A snake is a member of an elongated, predominantly limbless reptile lineage within Squamata. Limb reduction is one feature of its evolutionary history, not evidence that the lineage has no relationship to limbed ancestors. Different snakes retain different remnants of the ancestral limb-development system.
A study of a limb regulatory enhancer found progressive functional loss in snake sequences. Replacing the corresponding enhancer in mice with a snake-derived sequence produced severe limb reduction, linking a regulatory DNA change to developmental output. [ref] This identifies a contributing mechanism; it does not show that one sequence change alone explains every anatomical specialization of snakes.

Ancestors (10)

  1. Diapsida
  2. Sauropsida
  3. Amniote
  4. Tetrapod
  5. Vertebrate
  6. Animal
  7. Eukaryote
  8. Organism
  9. Biology
  10. Home

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