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Crab Concretion School (pics)


micropterus101

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After splitting too many concretions with a hammer and chisel and having them break the wrong way 80% of the time I have learned how to tell the crabs orientation within the rock without smashing it open with a hammer and chisel.

The concretion below is an easy example for learning purposes, it contains a pulalius vulgaris from the Lincoln creek formation Washington state. Not all concretions are this easy such as alot of the Porter area crab concretions, but they are deciferable. With patience preparing a crab without cracking it first will give you more quality specimens without having to do the repairs.

This is the view of the crab from the top. The front of the crab is always broader because The claws have more meat in them which enables more rock to form around them than the legs in the process of becoming a concretion.

concretionschool2.jpg

This is looking at the concretion sideways. The center line makes it easier for you to see the ventral side of the crab always has more material then the top. The ventral side of the crab has more rock due to all the cracks and crevaces that leak out the decomposing juices that aid in the formation of the concretion. This method of determining the orientation of crabs in concretions will work for all species with the most common features.

concretionschool1.jpg

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"The Crab Whisperer"

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

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Thanks for the lesson. Now if I could only find the dang things.

With rocks in my head, and fossils in my heart....

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