Grouped within the order Natantia, the swimming crustaceans possess ten paired legs, thereby being designated within the Order Decapoda. All familiar crustacea, from crabs to lobsters to shrimp, fall within this classification as ten-legged creatures, with the Natantia further being defined by having the anteriormost three pair of legs serving as chelicerae (mouthparts). The next five pairs of legs serve as walking legs, with one or more pairs sometimes possessing pincers. The remaining two pairs of legs serve as swimming legs. Two pair of antennae are evident, with the second pair of antennae typically longer than the first. The cephalothorax of the shrimp is commonly cylindrical, though compressed and elongated into a spike-like form. The Natantia are the most common crustacea found within the Solnhofen plattenkalks.


Grouped together with other species of the Reptantia, a clade within the order Decapoda which usually walk rather than swim, these creatures include both those crustaceans which hide within crevices or sand as well as bottom-dwelling varieties. The most powerful pincers are those of the first pair of legs, followed by smaller pincers upon the following two pairs of legs.

Unlike the Natantia (shrimp), the Reptantia are much less common within the Solnhofen Plattenkalk, with the long-armed crustacean Mecochirus being the most frequently found of this Order. Eryon was a crablike crustacean with an almost square cephalothorax, a flattened body and two deep and downwardly directed rounded notches along the side of the cephalothorax. The tail fan exhibits three points, with one exterior, semicircular component to each side; pincers are slender and rather gracile.

Horseshoe Crabs

Dating in the fossil record to the Silurian Period of more than 400 million years ago, this group of animals has changed very little over the last 300 million years. As the thin exoskeleton of the horseshoe crab does not typically preserve well, horseshoe crabs are rare in the fossil record.

PaleoElegance Compendium

View the PaleoElegance Crustacean Fossils: Shrimp, Lobsters, and Horseshoe Crabs.

Return to the PaleoElegance Compendium.