Jenis Crinoid Feather Stars

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• They are the most common fossils from Paleozoic-age marine rocks and were most diverse at this time because they were able to live in shallow water where plankton was abundant. • They were able to live in the shallow water where the predators could see them because Paleozoic predators were less efficient than modern predators. • Many different kinds of stalked crinoids were able to evolve by specializing on the kinds and sizes of plankton that they ate because plankton is variable in size and has a large range of different types of algae and microscopic animals. • They were major carbonate producing organisms during the Paleozoic and Mesozoic Eras with entire carbonate shelves composed mostly by crinoidal. Carboniferous crinoid • The geological history of the crinoids demonstrates how well the echinoderms have adapted to filter feeding and the fossils of other stalked filter-feeding echinoderms, such as blastoids, are also found in the rocks of the Palaeozoic era. o <strong>Crinoid</strong>s evolved a plant-like morphology so that they could remain attached to the seafloor while they spread their arms to catch food.
o Their Pinnules arose in several lineages during the Paleozoic and are characteristic of all post-Palaeozoic crinoids. o The comatulids evolved from stalked crinoids by losing their column during their larval development. • <strong>Crinoid</strong>s came close to extinction towards the end of the Permian Period, about 250 million years ago. • The end of the Permian was marked by the largest extinction event in the history of life and fossil records show that nearly all the crinoid species died out at this time. • The one or two surviving lineages eventually gave rise to the crinoids populating the oceans today. • The close relatives are starfishes, sea urchins, sea cucumbers, and brittle stars which reside in the same phylum. • These species are related to eachother because they share many similar features. o For the most part, their body parts are arranged around a central axis. o They have rough, spiny surfaces which is what their phylum means (“spiny skin”). o They have a special kind of radial symmetry based on multiples of five. o They share a unique body system called the water-vascular system, which no other group of animals possess.
Page 1 and 2: Crinoid Feather Stars Scientific (G
Page 3: Evolutionary Relationships Fossil C
Page 8 and 9: o So each arm is a series of ossicl
Page 10 and 11: Locomotion • Most crinoids are fr
Page 12 and 13: Reproduction and life cycle • The
Page 14: • Thy approximate 80 surviving sp

Jenis Crinoid Feather Stars

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