Crabs (= brachyuran decapod crustaceans) are found in Jurassic to Holocene sedimentary rocks. Complete or near-complete specimens are scarce. They have a relatively shortened carapace, compared to lobsters and crayfish, and have the abdominal section of the body turned underneath & essentially fused with the carapace. Small to large claws (chelae) occur at the distal ends of the 1st pair of appendages. Decapods have 5 pairs of appendages - 10 in all - “decapod” means “ten-legged”.
Most crabs are marine (oceanic), but some forms are freshwater or terrestrial. Their feeding habits range from predation to scavenging to algal grazing to filter feeding, etc.
Harpactoxanthopsis from the Eocene of northern Italy.
Classification: Animalia, Arthropoda, Crustacea, Malacostraca, Eucarida, Decapoda, Brachyura, Xanthoidea, Xanthidae
OSU public display (Orton Geology Museum, Ohio State University, Columbus, Ohio, USA).