash, or lava from a volcano.
William Smith
Noun
(1769-1839) English geologist.
wingspan
Noun
the distance between the tips of a bird's wings when stretched out.
worm
Noun
animal with a long, limbless body.
Xenophanes
Noun
(570-480 BCE) Greek philosopher and poet.