Colin, J P; Danielopol, D L. (1981). Sur la morphologie, la systematique, la biogeographie et l'evolution des ostracodes Timiriaseviinae (Limnocytheridae). Paleobiologie Continentale. 11 (1), 1-52.

215402

Colin, J P; Danielopol, D L

1981

11 (1), 1-52

Publication

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Timiriaseviinae are a group of non-marine ostracods known since the Trias. This sub-family contains the genera Timiriasevia, Metacypris, Theriosynoecum, Vecticypris, Rosacythere n . gen., Frambocythere n.gen., Kovalevskiella, Afrocythere, Elpidium, ? Vlakomia, ? Praevlakomia, Sinometacypris? Several phylogenetic lineages are recognized : 1. Timiriasevia-Metacypris ; 2. Kovalevskiella-Rosacythere-Frambocythere; 3. Theriosynoecum ;4. Afrocythere-Elpidium: The diagnosis of the main generic and supra-generic taxa are presented. For a better understanding of the modalities of the diversification of the Timiriaseviinae ,the variability of the morphological characters and the evolutionary trends in the Limnocytheridae are reviewed. The taxonomical importance of the unchanging characters of the vestigial organs and the low functional value structures is emphasized. Certain morphological features such as the shape of the carapace and the fusion of the antennular articles were realized independently in several phylogenetic lineages following a mosaic evolution. The main axis of diversification of the Timiriaseviinae are presented here. Following the transverse axis, the morphology of the different taxa is compared without taking into account their evolution in time. This allows the identification of the evolutionary stages of the development of the different morphological features ; for example the brood pouch and the sulci are known since the Trias, whereas the genotypic tubercles in Theriosynoecum appear during the Bathonian. Taking into consideration their evolutionary diversification the Timiriaseviinae can be used for biostratigraphic purposes, for example small species with two sulci are restricted to the Uppermost Cretaceous-Lowermost Tertiary, species with rosette type ornementation and triangular foveae characterize the Middle Cretaceous. The rate of diversification during geological time is also very different, thus the genus Theriosynoecum which shows a fast differenciation can be used for biostratigraphic correlations. The relationships between carapace and appendages are also studied : 1. morpho-functional relationships in Elpidium for example ; 2. relationships between the interspecific diversification of the carapaces and the appendages in Kovalevskiella. The ecological and biogeographical distribution of the main groups of Timiriaseviinae is reviewed. The Timiriaseviinae have probably developped biologic specialization of "K" type. This is important for the knowledge of the evolutionary history of this group . Certain groups such as Theriosynoecum have disappeared sincet.,l&kMiddle Cretaceous, probably because of their lack of adaptative flexibility during the d¥t~1iofatIoir of the environment such as the explosion of the Cypridacea, climatic changes and disappearance of the great lacustrine basins. The details of the evolutionary history of the main groups of Timiriaseviinae are reviewed and finally the limits of utilization of the Timiriaseviinae as paleoecologic markers are discussed, ostracods with a brood pouch characteristic of still or slow running waters.

Europe

Evolution
Systematics, Taxonomy

Ostracoda

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