Lower Cambrian vertebrates from South China

Nature (Impact Factor: 42.35). 01/1999; 402:42-46. DOI: 10.1038/46965

ABSTRACT The first fossil chordates are found in deposits from the Cambrian
period (545-490 million years ago), but their earliest record is
exceptionally sporadic and is often controversial. Accordingly, it has
been difficult to construct a coherent phylogenetic synthesis for the
basal chordates. Until now, the available soft-bodied remains have
consisted almost entirely of cephalochordate-like animals from Burgess
Shale-type faunas. Definite examples of agnathan fish do not occur until
the Lower Ordovician (~475Myr BP), with a more questionable record
extending into the Cambrian. The discovery of two distinct types of
agnathan from the Lower Cambrian Chengjiang fossil-Lagerstätte is,
therefore, a very significant extension of their range. One form is
lamprey-like, whereas the other is closer to the more primitive hagfish.
These finds imply that the first agnathans may have evolved in the
earliest Cambrian, with the chordates arising from more primitive
deuterostomes in Ediacaran times (latest Neoproterozoic, ~555Myr BP), if
not earlier.

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