 Bipes (source code)

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= Bipes
{c}

<Bipes> is a <taxonomic genus> of burrowing <amphisbaenians> distinguished by retaining external forelimbs despite an elongated body and absence of external hindlimbs. It is an informative comparison with other <amphisbaenians>, which lack external limbs: external appearance alone does not reveal how much internal anatomy remains.<Pectoral myology of limb-reduced worm lizards (Squamata, Amphisbaenia) suggests decoupling of the musculoskeletal system during the evolution of body elongation by Natascha Westphal and others>[Abstract and Background, retained Bipes forelimbs]{ref}

In a 2019 anatomical study, investigators used iodine-enhanced <computed tomography> to distinguish soft tissues and reconstruct shoulder <muscles> as well as bones. <Bipes> retained an almost complete shoulder girdle, while other sampled <amphisbaenians> had much more reduced bony structures. Nevertheless, all sampled amphisbaenian forms retained the full set of 17 shoulder <muscles>, sometimes fused or rearranged. Muscle attachment could shift from bone to surrounding soft tissue.<Pectoral myology of limb-reduced worm lizards (Squamata, Amphisbaenia) suggests decoupling of the musculoskeletal system during the evolution of body elongation by Natascha Westphal and others>[Abstract, Methods and Results: contrast-enhanced CT and pectoral musculature]{ref}

The result challenges a tempting shortcut: losing a visible limb does not necessarily delete all its associated <muscles> at once. <Bipes> supplies the limbed comparison that helps reveal which internal components have persisted or changed during the evolution of the burrowing body form.

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