Article: The arm structure and mode of feeding of the Triassic crinoid Encrinus liliiformis
R. P. S. Jefferies
A characteristic ornament of alternating ridges and grooves (pectinate ornament or kammartige Ornamentierung of Hagdorn, 1982) exists on the interpinnular surfaces of Encrinus liliiformis Lamarck from the German Oberer Muschelkalk (Upper Anisian to Ladinian). These ridges and grooves run transverse to the length of the pinnule and in life would have formed a very large number of microscopic interpinnular channels. These channels would probably have been ciliated and suggest that E. liliiformis, unlike most other crinoids, was at least in part an active filter feeder, i.e. produced its own feeding currents, by active ciliary beat through the interpinnular channels. Passive nitration of bottom currents, like that observed in Recent crinoids, may also have been used, particularly near the tips of the arms.