Ordovician sponge spicules from Spitsbergen, Nevada and Newfoundland: new evidence for the Hexactinellida early differentiation

Division of Hexactinellida into the subclasses Amphidiscophora and Hexasterophora is now generally accepted due to their very distinct types of microscleres, namely amphidiscs and hexasters, respectively. Microscleres of this type have been recognized in the Lower Paleozoic. We examined exceptionall...

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Detalles Bibliográficos
Autores principales: Carrera, Marcelo G., Maletz, J.
Formato: Objeto de conferencia Resumen
Lenguaje:Inglés
Publicado: 2010
Materias:
Ciencias Naturales
Paleontología
Ordovician sponge spicules
Spitsbergen, Nevada
Newfoundland
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/16830
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-16830
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Naturales
Paleontología
Ordovician sponge spicules
Spitsbergen, Nevada
Newfoundland
spellingShingle Ciencias Naturales
Paleontología
Ordovician sponge spicules
Spitsbergen, Nevada
Newfoundland
Carrera, Marcelo G.
Maletz, J.
Ordovician sponge spicules from Spitsbergen, Nevada and Newfoundland: new evidence for the Hexactinellida early differentiation
topic_facet Ciencias Naturales
Paleontología
Ordovician sponge spicules
Spitsbergen, Nevada
Newfoundland
description Division of Hexactinellida into the subclasses Amphidiscophora and Hexasterophora is now generally accepted due to their very distinct types of microscleres, namely amphidiscs and hexasters, respectively. Microscleres of this type have been recognized in the Lower Paleozoic. We examined exceptionally well preserved spicule assemblages from three particular Lower to Middle Ordovician localities: Spitsb ergen (Floian-Dapingian), Nevada (Vinini Formation, Dapingian) and Newfoundland (Cow Head Formation, Tremadocian and Table Head Group, Darriwilian). The presence of hexaster-type spicules, hemidiscs and amphidiscs is reported here. The hexasters are certainly documented from the Lower Ordovician and possibly from the Cambrian. Although hemidiscs were reported from the Lower Ordovician, oldest true amphidiscs were reported from the Silurian. The occurrence of amphidiscs in these localities implies that the Amphidiscophora can be certainly traced back to the Lower Ordovician. The occurrence of five different types of scopules (typical microscleres of the Sceptrulophora) significantly increases the diversity of this group in the Ordovician. The collection also includes important and variable types of hexactinellid spicules (pinular hexactines and pentactines, equinate hexactines, tauactins and inflated pentactines, and different types of uncinate monactins), calcareous heteractines, and different types of demosponge spicules (oxiasters, C-shaped sigmata, trianes and dendroclones).
format Objeto de conferencia
Resumen
author Carrera, Marcelo G.
Maletz, J.
author_facet Carrera, Marcelo G.
Maletz, J.
author_sort Carrera, Marcelo G.
title Ordovician sponge spicules from Spitsbergen, Nevada and Newfoundland: new evidence for the Hexactinellida early differentiation
title_short Ordovician sponge spicules from Spitsbergen, Nevada and Newfoundland: new evidence for the Hexactinellida early differentiation
title_full Ordovician sponge spicules from Spitsbergen, Nevada and Newfoundland: new evidence for the Hexactinellida early differentiation
title_fullStr Ordovician sponge spicules from Spitsbergen, Nevada and Newfoundland: new evidence for the Hexactinellida early differentiation
title_full_unstemmed Ordovician sponge spicules from Spitsbergen, Nevada and Newfoundland: new evidence for the Hexactinellida early differentiation
title_sort ordovician sponge spicules from spitsbergen, nevada and newfoundland: new evidence for the hexactinellida early differentiation
publishDate 2010
url http://sedici.unlp.edu.ar/handle/10915/16830
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