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Science. 1992 Aug 7;257(5071):787-9.

Evidence from 18S ribosomal RNA sequences that lampreys and hagfishes form a natural group.

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Department of Ecology, Ethology, and Evolution, University of Illinois, Urbana 61801.


Lampreys and hagfishes (cyclostomes) traditionally were considered to be a natural (monophyletic) group. Recently, the consensus of opinion, based largely on morphological analyses, has shifted to a view that lampreys are more closely related to jawed vertebrates (gnathostomes) than to hagfishes. Phylogenetic comparisons of 18S ribosomal RNA sequences from two hagfishes, two lampreys, a tunicate, a lancelet, and a number of gnathostomes support the monophyly of the cyclostomes. These data force a reassessment of several features of early vertebrate evolution.

[Indexed for MEDLINE]

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