Search

Objectives Variation in primate masticatory form and function has been extensively researched through both morphological and experimental studies. As a result, symphyseal fusion in different primate clades has been linked to either the recruitment of vertically directed balancing-side muscle force, the timing and recruitment of transversely directed forces, or both. This study investigates the relationship between jaw muscle activity patterns and morphology in extant primates to make inferences about masticatory function in extinct primates, with implications for understanding the evolution of symphyseal fusion. Materials and methods Three-dimensional mandibular landmark data were collected for 31 extant primates and nine fossil anthropoids and subfossil lemur species. Published electromyography (EMG) data were available for nine of the extant primate species. Partial least squares analysis and phylogenetic partial least squares analysis were used to identify relationships between EMG and jaw shape data and evaluate variation in jaw morphology. Results Primates with partial and complete symphyseal fusion exhibit shape-function patterns associated with the wishboning motor pattern and loading regime, in contrast to shape-function patterns of primates with unfused jaws. All fossil primates examined (except Apidium) exhibit jaw morphologies suggestive of the wishboning motor pattern demonstrated in living anthropoids and indriids. Discussion Partial fusion in Catopithecus, similar to indriids and some subfossil lemurs, may be sufficient to resist, or transfer, some amounts of transversely directed balancing-side muscle force at the symphysis, representing a transition to greater reliance on transverse jaw movement during mastication. Furthermore, possible functional convergences in physiological patterns during chewing (i.e., Archaeolemur) are identified.

A new fossil site in a previously unexplored part of western Madagascar (the Beanka Protected Area) has yielded remains of many recently extinct vertebrates, including giant lemurs (Babakotia radofilai, Palaeopropithecus kelyus, Pachylemur sp., and Archaeolemur edwardsi), carnivores (Cryptoprocta spelea), the aardvark-like Plesiorycteropus sp., and giant ground cuckoos (Coua). Many of these represent considerable range extensions. Extant species that were extirpated from the region (e.g., Prolemur simus) are also present. Calibrated radiocarbon ages for 10 bones from extinct primates span the last three millennia. The largely undisturbed taphonomy of bone deposits supports the interpretation that many specimens fell in from a rock ledge above the entrance. Some primates and other mammals may have been prey items of avian predators, but human predation is also evident. Strontium isotope ratios (87Sr/86Sr) suggest that fossils were local to the area. Pottery sherds and bones of extinct and extant vertebrates with cut and chop marks indicate human activity in previous centuries. Scarcity of charcoal and human artifacts suggests only occasional visitation to the site by humans. The fossil assemblage from this site is unusual in that, while it contains many sloth lemurs, it lacks ratites, hippopotami, and crocodiles typical of nearly all other Holocene subfossil sites on Madagascar., Research at Beanka was supported by the National Geographic Society via Waitt Foundation grants W263-13 and W388-15 to DAB, and by the site-managing organization, Biodiversity Conservation Madagascar (BCM). EJdB was supported by a travel grant from the Society for Advancement of Research in the Tropics (Treub Maatschappij). The scientific study authorization was provided by the Bureau du Cadastre Minier de Madagascar with the reference 024/2015. Many thanks to faculty of the Université d'Antananarivo and staff of BCM and Association Vahatra for assistance with permits and logistics. To the staff of BCM and the people of the village of Ambinda, we extend special thanks for hospitality and assistance with fieldwork and information regarding sites and access. Bone specimens were identified from studies of comparative materials at the Field Museum of Natural History, the Université d'Antananarivo, Association Vahatra, Duke Lemur Center, Muséum national d'Histoire naturelle (Paris), the Natural History Museum (London), the Smithsonian Institution, the American Museum of Natural History, and the University of Massachusetts, Amherst. Species identifications were supported in part by NSF BCS-1750598 (to LRG). Isotopic and radiocarbon analyses were supported in part by NSF BCS-1749676 (to BEC).

The jaw adductor muscles of extinct mammals are often reconstructed to elucidate paleoecological relationships and to make broad comparisons among taxa. Muscle lever arms, bite load arms, muscle dimensions, and gape are often also reconstructed to better understand feeding. Several different approaches to these and related goals are discussed here. A protocol for reconstructing muscle dimensions and bite force using biomechanically informative skull measurements and osteological proxies of muscle dimensions is described and applied to a case study of subfossil Malagasy lemurs. The results of this case study show that most subfossil lemurs emphasized the masseter and medial pterygoid muscles over the temporalis. This supports the inference that these extinct lemurs depended heavily on tough food like leaves. Exceptions include signals of hard-object feeding in Archaeolemur that vary between A. majori and A. edwardsi. Reconstructions of soft-tissue and function are important for understanding past ecological relationships. Even those based on well-supported osteological proxies from extant analogues have limitations for making precise inferences. Anat Rec, 301:343-362, 2018. © 2018 Wiley Periodicals, Inc.

Among mammals, including anthropoid primates, the primary factors that affect mobility are body size (larger-bodied species move more than smaller ones), diet (frugivores and trophic omnivores are more mobile than folivores), and habit (terrestrial taxa have larger home ranges than arboreal ones). If similar factors hold for Lemuriformes, we would expect large-bodied (particularly frugivorous) extinct lemurs to have been more mobile than smaller-bodied (particularly folivorous) extant species. Yet multiple lines of evidence (e.g., low Retzius Periodicities, small semicircular canal size, small relative brain size) suggest that extinct lemurs were relatively inactive. If so, they may have had relatively small home ranges, perhaps on par with smaller-bodied extant lemurs. We used strontium isotopes (87Sr/86Sr), which vary spatially primarily as a function of geology, to compare mobility for eight lemur genera: Eulemur, Lemur, Lepilemur, and Propithecus (extant), and Archaeolemur, Megaladapis, Pachylemur, and Palaeopropithecus (extinct). Subfossils came from two sites: Ankilitelo/Mikoboka, a series of sinkholes in a limestone plateau, and Ampasambazimba, a wetland underlain by a variety of igneous and metamorphic rocks. Within either site, we expected more mobile taxa to exhibit more variable 87Sr/86Sr, reflecting larger movement across a diversity of geologies. We found no differences in median 87Sr/86Sr or variance between extinct and extant lemurs at either site (Wilcoxon and Bartlett p > 0.05 for all comparisons). There were apparent but insignificant differences among genera (Kruskal-Wallis and Bartlett p > 0.05). Isotopic variability was greater at Ampasambazimba than at Ankilitelo/Mikoboka, reflecting differences in the underlying geology. One Palaeopropithecus from Ankilitelo/Mikoboka and one Eulemur from Ampasambazimba had unusually elevated 87Sr/86Sr. Both of these individuals could have been deposited at their respective sites by a predatory bird. These results demonstrate the value of 87Sr/86Sr for testing hypotheses related to the behavior of now-extinct species. Strontium isotopes support low mobility for extinct lemurs, and suggest that Lemuriformes as a whole differ from anthropoids in having relatively depressed basal metabolic rates and reduced activity levels. These traits reduce energetic expenditure, and likely developed in response to Madagascar's harsh environments. However, small home ranges also make lemurs more vulnerable to extinction.

Over 40 years ago, Clifford Jolly noted different ways in which Hadropithecus stenognathus converged in its craniodental anatomy with basal hominins and with geladas. The Malagasy subfossil lemur Hadropithecus departs from its sister taxon, Archaeolemur, in that it displays comparatively large molars, reduced incisors and canines, a shortened rostrum, and thickened mandibular corpus. Its molars, however, look nothing like those of basal hominins; rather, they much more closely resemble molars of grazers such as Theropithecus. A number of tools have been used to interpret these traits, including dental microwear and texture analysis, molar internal and external morphology, and finite element analysis of crania. These tools, however, have failed to provide support for a simple dietary interpretation; whereas there is some consistency in the inferences they support, dietary inferences (e.g., that it was graminivorous, or that it specialized on hard objects) have been downright contradictory. Cranial shape may correlate poorly with diet. But a fundamental question remains unresolved: why do the various cranial and dental convergences exemplified by Hadropithecus, basal hominins, and Theropithecus exist? In this paper we review prior hypotheses regarding the diet of Hadropithecus. We then use stable carbon and nitrogen isotope data to elucidate this species' diet, summarizing earlier stable isotope analyses and presenting new data for lemurs from the central highlands of Madagascar, where Hadropithecus exhibits an isotopic signature strikingly different from that seen in other parts of the island. We offer a dietary explanation for these differences. Hadropithecus likely specialized neither on grasses nor hard objects; its staples were probably the succulent leaves of CAM plants. Nevertheless, aspects of prior hypotheses regarding the ecological significance of its morphology can be supported. Am. J. Primatol. 78:1098-1112, 2016. © 2015 Wiley Periodicals, Inc.

Objectives The external morphology of the sacrum is demonstrably informative regarding tail type (i.e., tail presence/absence, length, and prehensility) in living and extinct primates. However, little research has focused on the relationship between tail type and internal sacral morphology, a potentially important source of functional information when fossil sacra are incomplete. Here, we determine if cortical bone cross-sectional thickness of the last sacral vertebral body differs among tail types in extant primates and can be used to reconstruct tail types in extinct primates. Materials and methods Cortical bone cross-sectional thickness in the last sacral vertebral body was measured from high-resolution CT scans belonging to 20 extant primate species (N = 72) assigned to tail type categories ("tailless," "nonprehensile short-tailed," "nonprehensile long-tailed," and "prehensile-tailed"). The extant dataset was then used to reconstruct the tail types for four extinct primate species. Results Tailless primates had significantly thinner cortical bone than tail-bearing primates. Nonprehensile short-tailed primates had significantly thinner cortical bone than nonprehensile long-tailed primates. Cortical bone cross-sectional thickness did not distinguish between prehensile-tailed and nonprehensile long-tailed taxa. Results are strongly influenced by phylogeny. Corroborating previous studies, Epipliopithecus vindobonensis was reconstructed as tailless, Archaeolemur edwardsi as long-tailed, Megaladapis grandidieri as nonprehensile short-tailed, and Palaeopropithecus kelyus as nonprehensile short-tailed or tailless. Conclusions Results indicate that, in the context of phylogenetic clade, measures of cortical bone cross-sectional thickness can be used to allocate extinct primate species to tail type categories.

The fossil ‘monkey lemur’ Hadropithecus stenognathus has long excited palaeontologists because its skull bears an astonishing resemblance to those of robust australopiths, an enigmatic side branch of the human family tree. Multiple lines of evidence point to the likelihood that these australopiths ate at least some ‘hard’, stress-limited food items, but conflicting data from H. stenognathus pose a conundrum. While its hominin-like craniofacial architecture is suggestive of an ability to generate high bite forces, details of its tooth structure suggest that it was not well equipped to withstand the forces imposed by cracking hard objects. Here, we use three-dimensional digital reconstructions and finite-element analysis to test the hard-object processing hypothesis. We show that Archaeolemur sp. cf. A. edwardsi , a longer-faced close relative of H. stenognathus that lacked hominin convergences, was probably capable of breaking apart large, stress-limited food items, while Hadropithecus was better suited to processing small, displacement-limited (tougher but more compliant) foods. Our suggestion that H. stenognathus was not a hard-object feeder has bearing on the interpretation of hominin cranial architecture; the features shared by H. stenognathus and robust australopiths do not necessarily reflect adaptations for hard-object processing.

This study employs dental microwear texture analysis to reconstruct the diets of two families of subfossil lemurs from Madagascar, the archaeolemurids and megaladapids. This technique is based on three-dimensional surface measurements utilizing a white-light confocal profiler and scale-sensitive fractal analysis. Data were recorded for six texture variables previously used successfully to distinguish between living primates with known dietary differences. Statistical analyses revealed that the archaeolemurids and megaladapids have overlapping microwear texture signatures, suggesting that the two families occasionally depended on resources with similar mechanical properties. Even so, moderate variation in most attributes is evident, and results suggest potential differences in the foods consumed by the two families. The microwear pattern for the megaladapids indicates a preference for tougher foods, such as many leaves, while that of the archaeolemurids is consistent with the consumption of harder foods. The results also indicate some intraspecific differences among taxa within each family. This evidence suggests that the archaeolemurids and megaladapids, like many living primates, likely consumed a variety of food types.

This study evaluated the relationship between the morphology of the sacrum—the sole bony link between the tail or coccyx and the rest of the body—and tail length (including presence/absence) and function using a comparative sample of extant mammals spanning six orders (Primates, Carnivora, Rodentia, Diprotodontia, Pilosa, Scandentia; N = 472). Phylogenetically-informed regression methods were used to assess how tail length varied with respect to 11 external and internal (i.e., trabecular) bony sacral variables with known or suspected biomechanical significance across all mammals, only primates, and only non-primates. Sacral variables were also evaluated for primates assigned to tail categories (‘tailless,’ ‘nonprehensile short-tailed,’ ‘nonprehensile long-tailed,’ and ‘prehensile-tailed’). Compared to primates with reduced tail lengths, primates with longer tails generally exhibited sacra having larger caudal neural openings than cranial neural openings, and last sacral vertebrae with more mediolaterally-expanded caudal articular surfaces than cranial articular surfaces, more laterally-expanded transverse processes, more dorsally-projecting spinous processes, and larger caudal articular surface areas. Observations were corroborated by the comparative sample, which showed that shorter-tailed (e.g., Lynx rufus [bobcat]) and longer-tailed (e.g., Acinonyx jubatus [cheetah]) non-primate mammals morphologically converge with shorter-tailed (e.g., Macaca nemestrina) and longer-tailed (e.g., Macaca fascicularis) primates, respectively. ‘Prehensile-tailed’ primates exhibited last sacral vertebrae with more laterally-expanded transverse processes and greater caudal articular surface areas than ‘nonprehensile long-tailed’ primates. Internal sacral variables performed poorly compared to external sacral variables in analyses of extant primates, and were thus deemed less useful for making inferences concerning tail length and function in extinct primates. The tails lengths of five extinct primates were reconstructed from the external sacral variables: Archaeolemur edwardsi had a ‘nonprehensile long tail,’ Megaladapis grandidieri, Palaeopropithecus kelyus, and Epipliopithecus vindobonensis probably had ‘nonprehensile short tails,’ and Proconsul heseloni was ‘tailless.’

Remains of what appears to be a single, subadult Hadropithecus stenognathus were recovered from a previously unexcavated site at Andrahomana Cave (southeastern Madagascar). Specimens found comprise isolated teeth and cranial fragments (including the frontal processes of the orbits), as well as a partial postcranial skeleton. They include the first associated fore- and hind-limb bones, confirming the hind-limb attributions made by Godfrey and co-workers in 1997, and refuting earlier attributions by Lamberton in 1937/1938. Of particular interest here are the previously unknown elements, including a sacrum, other vertebrae and ribs, some hand bones, and the distal epiphysis of a femur. We briefly discuss the functional implications of previously unknown elements. Hadropithecus displayed a combination of characters reminiscent of lemurids, others more like those of the larger-bodied Old World monkeys, and still others more like those of African apes. Yet other characteristics appear unique. Lemurid-like postcranial characteristics may be primitive for the Archaeolemuridae. Hadropithecus diverges from the Lemuridae in the direction of Archaeolemur, but more extremely so. Thus, for example, it exhibits a stronger reduction in the size of the hamulus of the hamate, greater anteroposterior compression of the femoral shaft, and greater asymmetry of the femoral condyles. Nothing in its postcranial anatomy signals a close relationship to either the Indriidae or the Palaeopropithecidae.

Recent expeditions to Madagascar have recovered abundant skeletal remains of Archaeolemur, one of the so-called “monkey lemurs” known from Holocene deposits scattered across the island. These new skeletons are sufficiently complete to permit reassembly of entire hands and feet—postcranial elements crucial to drawing inferences about substrate preferences and positional behavior. Univariate and multivariate analysis of intrinsic hand and foot proportions, phalangeal indices, relative pollex and hallux lengths, phalangeal curvature, and distal phalangeal shape reveal a highly derived and unique morphology for an extinct strepsirrhine that diverges dramatically from that of living lemurs and converges in some respects on that of Old World monkeys (e.g., mandrills, but not baboons or geladas). The hands and feet of Archaeolemur are relatively short (extremely so relative to body size); the carpus and tarsus are both “long” relative to total hand and foot lengths, respectively; phalangeal indices of both the hands and feet are low; both pollex and hallux are reduced; the apical tufts of the distal phalanges are very broad; and the proximal phalanges are slightly curved (but more so than in baboons). Overall grasping capabilities may have been compromised to some extent, and dexterous handling of small objects seems improbable. Deliberate and noncursorial quadrupedalism was most likely practiced on both the ground and in the trees. A flexible locomotor repertoire in conjunction with a eurytopic trophic adaptation allowed Archaeolemur to inhabit much of Madagascar and may explain why it was one of the latest surviving subfossil lemurs.

Resume Les deux sites d’Antsingiavo A & B, nouvellement decouverts dans la presqu’ile de Narinda situee dans le Nord-Ouest de Madagascar, province de Mahajanga, presentent des breches contenant de la microfaune de vertebres dont des lemuriens de petite taille ( Microcebus ), associee a des lemuriens subfossiles eteints, de taille moyenne comme Archaeolemur . La microfaune subfossile de Madagascar est tres mal connue, voire inconnue, et devrait permettre de reconstituer le paleoenvironnement de cette region. Les nouvelles decouvertes contribuent a mettre en evidence la diversite de ces Archaeolemur qui se distinguent suivant les regions de Madagascar. Pour citer cet article : D. Gommery et al., C. R. Palevol 2 (2003).

Among the best known of recently extinct Malagasy lemurs is Archaeolemur, which is represented by many hundreds of specimens. The phylogenetic affinities of this taxon are unclear, especially in light of recent preliminary analysis of ancient DNA which does not support its previously accepted close relationship with the living Indridae. We examined the nearly complete skeletons of two adults and one juvenile and other less complete specimens to reconstruct aspects of the ontogeny of Archaeolemur. To compare the development of Archaeolemur to that of living strepsirrhines we collected data on Propithecus verreauxi, Eulemur fulvus, and Lemur catta. Additionally, because Archaeolemur exhibits some morphological convergences with distantly related papionins, we tested for convergence in the developmental patterns of Archaeolemur and Macaca fascicularis. Data include the status of tooth eruption, craniofacial sutural closure, and postcranial epiphyseal fusion, as well as linear measurements. We used discriminant function analysis and other tools to explore ontogenetic similarities and differences. The adaptive and phylogenetic significance of ontogenetic information is discussed. Our analysis shows that Archaeolemur displays a clear strepsirrhine pattern of development with only minor macaque convergences. Among the Strepsirrhini, Archaeolemur is slightly more similar developmentally to E. fulvus and L. catta than to P. verreauxi. Some of the distinctive features of the ontogeny of Archaeolemur may be related to diet, while others bear apparent testimony to a relatively rapid absolute pace of growth and development.

The size of the infraorbital foramen (IOF) has been used in drawing both phylogenetic and ecological inferences regarding fossil taxa. Within the order Primates, frugivores have relatively larger IOFs than folivores or insectivores. This study uses relative IOF size in lemurs to test prior trophic inferences for subfossil lemurs and to explore the pattern of variation within and across lemur families. The IOFs of individuals belonging to 12 extinct lemur species were measured and compared to those of extant Malagasy strepsirhines. Observations matched expectations drawn from more traditional approaches (e.g. dental morphology and microwear, stable isotope analysis) remarkably well. We confirm that extinct lemurs belonging to the families Megaladapidae and Palaeopropithecidae were predominantly folivorous and that species belonging to the genus Pachylemur (Lemuridae) were frugivores. Very high values for relative IOF area in Archaeolemur support frugivory but are also consistent with omnivory, as certain omnivores use facial touch cues while feeding. These results provide additional evidence that the IOF can be used as an informative osteological feature in both phylogenetic and paleoecological interpretations of the fossil record.

La dispersion des semences de baobabs malgaches, Adansonia spp., semble ne jamais avoir été étudiée de manière formelle, à ce jour. Elle relève d'hypothèses que cette synthèse bibliographique a pour objet de réunir. Si l'homme semble jouer un rôle important dans la dispersion d'Adansonia digitata en Afrique, une telle hypothèse reste rarement évoquée à l'é- gard des espèces malgaches. Divers auteurs privilégient l'hypothèse d'une dis- persion anachronique, liée à la disparition de la mégafaune malgache ; mais d'autres évoquent le rôle possible de vertébrés introduits. L'intervention de l'oiseau- éléphant, Aepyornis spp., des tortues géantes, Aldabrachelys spp., et des grands lémuriens disparus, Archaeolemur spp., ou actuels est plus particulièrement évoquée, en vis-à-vis du rôle possible d'animaux introduits, zébus, Bos indicus, pota- mochères, Potamochoerus larvatus. Des expérimentations conduites ex situ sur des animaux indigènes ou introduits, dont cer- tains se rapprochent par leur morphologie ou leur phylogenèse de vertébrés éteints, pourraient éclaircir cette énigme de la dis- persion chez les baobabs de Madagascar

La dispersion des semences de baobabs malgaches, Adansonia spp., semble ne jamais avoir été étudiée de manière formelle, à ce jour. Elle relève d¿hypothèses que cette synthèse bibliographique a pour objet de réunir. Si l¿homme semble jouer un rôle important dans la dispersion d¿Adansonia digitata en Afrique, une telle hypothèse reste rarement évoquée à l¿égard des espèces malgaches. Divers auteurs privilégient l¿hypothèse d¿une dispersion anachronique, liée à la disparition de la mégafaune malgache; mais d¿autres évoquent le rôle possible de vertébrés introduits. L¿intervention de l¿oiseauéléphant, Aepyornis spp., des tortues géantes, Aldabrachelys spp., et des grands lémuriens disparus, Archaeolemur spp., ou actuels est plus particulièrement évoquée, en vis-à-vis du rôle possible d¿animaux introduits, zébus, Bos indicus, potamochères, Potamochoerus larvatus. Des expérimentations conduites ex situ sur des animaux indigènes ou introduits, dont certains se rapprochent par leur morphologie ou leur phylogenèse de vertébrés éteints, pourraient éclaircir cette énigme de la dispersion chez les baobabs de Madagascar. (Résumé d'auteur)

Following human arrival, Madagascar suffered well-documented megafaunal extinctions and widespread deforestation. Although humans are widely considered to be the primary cause of the extinctions, the relative contributions of climate change and human activities to this ecological transformation remain uncertain. Reconstructing the habitats of the giant lemurs of Madagascar can provide key information for understanding the evolutionary mechanisms involved in their extinction. In this study, I present a faunal analysis of the subfossil assemblage from Ankilitelo Cave, southwestern Madagascar. This assemblage documents the latest known occurrence of five species of extinct giant lemur, in association with abundant well-preserved small mammal remains. I compared the small mammal fauna at Ankilitelo with 27 extant Malagasy mammal communities spanning the range of Madagascar's habitat types. Similarities in species composition between modern communities and Ankilitelo were assessed using cluster analysis. Ecological similarities were examined by assigning each species to dietary, locomotor, activity pattern, and body size categories. Multiple discriminant analysis was then used to classify Ankilitelo relative to modern habitat types in Madagascar, based on the ecological structure of the subfossil fauna. Results indicate that the habitat surrounding Ankilitelo during the late Holocene was similar to the succulent woodlands of modern southwestern Madagascar. This suggests that approximately 500 yr BP, these semi-arid habitats supported a subfossil lemur community that included the highly-suspensory Palaeopropithecus, and deliberate slow-climber Megaladapis, as well as Archaeolemur, Pachylemur, and Daubentonia robusta. In such environments, these giant lemurs would likely have been highly vulnerable to increasing human pressure in southwestern Madagascar.

Experimental and comparative studies among primates suggest that symphyseal fusion and relatively large mandibular symphysis and corpus dimensions are often part of the same functional pattern Hylander, 1977 , Hylander, 1979a , Hylander, 1979b , Hylander, 1984 , Hylander, 1985 , Hylander, 1988 ; Beecher, 1977 , Beecher, 1979 , Beecher, 1983 . To test this hypothesis further, the biomechanical scaling of corpus and symphysis dimensions was examined in prosimians and compared to anthropoids. Symphyseal fusion was similarly investigated in large-bodied Malagasy “subfossil” lemurs. Dietary influences on prosimian corpus and symphysis proportions were also considered, because leaf-eating positively affects the degree of symphyseal fusion ( Beecher, 1977 , Beecher, 1979 , Beecher, 1983 ; but see also Greaves, 1988 and mandibular robusticity ( Hylander, 1979a ; Bouvier, 1986a , Bouvier, 1986b ). Prosimian regression lines for mandibular corpus and symphysis measures are significantly transposed below those for anthropoids.Palaeopropithecus maximus, P. ingens, Hadropithecus stenognathus, Archaeolemur edwardsi andA. majori display relatively robust symphysis and corpus dimensions, which appear to be related to large body size and folivory.Megaladapis madagascariensis, M. grandidieri andM. edwardsi have more moderately positive residuals; thus symphyseal fusion appears more singularly the result of large size. Leaf-eating prosimians, such as indriids, do display relatively large corpora and symphyses. These data strongly support previous predictions about structural and functional differences between the masticatory system of extant primate suborders (e.g., Hylander, 1979a ; Beecher, 1977 , Beecher, 1979 ).

A database has been assembled with 278 age determinations for Madagascar. Materials 14 C dated include pretreated sediments and plant macrofossils from cores and excavations throughout the island, and bones, teeth, or eggshells of most of the extinct megafaunal taxa, including the giant lemurs, hippopotami, and ratites. Additional measurements come from uranium-series dates on speleothems and thermoluminescence dating of pottery. Changes documented include late Pleistocene climatic events and, in the late Holocene, the apparently human-caused transformation of the environment. Multiple lines of evidence point to the earliest human presence at ca. 2300 14 C yr BP (350 cal yr BC). A decline in megafauna, inferred from a drastic decrease in spores of the coprophilous fungus Sporormiella spp. in sediments at 1720 ± 40 14 C yr BP (230–410 cal yr AD), is followed by large increases in charcoal particles in sediment cores, beginning in the SW part of the island, and spreading to other coasts and the interior over the next millennium. The record of human occupation is initially sparse, but shows large human populations throughout the island by the beginning of the Second Millennium AD. Dating of the “subfossil” megafauna, including pygmy hippos, elephant birds, giant tortoises, and large lemurs, demonstrates that most if not all the extinct taxa were still present on the island when humans arrived. Many taxa overlapped chronologically with humans for a millennium or more. The extinct lemurs Hadropithecus stenognathus , Pachylemur insignis , Mesopropithecus pithecoides , and Daubentonia robusta , and the elephant birds Aepyornis spp. and Mullerornis spp., were still present near the end of the First Millennium AD. Palaeopropithecus ingens , Megaladapis edwardsi , and Archaeolemur sp. (cf. edwardsi ) may have survived until the middle of the Second Millennium A.D. One specimen of Hippopotamus of unknown provenance dates to the period of European colonization.

In this study we use molar microwear analyses to examine the trophic distinctions among various taxa of Malagasy subfossil lemurs. High resolution casts of the teeth of Megaladapis, Archaeolemur, Palaeopropithecus, Babakotia, and Hadropithecus were examined under a scanning electron microscope. Megaladapis was undoubtedly a browsing folivore, but there are significant differences between species of this genus. However, dietary specialists appear to be the exception; for example, Palaeopropithecus and Babakotia probably supplemented their leaf-eating with substantial amounts of seed-predation, much like modern indrids. Hadropithecus was decidedly not like the modern gelada baboon, but probably did feed on hard objects. Evidence from microwear and coprolites suggests that Archaeolemur probably had an eclectic diet that differed regionally and perhaps seasonally. Substantial trophic diversity within Madgascar's primate community was diminished by the late Quaternary extinctions of the large-bodied species (>9 kg).

A new technique for molar use-wear analysis is applied to samples of all 16 species of extinct lemurs with known dentitions, as well as to a large comparative sample of extant primates. This technique, which relies on the light refractive properties of wear pits and scratches as seen under a standard stereoscopic microscope, has shown itself to be effective in distinguishing the diets of ungulates and extant primates. We draw dietary inferences for each of the 16 extinct lemur species in our database. There is a strong phylogenetic signal, with the Palaeopropithecidae showing use-wear signatures similar to those of the Indriidae; extinct lemurids (Pachylemur spp.) showing striking similarities to extant lemurids (except Hapalemur spp.); and Megaladapis showing similarities to Lepilemur spp. Only the Archaeolemuridae have dietary signatures unlike those of any extant lemurs, with the partial exception of Daubentonia. We conclude that the Archaeolemuridae were hard-object feeders; the Palaeopropithecidae were seed predators, consuming a mixed diet of foliage and fruit to varying degrees; Pachylemur was a fruit-dominated mixed feeder, but not a seed predator; and all Megaladapis were leaf browsers. There is no molar use wear evidence that any of the extinct lemurs relied on terrestrial foods (C4 grasses, tubers, rhizomes). This has possible implications for the role of the disappearance of wooded habitats in the extinction of lemurs.

This overview of the positional behavior and evolutionary history of Malagasy strepsirrhines is based on the humeral and femoral morphology of extinct and extant forms. It argues against the hypothesis that vertical clinging and leaping was ancestral for Malagasy lemurs in general, and for indroids in particular. Special attention is given to the evolutionary history of the Indroidea, and a new interpretation of their relationships is offered. It appears that specialized forms of leaping, as well as specialized slow, quadrupedal climbing, evolved repeatedly within the Malagasy strepsirrhines (i.e., in both Indroidea and Lemuroidea) from a generalized quadrupedal ancestor that would have included a certain amount of leaping and bounding in its positional repertory, but also slow climbing and occasional hindlimb suspension.

The island of Madagascar exhibits an exceptional degree of topographical, climatic, and ecological diversity. This great internal complexity has been characterized by Martin (1972) as similar to "a closed group of (somewhat elastic) islands". The evolutionary implications of such a situation are readily apparent; the colonizing prosimian fauna no doubt encountered numerous op portunities for geographical separation of different populations, allopatric speciation, and subsequent competition leading to niche specializations. The considerable diversity in behavioral and morphological adaptations among living Malagasy prosimians strongly supports such an "adaptive radiation" scenario (Petter et al., 1977). Moreover, if recently extinct (subfossil) forms are taken into account, the entire remainder of the primate order strains to find suitable morphological and eco-ethological analogies to the Malagasy prosimians (Tatter sall, 1973 a; Walker, 1974). It is possible to demonstrate quite close taxonomic relationships among various subf ossil and extant Malagasy lemurs (Table 1). All recognized families except the Cheirogaleidae possess both living and extinct representatives. Pachylemur is the lone subf ossil member of the Lemuridae; similary, Megaladapis (three species) is the only extinct representative of the Lepilemuridae. Daubentonia robustus is little more than a larger, more robust form of the living aye-aye. Only within the Indriidae are there more known subfossil than living genera. Several of the subfossil deposits have yielded extinct specimens in association with living species (e. g., Lemur catta and Propithecus verreauxi at Andrahomana in association with Archaeolemur and Megaladapis), and radiocarbon dating of the various localities spans a narrow period of approximately 1,000?3,000 years B. P. (Tattersall, 1973 b). One of the most consistent differences between the living and the subfossil members of each family is that of size; the extinct forms tend to be larger than