Resurrecting embryos of the tuatara, Sphenodon punctatus, to resolve vertebrate phallus evolution

@article{Sanger2015ResurrectingEO,
  title={Resurrecting embryos of the tuatara, Sphenodon punctatus, to resolve vertebrate phallus evolution},
  author={Thomas J. Sanger and Marissa L. Gredler and Martin J. Cohn},
  journal={Biology Letters},
  year={2015},
  volume={11}
}
The breadth of anatomical and functional diversity among amniote external genitalia has led to uncertainty about the evolutionary origins of the phallus. In several lineages, including the tuatara, Sphenodon punctatus, adults lack an intromittent phallus, raising the possibility that the amniote ancestor lacked external genitalia and reproduced using cloacal apposition. Accordingly, a phallus may have evolved multiple times in amniotes. However, similarities in development across amniote… Expand
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