Research Paper
Rhombifera Barrande, 1867, and the origin of the Blastoidea (Echinodermata, Blastozoa)
CHRISTOPHER R. C. PAUL
School of Earth Sciences, University of Bristol; Life Sciences Building, 24 Tyndall Avenue, Bristol, BS8 1TQ, Bristol, United Kingdom; glcrcp@bristol.ac.uk.
Corresponding author
BERTRAND LEFEBVRE
Université Claude Bernard Lyon 1, ENSL, CNRS, LGL-TPE, F-69622, Villeurbanne, France; bertrand.lefebvre@univ-lyon1.fr
MARTINA NOHEJLOVÁ
Czech Geological Survey, Klárov 3, Praha 1, 118 21 Czech Republic; martina.nohejlova@geology.cz.
SAMUEL ZAMORA
Instituto Geológico y Minero de España (IGME-CSIC), Residencia CSIC, Campus Aula Dei, Av. Montañana 1005, 50059 Zaragoza, Spain; s.zamora@igme.es.
Grupo Aragosaurus-IUCA, Área de Paleontología, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza; Spain
ABSTRACT
Rhombifera bohemica Barrande is redescribed from Barrande’s original material and new specimens from Spain and the Czech Republic. Rhombifera had a heteromorphic proximal stem, a theca with three basals, three infralaterals and five laterals, both greatly elongated, but a reduced oral area in which five, facet-bearing radials alternate with five interradial orals which form the oral frame. The CD oral plus two others share the hydropore and gonopore. Rhombifera is the only glyptocystitoid rhombiferan with a periproct surrounded by two plates, L4 and L5, and ambulacral facets on radial not oral plates. Rhombifera was derived from echinoencrinitid glyptocystitoids, both sharing reduced oral areas with five, not six, radial plates and pectinirhombs with short oval slits. The oral areas of Rhombifera and Lysocystites are similar. In Lysocystitesfive facet-bearing ‘ambulacral plates’ alternate with five interradial orals forming the oral frame. Extra orals in the CD interambulacrum share the hydropore and gonopore. Lysocystites, coronates and blastoids all possess three basals, five ‘radials’, five deltoids and five homologues of blastoid lancet plates. We suggest that basals, laterals, radials and orals of glyptocystitoids are homologous with basals, radials, lancet plates and deltoids of blastoids, respectively. Rhombifera is a link between glyptocystitoid rhombiferans and blastoids.
Key words: Blastozoa, Glyptocystitoida, Rhombifera, Blastoidea, Coronata, plate homology.
How to cite: Paul, C.R. C., Lefebvre, B., Nohejlová, M., & Zamora S. (2024).Rhombifera Barrande, 1867, and the origin of the Blastoidea (Echinodermata, Blastozoa). Spanish Journal of Palaeontology, 39(1), 71-90.
Received 18 January 2024, Accepted 3 May 2024, Published online 23 May 2024
https://doi.org/10.7203/sjp.28729
