Context: The Ediacaran Period, spans 94 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 541 Mya. It marks the end of the Proterozoic Eon, and the beginning of the Phanerozoic Eon. It is named after the Ediacara Hills of South Australia., Ediacara Hills are a range of low hills in the northern part of the Flinders Ranges of South Australia, around north of Adelaide. The area has many old copper and silver mines from mining activity during the late 19th century. The hills also contain fossils of early multicellular life forms, the Ediacaran biota (lagerstätte), and have given their name to the Ediacaran geological period., The Carboniferous is a geologic period and system that spans 60 million years from the end of the Devonian Period million years ago (Mya), to the beginning of the Permian Period, Mya. The name "Carboniferous" means "coal-bearing" and derives from the Latin words "carb" ("coal") and "fer" ("I bear, I carry"), and was coined by geologists William Conybeare and William Phillips in 1822. Based on a study of the British rock succession, it was the first of the modern 'system' names to be employed, and reflects the fact that many coal beds were formed globally during that time. The Carboniferous is often treated in North America as two geological periods, the earlier Mississippian and the later Pennsylvanian., The Permian is a geologic period and system which spans 46.7 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 252.2 Mya. It is the last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm., South Australia (abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories. It has a total of 1.7 million people, and its population is the most highly centralised of any state in Australia, with more than 75 percent of South Australians living in the capital, Adelaide, or its environs. Other population centres in the state are relatively small., Arkarua adami is a small, Precambrian disk-like fossil with a raised center, a number of radial ridges on the rim, and a five-pointed central depression marked with radial lines of 5 small dots from the middle of the disk center. Fossils range from 3 to 10 mm in diameter., Echinoderm is the common name given to any member of the phylum Echinodermata (from Ancient Greek, , "echinos"  "hedgehog" and , "derma"  "skin") of marine animals. The adults are recognizable by their (usually five-point) radial symmetry, and include such well-known animals as sea stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone.
The phylum contains about 7000 living species, making it the second-largest grouping of deuterostomes (a superphylum), after the chordates (which include the vertebrates, such as birds, fishes, mammals, and reptiles). Echinoderms are also the largest phylum that has no freshwater or terrestrial (land-based) representatives., The Cambrian Period (or ) was the first geological period of the Paleozoic Era, of the Phanerozoic Eon. The Cambrian lasted 55.6 million years from the end of the preceding Ediacaran Period 541 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established (as Cambrian series) by Adam Sedgwick, who named it after Cambria, the Latinised form of "Cymru", the Welsh name for Wales, where Britain's Cambrian rocks are best exposed. The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biology surpasses that of some later periods., The Triassic is a geologic period and system which spans 50.9 million years from the end of the Permian Period million years ago (Mya), to the beginning of the Jurassic Period Mya. The Triassic is the first period of the Mesozoic Era. Both the start and end of the period are marked by major extinction events. The Triassic was named in 1834 by Friedrich von Alberti, after the three distinct rock layers ("tri" meaning "three") that are found throughout Germany and northwestern Europered beds, capped by marine limestone, followed by a series of terrestrial mud- and sandstonescalled the "Trias"., Edrioasteroidea is an extinct class of echinoderms that lived from the Ediacaran ( if Arkarua was indeed an edrioasteroid ) until the Permian , about 300 million years ago . The living animal would have resembled a pentamerously symmetrical disc or cushion . The body plan for this class was simple : a main body ( theca ) , composed of many small plates , a peripheral rim for attachment , and ( in some species ) a pedunculate zone for extension and retraction . Circling and sometimes attached to the body was a peripheral rim of plates . The main feature was five arms , or ambulacra , in the body wall radiating from the central mouth outwards . The ambulacra grew either curved or straight . When curved , they may all turn in the same direction or else one or two on the right side will curve opposite the others . The ambulacra are built of underlying floor plates that form the food groove and protective cover plates the roof the food groove . The anus was under the mouth region and was made of small triangular plates to form a cone - shaped area . The bottom surface of the theca is unplated . Edrioasteroidea were obligate encrusters and attached themselves to inorganic or biologic hard substrates ( frequently hardgrounds or brachiopods ) . Edrioasteroid species are distinguished by differences in the ambulacral curvature , the relationships of the cover plates , and ornamentation . The mode of life was sessile ; they were often attached via a stalk made of small plates to a hard object such as a carbonate hardground or shell . Several examples of epibiotic attachment have also been noted . In the discocystinids , the area between the body and peripheral rim could be extended and retracted ; in so doing the two were separated . The peripheral rim became the base of the stalk which was attached to a surface . Underneath the body was a recumbent zone about 12 millimetres ( 0.47 in ) wide in the genus Giganticlavus , followed by the pedunculate zone attached to the peripheral rim of 12 millimetres ( 0.47 in ) ., Subject: edrioasteroidea, Relation: parent_taxon, Options: (A) area (B) arkarua (C) bear (D) biota (E) echinodermata (F) mya
Output: echinodermata