PRESERVED TUBE FEET ON CODIACRINUS SCHULTZEI (LOWER DEVONIAN, HUNSRÜCK SLATE, GERMANY)

A thin film of pyrite preserves the first definitive tube feet known in a fossil crinoid. This new soft-tissue preservation is from the Wingertshell Member of the middle Kaub Formation (lower Emsian), Hunsrück Slate from Rhenish Massif of Germany. The cyathocrine cladid Codiacrinus schultzei has three tube feet projecting from one arm into an adjacent interray. The best preserved tube foot is elongate, flattened, and folds over onto itself. If straightened, the preserved portion of this tube foot would be approximately 7.0 mm long, and the maximum flattened diameter is approximately 1.4 mm. The distal tip of the tube foot tapers and is rounded. Similar to tube feet described previously on Hunsrück ophiuroids, these new crinoid tube feet are divided along the tube feet length with a ‘beaded’ pattern. Unlike Hunsrück ophiuroids but similar to living crinoids, the Codiacrinustube feet have small papillae along their length.

Because cyathocrine cladids lack pinnules, these pyritized structures are not pinnules. Further, these structures would not be folded back onto themselves unless it was originally soft tissue. Soft-tissue preservation, especially tube feet, is very rare in the fossil record. This is only the second know occurrence of soft-tissue preservation in Paleozoic crinoids.