Hederellid

From Wikipedia, the free encyclopedia

Hederellid
Scanning electron microscope image of a hederelloid from the Devonian of Michigan (largest tube diameter is 0.75 mm).
Scientific classification
Kingdom: Animalia Phylum: incertae sedis

Hederellids are extinct colonial animals with calcitic tubular branching exoskeletons. They range from the Silurian to the Permian and were most common in the Devonian period. They are more properly known as "hederelloids" because they were originally defined as a suborder by Bassler (1939). Although they have traditionally been considered bryozoans, they are clearly not because of their branching patterns, lack of an astogenetic gradient, and wide range in tube diameters (Wilson and Taylor, 2001). Work continues on assessing the true affinities of hederelloids.

Three hederelloid species on a Devonian rugose coral; the largest zooids are about 1.0 mm wide.

Hederelloids encrusting a brachiopod from the Devonian of Ohio; the largest zooids are about 1.0 mm wide.

[edit] References

Bassler, R.S.(1939) The Hederelloidea. A suborder of Paleozoic cyclostomatous Bryozoa. Proceedings of the United States National Museum, 87:25-91.

Wilson, M.A. and Taylor, P.D. (2001) “Pseudobryozoans” and the problem of encruster diversity in the Paleozoic. PaleoBios, 21 (supplement to no. 2):134-135.

Wilson, M.A. and Taylor, P.D. (2006) Predatory drillholes and partial mortality in Devonian colonial metazoans. Geology 34: 565-568.

[1]