Fossils
Fossils are the preserved remains, or traces of remains, of ancient animals and plants
Pterodactyl Fossil
For upon|This fossil of the pterosaur Pterodactylus Kochi is preserved in limestone. Fossils of pterodactyls like this one have mostly been found in the Bavaria region of Germany.
Coral Fossil
Some specimens of coral, like the one in this photograph, were fossilized more than 450 million years ago. The presence of coral fossils in areas like the U.S. state of Kansas or the country of Mongolia helps show that such landlocked areas were once part of large, inland seas.
Dinosaur Fossils
Dinosaur fossils like the ones above are common in Utah’s Dinosaur National Monument. About 150 million years ago, huge floods carried the remains of dinosaurs and other creatures to the area, where they were buried beneath layers of sediment. Hundreds of fossils, from such dinosaurs as Allosaurus, stegosaurus, and Diplodocus, have been uncovered at the site.
Diplocaulus Fossil
This fossil of a diplocaulus was found in central Texas. Diplocaulus was a type of amphibian that lived during the Permian period, between 300 million and 250 million years ago.
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Homo Erectus Skull
The 1.54-million-year-old fossilized skull of a Homo erectus boy found near Lake Turkana, Kenya is part of the most complete skeleton of an early human ever found. The fossil, called Turkana Boy, was found in 1984. Next to the skull is a white cast of the boy’s brain. The two vertebrae in the spotlight are from a modern man (left) and Turkana Boy (right).
Human Jaw
The jaw of an ancient Native American is preserved by peat. Peat, a material found in some bogs, is the decaying remains of ancient plants. Peat eventually hardens and becomes coal, a fossil fuel. The low level of oxygen in peat bogs preserves organic remains like this “bog body.” The fossil was found in Titusville, Florida.
Megalodon Fossil
This fossilized tooth belonged to a giant prehistoric shark, megalodon. Estimating the fish’s size from fossils like this, scientists say megalodon could measure more than 20 meters (65 feet). Megalodon became extinct about 1.5 million years ago.
Ammonite Fossils
These spiral shells are fossils of an extinct species of marine animals called ammonites. Ammonite fossils are fairly common and serve as excellent index fossils. Index fossils are fossils used to reliably identify geologic periods. The presence of ammonite fossils usually indicates a Jurassic (200 million to 145 million years ago) or Triassic (250 million to 200 million years ago) period.
Cow Skeleton
A cow skeleton decays in the desert near Gerlach, Nevada. This skeleton, like the remains of most living things, will not become a fossil. It will decay and erode without being covered by sediments.
Fossils are the preserved remains, or traces of remains, of ancient organisms. Fossils are not the remains of the organism itself! They are rocks.
A fossil can preserve an entire organism or just part of one. Bones, shells, feathers, and leaves can all become fossils.
Fossils can be very large or very small. Microfossils are only visible with a microscope. Bacteria and pollen are microfossils. Macrofossils can be several meters long and weigh several tons. Macrofossils can be petrified trees or dinosaur bones.
Preserved remains become fossils if they reach an age of about 10,000 years. Fossils can come from the Archaean Eon (which began almost 4 billion years ago) up to the Holocene Epoch (which continues today). The fossilized teeth of wooly mammoths are some of our most “recent” fossils. Some of the oldest fossils are those of ancient algae that lived in the ocean more than 3 billion years ago.
Fossilization
The word fossil comes from the Latin word focus, meaning “having been dug up.” Fossils are often found in rock formations deep in the earth.
Fossilization is the process of remains becoming fossil,s. Fossilization is rare. Most organisms decompose fairly quickly after they die.
For an organism to be fossilized, the remains usually need to be covered by sediment soon after death. Sediment can include the sandy seafloor, lava, and even sticky tar.
Over time, minerals in the sediment seep into the remains. The remains become fossilized. Fossilization usually occurs in organisms with hard, bony body parts, such as skeletons, teeth, or shells. Soft-bodied organisms, such as worms, are rarely fossilized.
Sometimes, however, the sticky resin of a tree can become fossilized. This is called fossilized resin or amber. Amber can preserve the bodies of many delicate, soft-bodied organisms, such as ants, flies, and mosquitoes.
Body Fossils and Trace Fossils
The fossils of bones, teeth, and shells are called body fossil. Most dinosaur fossils are collections of body fossils.
Trace fossils are rocks that have preserved evidence of biological activity. They are not fossilized remains, just the traces of organisms. The imprint of an ancient leaf or footprint is a trace fossil. Burrows can also create impressions in soft rocks or mud, leaving a trace fossil.
Paleontologists
Paleontologists are people who study fossil. Paleontologists find and study fossil all over the world, in almost every environment, from the hot desert to the humid jungle. Studying fossil helps them learn about when and how different species lived millions of years ago. Sometimes, fossil tell scientists how the Earth has changed.
Fossil of ancient marine animals called ammonites has been unearthed in the highest mountain range in the world, the Himalayas in Nepal. This tells scientists that millions of years ago, the rocks that became the Himalayas were at the bottom of the ocean.
Fossil of an ancient giant shark, a megalodon, have been found in the landlocked U.S. state of Utah. This tells scientists that millions of years ago, the middle of North America was probably entirely underwater.
Juvenile pterodactyls like this one are called “flaplings.”
Photograph by Jonathan Blair
Mary Anning
The 19th-century British fossil collector Mary Anning proved you don’t have to be a paleontologist to contribute to science. Anning was one of the first people to collect, display, and correctly identify the fossil,s of ichthyosaurs, plesiosaurs, and pterosaurs. Her contributions to the understanding of Jurassic life were so impressive that in 2010, Anning was named among the ten British women who have most influenced the history of science.
Microfossils
Even though most of us have only seen dinosaur fossil,s in museums, most fossil,s are not that big. Some of them are so small, you can’t see them without a microscope.
The article was originally published here.
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