''Acadiocaris'' is an extinct genus of

malacostraca Malacostraca is the second largest of the six classes of pancrustaceans behind insects, containing about 40,000 living species, divided among 16 orders. Its members, the malacostracans, display a great diversity of body forms and include crab ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

that existed in

Canada Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...

during the

Early Carboniferous Early may refer to: Places in the United States * Early, Iowa, a city * Early, Texas, a city * Early Branch, a stream in Missouri * Early County, Georgia * Fort Early, Georgia, an early 19th century fort Music * Early B, stage name of Jamaican d ...

. It was named by Copeland in 1957. It is the earliest known member of

Spelaeogriphacea Spelaeogriphacea is an order of crustaceans that grow to no more than . Little is known about the ecology of the order. Only four species, all subterranean, have been described. Of the three genera, '' Potiicoara '' is known only from a cave in ...

, which only has a handful of living species. Analysis of fossils shows that Acadiocaris retained a number of primitive morphological features compared to more modern spelaeogriphaceans: an optic notch was not developed under its rectangular carapace; thoracopodal endopods were elongated, and five pairs of well-developed but relatively small and simple pleopods.

References

Shen, Y. & Taylor, R.S. (1999). A new spelaeogriphacean (Crustacea: Peracarida) from the Upper Jurassic of China. Contributions to Zoology, 68(1), 19-35 Prehistoric Malacostraca Jurassic crustaceans Prehistoric crustacean genera Monotypic Malacostraca genera Fossils of Canada Paleontology in Nova Scotia {{paleo-crustacean-stub