Bulletin of the Mizunami Fossil Museum Vol. 52, No. 1
Notes on silicified screwstones (Lower Carboniferous, Mississippian) from River Maas gravel in the Netherland
- BMFM52-001Donovan（PDF 40.49MB）
- BMFM52-001Donovan_web（PDF 0.61MB）
Donovan et al. (2025) print-version
Donovan et al. (2025) small-version
Published: 2025/3/6 Page: 1–8
Crinoid pluricolumnals and natural moulds are amongst the least loved of fossils, yet may provide important information on crinoid form. Herein, we document two crinoid columnal taxa in open no-menclature based on moulds, namely platycrinitid gen. et sp. indet. and Pentagonocyclicus? (col.) sp. Platycrinitids can rarely be classified to below family level from columnals alone; they presumably evolved neotenously from juveniles with synarthrial articulations. Pentagonocyclicus? (col.) sp. is rec-ognised by ‘lumping’ together pluricolumnals of unimportantly differing morphologies, the sum of which might be found in the xenomorphic column of a single species. The pluricolumnal is robust, homoeomorphic to heteromorphic, N2221222; column circular or rounded pentagonal in section; columnals low; articulation radial symplectial; no areola; lumen rounded pentagonal; broad spatium and narrow axial canal.