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    On dating stages in prebiotic chemical evolution Free live chat no registration

    Tooth counts are presented as a formula such as 2,5-4,1 which indicates 2 teeth in the outer left row and 4 on the inner right row.

    Teeth may be lost from major or minor rows so variant formulae are given after the principal one.

    Nuptial, pearl or breeding tubercles develop on the head, scales and fin rays often in distinct patterns, and there are swellings of the head or fin rays in some species. Tubercles and swollen rays are used to clasp females during the spawning act.

    Generally males have longer pectoral fins than females.

    Chen and Mayden (2009) investigated the major clades of cyprinids using a multiple nuclear gene approach and tentatively recommended elevation of certain subfamilies to family.

    This is not in general use at this writing and the Cyprinidae is retained as a single family here. (2002) using cytochrome b DNA of Cyprinidae conclude that the the Middle East is an important interchange area for this freshwater ichthyofauna rather than a centre of speciation.

    Diet is reflected in pharyngeal tooth shape as mentioned above. A long intestine indicates a reliance on plant material which takes longer to digest.Two subfamilies, the Alburninae and Leuciscinae, are paraphyletic but together seem to form a monophyletic group with a radiation about 20 million years ago, based on allozyme, cytochrome b, 16S r DNA and mitochondrial control region data from European cyprinids (Hnfling and Brandl, 2000; Gilles et al., 2001). Zardoya and Doadrio (1999) analysed the cytochrome b nucleotide sequence of a variety of cyprinids, mostly European, and found support for two subfamilies Cyprininae (including barbins) and Leuciscinae (including cultrins, tincins, gobionins, phoxinins and alburnins leuciscins).The origin of cyprinids is estimated at 38.9MYA and the separation of Cyprininae and Leuciscinae at 27.7MYA.(2002) as relicts of older colonization waves and show an eastern influence consistent with an Asian origin of the family Cyprinidae.Cyprinion has no sister species in the Euro-Mediterranean area and has been isolated in the Middle East since before the salinity crisis, 7.8-8.8 MY ago.

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