Triassic Fossil Shrimp Nodule from Madagascar

Name: : Decapoda; Ambilobeia karojoi

Phylum Arthropoda; Subphylum Crustacea; Class Malacostraca; Order Decapoda; Suborder Pleocyemata

Geological Time: Early Triassic Olenekian Stage (~240 m.y.a.)

Size: 44 mm long (tip of rostrum to tip of telson, straightened) Matrix: 59 mm by 30 mm

Fossil Site: Ambilobe, Madagascar

Triassic Fossil ShrimpThis nodule from the early Triassic of Madagascar contains a very detailed fossil shrimp known as Ambilobeia karojoi. This taxon was only erected three years ago, and the genus derives its name from the locality in which it is found. Notice the incredible detail preserved here, remarkable for a specimen nearly a quarter of a billion years old. What is even more remarkable about nodules from the region is that unlike most nodules that are part/counterpart examples, this one is a natural mold, preserving the details of both the left and right sides with remarkable fidelity. Shrimp are differentiated from the similar prawns by the structure of their gills, and by the fact that female shrimp (like all pleocyemates) brood the eggs on their pleopods (swimming legs).

click fossil pictures to enlarge

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