Cup nodes on Lochriea commutata Pa elements bear microsculpture fields composed of polygonal microsculpture. As Pa elements grow larger, the cup nodes and their microsculpture fields increase in size during early to middle growth. With subsequent growth, cup nodes may broaden transversely, split, fuse, or cease to broaden; similarly, their microsculpture fields may increase in size, split, or disappear as the element gets larger. The loss of microsculpture fields results in the loss of polygonal microsculpture.The presence of polygonal microsculpture on the cup nodes of Pa elements of the holotype of Lochriea montanaensis Scott, 1942, on topotype Pa elements of L. commutata (Branson and Mehl, 1941), as well as on L. commutata Pa elements from diverse localities, suggests that this micromorphological feature cannot be used to distinguish them. Instead, these similarities support the practice of treating L. montanaensis as a junior synonym of L. commutata. The fact that cup node, microsculpture field, and polygonal microsculpture development are closely related to growth and ontogeny and are variable in the larger growth stages suggests that these morphological features should be used with caution in taxonomy. This lack of reliability contrasts with the taxonomic utility of pustulose micrornamentation on the homeomorphic Pa elements of the Permian genus Sweetognathus.

von Bitter, P.H. & Norby, R.D. 1994 10 15: Fossil epithelial cell imprints as indicators of conodont biology. Size and growth characteristics of microsculpture polygons on the cup nodes of the bladelike Pa elements of the conodont Lochriea commutata support the hypothesis that they are epithelial cell imprints. They are ˜2–6 pn wide and ˜4–10 pn long and are the same size throughout growth of the element. The epithelial imprints increased in number with growth, either linearly or periodically; the latter possibility may be important for defining specific growth stages of conodont elements. The imprint location on the top of nodes suggests that the latter were tissue‐covered and that the scissor‐model of function applies to these bladelike Pa elements. The location of the imprints also reflects evolutionary history: a probable ancestor, L. cracoviensis (Belka), also lacks a platform and possesses well‐developed microsculpture polygons on broad cup nodes. Finally, correlation between internal white matter and external microsculpture suggests that internal osteocytes may have supplied the external secreting cells with calcium phosphate from the inner storage bank. Conodont biology, fossil epithelial imprints, polygonal microsculpture, Carbonferous, Lochriea commutata.

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