Editor's Summary
27 November 2008
Turning turtle: how proto-turtles gained a shell
A well preserved 220-million-year-old fossil from marine deposits of the Late Triassic of Guizhou in southwest China sheds light on the intermediate steps in the acquisition of the unique turtle body-plan. Transitional forms are scarce in this lineage, making this transition one of the mysteries of reptile evolution. The find is the most primitive turtle known. It has a fully developed plastron, the ventral dermal armour, evolved before the carapace, the dorsal (upper) part of the shell structure. In this fossil the carapace consists of neural plates only. This suggest that the carapace developed via ossification of the neural plates and broadening of the ribs — a sequence that echoes the developmental pattern in young turtles today.
News and Views: Palaeontology: Turtle origins out to sea
Various aspects of turtle evolution are the subject of vigorous debate among vertebrate palaeontologists. A newly described fossil species, the oldest yet discovered, adds grist to the mill.
Robert R. Reisz & Jason J. Head
doi:10.1038/456450a
Letter: An ancestral turtle from the Late Triassic of southwestern China
Chun Li, Xiao-Chun Wu, Olivier Rieppel, Li-Ting Wang & Li-Jun Zhao
doi:10.1038/nature07533
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