Wednesday, August 31, 2011


Myriacantherpestes (MEER-ee-uh-canth-er-PEST-eez) is a very spiny millipede that lived from the Silurian to the Carboniferous. Its many spines could have been used for protection against predators, or for identifying each other. I first heard about this creature in the book Paleo Bugs, by Timothy J. Bradley.

In the picture below, Myriacantherpestes is on the right and Archidesmus is on the left. Myriacantherpestes was three feet long, but Archidesmus was about 2.5 cm, as big as most extant North American millipedes. They both lived in the Silurian Period, along with the millipede that resembled a miniature Arthropleura, which was called Eoarthorpleura.

Myriacantherpestes was probably a descendant of the earliest known land animal, Pneumodesmus. In the Silurian, millipedes like Myriacantherpestes were the dominant animals on land.

Tuesday, August 30, 2011


Halysites, commonly called "chain coral," is a coral that lived from the Ordovician to the Silurian Period. It looked like a bunch of straws or tubes linked together. From above, Halysites looks like a mass of chains or a brain.

From the side it looks like a fence.

Each individual corallite, or cell, is 2 to 6 mm in diameter. In each individual tube there was a tiny sea anemone-like animal called a polyp, similar to what you find in modern corals.

Corals today prefer warm, shallow, clear seas, so tabulate corals like Halysites and their relatives probably did too. So when sea levels rose in the Devonian, they became rare and then died out two periods later, in the Permian mass extinction.

Sunday, August 28, 2011


Phacops is a trilobite that lived from the Silurian to the Devonian Period. It had a large and bumpy glabella, or middle cheek.

Even though many other trilobites could roll up like pill bugs, Phacops could do it more efficiently than other trilobites. But sometimes when they were rolled up they could get buried in sediment. Many fossils of Phacops are found rolled up into balls.

Phacops was up to six inches long. Some people recognize it by its eyes, which resembled frog eyes.

Phacops has been found in the northeast United States and Morocco, and is the state fossil of Pennsylvania.

Phacops had a 360 degree view because it could turn its eyes to different angles. Phacops is one of the most common Devonian trilobites.

Saturday, August 27, 2011


Charnia (char-NEE-uh) was an Ediacaran sea pen-like animal which is named after Charnwood Forest in England, the place where it was first discovered.

Charnia was first thought to be a Cambrian alga, but now it is believed to be a mysterious Ediacaran animal. Even though Charnia resembled a sea pen, it probably wasn't a sea pen. Charnia was a fractal animal, so it couldn't have developed organs that animals alive today have.

Charnia probably lived anchored to the sea floor with its holdfast. Charnia may have either absorbed food through its body or it could have been a filter feeder.

Charnia is one of the oldest known animals. Charnia was the first fossil ever found in Precambrian rocks. Before Charnia was discovered, scientists used to believe that there were no Precambrian fossils, or possibly no Precambrian life.

Friday, August 26, 2011


Alalcomenaeus is a Cambrian arthropod that was first classified as a crustacean, then an opabinid, but now some people believe it was an arachnomorph.

Alalcomenaeus had five eyes. Three of its eyes were very small and were together on the front of its head. It also had two large stalked eyes. The arrangement of the eyes is similar to the eyes of a modern cicada. Alalcomenaeus had legs, but they were probably not for walking. The legs may have been for clinging onto plants or sponges, or for tearing up prey.

Alalcomenaeus had eleven body segments and a shield covering its head. It had a flat telson, with short spikes on the back, that could have helped it swim. It had hairy lobes along the side, which could have also helped it swim.

At first, when Alalcomenaeus was discovered in the Walcott quarry, only six specimens of it were found, and it was thought to be rare. But later, as the quarry was expanded, scientists found many specimens of Alalcomenaeus, and now it's believed to be a dominant species.

Thursday, August 25, 2011


Fusulinids are extinct single-celled organisms called protists that lived from the Silurian to the Permian. Most fusulinids were about the size of a grain of rice, but some were up to two inches long. They had a hard wall that protected the cell inside.

Some fusulinids are so similar in shape that scientists have to use a cross section of the fossil to identify them.

Fusulinids probably lived in clear water and may have lived on reefs.

Fusulinids are very large and complex for single-celled life, which is usually microscopic. Fusulinids are marker fossils, which means by looking at the fusulinids in a rock formation, scientists can tell how old the rock is.

Note: Edited 8/31/11 to remove the word "animal" and replace it with "organism." Fusulinida was a protist, not an animal.

Wednesday, August 24, 2011


Archimedes (bryozoan) is an extinct animal that lived from the Carboniferous to the Permian Period. Archimedes had a spiral wall that wrapped around a corkscrew stalk that was anchored to the sea floor. The wall was covered in zooids, like all bryozoans. 

Archimedes is named after the Archimedes Screw, because of the corkscrew stalk. Most fossils of Archimedes do not preserve the spiral wall. Instead they only preserve the unusual stalk. 

Archimedes is unique because of its spiral shape. It is a kind of animal called a bryozoan, which means "moss animal." They are also commonly called "moss animals," and they are still alive today. But Archimedes has been extinct since the Permian.

These fossils of Archimedes only preserves the corkscrew stalk. The rest of it is usually not preserved because it is very brittle, like all bryozoans.

Tuesday, August 23, 2011


Thaumaptilon (thaw-muh-TIL-on) is a Cambrian sea pen-like animal from the Burgess Shale. Its name means "wonderful soft feather." Even though Thaumaptilon was leaf-life, it was not a plant.

Thaumaptilon had a holdfast that appears to not have had an anchor-like part at the bottom, so it could have used its holdfast to move across the sea floor and attach itself to different locations.

Thaumaptilon had small spots on one side of its body which could have been zooids. If these were zooids, they could have been part of Thaumaptilon or a different species of animal. Zooids are tiny animals that make up one colonial animal.

Thaumaptilon could possibly be related to late pre-Cambrian Ediacaran feather-like animals, but not everybody agrees on that.

Monday, August 22, 2011


Coccosteus is a Devonian arthrodire placoderm that resembles the larger Dunkleosteus. Coccosteus mainly lived in fresh water, but could have possibly also lived in the sea, like a bull shark in reverse. Fossils of Coccosteus have been found in Europe and North America.

Coccosteus was usually about 8 to 10 inches, but the largest specimen is 16 inches long. Its name means "seed bone."

Like all other arthrodires, Coccosteus had a joint in its neck that would have allowed it to open its mouth wider than most fish and swallow larger prey. Coccosteus had a sharp beak which would have helped it slice open prey. It had bony plates covering its head which could have protected it from predators.

Coccosteus lived from the middle to late Devonian Period.

Sunday, August 21, 2011


Escumsia is a unusual genus of animal that is only found in Pit 11 in the Mazon Creek formation. It lived in the Pennsylvanian epoch of the Carboniferous Period.

Escumasia had a stalk with a circular holdfast at the bottom, a sack-like body, two long arms, and a slit-like mouth on top. It also had an opening on the body which could have been an anus.

Escumasia was usually about 4.5 inches tall. Its arms may have been for stinging food then sweeping it into the mouth. But nobody knows for sure.

[Image removed by request of the photographer]

The affinity of Escumasia is highly disputed. It could possibly be related to cnadarians (nuh-dare-EE-inz), which include jellyfish, sea anemones, and corals. But Escumasia had bilateral symmetry, which means that it could not have been a true cnadarian. Some scientists believe that it could have been in its own separate group. Possibly it died out because it was not well enough adapted to its surroundings. It was probably not a very successful form, because Escumasia is the only known animal of its kind. I've been able to find almost nothing about Escumasia, which means it could be very mysterious.

[Image removed by request of the photographer]

[Primary sources for this post: and]

Saturday, August 20, 2011


Amiskwia was a bizarre genus of Cambrian animal. It was about one inch long and probably used its flat tail to swim. When Charles Doolittle Walcott first discovered Amiskwia in the Burgess Shale, he described it to be a chaetognath, sometimes called an arrow worm. Then later, other scientists classified it as a ribbon worm. But now no one really knows what it was.

Amiskwia looked like a fat worm with a head that had two antenna-like tentacles on it. On the side it had stubby fins, and on the back end it had a paddle-like tail possibly for locomotion. Specimens of Amiskwia are almost transparent so that the internal organs are visible.

Amiskwia is a rare fossil because only 18 specimens have been found in the Burgess Shale. Because of its hydrodynamic shape and its powerful tail, Amiskwia looks like it could have been a fast swimmer. Maybe the reason why Amiskwia is rare could be that they were territorial and living very far away from each other. But that's just my hypothesis.

Friday, August 19, 2011


Helicoplacus was a peculiar Cambrian echinoderm that was about seven centimeters long. When Helicoplacus was alive it was in an upright position, either anchored to the sea floor or floating in the water column. The location of its mouth is highly disputed, but scientists do know how it fed. It had a spiral groove around the sides of its body that led to the mouth. This would allow food to go along the groove into the mouth.

Helicoplacus is the earliest well-preserved echinoderm. It may have resembled a miniature water tower or a pinecone. Helicoplacus means "spiral plate," because of its spiral groove and its armored body. Fossils of Helicoplacus have been found in California. Helicoplacoids like Helicaplacus did not live for a very long time, and did not survive past the early Cambrian.

Helicoplacus was probably an extremely primitive echinoderm. It didn't have five-fold symmetry like most echinoderms do, and it had a primitive way of feeding and also a very early respiratory system.

Thursday, August 18, 2011


Choia is an extinct sponge that lived from the Cambrian to the early Ordovician. Choia was about one inch in diameter and it looked like a cone flattened from the top, with spines radiating out the sides.

My drawing of a group of Choia on the sea floor.

At first scientists thought that Choia's spines radiated out in all directions, like a sea urchin. But now they believe that Choia's spines radiated out the side. Choia lived flat against the sea floor and was probably convex so that it would not be turned over by waves and currents because it was not attached to the sea floor like most sponges. Choia lived in groups and was similar to Choiaella, which looked like a spineless Choia. 

Scientists have found 127 specimens of Choia in the Phyllopod bed of the Burgess Shale. It has also been found in the Wheeler Shale in Utah, and in China, Morocco, and Greenland.

I believe that Choia's spines may have kept the sponge from sinking into the soft sediment. But that is just my hypothesis.

Wednesday, August 17, 2011


Greenops is a Devonian trilobite with odd spines growing out of the pygidium (the last body section). Finding a complete specimen is very rare, but scattered bits and pieces are common in New York State and Ontario, Canada.

Greenops was about 1 to 1.5 inches long and probably had to avoid being eaten by predators like placoderms, ammonoids, orthocones, and sharks. It lived in deep warm water, but usually not very deep. Fossils of Greenops are often found in Devonian limestone deposits.

Greenops had a schizochroal eye, which are compound eyes that had few large lenses separated by thick walls. This type of eye in found only in some phacopid trilobites.

Tuesday, August 16, 2011


Sidneyia is a Cambrian arthropod that was found in the Burgess Shale by Walcott. He found it in 1910 on his first day at the Burgess Shale. Its name, Sidneyia inexpectans, means "Sidney's discovery." Walcott's son Sidney helped him discover it. Walcott named many other animals after members of his family. 

Sidneyia was about two to five inches long and was probably a bottom-dwelling carnivore that crawled across the sea floor in search of prey. It probably fed on animals like hyoliths and trilobites.

Sidneyia's wide, flat telson probably could have propelled it across the sea floor for a burst of speed, but that is just my hypothesis. 

Monday, August 15, 2011


Isotelus is a trilobite that lived in the Ordovician Period. The biggest species of Isotelus is I. rex, which is one of the largest trilobites found yet. I. rex was about three feet long. Isotelus has been found in the United States, Canada, and Europe, and is the state fossil of Ohio.

Isotelus rex is on the far right.

Isotelus probably crawled along the sea floor and probably had to avoid predators like nautiloids. It was a kind of trilobite called an asaphid, which were trilobites that usually had between five and twelve segments in the thorax, and the pygidium and cephalon were similar in size.

The largest complete specimen of Isotelus rex was found in Manitoba, Canada in 1999. Isotelus maxiumus, another large species, has been found in Ohio.

Sunday, August 14, 2011


Mixopterus was a peculiar genus of eurypterid that lived in the late Silurian Period. Its spiny claws were similar to those of the Ordovician eurypterid Megalograptus.

Thanks to Wade Harrell for the cool illustration!

At the posterior end, Mixopterus has a stinger that it could have used to injure or kill its prey before eating it, like scorpions do today.

Mixopterus was a type of arthropod called a eurypterid. In the Silurian, eurypterids like Mixopterus were the top predators. It was about 75 centimeters long and was found in Norway.

Mixopterus had a very bumpy exoskeleton and spiny legs. It probably kept its stinger raised above its head like scorpions do. Eurypterids like Mixopterus are believed to be related to horseshoe crabs and scorpions.

Saturday, August 13, 2011


Canadia is an annelid worm that lived in the Cambrian Period. It was probably about 1 to 2 inches long, but could have been larger. Canadia might have had diffraction grating, which would mean that from some angles it may have appeared colorful, like Marrella.

Canadia was discovered by Charles Doolittle Walcott. It could have used its setae (short bristles) to swim, but it could also crawl along the sea floor with its legs. Canadia was probably either a carnivore or a scavenger, because it had a proboscis, and because no sediment has been found in the gut. Canadia means "of Canada" or "after Canada," because it was discovered in Canada.

Canadia's gills looked like mollusk gills, so Canadia could be related to mollusks. Its setae were armor-like and could have been used for defense as well as swimming.