Morphology and environment in the Jurassic Nucleatidae (Brachiopoda) from Western Tethys

Nucleatidae (Brachiopoda, Terebratulida) are commonly considered as typical members of the Mediterranean assemblages during the Jurassic. However, nucleatids occasionally also occur in the margins of Western Tethys (Northwestern European shelf). Some of these occurrences in northeastern Spain are an...

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Bibliographic Details
Authors: Colás, Jorge; García Joral, Fernando
Format: Article
Publication date:2012
Country:España
Institution:Universidad Complutense de Madrid (UCM)
Repository:Docta Complutense
Language:English
OAI Identifier:oai:docta.ucm.es:20.500.14352/42980
Online Access:https://hdl.handle.net/20.500.14352/42980
Access Level:Open access
Keyword:564.8 (460)
551.762 (460)
Brachiopods
Nucleatidae
Functional morphology
adaptation
Systematics
Jurassic
Spain.
Paleontología
2416 Paleontología
Description
Summary:Nucleatidae (Brachiopoda, Terebratulida) are commonly considered as typical members of the Mediterranean assemblages during the Jurassic. However, nucleatids occasionally also occur in the margins of Western Tethys (Northwestern European shelf). Some of these occurrences in northeastern Spain are analysed, detecting a relation between nucleatid morphology and palaeoenvironment during the Jurassic. The validity of this relationship for the whole of the representatives of the group in the Western Tethys during the Jurassic is tested by means of morphofunctional analyses (principal components analysis and discriminant analysis), concluding that reduction of the lateral expansion of the shell is the key morphological feature whereby epioceanic and epicontinental taxa differ. This change can have functional significance because it can be interpreted as a mechanism to reduce the area exposed when the valves gape, increasing protection against harmful particles in environments characterized by higher terrigenous input. Some modifications on the systematics of the Nucleatidae at the genus level are proposed on the basis of the temporal and biogeographical distribution of these adaptations.