A robust crinoid from the Llandovery (Lower Silurian) of Norbury, Shropshire: systematics, palaeoecology and taphonomy
  • 【摘要】

    Crinoids remain poorly known from the Llandovery of the British Isles despite disarticulated columnals being locally common. Cyclocyclicus (col.) geoffnewalli sp. nov. is based on common columnals and... 展开>>Crinoids remain poorly known from the Llandovery of the British Isles despite disarticulated columnals being locally common. Cyclocyclicus (col.) geoffnewalli sp. nov. is based on common columnals and rarer pluricolumnals from Norbury quarry, south Shropshire (upper Llandovery, Telychian, Pentamerus Beds). It most probably represents a camerate or perhaps a cladid. The radial symplectial articulation of this species extends to the edge of the jugulum, claustra are sloping, there is no areola and the heteromorphic column, N212, has nodals with convex latera. Radice (=holdfast) ossicles are gracile, of similar morphology to columnals, but small and low. Cyclocyclicus (col.) geoffnewalli is a common component of the Pentamerus community at Norbury, where it dominated the sessile benthos with Pentamerus. Constrictions of the axial canal suggest that it contained only a limited amount of soft tissues whatever the diameter. Similar columnals are known from elsewhere in the Telychian of the Welsh Borderland, suggesting that C. (col.) geoffnewalli may have been distributed broadly in the shelly benthos of this region. 收起<<

  • 【作者】

    Fearnhead FE  Donovan SK 

  • 【刊期】

    Proceedings of the Geologists' Association SCI 2007年4期

  • 【语种】

    eng