Body Fossils

Photo by Mike Viney

Molds– The dead organism’s body disintegrated and left a hollow area in the shape of the organism in the rock- a negative impression. (Left ammonite)
Casts– When the hollow space of the mold is filled in with minerals and/ or sediments, a positive impression is made. (Right Ammonite)

A steinkern is a stony mass that is left when the shell of a bivalve dissolves away leaving the cast of the inside of the shell behind. Mud and sediments can fill other hollow natural objects creating steinkerns as well.

“Heart of Texas” clam steinkern
Photo by : CSCollins– Texas Hill Country
Petrified Wood- Wikipedia

Permineralization used to be known as petrification– Water is full of dissolved minerals like calcite, silica, and pyrite (Fool’s gold) which seep through the layers of a dead plant or organism and evaporate. Wood is the most common permineralized fossil and then teeth and bones.
Bones are made mostly of the mineral apatite (Moh’s Mineral Hardness Scale rating of 5 out of 10), so it is not hard to imagine them being preserved as a fossil.  Permineralization usually occurred within the marrow space of the bone that is filled in with calcite– the main component of limestone and marble. Paleontologists study the growth rings of the bone as botanists study the growth rings of trees. The rings determine the growth rate and diet of the ancient animal. 

Visit Mike Viney’s site with beautiful permineralized fossils!

Priscacara serrata carbon film fossil fish
from the Green River Formation

Carbon Film Fossils – All living things contain carbon, hydrogen, oxygen, and nitrogen. When an organism dies and is buried in the sediment, hydrogen, oxygen, and nitrogen vaporize or dissolve in the underwater environment leaving a shiny, detailed black or brown carbon film on the rock’s surface. Carbon film fossils are usually water-dwelling organisms such as crustaceans and fish, but this is the primary way for plants to fossilize. Carbon film fossils give a more detailed two-dimensional image than mold or cast fossils. In fact, carbon fossilized feathers left so much detail that paleontologists were able to tell what color the feather had been before fossilized.

         Be sure to Explore the incredible carbon film fossils of the Burgess Shale Formation in Canada.

References: Updated April 25, 2017 By Drew Lichtenstein
and Wikipedia.

Original Bone and Tissue “Fossils”

40,000-year-old Wolf head found in Siberia

Frozen “Fossils” occur when animals are trapped and the temperature drops rapidly called a “flash freeze” The animals may have been trapped in mud, tar, or fallen into a crevasse or deep pit. Frozen remains are a treasury of information for paleontologists with samples of skin, hair, muscles, and internal organs. In the case above, there may be an opportunity to learn from brain matter. Teeth and head structure can be compared to extant (opposite of extinct) wolves to learn how they have evolved.
These fossils occurred during the Quaternary glaciation with the formation of the Arctic Ice Cap -2.58 million years ago to 11,700 throughout the Pleistocene epoch.

Anthropornis – an enormous penguin fossil found in 1905 on Seymour Island off the coast of Antarctica.
It weighed about 200 lbs (90 kg). Artwork by Discott.

Antarctica began to freeze in ice sheets or continental glaciers about 34 million years ago at the Eocene and Oligocene boundary. There was an extinction event during this time but it is not clear on its cause except that climate was definitely getting cooler. Frozen remains were also found on and near Antarctica- and with new technology- be listening for more.

Tar “Fossils” – When animals died from a fall into a naturally-occurring tar pit only the hard parts like bones, teeth, beaks, claws, and exoskeletons were preserved in the thick, sticky asphalt due to lack of oxygen. Bacteria in the tar would decay the soft parts leaving the hard parts to soak up the tar. When saturated, the dark brown or black bones, etc. would sink to the bottom of the pit preserved until found by paleontologists.
See “Fossil Geology” under “Fossils” for an explanation of how tar occurs naturally and other places around the world where you can see tar fossils.

In Los Angeles, California is the famous La Brea (means “tar” in Spanish) Tar Pits, where a total of 660 species of organisms have been found so far.
Dire wolves are the most common fossils found, saber-toothed cats are second, and coyotes are third. Other animals found were turtles, porcupines, badgers, early horses, ground sloths, giant short-faced bears, camels, long-horned bison, mammoths and mastodons, and an American lion that was not a cougar but was 25% larger than today’s African lions.
Birds (135 species) were found and included vultures, condors, eagles, and extinct giant stork-like birds called teratorns.

See “Fossil Geology” under this website”s “Fossils” page for an explanation of how tar occurs naturally and other places around the world where you can see tar fossils.
(Below) How mummies are preserved in the peat moss bogs are explained there as well.

Bog Mummies are mostly humans that were killed for mainly religious reasons and preserved through the chemistry of the acidic water in the raised water-logged bogs in cold Northern Europe. The dead layers of sphagnum or peat moss and the mud in the bog tans the skin a dark brown and colors the hair a reddish-brown. The environment delayed decomposition and preserved the bodies for thousands of years.

Florida has the Oldest Bog People Discovered Yet!

Titusville, Florida is the home of the largest, oldest, and well-preserved bog bodies and artifacts yet to be discovered! In 1982, a backhoe operator was clearing an area and came upon a human skull and bones. At first, thought to be an ancient crime scene, it was later found to contain 168 bodies of an old hunters and gatherers group of south Florida. The radiocarbon-dates ranged from 6,990-8,120 years ago plus or minus 70 years which were 4000 years older than Jesus Christ, older than ceramics, and 2000 years older than the pyramids of Egypt!
Called the Windover Archeological Burial Site, many artifacts were found with the bodies such as children’s toys, a dog’s tooth-manatee rib hammer, and a deer antler hook for an atlatl. An atlatl is a launching device for a spear to send it farther and stronger toward the prey. It was used before the bow and arrow were developed.

The black peat bogs here had been forming since the last Ice Age about 11,000 years ago. What makes them so special is that there were crushed shells of snails and bivalves on the bottom of the bog that made the environment more alkaline. Less acid and more calcium carbonate and magnesium from the shells kept the bones of the buried bodies here more intact.
For more information visit:

Amber or Tree Resin Fossils

When plants such as coniferous trees are injured or diseased, resin will drip or ooze from its injury. The resin will pool inside the tree, collect on the bark, or drip to the ground. Insects, seeds, leaves, and other forest objects get trapped in the sticky substance and are known as inclusions. More resin will fall to cover the object encasing it in resin.
High pressures and temperatures from overlying sediments and the chemical reactions with oxygen transforms resin into copal and over time- between 2-10 million years- harden and become amber.
Please visit Mike Viney’s Virtual Petrified Wood Museum for more extensive information about amber:

Ichnofossils or Trace Fossils

Ichnology (IK-nah-loh-jee) “the study of tracks or traces” studies the actions of prehistoric creatures and how they lived in their environments. Trace fossils include their foot or track prints, burrows, nests and eggs, gastroliths, borings, coprolites, and urolites.

Foot or Track Prints

Fossilized Human Footprints of Hunters and Gatherers of ancient Africa.
Photo by Cynthia Liutkus-Pierce

Read about “Africa’s biggest collection of ancient human footprints has been found” by Bruce Bower in Science News.

Ghostly Columbian Mammoth Footprints Found in White Sands National Park in New Mexico.
NPS Photo


Polar bears are the largest mammals that burrow to small mammals like beavers, rabbits, and mice. Reptiles, Insects, and birds also live and evade predators in burrows. Fish, sea urchins, clams, crustaceans, and. in this case (below), enormous worms are fossorial (burrowing)organisms.

Found along the Grand Canyon rim trail near Bright Angel Trailhead
Ransom, Kenneth. dsc_0114.jpg. June 28, 2015. Pics4Learning. 20 May 2020

Fossilized Eggs and Nests

Ammonite Eggs © The Etches Collection. Photo: Terry Keenan

Invertebrate Eggs that are the best-preserved belonged to ammonoids (ammonites and relatives), a cephalopod (“head foot”) that resembled the present-day nautilus. These eggs were found in the Late Jurassic- to Early Cretaceous-aged Kimmeridge Clay near Dorset in England. This formation included a number of invertebrate species as well as turtles, crocodiles, plesiosaurs, crocodiles, ichthyosaurs, and pliosaurs.

Mary Anning was a famous fossil collector and paleontological hobbyist in Lyme Regis- a Dorset coast town in southern England. She found the first complete ichthyosaur in 1811 when she was 12 years old. In 1823 she found a complete plesiosaur and later the first pterosaur to be found in the British Isles.

Fish and Amphibian Eggs

Mazonova helmichnus– Fish or Amphibian Eggs
Photo by RCFossils

The Mazon Creek deposits near Braidwood, Illinois have a variety of life preserved in detail like the famous Lagerstatten of Canada’s Burgess Shale. The fossils are found in the ironstone nodules that are the spoil heaps of abandoned coal mines, such as the famous Peabody Coal Pit 11 which is now a cooling pond for the Braidwood nuclear power plant. but with over 100 other localities, specimens still come to light. Masonova means “egg found in Mason Creek” are rare egg fossils of either fish or amphibian vertebrates from the Paleozoic Era (Pennsylvanian/ Carboniferous Period).

Reptile Eggs, in the fossil record, go back to the Early Permian, but reptiles evolved to lay amniotic eggs during the Carboniferous about 340 million years ago. They began as soft tissue eggs that did not preserve well in the warm, humid environment. Crocodilians, turtles, and dinosaurs are well-known for fossilized eggs. In fact, crocodilian eggs evolved rigid shells and have stayed that way through time.

An Illustration of life in a Maiasaura Colonial Nest.
Montana Geologic Road sign program

Marion Brandvold, a rock shop owner, found the remains of juvenile dinosaurs in 1977 and contacted paleontologist Dr. Jack Horner of the Museum of the Rockies. Fourteen nests of Maiasaura “caring mother lizard” a duck-billed hadrosaur were found. With over a hundred specimens of this dinosaur in all stages of development, this locality was named Egg Mountain. Maiasaura peeblesorum has become the state fossil of Montana. Egg Mountain is located near Choteau, Montana.


(G)Gastrochaenolites (E) Entobia borings
Photo by Wilson44691

Borings aka bioerosion are made by marine invertebrates in rocks, shells, or hardground (lithified seafloor) in which to exist, to filter-feed, or to prey on the animal within the shells.
A few examples of “boring” trace fossils:
(G) Gastrochaenolites make a circular, oval, or club-shaped hole in the shells of saltwater mussels.
(E) Entobia borings are made by sponges to direct the water to assist in better filter feeding.
Time Span on Earth for both: Ordovician to Present.

Bromolites are fossilized materials found in various parts of the digestive tracts of ancient organisms.

Some examples of bromolites that have “left the ancient body” are coprolites/ paleofeces and regurgitites. Other bromolites that were found within (in situ)the areas of the organs of digestion are colonites ( from intestines) and gastrolites (stomach contents). Gastrolites are different from gastroliths.


Coprolites aka coproliths are geologically fossilized fecal matter (poo) of animals that have been replaced with calcium carbonates and silicates making them more rock than poo. It is possible for paleontologists to find fish scales, bones of previous prey, osteoderms- scales of reptiles, and plant material like seeds, within the fossilized excrement.

Scapanorhynchus– a shark coprolite
Photo by Steve Wick

A coprolite was found of a close member of the Goblin shark family, Scapanorhynchus, and identified by paleontologists Dr. Tom Lehman and Steve Wick in Big Bend National Park in Texas. They could tell by the gar scales (small, dark angular parts) inside the poo, and the twisted shape of the coprolite that it came from this particular shark. Teeth found in the surrounding area gave more clues to its identity.
Isn’t it amazing what paleontologists know about even the excrement of ancient animals?

Previously called “bezoar stones”, bezoar means “antidote” and was previously ground up and consumed as the universal antidote for any kind of poisoning. The first female fossil hunter in England, the famous Mary Anning, came upon a bezoar stone within the fossilized stomach area of an ichthyosaur in 1824. The name was later changed to coprolite “dung stone” by her friend, Dr. William Buckland, a pastor and paleontologist, five years later.
Coprolites are trace fossils that help scientists, and then the public, to understand better the prehistoric food web.

Hey Kids- Join Dr. Dirt, the Armadillo Archeologist, to solve The Case of the Prehistoric Poo”.
A recipe for Gross-Out Chocolate Chip “Coprolite” Cookies follows.


Ancient human feces are called paleofeces and coprolites that have been found in caves in arid climates. Ancient hunters and gatherers had inefficient digestive systems so seeds of various plants, scales of fish and lizards, as well as bones from small rodents have been found within the fecal matter. What is so amazing is that DNA analysis can be done on the ancient feces and has been more reliable than skeletal DNA (Poiner, et al., 2001).


Regurgitalites or regurgitaliths are the fossilized remains of vomited material produced by vertebrates. Hawks and owls have a recognizable shape to the pellet that they vomit that the pellet itself demonstrates the trace activity of the bird. Reptiles, birds, some fish, and even some invertebrates like cephalopods and brachiopods are said to regurgitate indigestible food matter.


Cololites are fossilized fecal matter that has not been discarded from the intestines. The tubular intestinal shape and the location posterior to the stomach within the body fossil makes it a cololite and not a coprolite. The cololite pictures below were found within the vast body fossil of a sperm whale found in Umbria, Italy. Ambergrisichnus alleronae is the name given to this trace fossil which includes the folded structure (#3 & #6) with striations and bulges (#2) like the actions that would occur in the large intestine or colon. Squid beaks (#5) were found within these cololites. This whale had lived between 1.75 to 1.55 million years ago(Ma).

Ambergrisichnus alleronae
Cololites from a Sperm Whale from the Pleistocene Epoch found in central Italy.
Pictures from Monico, et al., 2016

Gastroliths “stomach stones”

Psittacosaurus fossil with gastroliths in its stomach region, American Museum of Natural History- Photo by Ryan Somma

Gastroliths, geogastroliths, or gizzard stones are between sand- and cobble-sized rocks that are accidentally or deliberately held inside an animal’s gastrointestinal tract to aid in mixing, grinding, and crushing tough plant material. They were/are prominent in herbivorous birds and dinosaurs such as Cedarsaurus-a sauropod and Claosaurus– a hadrosaur.
Gastroliths used as ballasts to decrease buoyancy in crocodiles, alligators, seals, and ancient plesiosaurs are thought to be controversial.

If ichnology/trace fossils pique your interest, please see the professional paper below:
Lothar Herbert Vallon, Andrew Kinney Rindsberg & Richard Granville Bromley (2016) An updated classification of animal behavior preserved in substrates, Geodinamica Acta, 28:1-2, 5-20, DOI: 10.1080/09853111.2015.1065306

Ransom, Kenneth. dsc_0114.jpg. June 28, 2015. Pics4Learning. 20 May 2020
Wick, Steven L., and Corrick, Donald W., (2015), Paleontological Inventory of Big Bend National Park, Texas, The Place, the People, and the Fossils, Produced by Big Bend National Park Division of Science and Resource Management -unpublished.
Poinar, Hendrik N.; et al. (10 April 2001). “A Molecular Analysis of Dietary Diversity for Three Archaic Native Americans”. PNAS. 98 (8): 4317–4322.Lothar Herbert Vallon, Andrew Kinney Rindsberg & Richard Granville Bromley (2016) An updated classification of animal behavior preserved in substrates, Geodinamica Acta, 28:1-2, 5-20, DOI: 10.1080/09853111.2015.1065306
Monaco, Paolo, Baldanza, Angela, Bizzarri, Roberto, Famiani, Federico, Lezzerini, Marco, and Sciuto, Francesco. 2014. Ambergris cololites of Pleistocene sperm whales from central Italy and description of the new ichnogenus and ichnospecies Ambergrisichnus alleronae. Palaeontologia Electronica Vol. 17, Issue 2;29A; 20p.