Ectenocrinus Fossil Crinoid Sea Lily Feather Starfish Prehistoric Paleozoic Ordovician Collection

Description

Origin : Ohio (U.S.A.) Cincinnatian Kope Formation

Geological era : Upper Ordovician (Katian)

Age : 450 million of years

Size : cm 16.5 x 13 x 3 - 1.1 kg

Crinoid Fossil Sea Lily Feather Star Fish on matrix mm 165 x 47 x 130 x 30 Kg 1.1 Ectenocrinus simplex Invertebrata Echinoderma Crinozoa Articulata Crinoidea Prehistoric Extinct Paleozoic Silurian Collecting Paleontology Museum.

Remarkable Crinoid fossil find of Silurian, representative collectible specimen of high quality and in perfect state of conservation, with evident and appreciable details of the crown, complete with calyx and branched arms, and the peduncle or stalk that anchored it to the substrate.
Only a piece, as in photo.

The Crinoids (Crinoidea Miller, 1821) are a class of Echinoderms, the only class of the subphylum Crinozoa. They include 648 living species and over 5,000 fossil species. They are commonly known as Sea Lilies or Feather Starfish.
Appearing in the Ordovician, crinoids spread widely throughout the Paleozoic. During the Paleozoic and subsequent Mesozoic they were among the main carbonate-producing organisms, constituting the crinoid limestones or Encrinites. Since the end of the Permian, most of the evolutionary lines of crinoids have undergone mass extinction, with the sole exception of the Articulata subclass, to which all currently known living species belong.
Like the other Echinoderms (sea-urchins, starfishes and sea cucumbers), they are bilaterian organisms in the larval stage, while the adults have pentamerous radial symmetry and are equipped with a calcareous endoskeleton.
The characteristics that distinguish crinoids from other echinoderms are: a theca or cup-shaped calyx, which contains or supports the viscera, formed by small pentagonal bony plates fused together in the shape of a cup; it can be supported by a peduncle or stalk and have various permanent or temporary fixation organs to the substrate; five flexible arms with radiate symmetry, usually branched and feather-shaped; mouth and anus both located on the oral surface, which faces upwards. The chalice and arms together form the crown. They are benthic organisms; the majority of species (Comatulids), although always living in close contact with the seabed, have the ability to move freely (vagile), although the movements are a maximum of a few metres; some species however (Isocrinidae) are sessile, that is, strictly anchored to the seabed; still others, if threatened, can sever the peduncle (autoctomy) and temporarily regain mobility, using their arms as propellers. They are passive filter-feeding organisms, feeding on a variety of protists (actinopods, diatoms and other unicellular algae, foraminifera), invertebrate larvae, small crustaceans and organic debris. Nutrient particles are captured by the branched arms, covered with mucous secretions, and pushed towards the mouth.
They have separate sexes with external fertilization, with gametes released into the water from the base of the arms. After fertilization the eggs are preserved until hatching. Arms severed by predators are capable of self-healing.
Crinoids contract symbiosis or commensal relationships with various species of small crustaceans. Crinoids are still present in almost all the world's seas. They populate coral reefs and rocky seabeds, from the intertidal zone to the abyssal depths.