More than a century after their discovery, conodonts remain biologic orphans. These skeletal constituents of some as yet unspecified marine organisms have been assigned by various workers to: vertebrates (from ancestral to advanced), arthropods, several kinds of worms, several classes of mollusks, lophophorates, separate classes (or a phylum) all their own, and even algae and vascular plants. Functional interpretations of conodonts include: stem, gill, or tentacular supports; dermal spines and scales; radulae; digestive tract stirrers and sieves; jaws, teeth, or "superteeth;" and copulatory graspers. Each conodontophorid bore up to at least two dozen, commonly very differently shaped, conodont elements in an apparatus. The existence and makeup of these multi-element appar tuses are known from naturally occurring assemblages of elements that are interpreted as coprolitic, gut contents, in-situ burials, fused clusters, or empirical reconstructions based on numerical (clustering) techniques.

Current hypotheses about the form and function of the apparatuses, and hence the nature of the organism itself, center on whether some elements functioned as fused units for grasping or as members of an array of food-gathering and/or sieving digits and pectinate units, possibly in a lophophore. Bearing on these hypotheses are the questions. (1) Were all conodont elements always enveloped by soft tissue during life? (2) Do the fused clusters owe their fusion to biologic processes or to postmortem diagenetic mineralization? The question of biological affinity remains unresolved. However, recently discovered fused clusters suggest that fusion was diagenetic.

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