Where to Find Fossil Fish – Dig Sites

Two sites outside the small town of Kemmerer, Wyoming, offer pay-to-dig. Just make an appointment or register, show up and they will take great care of you, showing you how to fish… with a hammer and chisel.

One site is the Warfield Quarry, also known online as Fossil Safari, and the other is the American Quarry.

While visiting the pay-to-dig sites in Kemmerer, it is a must to travel a short distance away to the Fossil Butte National Monument. Sorry no collecting here, but the museum boasts a tremendous variety of animals and plants from the Green River Formation. Cut unobtrusively into the hillside, the visitor center is filled with wonderous fossils, a great compilation of the ecosystem 50 million years ago.

The Green River Formation

Pay-to-dig sites are part of the Green River Formation where there are hundreds, no, thousands of fish trapped in rock that was once a series of fairly shallow lakes. Streams and rivers drained the surrounding mountains enabling the formation of this special fossil location.

The Green River Formation is known as a lagerstatte, which loosely translated from German means “storage place.” The area butts up against the limestone of the Wasatch, Unita, Wind River and other mountain ranges. It is an area where fabulous and spectacularly preserved fossils including plants and animals represent a snapshot of life living within that ecosystem.

When & How was this Site Made?

The Eocene period, about 53 to 48 million years ago, was a transition from a warm and moist environment to one that was hotter and drier. This is evidenced by some of the fossil finds in the area. Palm fronds, crocodile and sycamore leaf remains point to a warm moist environment and deciduous tree leaves point to a drier climate. The mountains were partially made up of limestone. During heavy rains, water would run down into the streams and rivers bringing with it sand, mud and silt sediments filled with dissolved minerals such as calcium oxides, inorganic elements and calcium components.

This would wash into the lakes fouling the water, making it turbid and in some cases changing the pH levels. At times the change in the chemical composition of the water was detrimental to the life forms in it.

Fish would die along with many of the other creatures and become buried in the silty sediments. Paleontologists can tell by looking at the various layers, which were deposited during times of drought and which were deposited in times of flood. It is also possible by studying the cross-section of the quarry where the best location is to find fossil fish.

The spectacular fossilization and completeness of the fossil fish is because they were buried quickly. Even the bottomfeeding scavengers were not quick enough or did not survive to disarticulate the bodies of the dead fish. The sediments filtered down to the bottom of the lake and covered the creatures with thin layers. It is within these layers that spectacular fish specimens may be found.

Where to Find Fossil Fish – Digging

In specific horizons, one of which is called the split fish layer, a finely laminated limestone is present that entombed many fish. This is easy to split and if the rock contains a fossil, it splits so that you can easily see it in both a positive fish fossil and also a negative impression. The fish are beautifully preserved with bones, gill covers, ribs and even scales intact. In some cases, a bit of matrix, the limestone that clings to the fish skeleton, is still present. It is quite easy to remove. In many instances, all that is needed is a dental pick, or a pin vise to gently remove excess rock matrix. You must be very careful not to go too deep into the limestone so it’s best to attack it at an acute angle.

This limestone is so fine-grained that many plants and insects that fell into the water or were washed in from rivers and streams are also seen in spectacular detail.

In some areas birds, reptiles, turtles and even crocodiles may be found all preserved in exquisite detail.

This story about where to find fossil fish previously appeared in Rock & Gem magazine. Click here to subscribe! Story and photos by Joseph “PaleoJoe” Kchodl.

The post Where to Find Fossil Fish first appeared on Rock & Gem Magazine.

Trilobites were arthropods with segmented bodies, paired jointed legs and an exoskeleton. Modern arthropods are made up of insects, spiders, millipedes and crustaceans.

The name Isotelus is Greek. Translated, isos means equal and telos means end. Isotelus was first described by John Locke in 1838. Locke was involved in the first serious study of the geology of Ohio in 1837 and 1838.

What are Trilobite Fossils? – Body Segments

The name trilobite derives from the three distinct body divisions or lobes running vertically through the body. There is one central or axial lobe with two pleural lobes on either side. It is also divided three ways horizontally into the head section or cephalon, the body section or thorax and the tail section or pygidium.

Some species had long projecting spines emanating from various segments. In the case of Isotelus, it had long spines radiating backward from the sides of the head section, called genal spines. The head and tail sections were solid shields while the body was made up of individual segments, each with a corresponding pair of legs and gill branches.

Body Armor

Some species had as few as two body segments while others had as many as 60. Isotelus had eight body segments. With these segments, the trilobites were able to “enroll” or roll up their bodies, much like the modern-day pill bug or roly-poly. It is with this action called conglobation that they were able to pull the soft body tissues in for protection from danger.

They were covered by a thick exoskeleton, a skeleton on the outside of the body protecting the soft tissues including legs, gill branches and antennae. It also protected them from danger be it storms or predators.

What are Trilobite Fossils? – Fossil Remnants

It is this exoskeleton that is found as a fossil. To grow, trilobites would have to shed or molt their exoskeleton. While molting they would grow a bit and then the new exoskeleton would harden and they would continue on their way. In many cases, it is discarded and disarticulated sections of the exoskeleton that are found as fossils.

Complete trilobites are not that common.

Trilobites Day-to-Day

Trilobites were the first major creature on earth with complex eyes and many lenses. The eyes generally were crescent-shaped and sat high on the head section. As such it can be imagined they had nearly 360-degree vision. Some species had thousands of lenses in each eye. Some species were blind and had no eyes.

They were creatures that scurried about on the ocean floor eating decaying plant and animal material much as their relatives the horseshoe crabs, lobsters and shrimp do today. They had a mouthpart called a hypostome on the underside of the head section. One could almost imagine them as an undersea vacuum cleaner.

What are Trilobite Fossils? – Index Fossils

To date, there have been over 20,000 species named and described from the Cambrian Period some 521 to 252 million years ago when the Permian mass extinction erased almost 90% of life on earth. They ranged in size and shape from just under a quarter-inch to just over two feet long. They were quite a resilient and diverse group of creatures.

Trilobites are a well-known index fossil that can generally date the age of the rocks. Certain trilobites can be found in rocks of a certain geological age and no other, thus they are an index of the age of rocks.

Becoming a State Fossil

School children played a major role in having this magnificent trilobite designated as the State Fossil of Ohio. After students learned of a large Isotelus being found at Huffman Dam near Dayton in 1919, third and fourth-grade students and teachers lobbied for the designation. But it wasn’t until June 20, 1985, that Ohio House Bill 145 finally designated the Isotelus as Ohio’s State Invertebrate Fossil.

Other states have designated various species of trilobites as their state fossil — Pennsylvania has chosen Phacops rana and Wisconsin the Calymene celebra.

Finding Trilobite Fossils

Isotelus trilobites and Isotelus pieces can be found in several locations in Ohio. One of the most popular areas is along Caesar Creek State Park southeast of Dayton. There are restrictions and a fossil collecting permit must be obtained from the park office before heading to the large spillway where many fossils can be found.

This story about what are trilobite fossils previously appeared in Rock & Gem magazine. Click here to subscribe! Story and photos by Joseph “PaleoJoe” Kchodl.

The post What are Trilobite Fossils? first appeared on Rock & Gem Magazine.