TY - JOUR
T1 - New hand bones of Hadropithecus stenognathus
T2 - implications for the paleobiology of the Archaeolemuridae
AU - Lemelin, Pierre
AU - Hamrick, Mark W.
AU - Richmond, Brian G.
AU - Godfrey, Laurie R.
AU - Jungers, William L.
AU - Burney, David A.
N1 - Funding Information:
The research reported here was made possible because of a collaborative accord for paleoecological and paleontological research by David Burney, William Jungers, Laurie Godfrey, and the Laboratoire de Paléontologie et Anthropologie Biologique, Université d'Antananarivo, Madagascar. Field assistance by Ramilisonina, Mirya Ramarolahy, Lydia Raharivony, and Natalie Vasey, as well as our local guides, is gratefully acknowledged. We would like to thank Professor Elwyn Simons, Division of Fossil Primates at Duke University, and the United States National Museum of Natural History (Smithsonian Institution), Washington, D.C. for giving us access to their specimens of Archaeolemur . We also acknowledge the many museum curators who provided access to their extant primate skeletal collections and Paul Godfrey for his help with the photographs. The skeleton of Hadropithecus from Andrahomana is currently housed in the collections of the Department of Anthropology, University of Massachusetts, Amherst (contact Laurie Godfrey). This research was supported by: NSERC and The Leakey Foundation to P.L., NSF BCS-0129185 to D.A.B., W.L.J., and L.R.G.; NSF BCS-0237338 to L.R.G. We are grateful to Susan Antón and two anonymous reviewers for their very thorough reading of a previous draft of the manuscript and useful suggestions that improved the final version.
PY - 2008/3
Y1 - 2008/3
N2 - A partial, associated skeleton of Hadropithecus stenognathus (AHA-I) was discovered in 2003 at Andrahomana Cave in southeastern Madagascar. Among the postcranial elements found were the first hand bones (right scaphoid, right hamate, left first metacarpal, and right and left fifth metacarpals) attributed to this rare subfossil lemur. These hand bones were compared to those of extant strepsirrhines and catarrhines in order to infer the positional adaptations of Hadropithecus, and they were compared to those of Archaeolemur in order to assess variation in hand morphology among archaeolemurids. The scaphoid tubercle does not project palmarly as in suspensory and climbing taxa, and the hamate has no hook at all (just a small tubercle), which also points to a poorly developed carpal tunnel. There is a distinctive, radioulnarly directed "spiral" facet for articulation with the triquetrum that is most similar in orientation to that of more terrestrial primates (i.e., Lemur catta, Papio, and Gorilla). The first metacarpal is very reduced and represents only 48% of the length of metacarpal V, as in Archaeolemur, which suggests that pollical grasping of arboreal supports was not important. Compared to Archaeolemur, the shaft of metacarpal V is gracile, and the head has no dorsal ridge and lacks characteristics functionally associated with digitigrade, extended metacarpophalangeal joint postures. Proximally, the articular facet for the hamate is oriented more dorsally. Thus, the carpometacarpal joint V appears to have a distinctive hyperextended set, which has no analog among living or extinct primates. The carpals of Hadropithecus are diagnostic of a pronograde, arboreal and terrestrial (although not digitigrade) locomotor repertoire that typifies Lemur catta and some Old World monkeys. No clinging, suspensory, or climbing specializations that characterize indriids or lorises can be found in the hand of this subfossil lemur. The hand of Hadropithecus likely had similar ranges of movement at the radiocarpal and midcarpal joints as of those of pronograde primates, such as lemurids, for which the hand is held in a more extended, pronated, and neutral (i.e., showing less ulnar deviation) position during locomotion in comparison to that of vertical clingers or slow climbers. Although highly autapomorphic, the hand of Hadropithecus resembles that of its sister taxon, Archaeolemur, in having a very reduced pollex and an articular facet on the scaphoid for a sizeable prepollex. These unusual hand features reinforce the monophyly of the Archaeolemuridae.
AB - A partial, associated skeleton of Hadropithecus stenognathus (AHA-I) was discovered in 2003 at Andrahomana Cave in southeastern Madagascar. Among the postcranial elements found were the first hand bones (right scaphoid, right hamate, left first metacarpal, and right and left fifth metacarpals) attributed to this rare subfossil lemur. These hand bones were compared to those of extant strepsirrhines and catarrhines in order to infer the positional adaptations of Hadropithecus, and they were compared to those of Archaeolemur in order to assess variation in hand morphology among archaeolemurids. The scaphoid tubercle does not project palmarly as in suspensory and climbing taxa, and the hamate has no hook at all (just a small tubercle), which also points to a poorly developed carpal tunnel. There is a distinctive, radioulnarly directed "spiral" facet for articulation with the triquetrum that is most similar in orientation to that of more terrestrial primates (i.e., Lemur catta, Papio, and Gorilla). The first metacarpal is very reduced and represents only 48% of the length of metacarpal V, as in Archaeolemur, which suggests that pollical grasping of arboreal supports was not important. Compared to Archaeolemur, the shaft of metacarpal V is gracile, and the head has no dorsal ridge and lacks characteristics functionally associated with digitigrade, extended metacarpophalangeal joint postures. Proximally, the articular facet for the hamate is oriented more dorsally. Thus, the carpometacarpal joint V appears to have a distinctive hyperextended set, which has no analog among living or extinct primates. The carpals of Hadropithecus are diagnostic of a pronograde, arboreal and terrestrial (although not digitigrade) locomotor repertoire that typifies Lemur catta and some Old World monkeys. No clinging, suspensory, or climbing specializations that characterize indriids or lorises can be found in the hand of this subfossil lemur. The hand of Hadropithecus likely had similar ranges of movement at the radiocarpal and midcarpal joints as of those of pronograde primates, such as lemurids, for which the hand is held in a more extended, pronated, and neutral (i.e., showing less ulnar deviation) position during locomotion in comparison to that of vertical clingers or slow climbers. Although highly autapomorphic, the hand of Hadropithecus resembles that of its sister taxon, Archaeolemur, in having a very reduced pollex and an articular facet on the scaphoid for a sizeable prepollex. These unusual hand features reinforce the monophyly of the Archaeolemuridae.
KW - Archaeolemur
KW - Carpals
KW - Locomotion
KW - Madagascar
KW - Metacarpals
KW - Strepsirrhines
KW - Subfossil lemurs
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U2 - 10.1016/j.jhevol.2007.09.010
DO - 10.1016/j.jhevol.2007.09.010
M3 - Article
C2 - 18068213
AN - SCOPUS:39149136563
SN - 0047-2484
VL - 54
SP - 405
EP - 413
JO - Journal of Human Evolution
JF - Journal of Human Evolution
IS - 3
ER -