In other species: chicken , dog , domestic cat , pig , taurine cattle , sheep , Swainson's hawk

Categories: Skeleton phene (incl. short stature & teeth) , Limbs / fins / digit / tail phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 212780 (trait) , 186100 (trait) , 186200 (trait) , 186300 (trait) , 604270 (gene)

Single-gene trait/disorder: unknown

Disease-related: no

Cross-species summary: Fusion of the claws (cleats or digits). Occurs in one, two, three or (rarely) four limbs.

Species summary: Chew et al. 2012: In kangaroos and wallabies "the hindlimb autopod has only four digits, the fourth of which is greatly elongated, while digits two and three are syndactylous." 
[IT thanks Emma Faull for contributions to this entry in September 2025]

Molecular basis: Chew et al. (2012) investigated the expression of HOXA13 and HOXD13 in normal tammar wallaby limb development and concluded that "timing of HOX gene expression may contribute to the heterochrony of the forelimb and hindlimb and that alteration to HOX domains may influence phenotypic differences that lead to the development of [normal] marsupial syndactylous digits."