Silurian brachiopods with soft-tissue preservation.
'Articulated' rhynchonelliformean brachiopods are abundant shelly fossils, but the direct fossil record of their soft parts was hitherto confined to a single pyritized trace possibly representing a lophophore. Anatomical knowledge of extinct rhynchonelliformeans relies heavily on analogies to extant species; these analogies are untested for stem-group clades. The Silurian Herefordshire (UK) Konservat-Lagerstätte (about 425 Myr bp) yields exceptionally preserved three-dimensional fossils that provide unrivalled insights into the palaeobiology of a variety of invertebrates. The fossils are preserved as calcitic void in-fills in carbonate concretions within a volcaniclastic horizon, and are reconstructed digitally. Here we describe a stem-group rhynchonelliformean specimen from this deposit; it most probably belongs in the order Orthida. A robust ridged pedicle with distal rootlets is preserved, together with a lophophore and other soft-tissue structures. The pedicle morphology is novel, urging caution in inferring stem-group rhynchonelliformean anatomy from that of crown-group species. Smaller brachiopods are attached to the specimen; these include a probable atrypide, with pedicle and marginal setae preserved.
Sutton
Mark D
MD
Department of Earth Science and Engineering, Imperial College, London SW7 2AZ, UK. m.sutton@imperial.ac.uk
Briggs
Derek E G
DE
Siveter
David J
DJ
Siveter
Derek J
DJ
D000818:Animals; D002965:Classification; D003238:Connective Tissue / Q000033:anatomy & histology*; D005580:Fossils; D049690:History, Ancient; D007448:Invertebrates / Q000033:anatomy & histology* / Q000145:classification*; D006113:United Kingdom