A new species of Pliopithecus from the Indian S̀ivaliks

This paper gives a detailed account of an isolated upper third molar of a gibbon-like primate, the first of its kind ever found from the S?ivalik hills. The tooth comes from the Nagri beds comparable to the Middle Miocene Formations. This tooth has been assigned to a new species of Pliopithecus, namely P. krishnaii, on the basis of morphological and metrical comparisons with the fossil gibbon-like primates and living gibbons.     

Abrasive, silica phytoliths and the evolution of thick molar enamel in primates, with implications for the diet of Paranthropus boisei

Background

Primates—including fossil species of apes and hominins—show variation in their degree of molar enamel thickness, a trait long thought to reflect a diet of hard or tough foods. The early hominins demonstrated molar enamel thickness of moderate to extreme degrees, which suggested to most researchers that they ate hard foods obtained on or near the ground, such as nuts, seeds, tubers, and roots. We propose an alternative hypothesis—that the amount of phytoliths in foods correlates with the evolution of thick molar enamel in primates, although this effect is constrained by a species'' degree of folivory.

Methodology/Principal Findings

From a combination of dietary data and evidence for the levels of phytoliths in plant families in the literature, we calculated the percentage of plant foods rich in phytoliths in the diets of twelve extant primates with wide variation in their molar enamel thickness. Additional dietary data from the literature provided the percentage of each primate''s diet made up of plants and of leaves. A statistical analysis of these variables showed that the amount of abrasive silica phytoliths in the diets of our sample primates correlated positively with the thickness of their molar enamel, constrained by the amount of leaves in their diet (R² = 0.875; p<.0006).

Conclusions/Significance

The need to resist abrasion from phytoliths appears to be a key selective force behind the evolution of thick molar enamel in primates. The extreme molar enamel thickness of the teeth of the East African hominin Paranthropus boisei, long thought to suggest a diet comprising predominantly hard objects, instead appears to indicate a diet with plants high in abrasive silica phytoliths.     

A new Pitheciin primate from the middle Miocene of Argentina

We report here a new fossil primate from the middle Miocene of Argentina. The material consists of isolated teeth, mandibular fragments, and a talus. The fossils were collected in the Collón Cura formation at Cañadón del Tordillo in Neuquén Province. An age of 15.71 ± 0.07 Ma has been reported for the Pilcaniyeu Ignimbrite, which lies just below the paleosols in which the fossils were found. This material is thus the youngest occurrence of fossil primates in Argentina (hitherto documented in the Santacrucian and older land mammal ages) but still is older than the middle Miocene platyrrhine primates from La Venta, Colombia, in particular the pitheciins Nuciruptor and Cebupithecia. The material is recognized as a new genus and species of Pitheciinae, Propithecia neuquenensis. The mesiodistally compressed, high-crowned incisors are specialized and similar to species in the tribe Pithecini and to the nonpitheciin Soriacebus (early Miocene, Patagonia). We rule out a phylogenetic relationship to the latter because of differences in molar morphology. Propithecia does, however, fit well into the pattern of pitheciin evolution, being more derived than the middle Miocene pitheciin Nuciruptor but not as much as another middle Miocene taxon, Cebupithecia. As such, this makes Propithecia the oldest taxon that can be confidently placed within this modern New World monkey subfamily. By analogy with the molar structures and diets of extant platyrrhines, Propithecia has a molar structure consistent with a variety of low-fiber diets ranging from fruit and gum to seeds. Its incisors suggest seed-eating in much the same way as extant pitheciins, like Pithecia. The talus resembles that of Callicebus, suggesting arboreal quadrupedal locomotion. Am. J. Primatol. 45:317–336, 1998. © 1998 Wiley-Liss, Inc.     

A model for comparison of masticatory effectiveness in primates

A model is presented to express how effectively animals increase the exposed surface area of their food by chewing. It includes a coefficient of masticatory effectiveness (E) the value of which increases with effectiveness of exposing new food surface area with each chew. Humans and other species of primates differ significantly in their values of E; among the nonhuman primates studies, Lemur catta has a higher coefficient than Lemur fulvus, and both have higher coefficients than either Varecia variegatus or Galago crassicaudatus argentatus. The differences among the coefficients to these prosimians are correlated with variations in specific features of the molar morphology. Of six lower molar shearing crests considered, the relative length of the post-metacristid correlates most highly with the coefficient of masticatory effectiveness for the prosimian species. Also, among comparable-sized prosimians, E correlates significantly with the absolute postmetacristid length. Both these findings indicate that the relative size of molar shearing crests is related significantly to how effectively an animal chews its food. There are also implications for an adaptation to a high-fiber diet.     

New platyrrhine monkeys from the Solimões Formation (late Miocene, Acre State, Brazil)

We report here a new fossil primate from the late Miocene of Brazil. The material consists of a lower first molar and a maxilla with P3-4. The fossils were collected in the Solim?es Formation at the locality of Patos, upper Acre River, Acre State, Brazil. The locality is assigned to the Huayquerian South American Land Mammal Age based on faunal content (late Miocene; dated to between 9 and 6 Ma). The new material is the oldest known occurrence of fossil primates in Brazil and is recognized as a new genus and species, Solimoea acrensis. Solimoea is the oldest known member of the ateline subfamily, which includes the living genera Ateles, Lagothrix, and Brachyteles. By analogy with the molar structures and diets of extant platyrrhines, Solimoea primarily had a diet of fruit, perhaps similar to that of the spider monkey, Ateles. Two other primate teeth described previously from the same formation in Bolivia document the occurrence of alouattines and cebines. One of those specimens is a late Miocene representative of the middle Miocene Colombian genus Stirtonia. The other represents one of the largest known platyrrhine primates, for which is erected a new primate genus, Acrecebus fraileyi.     

Dental use wear in extinct lemurs: evidence of diet and niche differentiation

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.     

Estimating the body size of eocene primates: A comparison of results from dental and postcranial variables

Estimating body weights for fossil primates is an important step in reconstructing aspects of their behavior and ecology. To date, the body size of Eocene euprimates—the Adapidae and Omomyidae—has been estimated only from molar area. Studies on other primates and mammals demonstrate that body weights estimated from teeth are not always concordant with those estimated from postcranial variables. We derive estimates for Eocene primates based on tarsal bone variables to compare with previously published values derived from dental measures. Stepsirhine-wide, family-level, and subfamily-level models are developed and compared. We also compare the accuracy and precision of dental- and tarsal-based regression models for predicting weight in extant species. Tarsal bone and dental area measures prove to be equally robust in predicting body weight; however, highly disparate estimates are often obtained from different variables. Equations based on lower-level taxonomic groups perform better than more widely based models. However, all equations considered yield fairly large errors, which can affect interpretations of paleoecology. The choice of the more robust prediction is not straightforward.     

Relationships between the diet and dentition of Asian leaf monkeys

Colobines have been generally described as primates that use the anterior teeth minimally, but the posterior teeth extensively, to process leaves and related food items. However, variation among leaf monkeys in both anterior and posterior dental morphology has been recognized for decades. In this study, we turn to Hylander's (Science 189 (1975) 1095-1098) analysis of anterior incisor row length and Kay's (Adaptations for foraging in nonhuman primates, 1984) examination of relative molar crest length to test hypotheses proposed by them for Asian colobines. We present findings based on data from the largest Asian colobine sample measured to date. Our findings for incisor row length and molar cresting are not amenable to broad generalizations. In those instances when our morphological findings concur with those of Hylander (Science 189 (1975) 1095-1098) and Kay and Hylander (The ecology of arboreal folivores, 1978), the ecological evidence seldom supports the morphological predictions. The disassociation between diet and dental patterns may be a consequence of differential selection by fallback foods, anthropogenic disturbance or climatic shifts limiting preferred diets, or the use of food types as opposed to food mechanical properties for dietary categorization. We also found that in the case of both incisor row length and molar crest length, the patterns for males and females differed markedly. The reasons for these differences may in part be ascribed to the metabolic challenges faced by females and subsequent niche partitioning. We propose integrated analyses of the ingestive and digestive systems of our study taxa to clarify relationships among behavior, dental morphology, and diet in extant and extinct colobines.     

The ecology of oligocene African anthropoidea

African anthropoids are first recorded in Early Oligocene deposits of the Fayum Province, Egypt. Six genera and nine species are recognized. Estimated body weights for these taxa are based on the regression equation log ₁₀(B) = 2.86log ₁₀(L) + 1.37, whereB is the bodyweight in grams, and Lis the M ₂ length in millimeters. The equation is derived from 106 species of living primates. Fayum species range in body weight from about 600 g (Apidium moustafai)to about 6000 g (Aegyptopithecus zeuxis).A similar range of body weight is found among extant Cebidae. The Fayum primates are larger than any extant insectivorous primates;this fact probably rules out a predominantly insectivorous diet. Extant frugivorous hominoids can be separated from folivorous hominoids on the basis of molar morphology. Folivorous apes (gorilla and siamang) have proportionately more shearing on their molars than do frugivorous species. Based on the hominoid analogy, the molar morphology of the Fayum species is consistent with a frugivorous diet. Parapithecus grangeristands apart from other Fayum species in having better developed molar shearing, possibly indicating that it had more fiber in its diet. Terrestrial species of Old World monkeys tend to have significantly higher molar crowns than do more arboreal species. This difference may relate to an increased amount of grit in the diet of the more terrestrial species, selecting for greater resistance to wear. Oligocene primates have molar crown heights consistent with a primarily arboreal mode of existence. However, the particularly high molar crowns of Parapithecus grangerisuggest that this species may have foraged on the ground to a considerable degree. Other evidence is advanced suggesting that Apidiummay have had a diurnal activity pattern.     

Taxonomy and phylogenetic relationships of early Miocene catarrhines from Sihong, China.

Paleontological investigations at sites in Sihong County, Jiangsu Province, China since 1981 have yielded a sizeable collection of previously undescribed fossil catarrhines from the Xiacaowan Formation. The associated vertebrate fauna indicates a late early Miocene age (correlating with MN 4, late Orleanian of Europe, approximately 17-18 Ma), which establishes the Sihong primates as the earliest known catarrhines from Eurasia. The fossil primates are assigned to two species: Dionysopithecus shuangouensis Li, 1978 and Platodontopithecus jianghuaiensis Gu & Lin, 1983. Although the new material from Sihong consists mainly of isolated teeth, it does provide important new information on the anatomy of Dionysopithecus and Platodontopithecus that helps to clarify their phylogenetic and taxonomic status. Previous studies have suggested that the Sihong catarrhines might be closely related to the proconsulids from the early Miocene of East Africa. However, with more extensive material available for comparison, the Sihong primates can now be shown to share a number of key derived features with pliopithecids. This new evidence helps to resolve a longstanding problem concerning the origins of the Pliopithecidae. It was previously considered that specialized pliopithecids migrated into Europe during MN 5, originating from an unknown antecedent and location in Africa. Recognition that the Sihong primates have affinities with pliopithecids, but are more primitive, suggests that the initial differentiation and diversification of the clade may have taken place in Asia rather than Africa. The earliest Eurasian catarrhines probably migrated into tropical Asia as part of a major faunal interchange with Africa that occurred during MN 3.     

Age at first molar emergence in Lufengpithecus lufengensis and its implications for life-history evolution

The late Miocene hominoid Lufengpithecus from Yunnan Province, China, is crucial for understanding hominoid evolution in Asia. Given that age at first permanent molar emergence is a key life-history trait in primates, the present study determined the age at death of the Lufengpithecus lufengensis juvenile PA868, which was in the process of erupting its first molar. Using a perikymata periodicity of 7-11 days, along with estimation of cusp formation time and the postnatal delay of crown mineralization, perikymata counts obtained from the permanent central incisor and canine germs indicate that the age at death of PA868 was 2.4-4.5 years based on the central incisor germ, and 2.5-4.7 years based on the canine germ. The age at the first molar emergence was actually slightly younger (by about 0.3 years), as demonstrated by tiny wear facets on this tooth, which indicate that gingival emergence had occurred sometime before death. The average age at first molar emergence of Lufengpithecus lufengensis PA868 is estimated to be 3.2-3.3 years, with a range of 2.1-4.4 years. In comparison to extant primates and other fossil hominoids, the life history of Lufengpithecus lufengensis is similar to that of extant great apes and the Miocene hominoids Afropithecus turkanensis and Sivapithecus parvada, as well as Plio-Pleistocene Australopithecus, and different from monkeys, gibbons, and modern humans.     

A new method for the study of glutaraldehyde-induced crosslinking properties in proteins with special reference to the reaction with amino groups.

A new method for the study of glutaraldehyde reactions with proteins is presented. Glutaraldehyde-reacted protein is in a first step isolated and then in a second step reacted with aminohexyl groups bound to Sepharose particles. This reaction is linear at low protein concentrations and proceeds rapidly when proteins are reacted with 100-fold and 1000-fold molar excess of glutaraldehyde. This method enables the study of glutaraldehyde-induced crosslinking properties of the modified proteins as an isolated property with high reliability.     

Subtype distribution of Blastocystis isolates from synanthropic and zoo animals and identification of a new subtype

Blastocystis isolates from 56 Danish synanthropic and zoo animals, 62 primates primarily from United Kingdom (UK) collections and 16 UK primate handlers were subtyped by PCR, sequencing and phylogenetic analysis. A new subtype (ST) from primates and artiodactyls was identified and designated as Blastocystis sp. ST10. STs isolated from non-human primates (n = 70) included ST3 (33%), ST8 (21%), ST2 (16%), ST5 (13%), ST1 (10%), ST4 (4%) and ST10 (3%). A high prevalence of ST8 was seen among primate handlers (25%). This ST is normally very rare in humans, suggesting that acquisition of Blastocystis ST8 infections from primates by their handlers had occurred in these cases. Data from published studies of non-human primates, other mammals and birds were collected and interpreted to generate a comprehensive overview on the ST distribution in such animals. On the basis of information on 438 samples, it was found that Blastocystis from primates belong mainly to ST1, ST2, ST3, ST5 and ST8, ungulates and dogs mainly ST1, ST2, ST3, ST5 and ST10, rodents ST4 and birds mainly ST6 and ST7. The data indicate moderate host specificity, most clearly exemplified by the fact that STs isolated from avian and non-avian hosts rarely overlap.     

The gibbons of the Malay Peninsula and of Sumatra

Three species of gibbons living now both on the Malay Peninsula and on the island of Sumatra are compared as regards the morphology of the molar teeth. Since the continental and the island populations of these species are known to have been separated since early or middle Pleistocene times, the comparison here made provides information on the amount of morphological evolution that has occurred in the dentition of these primates since that time. It is found that, of the 3 species studied,Symphalangus syndactylus has better retained a number of conservative features on the island than on the continent;Hylobates lar, on the contrary, appears to have evolved further away from the ancestral form on the island than on the continent. These findings warn against an oversimplified view of the effects of isolation on the evolution of higher primates.     

New early Eocene anaptomorphine primate (Omomyidae) from the Washakie Basin,Wyoming, with comments on the phylogeny and paleobiology of anaptomorphines

Recent paleontological collecting in the Washakie Basin, southcentral Wyoming, has resulted in the recovery of over 100 specimens of omomyid primates from the lower Eocene Wasatch Formation. Much of what is known about anaptomorphine omomyids is based upon work in the Bighorn and Wind River Basins of Wyoming. This new sample documents greater taxonomic diversity of omomyids during the early Eocene and contributes to our understanding of the phylogeny and adaptations of some of these earliest North American primates. A new middle Wasatchian (Lysitean) anaptomorphine, Anemorhysis savagei, n. sp., is structurally intermediate between Teilhardina americana and other species of Anemorhysis and may be a sister group of other Anemorhysis and Trogolemur. Body size estimates for Anemorhysis, Tetonoides, Trogolemur, and Teilhardina americana indicate that these animals were extremely small, probably less than 50 grams. Analysis of relative shearing potential of lower molars of these taxa indicates that some were primarily insectivorous, some primarily frugivorous, and some may have been more mixed feeders. Anaptomorphines did not develop the extremes of molar specialization for frugivory or insectivory seen in extant prosimians. Incisor enlargement does not appear to be associated with specialization in either fruits or insects but may have been an adaptation for specialized grooming or food manipulation. © 1994 Wiley-Liss, Inc.     

Mandibular biomechanics and temporomandibular joint function in primates.

There is disagreement as to whether the mandibular condyles are stress-bearing or stress-free during mastication. In support of alternative models, analogies have been drawn with Class III levers, links, and couple systems. Physiological data are reviewed which indicate that maximum masticatory forces are generated when maxillary and mandibular teeth are in contact, and that this phase lasts for over 100 msec during many chewing strokes. During this period, the mandible can be modeled as a beam with multiple supports. Equations of simple beam theory suggest that large condylar reaction forces are present during mastication. With unilateral molar biting in man, the total condylar reaction force may be over 75% of the bite force. Analysis of a frontal projection demonstrates that up to 80% of the total condylar reaction force is borne by the contralateral (balancing side) condyle during unilateral molar biting. A comparison of human, chimpanzee (P. troglodytes), spider monkey (A. belzebuth), and macaque (Macaca sp.) morphology indicates that the frugivorous chimpanzee and spider monkey have a relatively lower condylar reaction force than the omnivorous macaque or man during molar biting. The percentage reaction force during incisal biting is lower in man than in the other primates, and lower in the frugivorous primates than in the macaque.     

灵长类化石在内蒙古二连地区上始新统的首次记录

记录了内蒙古晚始新世的3种原始灵长类化石(Eosimias sp.A,Eosimias sp.B和Pseudo- loris erenensis sp.nov.)。Eosimias sp.A系该属个体较大者,仅小于E.paukkaungensis。Eosi- mias sp.B个体较小,齿冠较低,主尖较细小。Pseudoloris erenensis的主要特征为:个体小,m2的下次小尖较靠舌侧,无颊、舌侧齿带等。Eosimias在内蒙古上始新统的发现,表明内蒙古在晚始新世时也是高等灵长类活动的舞台。过去已知仅分布于欧洲的Pseudoloris在内蒙古上始新统的发现表明,哺乳动物在晚始新世时,在亚、欧问已有某种交流。上述发现还表明,内蒙古地区晚始新世的气候可能属亚热带型,有过树木繁茂的林地。     

Evolutionary development and co-phylogeny of primate-associated bifidobacteria

In recent years, bifidobacterial populations in the gut of various monkey species have been assessed in several ecological surveys, unveiling a diverse, yet unexplored ecosystem harbouring novel species. In the current study, we investigated the species distribution of bifidobacteria present in 23 different species of primates, including human samples, by means of 16S rRNA microbial profiling and internal transcribed spacer bifidobacterial profiling. Based on the observed bifidobacterial-host co-phylogeny, we found a statistically significant correlation between the Hominidae family and particular bifidobacterial species isolated from humans, indicating phylosymbiosis between these lineages. Furthermore, phylogenetic and glycobiome analyses, based on 40 bifidobacterial species isolated from primates, revealed that members of the Bifidobacterium tissieri phylogenetic group, which are typical gut inhabitants of members of the Cebidae family, descend from an ancient ancestor with respect to other bifidobacterial taxa isolated from primates.     

Evolution of genetically correlated traits: tooth size and body size in baboons

Within a population, only phenotypic variation that is influenced by genes will respond to selection. Genes with pleiotropic effects are known to influence numerous traits, complicating our understanding of their evolution through time. Here we use quantitative genetic analyses to identify and estimate the shared genetic effects between molar size and trunk length in a pedigreed, breeding population of baboons housed at the Southwest National Primate Research Center. While crown area has a genetic correlation with trunk length, specific linear measurements yield different results. We find that variation in molar buccolingual width and trunk length is influenced by overlapping additive genetic effects. In contrast, mesiodistal molar length appears to be genetically independent of body size. This is the first study to demonstrate a significant genetic correlation between tooth size and body size in primates. The evolutionary implications are discussed.     

Evolution of Metamorphism in Thymidylate Synthases Within the Primate Lineages

Crystal structures of human thymidylate synthase (hTS) revealed that the protein exists in active and inactive conformations, defined by the position of a loop containing the active site nucleophile. TS is highly homologous among diverse species; however, the residue at position 163 (hTS) differs among species. Arginine at this position is predicted by structural modeling to enable conformational switching. Arginine or lysine is reported at this position in all mammals in the GenBank and Ensembl databases, with arginine reported in only primates. Sequence analysis of the TS gene of representative primates revealed that arginine occurs at this relative position in all primates except a representative of prosimians. Mutant human proteins were created with residues at position 163 that occur in TSs from prokaryotes and eukaryotes. Catalytic constants (k _cat) of mutant enzymes were 45–149% of hTS, with the lysine mutant (R163K) exhibiting the highest k _cat. The effect of lysine substitution on solution structure and on ligand binding was investigated. R163K exhibited higher intrinsic fluorescence, a more negative molar ellipticity, and higher dissociation constants (K _d) for ligands that modulate protein conformation than hTS. Temperature effects on intrinsic fluorescence and catalytic activity of hTS and R163K are consistent with proteins populating different conformational states. The data indicate that the enzyme with arginine at the position corresponding to 163 (hTS) evolved after the divergence of prosimians and simians and that substitution of lysine by arginine confers unique structural and functional properties to the enzyme expressed in simian primates.