FOSSIL Crab: Did you know?

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Pulalius vulgaris  (Rathburn, 1926)
Crabs​ ​are​ ​primarily​​ ​​aquatic​ ​invertebrates​ ​with​ ​an​ ​exoskeleton​ ​and​ ​jointed​ ​appendages. Many​ ​crabs​ ​are​ ​predators/scavengers​ ​and​ ​eat​ ​mollusks​ ​and​ ​other​ ​small​ ​living​ ​or​ ​dead animals.​ ​Though​ ​thousands​ ​of​ ​species​ ​of​ ​crabs​ ​live​ ​in​ ​today’s​ ​oceans,​ ​the​ ​entire​ ​family that includes this crab is extinct.

This​ ​crab​ ​may​ ​have​ ​used​ ​its​ ​claws​ ​to​ ​crush​ ​the​ ​shells​ ​of​ ​mollusks.​ ​Crabs​ ​living​ ​today crush​ ​and​ ​chip​ ​shells​ ​as​ ​well​ ​as​ ​prying​ ​them​ ​open​ ​in​ ​order​ ​to​ ​eat​ ​the​ ​organism​ ​inside the​ ​shell.​ ​The​ ​claws​ ​on​ ​this​ ​specimen​ ​include​ ​molariform​ ​teeth​ ​(see​ ​photo​ ​below),​ ​which may​ ​be​ ​fortified​ ​with​ ​minerals​ ​to​ ​increase​ ​their​ ​strength.  
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​Attached​ ​to​ ​the​ ​exoskeleton​ ​of​ ​this​ ​crab​ ​are​ ​two​ ​white​ ​barnacles.​ ​Barnacles​ ​are​ ​another type​ ​of​ ​arthropod​ ​that​ ​permanently​ ​attach​ ​itself​ ​to​ ​hard​ ​surfaces.​ ​The red circle in the image below shows two white barnacles attached to the exoskeleton of the crab. 
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These​ ​barnacles likely​ ​attached​ ​to​ ​the​ ​crab​ ​while​ ​it​ ​was​ ​still​ ​alive,​ ​but​ ​would​ ​not​ ​have​ ​harmed​ ​the​ ​crab. Barnacles​ ​are​ ​filter​ ​feeders​ ​and​ ​feed​ ​on​ ​microscopic​ ​organisms​ ​in​ ​the​ ​water. This crab was collected from the Lincoln Creek Formation of Washington state, though the exact environment it came from is a mystery. The completeness of this crab suggests it was buried quickly. When crabs are exposed on the surface after death, their claws and legs separate from the main carapace. This specimen is approximately 30 million years old. The completeness of the specimen allows scientists to learn about the anatomy of this extinct family (Tumidocarcinidae). 

The iDigBio portal has at least 20 occurrences of this species of crab, including this specimen from the Smithsonian National Museum of Natural History. 
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You can view hundreds of records of crab specimens on the iDigBio portal by clicking on the map below! ​
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​Credits:

Project's Library of Life Lead: Erica Clites
3-D Model: Holly Little
Page Images:  Credit to James Di Loreto, Smithsonian Institution 
Acknowledgements: Adiel A. Klompmaker


More information:
http://epicctcn.org  

EPICC Vitual Field Experiences
http://epiccvfe.berkeley.edu