The bizarre body plan of turtles may be less of an evolutionary feat than scientists once believed. According to a linkurl:study; published online today in Science, the unique organization of the ribs and the development of the unusual shell that turtles call home may be explained by a relatively small structural variation from their animal relatives that occurs during embryonic development.
Image: Wikimedia commons
"The turtle body plan was so enigmatic, so mysterious," said comparative embryologist linkurl:Shigeru Kuratani; of the RIKEN Center for Developmental Biology in Japan, who led the study, "but developmentally viewed, it's reasonable." These findings support the notion that morphological novelties can arise from relatively minor changes during embryonic development -- a view known as evolutionary development, or more colloquially, evo-devo, explained paleontologist linkurl:Olivier Rieppel; of the Field Museum in Chicago, who was not involved in the research. "They show now how developmental steps [in the...
The scapula (red) is outside
ribs in the mouse and the chicken,
and inside the ribs in turtle.

Image: Shigeru Kuratani and
Hiroshi Nagashima

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