| 21. | Some salamanders, such as the olm, and the mudpuppy, retain their external gills upon reaching adulthood.
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| 22. | Soft tissue, such as scales and external gills, were found in many well-preserved branchiosaur fossils from Germany.
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| 23. | By the time the embryo is across, it has fully resorbed its yolk sac and external gills.
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| 24. | Embryos long have well-developed external gill filaments.
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| 25. | As development continues, the external gills disappear.
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| 26. | Body pigmentation appears when the embryo is long; the external gills regress at around the same time.
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| 27. | In some primitive bony fishes and amphibians, the larvae bear external gills, branching off from the gill arches.
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| 28. | In amphibians and some primitive bony fishes, the larvae bear external gills, branching off from the gill arches.
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| 29. | The external gill rami are lined with filaments ( fimbriae ) to increase surface area for gas exchange.
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| 30. | In amphibians and some primitive bony fish, the larvae bear external gills, branching off from the gill arches.
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