New data and interpretations of the crinoid-platyceratid interaction

Using platyceratid gastropod behaviour to test functional morphology

“…Thus, even though camerate anal tubes were effective at preventing gastropods from attaching to the anal vent, they continued to infest tubed crinoids and to feed from them via drilling. Drill holes occur either directly beneath platyceratids infesting tubed crinoids, or at the base of tubes in genera known to have been infested, but in specimens that are preserved without attached snails (Baumiller 1990a,b;Baumiller et al 2004). During this study, a specimen of A. gibsoni was discovered with a drill hole at the base of the anal tube (Figure 4), the first reported occurrence of such a trace in Actinocrinites.…”

“…Camerate crinoids had significantly higher rates of infestation than non-camerate crinoids throughout the Paleozoic (Baumiller et al 2004). High relative infestation of camerates vs. non-camerates, similarity in stratigraphic occurrence and extinction, and coincident increases in camerate diversity and infestation indicate that camerates were the preferred hosts of platyceratids.…”

“…Evidence suggests that crinoids of the subclass Camerata were the preferred host of platyceratids (Baumiller 2003;Baumiller et al 2004). Of the 61 crinoid genera known to be infested during the Paleozoic, 49 (80%) are camerates (Table I).…”

“…However, when platyceratids evolved drilling ability and if this ability evolved more than once are unknown. Evidence suggests that gastropods were able to drill before widespread tube presence Baumiller et al 2004), but such cases are rare and probably restricted to instances of multiple platyceratid infestation (Kesling and Chilman 1975;Baumiller 2002). Nevertheless, despite the drilling abilities of platyceratids, this study demonstrates that platyceratids preferred tubeless hosts, perhaps because of the energetic costs of drilling.…”

New taxa and revised stratigraphic distribution of the crinoid fauna from Anticosti Island, Québec, Canada (Late Ordovician-early Silurian)

“…The presence of gastropods on the tegmen or on other locations on crinoids is a well-known association in Paleozoic faunas, although the exact ecological interaction between gastropods and crinoids has engendered much discussion (e.g., Bowsher, 1955; Meyer and Ausich, 1983; Baumiller, 1990, 2002; Baumiller and Gahn, 2003; Gahn and Baumiller, 2003, 2006; Baumiller et al, 2004). MPEP1138.6 is a specimen of Fibrocrinus phragmos Ausich and Copper (2010) from the East Point Member of the Menier Formation (Aeronian).…”