A review of the identification, occurence and evolution of pentapedal locomotion in macropodiform marsupials

Pentapedal locomotion was investigated in the three extant families of macropodiform marsupials using videos, photographs and tracks. These methods in combination with published information reveal that the gait is utilized by at least 23 extant macropodiform species including many that have been identified as users of ‘slow progression’. However, it is not used by the sole extant hypsiprymnodontid. In potoroids most slow locomotion is by quadrupedal bounding, although Potorous tridactylus sometimes uses pentapedal locomotion. Whether other potoroids do is unclear. The situation in the macropodid subfamily Lagostrophinae is also unclear. In the subfamily Macropodinae pentapedal locomotion is used by 8 of the 11 extant genera and at least 22 of the 61 species and the two slow gaits are not mutually exclusive. Previous failure to observe pentapedal locomotion in small-bodied macropodids may reflect agoraphobia and the greater speed that quadrupedal bounding allows in the open. Pentapedal locomotion evidently appeared within the superfamily Macropodoidea after it diverged from hypsiprymnodontids and its taxonomic distribution suggests early adoption by macropodines. Ignorance about slow gait usage in Lagostrophus and potoroids makes it difficult to assess the broader history of the gait. Energy savings likely explain replacement of quadrupedal bounding by pentapedal locomotion in macropodids.