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.