Homologies in stylophora: A test of the 'calcichordate theory'

Authors
Citation
B. Lefebvre, Homologies in stylophora: A test of the 'calcichordate theory', GEOBIOS, 33(3), 2000, pp. 359-364
Citations number
30
Categorie Soggetti
Earth Sciences
Journal title
GEOBIOS
ISSN journal
00166995 → ACNP
Volume
33
Issue
3
Year of publication
2000
Pages
359 - 364
Database
ISI
SICI code
0016-6995(2000)33:3<359:HISATO>2.0.ZU;2-9
Abstract
Stylophora (cornutes and mitrates) are controversial Paleozoic fossils, var iously interpreted as 'bizarre' echinoderms or as 'calcichordates' (primiti ve chordates). The calcichordate theory is based on the identification of l eft/right asymmetries supposed to be homologous in stylophorans and modern chordates. This theory imposes the homology of the plano-concave surface of the cornute test with the convex surface of the mitrate test. A detailed a nalysis of numerous internal and external structures exhibited by the appen dage and the test demonstrates the homology of the plano-concave surface of the test in all stylophorans. The basic assumption of the calcichordate th eory is thus not valid, Comparison of left/right asymmetries in these organ isms with those of modem chordates is not grounded. Stylophora do not; repr esent 'calcichordates' but actual echinoderms.