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  2. Yorkicystis - Wikipedia

    en.wikipedia.org/wiki/Yorkicystis

    Yorkicystis is a genus of edrioasteroid echinoderm that lived 510 million years ago in the Cambrian aged Kinzers Formation in what is now Pennsylvania. [1] This genus is important as it provides some of the oldest evidence of echinoderms losing their hard mineralized outer skeletons. [1]

  3. Edrioasteroidea - Wikipedia

    en.wikipedia.org/wiki/Edrioasteroidea

    The oldest undisputed fossils of Edrioasteroidea are known from Cambrian (Stage 3, about 515-520 Ma ago) of Laurentia and are among the oldest known fossils of echinoderms. Some authors propose that an enigmatic Ediacaran (about 600 Ma) organism Arkarua is also an edrioasteroid, but this interpretation did not gain wide acceptance. [ 3 ]

  4. Fossil echinoids - Wikipedia

    en.wikipedia.org/wiki/Fossil_echinoids

    Echinoid fossils are sometimes found associated with archaeological sites. The earliest known example in England is an Acheulean hand axe from the Middle Pleistocene found in Kent. The craftsman had evidently chosen to use this flint for his tool; the exposed area around the sea urchin's jaws known as Aristotle's lantern are clearly visible.

  5. Eocrinoidea - Wikipedia

    en.wikipedia.org/wiki/Eocrinoidea

    The Eocrinoidea were an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, brachiole-bearing echinoderms, and were the most common echinoderms during the Cambrian. The earliest genera had a short holdfast and irregularly structured plates. Later forms had a ...

  6. Ctenocystoidea - Wikipedia

    en.wikipedia.org/wiki/Ctenocystoidea

    Ctenocystoids were widespread during the Middle Cambrian, and have been found in the United States, the United Kingdom, Australia, France, the Czech Republic, Poland, Spain, and Morocco. [11] The earliest ctenocystoids date to the beginning of Stage 5 of the Cambrian, [ 12 ] now known as the Wuliuan age, [ 13 ] or possibly slightly earlier, in ...

  7. Echinoderm - Wikipedia

    en.wikipedia.org/wiki/Echinoderm

    The three oldest known candidate echinoderms all lack stereom and other echinoderm apomorphies, making their inclusion in the phylum controversial. [147] Arkarua adami illustration by Pennetta. The oldest potential echinoderm fossil is Arkarua from the late Ediacaran of Australia circa 555 Ma. These fossils are disc-like, with radial ridges on ...

  8. Helicoplacus - Wikipedia

    en.wikipedia.org/wiki/Helicoplacus

    Helicoplacus (often misspelled Helioplacus) is the earliest well-studied fossil echinoderm. Fossil plates are known from several regions. Complete specimens were found in Lower Cambrian strata of the White Mountains of California. The animal was a cigar-shaped creature up to 7 centimetres (2.8 in) long that stood upright on one end.

  9. Blastoid - Wikipedia

    en.wikipedia.org/wiki/Blastoid

    Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. [1] They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississippian subperiod of the Carboniferous period. However, blastoids may have originated in the Cambrian.