Palaeopropithecids, or ‘loth lemurs’, are a diverse clade of large-bodied Malagasy subfossil primates characterized by their inferred suspensory positional behaviour. The most recently discovered genus of the family is Babakotia. This genus has been described as more arboreal than Mesopropithecus, but less than Palaeopropithecus. For better understanding of arboreal adaptations of Babakotia we compared within-bone and between-bones articular and cross-sectional diaphyseal proportions of limb long bones of this specimen to suspensory hominoids, true sloths (Choloepus and Bradypus) and to present-day lemurs. Results show that Babakotia humeral articular to diaphyseal proportions are generally more similar to those of true sloths than to those of apes. Babakotia femoral proportions are likewise similar to true sloth distributions, but are also comparable to orangutans in their proximal ends (i.e., relative femoral head surface area and superoinferior breadth). Interlimb proportions show that Babakotia’s relative diaphyseal strengths are similar to the mean value for orangutans and in the range of true sloths. As for interlimb articular proportions, Babakotia overlaps with great apes for proximal articulations, but with true sloths for distal articulations. Both principal component analysis (PCA) done on the limb measurements and phylogenetic PCA, show that the limb proportions of Babakotia are very close to those of Bradypus and Choloepus, and very different to those of present-day lemurs (its closest living relatives). These results provide new evidence of the arboreal adaptations of Babakotia and further highlight similarities to both extant suspensory primates and non-primate slow arboreal climbers and hangers, i.e., true sloths.

Post-cranial suspensory adaptations of the subfossil lemur Babakotia radofilai

MARCHI, DAMIANO;
2015

Abstract

Palaeopropithecids, or ‘loth lemurs’, are a diverse clade of large-bodied Malagasy subfossil primates characterized by their inferred suspensory positional behaviour. The most recently discovered genus of the family is Babakotia. This genus has been described as more arboreal than Mesopropithecus, but less than Palaeopropithecus. For better understanding of arboreal adaptations of Babakotia we compared within-bone and between-bones articular and cross-sectional diaphyseal proportions of limb long bones of this specimen to suspensory hominoids, true sloths (Choloepus and Bradypus) and to present-day lemurs. Results show that Babakotia humeral articular to diaphyseal proportions are generally more similar to those of true sloths than to those of apes. Babakotia femoral proportions are likewise similar to true sloth distributions, but are also comparable to orangutans in their proximal ends (i.e., relative femoral head surface area and superoinferior breadth). Interlimb proportions show that Babakotia’s relative diaphyseal strengths are similar to the mean value for orangutans and in the range of true sloths. As for interlimb articular proportions, Babakotia overlaps with great apes for proximal articulations, but with true sloths for distal articulations. Both principal component analysis (PCA) done on the limb measurements and phylogenetic PCA, show that the limb proportions of Babakotia are very close to those of Bradypus and Choloepus, and very different to those of present-day lemurs (its closest living relatives). These results provide new evidence of the arboreal adaptations of Babakotia and further highlight similarities to both extant suspensory primates and non-primate slow arboreal climbers and hangers, i.e., true sloths.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/750321
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