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Elrathia Triolobites
Americas Most Common Trilobite

Beautiful Red Elrathia kingii trilobite fossil on a rainbow matrix. House Range of Utah

Fast Facts about the Elrathia Trilobites

These are how Elrathia trilobite fossils are commonly preserved; black in color, and they easily flake off the matrix.

Name: Elrathia kingii: The name Elrathia is based off the town Elrath in Alabama where these trilobites were discovered.

The main species name is kingii, not kingi. It was named by Meek in 1870. The work Kingii means King.

Taxonomy: Phylum: Arthropoda - Class: Trilobita - Order: Ptychopariida - Family: Alokistocaridae - Genus: Elrathia

Species: E. kingii & E. marjumi

Age: Cambrian

Distribution: North America
These are Americas most common Trilobite

Body Size:
Elrathia are small trilobites. They are usually around an inch in length. Small ones are around 1/8" (a few mm) in size, while large ones can reach lengths of around 2 inches (50 mm).

Particle Feeder
They scavanged the ocean floor.

Physical Appearance:
Elrathia have a wide thorax and have short genial spines on their cephalon. Other than that, they are rather plain looking trilobites.

Fun Fact 1:
Elrathia trilobites could survive in low oxygen environments, lower than what most living things could survive.

Fun Fact 2:
Living in low oxygen areas allowed these trilobites to easily fossilize. This makes them the most common trilobite fossil in North America.

Elrathia Trilobite Facts and Information - The Details

Elrathia kingii trilobite fossils of the Cambrian are one of the most recognizable and abundant fossils. They are found in huge concentrations in certain layers of the Wheeler shale in Utah. They are so abundant, there are comercial quarries in Utah dedicated to extracting these trilobite fossils.

Elrathia trilobites have a wide thorax and have short genial spines on their cephalon. Other than that, they are rather plain looking. The typical size of an Elrathia is around an inch. Small ones are mere millimeters in length, while large ones can get around 2 inches in length.

Their mouth parts and body shape suggest they were particle feeders that scavenged the ocean floor. One interesting fact about Elrathia is they are found in zones below the oxygen level required by most organisms, in a zone called the exareobic, a zone that borders the anaerobic zone, which lacks sufficient oxygen. This may be why Elrathia are preserved in such vast numbers, as poor oxygen environments are more favorable for fossilization.

Where to find Elrathia Trilobite Fossils

U Dig Quarry - An easy place to find Elrathia Trilobites.
U-Dig images by Albert B. Dickas, who is the author of some great Geology and Fossil Books!

Elrathi trilobites are mainly found in the Cambrian Wheeler Shale in Utah and Nevada. They are the most common trilobite found in these areas.

To try and find your own Elrathi kingii trilobites, I would suggest going to the U-Dig quarry near Delta, Utah.

Click here to read about my trilobite fossil collecing trip in the Wheeler Shale near Delta, Utah

Recommended Books

Trilobites: Common Trilobites of North America (A NatureGuide Book)
by Jasper Burns, 2000

Jasper Burns has some great illustrated fossil guide books. This one is on the Trilobites of North America. It has detailed illustrations of 41 species of North American trilobites and includes information about trilobite paleobiology, vision, growth, extinction, and much more! It's a nice little resource book for those interested in North American trilobites. It's also a very inexpensive book. Check it out!

The Trilobite Book: A Visual Journey
by Dr. Riccardo Levi-Setti, 2014

This is an updated (2014) hardcover (kindle available) of his famous 1994 book. It now has color images instead of black and white ones. The images are of prefectly prepared trilobites from all over the world. this book is geared toward the beginner and does not get overly technical. However, it's wonderful just to see the pictures and is a must for any trilobite enthusiast.

Trilobites for Sale:

Trilobites from Fossil Era
Trilobite fossils are some of the most beautiful and collectible fossils in the world! There are countless species of trilobites. They make beautiful display and conversation pieces. Common ones make very affordable for gifts to fossil and paleontology enthusiasts. Fossil Era has a huge selection of top quality trilobites from many states and many countries. It's fun just to browse through the inventory and look at all the different types!

Elrathia Kingii Fossil Examples

Elrathia kingii from the House Range in Utah

This is a stunning Red Elrathia kingii trilobite fossil on a rainbow matrix. Unfortunately I cracked in in half before I discovered the bug!

Formation:Wheeler Shale
Location:House Range, Utah

This is another beautiful fossil plate. It has 2 complete red Elrathia trilobites on it, plus a complete red peronopsis trilobite on the very bottom. The matrix has a nice red stripe running down it with hints of yellow throughout.

There is also a tiny Peronopsis interstricta trilobite at the bottom of the plate.
Formation:Wheeler Shale
Location:House Range, Utah

These are two small Elrathia kingii trilobites. Elrathia tend to flake out of the matrix easily, like these two.

Formation:Wheeler Shale
Location:House Range, Utah

This is an example of an Elrathi without the cheeks. Elrathia are often found without cheeks.

Formation:Wheeler Shale
Location:House Range, Utah

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