 Ramba uchinyora ndima iyi - Kupararira kweSouth American siskins kwakanga kuchikurumidza, uye pakutanga kwaifungidzirwa kuti kwakaitika makore anenge mamiriyoni 3.5 akapfuura nemhaka yokuwedzera kwenharaunda yakabatanidzwa neGreat American Interchangeuye zvichienderana nekupararira kwezvirimwa zve mesothermal kubva kuRocky Mountains kuenda kuAndes. Basa razvino rinoratidza kuti mwaranzi yakaitika gare gare, mukati memakore 1 miriyoni apfuura, uye zviitiko zvemarudzi zvingave zvakatangwa nekusiyana kwemamiriro ekunze kwekupedzisira kwePleistocene. 