from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • proper noun A taxonomic genus within the family Accipitridae — certain harrier-hawks.


from Wiktionary, Creative Commons Attribution/Share-Alike License

Polyborus (“former genus name for a caracara”) +‎ -oides


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  • Recent studies agree that Polyboroides is in this clade, and within it one of the most basal members (Holdaway 1994, Lerner et al. 2005).

    Archive 2006-05-01

  • Polyboroides is ‘beautifully interesting’ for two other reasons.

    Archive 2006-05-01

  • Sometimes called the Gymnogene, Polyboroides is a gracile, naked-faced raptor with grey and black plumage, but best known for the so-called double-jointedness present in its intertarsal joints.

    Archive 2006-05-01

  • Secondly, Polyboroides is interesting for being one of the most basal members of Accipitridae (the hawk-eagle-Old World vulture family).

    Archive 2006-05-01

  • Polyboroides and Geranospiza thus represent striking, amazing instances of convergent evolution, one of the best examples of this among birds.

    Archive 2006-05-01

  • While unfortunately few phylogenetic studies include both species together, a comprehensive recent DNA-based phylogeny found the two to be well apart, with Polyboroides down with Old World vultures and honey buzzards, while Geranospiza was in the buteonine clade that also includes Buteo (of course) and Leucopternus (Lerner et al. 2005).

    Archive 2006-05-01

  • You might presume, as I did, that Polyboroides has a unique sort of intertarsal joint, perhaps with the trochlear surfaces of the distal tibiotarsus wrapping onto the posterior surface of the bone as well as the anterior surface.

    Archive 2006-05-01

  • Geranospiza looks pretty much the same as Polyboroides, occupies the same ecological niche, behaves in the same manner, and even has the same bizarrely mobile intertarsal joint.

    Archive 2006-05-01

  • * Pengana robertbolesi, a Riversleigh raptor named by Boles (after his father), is yet another raptor that convergently evolved a hyper-mobile tarsal joint like that of Polyboroides (Boles 1993).

    Archive 2006-06-01

  • Incidentally, there's a second raptor that also evolved striking convergence with Polyboroides, but it's a fossil form and I'll have to talk about it another time.

    Archive 2006-05-01


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