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Updated: Jun 21, 2026

In Vivo Imaging of Muscle-tendon Morphogenesis in Drosophila Pupae
Published on: February 6, 2018
Evolution of the turtle body plan by the folding and creation of new muscle connections
Hiroshi Nagashima1, Fumiaki Sugahara, Masaki Takechi
1Laboratory for Evolutionary Morphology, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minami, Kobe 650-0047, Japan.
Abstract:
The turtle shell offers a fascinating case study of vertebrate evolution, based on the modification of a common body plan. The carapace is formed from ribs, which encapsulate the scapula; this stands in contrast to the typical amniote body plan and serves as a key to understanding turtle evolution. Comparative analyses of musculoskeletal development between the Chinese soft-shelled turtle and other amniotes revealed that initial turtle development conforms to the amniote pattern; however, during embryogenesis, lateral rib growth results in a shift of elements. In addition, some limb muscles establish new turtle-specific attachments associated with carapace formation. We propose that the evolutionary origin of the turtle body plan results from heterotopy based on folding and novel connectivities.
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