▪ fossil subphylummember of an extinct group of unusual echinoderms (modern echinoderms include starfish, sea urchins, and sea lilies), known as fossils from rocks of Middle Cambrian to Early Devonian age (the Cambrian Period began about 542 million years ago, and the Devonian Period began 416 million years ago). Unlike other echinoderms, the carpoids display no radial symmetry, nor do they seem to have had a water-vascular system. They do possess a calcitic system of plates, however, as well as stemlike or armlike appendages; carpoids generally have flat bodies. Some seem to possess gill slits, a feature found in primitive chordates; the carpoids may be related to the most primitive chordates or vertebrates and are ancestral to the more advanced echinoderms.
* * *
Look at other dictionaries:
carpoid — noun Any of several classes of extinct echinoderm previously placed in the class Carpoidea but now placed within the subphylum Homalozoa … Wiktionary
echinoderm — /i kuy neuh derrm , ek euh neuh /, n. any marine animal of the invertebrate phylum Echinodermata, having a radiating arrangement of parts and a body wall stiffened by calcareous pieces that may protrude as spines and including the starfishes, sea … Universalium
Dick Jefferies — Richard P.S. Jefferies was a paleontologist famous for developing the Calcichordate Theory of the origin of chordates, now widely discredited. Jefferies joined the British Museum in 1960, and was largely based there for the remainder of his… … Wikipedia