Stem Structure and Evolution in the Earliest Pelmatozoan Echinoderms
- 1 July 2008
- journal article
- Published by Cambridge University Press (CUP) in Journal of Paleontology
- Vol. 82 (4) , 737-748
- https://doi.org/10.1666/06-067.1
Abstract
Echinoderm skeletal debris from the Early–Middle Cambrian boundary Micmacca Breccia of Morocco includes the oldest known holomeric columnals. The original calcite of these ossicles is coated and replaced by iron oxides, occasionally overlain by a late coating of silica, and preserves with high fidelity fine details of their three-dimensional microstructure. Irrespective of their external morphology, columnals can be divided into three groups based on the distribution of stereom microfabrics, which we suggest indicates the presence of at least three different holomeric stemmed taxa. One of these columnal types has well-developed galleried stereom perpendicular to its articulation facets, a sure sign that long, penetrative collagen bundles bound columnals together, as in modern stemmed crinoids. This columnal morphology also shows a primitive type of interlocking articulation, which we term parasymplexy and which may have helped to counter torsional stresses. The two other columnals either lacked f...Keywords
This publication has 29 references indexed in Scilit:
- Microbial crusts as indicators of stratigraphic diastems in the Cambrian Brèche à Micmacca, Atlas Mountains of MoroccoSedimentary Geology, 2006
- HALKIERIIDS IN MIDDLE CAMBRIAN PHOSPHATIC LIMESTONES FROM AUSTRALIAJournal of Paleontology, 2004
- Palaeogeographical and palaeoecological aspects of the Cambro–Ordovician radiation of echinoderms in Gondwanan Africa and peri-Gondwanan EuropePalaeogeography, Palaeoclimatology, Palaeoecology, 2003
- Palaeogeographical controls on the Cambrian trilobite immigration and evolutionary patterns reported in the western Gondwana marginPalaeogeography, Palaeoclimatology, Palaeoecology, 2003
- Echmatocrinus, a Burgess Shale animal reconsideredLethaia, 2000
- Revision of Echmatocrinus from the Middle Cambrian Burgess Shale of British ColumbiaLethaia, 1998
- Échinodermes nouveauxdu Cambrien supérieur de la Montagne noire (France méridionale)Geobios, 1998
- The improbability of a muscular crinoid columnLethaia, 1989
- Middle Cambrian cystoid (sensu lato) stem columnals from Bornholm, DenmarkLethaia, 1986
- THE EARLY RADIATION AND PHYLOGENY OF ECHINODERMSBiological Reviews, 1984