Article: Palaeocorynid-type appendages in Upper Palaeozoic fenestellid Bryozoa

Palaeocorynid-type structures (Family Palaeocorynidae Duncan and Jenkins 1869), currently regarded as being of uncertain zoological affinities, are here interpreted as being a specialized form-appendage of Upper Palaeozoic fenestellid Bryozoa. Palaeocorynid-type appendages are morphologically complex, and consist of a short stem developed at right angles from the branch of the bryozoan, terminating in a cone-shaped body from whose lateral margins a variable number of long slender spines or branchlets emanate at high angles. Spines form simple, distally tapering structures; branchlets are much longer and repeatedly bifurcate, converge and fuse to develop an anastomosing reticulate meshwork. The external ornament and internal microstructure of these structures is identical and continuous with that of the branch of the bryozoan on which they occur. Up to five developments have been found in situ on a colony, occurring anywhere over the colony surface, and nearly all are developed from the obverse surface of branches. They are interpreted as having a defensive function, giving a protective covering to feeding autozooecial polypides beneath by providing a surface deterrent to predatory organisms.