Search results for "Mitrate"
showing 4 items of 4 documents
A critical comment on ‘ankyroids’ (Echinodermata, Stylophora)
2001
Abstract A recent cladistic analysis of stylophoran echinoderms performed by Parsley suggested that mitrates are polyphyletic and derived from symmetrical cornutes. Parsley erected the order Ankyroida to include all derived cornutes and mitrates. The present paper addresses several significant problems in the data matrix of Parsley's cladistic analysis. Detailed morphological comparisons of various stylophorans suggest that important homologies have been ignored: cornute zygal crest and mitrate septum, adorals, glossal and digital. Subanals are not homologous in mitrates. Identification of plate homologies shows that similar-looking symmetrical thecal outlines have been acquired independent…
Tremadocian Stylophoran Echinoderms From The Taebaeksan Basin, Korea.
2006
15 pages; International audience; Abundant isolated elements of cornute and mitrate stylophorans were recovered from the upper Tremadocian Tumugol Formation in the Taebaeksan Basin, Korea. Cornute skeletal elements comprise a diverse assemblage of marginals and brachials of cothurnocystid affinities, suggesting the presence of no fewer than four different species. Mitrate remains include numerous isolated adorals, marginals, and aulacophoral plates with typical peltocystidan morphologies. Two adorals are identified as Anatifopsis sp., while all the others are attributable to A. cocaban. However, the two previously documented peltocystidans of Korea, A. cocaban and A. truncata, are sufficien…
First report of the mitrate Peltocystis cornuta Thoral (Echinodermata, Stylophora) in the Lower Ordovician of central Anti-Atlas (Morocco)
2007
The mitrate Peltocystis cornuta is one the best known and most abundant stylophoran echinoderms in the Lower Ordovician (upper Tremadoc - lower Arenig) of Montagne Noire (southern France). It is here documented outside this region for the first time, in coeval deposits of central Anti-Atlas (Morocco). This report confirms the strong faunal affinities between Montagne Noire and Moroccan assemblages in the Ordovician. Twenty-eight individuals of P. cornuta are described from two distinct localities of the Zagora region. Their overall morphology is very comparable to that of Montagne Noire specimens. However, the Moroccan Peltocystis differ from the French ones in their smaller mean size, and …
Stephen J. Gould, les mitrates et les monstres
2003
Resume L'interet de l'analyse des cas teratologiques pour la comprehension des mecanismes du developpement ontogenetique est un theme recurrent dans l'œuvre litteraire de Gould. Cet article aborde le theme des monstres a travers deux problematiques ayant pour sujet des echinodermes paleozoiques atypiques: les stylophores mitrates. Le premier theme s'interesse au debat concernant la position phyletique des stylophores au sein des deuterostomes. Trois interpretations ont ete proposees pour leur appendice articule, dont l'une implique que les mitrates soient des « monstres prometteurs » (modele calcichorde). Une analogie avec differents scenarios proposes pour l'extinction des dinosaures demon…