TY - JOUR
T1 - Proximal Humerus Morphology Indicates Divergent Patterns of Locomotion in Extinct Giant Kangaroos
AU - Janis, Christine M.
AU - Napoli, James G.
AU - Billingham, Coral
AU - Martín-Serra, Alberto
N1 - Acceptance date is provisional and based on date of publication.
PY - 2020/1/16
Y1 - 2020/1/16
N2 - Sthenurine kangaroos, extinct “giant kangaroos” known predominantly from the Plio-Pleistocene, have been proposed to have used bipedal striding as a mode of locomotion, based on the morphology of their hind limbs. However, sthenurine forelimb morphology has not been considered in this context, and has important bearing as to whether these kangaroos employed quadrupedal or pentapedal locomotion as a slow gait, as in extant kangaroos. Study of the correlation of morphology of the proximal humerus in a broad range of therian mammals shows that humeral morphology is indicative of the degree of weight-bearing on the forelimbs during locomotion, with terrestrial species being distinctly different from arboreal ones. Extant kangaroos have a proximal humeral morphology similar to extant scansorial (semi-arboreal) mammals, but sthenurine humeri resemble those of suspensory arboreal taxa, which rarely bear weight on their forelimbs, supporting the hypothesis that they used bipedal striding rather than quadrupedal locomotion at slow gaits. The humeral morphology of the enigmatic extinct “giant wallaby,” Protemnodon, may be indicative of a greater extent of quadrupedal locomotion than in extant kangaroos.
AB - Sthenurine kangaroos, extinct “giant kangaroos” known predominantly from the Plio-Pleistocene, have been proposed to have used bipedal striding as a mode of locomotion, based on the morphology of their hind limbs. However, sthenurine forelimb morphology has not been considered in this context, and has important bearing as to whether these kangaroos employed quadrupedal or pentapedal locomotion as a slow gait, as in extant kangaroos. Study of the correlation of morphology of the proximal humerus in a broad range of therian mammals shows that humeral morphology is indicative of the degree of weight-bearing on the forelimbs during locomotion, with terrestrial species being distinctly different from arboreal ones. Extant kangaroos have a proximal humeral morphology similar to extant scansorial (semi-arboreal) mammals, but sthenurine humeri resemble those of suspensory arboreal taxa, which rarely bear weight on their forelimbs, supporting the hypothesis that they used bipedal striding rather than quadrupedal locomotion at slow gaits. The humeral morphology of the enigmatic extinct “giant wallaby,” Protemnodon, may be indicative of a greater extent of quadrupedal locomotion than in extant kangaroos.
KW - Functional anatomy
KW - Humerus
KW - Locomotion
KW - Macropodidae
KW - Macropodoidea
KW - Protemnodon
KW - Sthenurinae
UR - http://www.scopus.com/inward/record.url?scp=85078599522&partnerID=8YFLogxK
U2 - 10.1007/s10914-019-09494-5
DO - 10.1007/s10914-019-09494-5
M3 - Article (Academic Journal)
AN - SCOPUS:85078599522
SN - 1064-7554
VL - 2020
JO - Journal of Mammalian Evolution
JF - Journal of Mammalian Evolution
ER -