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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.

Previous analyses of symphyseal fusion in the extinct Malagasy lemur Archaeolemur identified several functional characteristics of joint morphology that vary postnatally (Ravosa and Simons in American Journal of Physical Anthropology 95:63–76, 1994). To complement that study, we used an imaging technique (microCT) that provides novel data on ontogenetic and local variation in biomineralization along the mandibular symphysis before complete ossification among adult Archaeolemur. Our sample of unfused symphyses comprised juveniles from the 2 earliest postnatal dental ages examined previously. We imaged each specimen (ca.18 μm volume elements) with slices parallel to the coronal plane, i.e., orthogonal to the joint articular surface. In ≤5 labiolingually equidistant joint sites, we collected 40 contiguous slices (18-μm intervals). Each of the 5 joint sites is represented by 1 slice, with biomineralization values sampled at 5 equidistant points along the articular surface and at 3 external cortical bone points. Our analysis of Archaeolemur indicates the presence of ontogenetic increases in bone mineral density accompanying increases in joint size and the number and distribution of symphyseal rugosities. Such postnatal changes are particularly marked for the middle of the joint presumed to lie adjacent to a degrading fibrocartilage pad. In Archaeolemur, labial regions of the symphysis ossify earlier and are likewise more biomineralized. Ontogenetic increases in symphyseal biomineralization, overall size, and fusion are consistent with elevated masticatory stresses owing to the postweaning shift to adult-like feeding behaviors. However, the labiolingual pattern of fusion and biomineralization in Archaeolemur appears related more to constraints on synostosis owing to the lingually located vascular supply characteristic of mammalian symphyses.

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.

Modern tools of paleoecological and ecomorphological research have enabled researchers to reconstruct the lifeways of extinct species more thoroughly than ever before. We apply a variety of tools in an attempt to reconstruct the diets of the extinct archaeolemurids of Madagascar. Our data include dental use wear (examined across species and across ontogenetic series of single species), enamel microstructure, enamel thickness, and δ13C. The data are complemented by field data on the environmental contexts in which the species lived and 14C determinations that demonstrate the surprisingly late survival of archaeolemurids. Several lines of evidence converge to suggest that all archaeolemurid species were hard-object processors, but with different diets and different methods of food processing. Past reconstructions of the diet of Hadropithecus as a specialized grass consumer fail under the scrutiny of multiple lines of evidence.

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 site of ‘Bungo Tsimanindroa’ augments the collection of Archaeolemur from the Malagasy north -west zone. Th is genus is well known but there are many questions about the ecogeographic body size variation and the presence of another species in the region. One of the main interests of this new site is that the entire macrofauna is constituted of the remains of Archaeolemur and that the site has not been disturbed. Some specimens are in anatomical connection.

Hadropithecus stenognathus (Lorenz von Liburnau [1899] Anz. Akad. Wiss. Wien 36:255-257), a giant extinct lemur from Madagascar, has been reconstructed as primarily terrestrial and probably cursorial on the basis of its postcranial anatomy, especially long bone gracility and interlimb proportions. We show here that aspects of this reconstruction are almost certainly incorrect. Hindlimb bones of Archaeolemur have been misattributed to Hadropithecus, and new hindlimb allocations (including newly recognized elements such as the calcaneus) indicate that Hadropithecus had a robust body build and lacked osteological specializations for cursoriality. We review the evidence for the existence of Bradylemur' and offer a view of archaeolemurid positional behavior that includes terrestrial and arboreal components. Body size and limb proportions of Hadropithecus are reassessed in light of our new allocations. Am J Phys Anthropol 103:529-556, 1997.

An extensive late Quaternary fauna, including many extinct giant lemurs, has been collected recently in a 110+-km system of caves in the Ankarana Massif of northern Madagascar. AMS 14C dates for the acid-insoluble (collagen/gelatin) fraction of bones of the giant lemur Megaladapis (26,150 ± 400 and 12,760 ± 70 yr B.P.) confirm its presence in the area during the late Pleistocene and provide the first Pleistocene 14 C ages from bones of the extinct megafauna of the island. The first date from bones of the recently described extinct Babakotia radofilai (4400 ± 60 yr B.P.) shows that it was present in northern Madagascar in mid-Holocene times. A comparatively recent age of 1020 ± 50 yr B.P. for the extinct Archaeolemur indicates survival of this genus for at least a millennium after the first direct evidence for humans in Madagascar. This suggests that the island's "extinction window" may have represented a longer time span than would have been expected under the Blitzkrieg model of late Quaternary extinctions. A mid-Holocene age (4560 ± 70 yr B.P.) for a bone sample of the small extant lemur Hapalemur simus indicates that the disappearance of this now-restricted species from the Ankarana occurred after this date. New data from the Ankarana and other sites on the island add to the consensus that major biotic changes occurred on Madagascar in the late Holocene.

Subfossil fecal pellets associated with Archaeolemur cf. edwardsi skeletal material from Anjohikely Cave in north-western Madagascar were probably derived from this large extinct lemur. Pellets were photographed, measured, and dissected. One of the pellets dates to 830 ± 60 years BP. Pellets contain a wide variety of items indicative of omnivory, including fibrous fruit exocarps and seeds; bat, rodent, frog, and lizard bone; gastropod shell; and crustacean and arthropod exoskeletons—all within a matrix of comminuted vegetation. Pollen contents from inside intact pellets support other paleoecological evidence that recent feeding had taken place in wooded grassland habitat. This diet is consistent with ethnohistorical data and anatomical studies that indicate hard-object feeding in Archaeolemur. Archaeolemur may have deliberately entered caves to forage, although caves would also have offered water, abundant shade, cool conditions, cryptic sleeping sites, and refuge from predators. Cave-exploring behavior is rare in primates, but consistent with anatomical evidence that Archaeolemur was well adapted for terrestrial locomotion as well as arboreal climbing.

Ontogenetic changes in the morphology of the mandibular symphysis are described in Archaeolemur so as to infer the functional significance of symphyseal fusion in this subfossil Malagasy lemur. The first regions of the symphysis to show a more complex morphology were the lower and anterior borders of the joint and, to a lesser extent, the lingual borders of the superior and inferior transverse tori. During growth, these regions became increasingly rugose and encroached upon a centrally located, smooth, “oval” region, which may have been a principal pathway for neurovascular structures communicating with the unfused joint. In subadults, the symphysis was completely fused except for the lingual surface of the inferior transverse torus, where a patent suture and potential space were present between dentaries. Thus, in Archaeolemur there was an age- and size-related pattern of increased symphyseal ossification or fusion that was complete by adulthood. The morphology of the interlocking bony processes and the sequence of ossification in the symphysis suggest that increased dorsoventral shear stress during mastication was the most likely determinant of symphyseal fusion in Archaeolemur: The allometric pattern of greater symphyseal fusion may be linked to the presence of relatively greater dorsoventral shear in adults due to an increased recruitment of balancing-side jaw-muscle force. There is little indication that the symphysis of juvenile Archaeolemur was buttressed to resist forces associated with “wishboning” during mastication or vertical bending during incision. Our observations, as well as those of others, suggest that symphyseal fusion in primates occurs initially as a response to increased dorsoventral shear during mastication. Therefore, wishboning stress might only become a major determinant of symphyseal form and function in those taxa that develop a fused symphysis to counter increased dorsoventral shear. © 1994 Wiley-Liss, Inc.

Large body size has evolved repeatedly in the order Primates, not merely among anthropoids but also among prosimians. Whereas high degrees of sexual size dimorphism characterize many of the large-bodied anthropoids, this is not the case for extinct large-bodied lemurs. This paper uses finite mixture analysis and other techniques to ascertain just how much skull length dimorphism might be embedded in the generally unimodal distributions of skull lengths of giant extinct lemurs from single localities, and then compares these results with known skull length dimorphisms in extant lemurs and large-bodied catarrhines. We show that low levels of skull length sexual dimorphism (or none at all) characterize subfossil lemurs, and we explore several possible explanations for this phenomenon. Traditional explanations of sexual size dimorphism generally focus on body size or mating systems. These are not sufficient to explain the variation in sexual dimorphism that can be observed in the order Primates. © 1993 Wiley-Liss, Inc.

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 ).

Previous research on subfossil lemurs has revealed much about the positional behavior of these extinct strepsirrhines, but a thorough quantitative analysis of their vertebral form and function has not been performed. In this study, 156 lumbar vertebrae of Pachylemur, Archaeolemur, Megaladapis, Mesopropithecus, Babakotia, and Palaeopropithecus (11 species in all) were compared to those of 26 species of extant strepsirrhines and haplorhines. Lumbar shape was compared among species, using a principal components analysis (PCA) in conjunction with selected vertebral indices. The first principal component revealed strong separation between Palaeopropithecus at one extreme, and Archaeolemur/Pachylemur at the other, with Babakotia, Mesopropithecus, and Megaladapis in an intermediate position. Palaeopropithecus has markedly shorter spinous processes and wider laminae than do the other subfossil taxa, consistent with sloth-like, inverted suspensory postures. The moderately reduced lumbar spinous processes of Babakotia, Mesopropithecus, and Megaladapis are convergent with those of lorisids and Pongo, reflecting antipronogrady, but a less specialized adaptation than that of Palaeopropithecus. Archaeolemur and Pachylemur share relatively elongated spinous processes, in conjunction with other features (e.g., transverse process orientation and relatively short vertebral bodies) indicative of pronograde, quadrupedal locomotion characterized by reduced agility. All subfossil taxa exhibit adaptations emphasizing lumbar spinal stability (e.g., relatively short vertebral bodies, and transverse processes that are not oriented ventrally); we believe this probably reflects convergent mechanical demands connected to large body size, irrespective of specific locomotor mode. Reconstructions of positional behavior in subfossil lemurs based on lumbar vertebrae are largely consistent with those based on other aspects of the postcrania. Am J Phys Anthropol, 2005. © 2005 Wiley-Liss, Inc.

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.

Inferring the behavior of extinct organisms is a formidable task, even under the best of circumstances (Rudwick, 1964; Stern and Susman, 1983; Kay, 1984; Thomason, 1995). Nevertheless, and in spite of inevitable complications and limitations, such inferences remain the ultimate goal of paleobiologists if we are to understand fossils as integrated organisms rather than isolated bones and atomized character states. In this chapter we attempt to breathe life back into the osteological remains of recently extinct (or “subfossil”) prosimian primates from the Quaternary of Madagascar. Subfossil lemurs provide many special opportunities to the optimistic functional morphologist, but they also present their own unusual set of complications and potential frustrations. Approximately one-third of Madagascar’s known primate species were driven to extinction in the late Holocene by the lethal interaction of aridification and human colonization (Burney, 1997; Dewar, 1997; Simons, 1997), including all taxa of large body size (> 9 kg). Two new extinct species from northern Madagascar (Babakotia radofilai and Mesopropithecus dolichobrachion) have been discovered and described in the last decade (Godfrey et al., 1990; Simons et al., 1995), and a third new species from the northwest will be diagnosed soon (Jungers et al., in prep.). Sixteen currently recognized subfossil species of Malagasy primates are represented in museum collections, most by numerous individuals, including a growing tally of specimens with associated craniodental and postcranial elements (e.g., MacPhee et al., 1984; Simons et al., 1992,Simons et al., 1995; Wunderlich et al., 1996). Table I summarizes the current taxonomy of the extinct lemurs. Aspects of morphology suggest that cheirogaleids are more closely related to galagos and lorises than to other Malagasy primates (Szalay and Katz, 1973; Cartmill, 1975; Schwartz and Tattersall, 1985; Yoder, 1992). Molecular results, as well as “total evidence” analyses that combine morphological and molecular data, argue instead that the Malagasy primates are probably monophyletic (Yoder, 1994,Yoder, 1996). Regardless of the placement of the cheirogaleids within strepsirrhines, the precise relationships among the various ancient clades of Malagasy primates remain somewhat fuzzy, even from a biomolecular perspective (Yoder, 1997; Yoderet al., 1999).

Holocene cave, marsh, and stream deposits on the island of Madagascar have yielded thousands of “subfossil” specimens that document recent megafaunal extinctions. Excavations conducted during the past 15 years of archaeological and paleontological sites in northern, northwestern and southwestern Madagascar have unearthed, in addition to new specimens of extinct lemurs and other megafauna, an abundance of bones of still-extant lemur species. These specimens, as well as specimens of extant lemurs from subfossil sites excavated in the early and mid-1900’s, prove that living lemur species once had much broader geographic ranges than they have today, and they help to explain the currently disjunct distributions of a number of species. This paper examines the pattern of distribution of extant primate species at subfossil sites, and compares recent to modern primate communities.

We examine several explanations for the geographic pattern of body size variation exhibited by the subfossil lemur Archaeolemur. Part and partial correlation analysis and multiple regression analysis are applied in a stepwise, hierarchical fashion to help to determine variable interdependencies. Variance in site means for body size is best explained by the richness of the plant community and by several correlated climatic variables (bioclimatic zone and mean annual rainfall). Body size differentiation in Archaeolemur roughly mirrors patterns observed among many other Malagasy lemur species and subspecies groups. This consistency alone suggests that common ecological factors have strongly affected size differentiation in lemurs, most probably (as suggested by our correlation analyses) by uniformly influencing the productivity of their niches. Smaller individuals tend to inhabit arid regions, and larger individuals tend to inhabit wetter regions. The interplay between selective differentiation and allopatric speciation appears to have yielded the concordant pattern of size variation observed in Malagasy 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 model of primate dental homologies and development recently proposed by Schwartz ('75, '78) is re-evaluated in view of documented exceptions to his account of postcanine supernumerary teeth in both anthropoids and prosimians. Schwartz concluded that catarrhines and living indriids retain only two true molars in each dental quadrant. As many as six molars on one side of the jaw can develop in rare instances in catarrhines, and supernumerary molars are also known for a wide range of other primates, including Cebidae, Adapidae, and subfossil Indriidae. Polydontia cannot be explained exclusively by atavistic development. More convincing explanations regard supernumerary teeth as the result of excessive growth of the dental lamina or localized twinning of tooth buds during early development. Conventional dental formulae of catarrhines and indriids including three permanent molars remain the most plausible.

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

Researchers in primatology have historically viewed size as a confounding variable in the analysis of skeletal remains. A decade ago it was common knowledge that in order to discover what was interesting about morphological Variation one had to somehow “get rid of” size Variation (“correct” for Variation in shape which depends upon size). However, in more recent years attention has increasingly focused on size as “adaptive strategy”. The study of scale has influenced almost every aspect of primatological research, as, for example, research on postcranial morphology and positional behavior (Cartmill 1974, Rose 1974, Fleagle 1979), dental morphology and diet (Kay 1975, Pirie 1978), activity rhythms (Charles-Dominique 1975), the evolution of the brain (Stephan and Bauchot 1965, Jerison 1973, Passingham 1975, Pilbeam and Gould 1974, Gould 1975), gestation and reproductive behavior (Leutenegger 1973, Sacher and Staffeidt 1974, Martin 1975), ranging behavior, social strukture and ecology (Milton and May 1976, Clutton-Brock and Harvey 1977, Ripley 1979), and phylogenetic reconstruction (Martin 1979).