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At least 37 records · Page 2Linked to original sources
PubMed1996

Brief communication: new primate remains from the Miocene of Namibia, southern Africa.

Miocene primates from southern Africa are extremely rare. For this reason we wish to place on record several interesting new fossil primate specimens recently recovered from the Miocene sites of Berg Aukas and Harasib in the Otavi Mountain region of northern Namibia. The new finds consist of a virtually complete atlas vertebra from Berg Aukas attributable to the hominoid Otavipithecus namibiensis and two teeth and four postcranial fragments from Harasib referrable to Cercopithecoidea. The atlas vertebra exhibits anatomical characteristics intermediate between those of modern cercopithecoids and hominoids which may be indicative of a transition from pronograde to orthograde postures. The cercopithecoid remains show that the earliest Old World monkeys known from southern Africa were small, approximately the size of vervet monkeys. These new specimens are important because they provide the first evidence relating to possible positional behaviors of Otavipithecus and the earliest fossil record of cercopithecoids from southern Africa.

Animals↗
PubMed2000

Molecular estimates of primate divergences and new hypotheses for primate dispersal and the origin of modern humans.

The concept of recent hominoid divergences has been a mainstay in molecular primatology since the 1970's. However, the ages allocated to the calibration points used to establish these divergence times and the estimates resulting from their application, notably the commonly accepted divergence between Pan (chimpanzees) and Homo 5 million years before present (MYBP), are now palaeontologically refutable. Here we estimate the ages of various primate divergences using three references with a more detailed fossil record than any of the traditional primate calibration points. Our findings suggest that the latter yield datings that are too recent by a factor of about two. For example, our estimates place the divergence between Pan and Homo 10.5-13 MYBP. The revised estimates of primate divergence times suggest a new hypothesis for primate evolution and dispersal: that the divergence between strepsirhines (lorises, lemurs) and anthropoids was contemporary with the break-up of Southern continents about 90 MYBP, with strepsirhines becoming isolated on Madagascar and later dispersing to Africa (and Asia) and anthropoids evolving in South America and subsequently colonizing Africa (and Asia), or possibly North America. In addition we present a new hypothesis, which accommodates the strikingly similar coalescence times for human mitochondrial DNA and the Y-chromosome. This hypothesis posits a common mitochondrial and Y-chromosome bottleneck about 400,000 years ago, associated with the origination of the human 2n = 46 karyotype, obstructing genetic exchange with the 2n = 48 Homo contemporaries.

Africa↗
PubMed2000

Analysis of a bone assemblage made by chimpanzees at Gombe National Park, Tanzania.

Chimpanzee hunting provides information on prey characteristics and constraints acting on a large-bodied primate lacking a hunting technology, and has important implications for modeling hunting by fossil hominids. Analysis of the remains of five red colobus monkeys captured and consumed by Gombe chimpanzees in a single hunting bout provides one of the first opportunities to investigate the characteristics of prey bones surviving chimpanzee consumption. Four of the five individuals (an older infant, two juveniles and one subadult) were preserved in the bone assemblage; a neonate was entirely consumed. Cranial and mandibular fragments had the highest survivorships, followed by the scapulae and long bones. Post-cranial axial elements had the lowest survivorships. A high percentage (80%) of the long bones and ribs surviving consumption were damaged, most commonly through crenulation and step fracturing of bone ends. One of two partially reconstructed crania preserves a canine puncture through its left parietal. Proposed characteristics of faunal assemblages formed through chimpanzee-like hunting include small modal prey size, limited taxonomic diversity, a high proportion of immature individuals and a high frequency of skull bones. These characteristics would not uniquely identify hunting by fossil primates in the geological record, necessitating a contextual approach to diagnose hunting by hominids not forming an archeological record. Hominid utilization of vertebrate tissue is first unambiguously documented at 2.5 m.y.a. Rather than representing a strict "scavenging phase" in the evolution of hominid-prey interactions, Oldowan hominid carnivory may represent the overlay of large mammal scavenging on a tradition of small mammal hunting having a low archeological visibility.

Animals↗
PubMed1991

Adductor pollicis. The missing interosseous.

This paper highlights the many similarities between the adductor pollicis and the palmar interossei. In particular it compares their anatomy, innervation and function. It suggests that adductor pollicis should be considered as the first palmar interosseous and that this view simplifies the teaching of hand anatomy and the tests of ulnar nerve function. Further support for the view that adductor pollicis is the thenar counterpart of the second, third and fourth palmar interossei is gained from studies of the literature on hand evolution, in particular published details of fossil records and dissection of primate hands.

Animals↗
PubMed1998

Evolutionary history of lorisiform primates.

We integrate information from the fossil record, morphology, behavior and molecular studies to provide a current overview of lorisoid evolution. Several Eocene prosimians of the northern continents, including both omomyids and adapoids, have been suggested as possible lorisoid ancestors, but these cannot be substantiated as true strepsirhines. A small-bodied primate, Anchomomys, of the middle Eocene of Europe may be the best candidate among putative adapoids for status as a true strepsirhine. Recent finds of Eocene primates in Africa have revealed new prosimian taxa that are also viable contenders for strepsirhine status. Plesiopithecus teras is a Nycticebussized, nocturnal prosimian from the late Eocene, Fayum, Egypt, that shares cranial specializations with lorisoids, but it also retains primitive features (e.g. four premolars) and has unique specializations of the anterior teeth excluding it from direct lorisiform ancestry. Another unnamed Fayum primate resembles modern cheirogaleids in dental structure and body size. Two genera from Oman, Omanodon and Shizarodon, also reveal a mix of similarities to both cheirogaleids and anchomomyin adapoids. Resolving the phylogenetic position of these Africa primates of the early Tertiary will surely require more and better fossils. By the early to middle Miocene, lorisoids were well established in East Africa, and the debate about whether these represent lorisines or galagines is reviewed. Neontological data are used to address the controversial branching sequences among extent lorisid clades. Data from the skin and scent glands, when integrated with other lines of evidence, suggest that Asian and African lorisines share a common lorisine ancestry. The hypothesis of an African clade containing both pottos and galagos to the exclusion of Asian lorisines is less tenable. True galagines are found in the fossil record of Namibia, while true lorisines are known from the Miocene of Asia. The hypothetical branching sequences can be integrated with behavioral and morphological features to develop an adaptive model of lorisoid divergence. By specializing on two different foraging modes early in their radiation, lorisines and galagines subsequently underwent a chain of integrated evolutionary changes eventually having an impact on many components of locomotor behavior, anatomy, physiology, reproduction, life history, and social behavior. Ongoing evolutionary studies of extant galagines are illuminating population phenomena and processes of speciation in an ecological context.

Africa↗
PubMed1997

Cranial shape in fruit, nectar, and exudate feeders: implications for interpreting the fossil record.

At least 29 species of fossil primates have been referred to fruit, nectar, and/or exudate feeding dietary niches. Many studies have detailed the morphological correlates of fruit feeding in comparison to insectivory and folivory. In contrast, few studies have sought to differentiate the morphological correlates of fruit feeding from those of nectar and exudate feeding. This study investigates the differences between fruit, nectar, and exudate feeders using 22 cranial and dentary shape variables representing 28 species of living marsupials, bats, and primates. Discriminant function analysis is used to investigate the differences between these dietary categories using both the complete data set and a reduced data set composed of variables that might reasonably be available from fragmentary fossil material. The success rates of post-hoc classifications are 94 and 88%, respectively. These results demonstrate that it is possible to discriminate among fruit, nectar, and exudate feeders among fossil taxa with a reasonable degree of certainty using the data and techniques outlined here. Nectar feeders exhibit a unique combination of features that are associated with reduced masticatory strength and their role as pollination agents. Exudate feeder skulls and dentaries exhibit a combination of features that reflect the high stresses encountered by the anterior dentition through bark gouging behavior. Fruit feeders are morphologically diverse, exhibiting cranial and mandibular shape values that overlap with both nectar and exudate feeders. It is suggested that this diversity reflects the variety of physical properties represented among fruits, and the tendency for individual frugivore species to specialize on particular fruits.

Animals↗
PubMed1992

Earliest known simian primate found in Algeria.

The record of early fossil Simiiformes (Anthropoidea) from the Late Eocene and Early Oligocene of Africa and the Arabian Peninsula has increased dramatically in recent years. We report here the discovery of a new, diminutive and much older (Early or Middle Eocene) simian from an Algerian locality, Glib Zegdou. This species is smaller than any other living or fossil African simiiform. Derived similarities shared with Aegyptopithecus suggest that the new genus is more closely related to propliopithecines than to oligopithecines, implying that these two subfamilies differentiated during the Early Eocene. The new discovery confirms predictions about the great antiquity of Simiiformes and emphasizes a long and endemic African history for higher primates.

Algeria↗
PubMed2005

Adaptive origins of primates revisited.

Interpretation of the adaptive profile of ancestral primates is controversial and has been constrained for decades by general acceptance of the premise that the first primates were very small. Here we show that neither the fossil record nor modern species provide evidence that the last common ancestor of living primates was small. Instead, comparative weight distributions of arboreal mammals and a phylogenetic reconstruction of ancestral primate body mass indicate that the reduction of functional claws to nails -- a primate characteristic that had up until now eluded satisfactory explanation - resulted from an increase in body mass to around 1000 g or more in the primate stem lineage. The associated shift to a largely vegetarian diet coincided with increased angiosperm diversity and the evolution of larger fruit size during the Late Cretaceous.

Adaptation, Physiological↗
PubMed2003

Rates of DNA duplication and mitochondrial DNA insertion in the human genome.

The hundreds of mitochondrial pseudogenes in the human nuclear genome sequence (numts) constitute an excellent system for studying and dating DNA duplications and insertions. These pseudogenes are associated with many complete mitochondrial genome sequences and through those with a good fossil record. By comparing individual numts with primate and other mammalian mitochondrial genome sequences, we estimate that these numts arose continuously over the last 58 million years. Our pairwise comparisons between numts suggest that most human numts arose from different mitochondrial insertion events and not by DNA duplication within the nuclear genome. The nuclear genome appears to accumulate mtDNA insertions at a rate high enough to predict within-population polymorphism for the presence/absence of many recent mtDNA insertions. Pairwise analysis of numts and their flanking DNA produces an estimate for the DNA duplication rate in humans of 2.2 x 10(-9) per numt per year. Thus, a nucleotide site is about as likely to be involved in a duplication event as it is to change by point substitution. This estimate of the rate of DNA duplication of noncoding DNA is based on sequences that are not in duplication hotspots, and is close to the rate reported for functional genes in other species.

Animals↗
PubMed2006

Environment and evolution through the Paleocene-Eocene thermal maximum.

The modern orders of mammals, Artiodactyla, Perissodactyla and Primates (APP taxa), first appear in the fossil record at the Paleocene-Eocene boundary, c. 55 million years ago. Their appearance on all three northern continents has been linked to diversification and dispersal in response to rapid environmental change at the beginning of a worldwide 100 000-200 000-year Paleocene-Eocene thermal maximum (PETM) and carbon isotope excursion. As I discuss here, global environmental events such as the PETM have had profound effects on evolution in the geological past and must be considered when modeling the history of life. The PETM is also relevant when considering the causes and consequences of global greenhouse warming.

Animals↗
PubMed1996

Evolution of eutherian cytochrome c oxidase subunit II: heterogeneous rates of protein evolution and altered interaction with cytochrome c.

Cytochrome c oxidase subunit II (COII), encoded by the mitochondrial genome, exhibits one of the most heterogeneous rates of amino acid replacement among placental mammals. Moreover, it has been demonstrated that cytochrome c oxidase has undergone a structural change in higher primates which has altered its physical interaction with cytochrome c. We collected a large data set of COII sequences from several orders of mammals with emphasis on primates, rodents, and artiodactyls. Using phylogenetic hypotheses based on data independent of the COII gene, we demonstrated that an increased number of amino acid replacements are concentrated among higher primates. Incorporating approximate divergence dates derived from the fossil record, we find that most of the change occurred independently along the New World monkey lineage and in a rapid burst before apes and Old World monkeys diverged. There is some evidence that Old World monkeys have undergone a faster rate of nonsynonymous substitution than have apes. Rates of substitution at four-fold degenerate sites in primates are relatively homogeneous, indicating that the rate heterogeneity is restricted to nondegenerate sites. Excluding the rate acceleration mentioned above, primates, rodents, and artiodactyls have remarkably similar nonsynonymous replacement rates. A different pattern is observed for transversions at four-fold degenerate sites, for which rodents exhibit a higher rate of replacement than do primates and artiodactyls. Finally, we hypothesize specific amino acid replacements which may account for much of the structural difference in cytochrome c oxidase between higher primates and other mammals.

Amino Acids↗
PubMed1999

Siamopithecus eocaenus, a late Eocene anthropoid primate from Thailand: its contribution to the evolution of anthropoids in Southeast Asia.

Dental remains of a late Eocene anthropoid primate from Thailand, Siamopithecus eocaenus, have been recently reported; complete description and comparisons of this material are given here. Siamopithecus displays several derived dental features that suggest close phylogenetic affinities among the Thai species, the Burmese Pondaungia, and the North African and Omani propliopithecines Aegyptopithecus and Moeripithecus. The geographic origin of anthropoid primates cannot be securely determined at present, but the available fossil record indicates that faunal exchanges between Africa and Southeast Asia were very probable during the Eocene, and that direct relationships between Asian and African anthropoid primates can be inferred.

Animals↗
PubMed1991

The relative rate of DNA evolution in primates.

In 73 relative-rate tests involving the sequences of 17 genes between humans and six nonhuman primate taxa, there is only one significant (P less than 0.01) difference in evolutionary rate--i.e., that between human and Old World-monkey psi eta-globin genes. No evolutionary rate difference between humans and Old World monkeys is evident from analysis of 18 other genes with a total length of 6 kb. This and the comparison, between humans and other primate taxa, of new extended psi eta-globin sequences suggest that earlier observations of evolutionary-rate differences between humans and other primates were based on differences that are peculiar to psi eta-globin and that are not representative of the whole genome, which appears to be evolving at a stochastically uniform rate. This is supported by whole-genome single-copy DNA and mitochondrial DNA comparisons, neither of which shows any evidence of evolutionary-rate variation among primate taxa. Uniformity in the evolutionary rate of the DNA of primate and other mammalian taxa is inconsistent with current mammalian fossil-record interpretation. Either there has been a general slowing down in rate across lineages or the fossil record has been misinterpreted.

Animals↗
PubMedDate not supplied

Wasatchian-Bridgerian (Eocene) paleoecology of the western interior of North America: changing paleoenvironments and taxonomic composition of omomyid (Tarsiiformes) primates.

Many changes in mammalian faunas occurred across the early (Wasatchian) to middle (Bridgerian) Eocene boundary as documented in the fossil record from the Western Interior of North America. One of the more striking changes took place within the tarsiiform primate family Omomyidae. In the early Eocene, omomyids were dominated, both in abundance and diversity, by the subfamily Anaptomorphinae. In the middle Eocene, the subfamily Omomyinae dominated in abundance, while both subfamilies were nearly equally diverse. Examination of a series of paleoecological indicators including leaf-margin analysis, cenogram analysis, ecological diversity analysis of trophic structure, the distribution and development of ancient soil horizons (paleosols), and the distribution of lacustrine and fluvial facies in the Bighorn and southern Green River basins of Wyoming reveals factors that may have influenced the composition of omomyid primates. Subtle but important changes occurred in paleoclimates with mean annual temperatures reaching Cenozoic maximums at the end of the Wasatchian into the early Bridgerian. Both land mammal ages were typified by subtropical, closed forested conditions, but the Bridgerian was probably more humid and wetter than the Wasatchian. Paleohabitats most commonly sampled in the Wasatchian of the Bighorn Basin are proximal and distal floodplains, while those of the Bridgerian in the southern Green River Basin are lake margins and proximal floodplains. Changes in paleoclimate may have triggered a wave of omomyine immigration near the end of the Wasatchian with omomyines entering into habitats previously occupied by anaptomorphines. Lake margin and proximal floodplain habitats are those most commonly occupied by omomyines in the Bridgerian with anaptomorphines being more common in basin margin and distal floodplain areas not commonly sampled. Omomyine immigration and sampling of differing paleohabitats are two possible explanations for the changes documented in omomyid diversity and abundance.

Animals↗
PubMed1993

Fixation times of retroposons in the ribosomal DNA spacer of human and other primates.

We have investigated the presence/absence of two types of retroposed sequences found in human ribosomal DNA in equivalent positions in chimpanzee, gorilla, orangutan, gibbon, and rhesus monkey rDNA. These sequences are one pseudogene derived from the single-copy cdc27hs gene and seven complete Alu elements. The 2-kb pseudogene is present in the apes but not in Old World monkeys, indicating fixation in an ape ancestor. Five of the Alu elements are shared by the whole set of primates studied, indicating insertion and fixation prior to the split of the ape and Old World monkey lineages. One is absent only from the rhesus monkey rDNA, and another is absent from both gibbon and rhesus rDNA, indicating fixation at different times in primate evolutionary history. Since branching times for the primate phylogenetic tree are known from a combination of the fossil record and multiple molecular data sets, it is possible to compare Alu fixation times determined from the phylogenetic information with those calculated from Alu element mutation rates.

Animals↗
PubMed1989

Lightmicroscopical investigations of the sublingua of Microcebus murinus (Cheirogaleidae, Lemuriformes) with remarks on the phylogenetic relations of the tree shrews (Scandentia) to primates.

The sublingua of Microcebus murinus was studied gross anatomically and light microscopically. The apex of the sublingua ends in two lobe-like projections separated by a distinct median cleft. The lobes exhibit at their oral, free margin tiny processes, but no "comb"-like specializations of intensely keratinized mucosa. At the ventral surface of the sublingua three longitudinally oriented keels or ridges are found; the mucosa of the keels is strongly keratinized, so that these structures maximize the rigidity of the undertongue. In none of the specimens examined was any trace of sublingual cartilage found; in the sublingua of Cheirogaleus (only one individual examined), the nearest relative of Microcebus, cartilage was also absent. The absence of sublingual cartilage and the incidental, irregular occurrence of cartilaginous elements in the sublingua of Tarsius and Tupaia indicate that the sublingual cartilaginous skeleton is not a derivative of the hyoid arch. It is a newly developed supporting structure which does not regularly occur. A sublingua occurs only in prosimians and Tarsius; whether the fimbria linguae of the Hominoidea is the homologue of a sublingua is still disputable. The exclusive occurrence of a sublingua in prosimians and Tarsius indicates a phylogenetic relationship between these two groups and Tupaia. The "Tupaia-problem" concerns the origin of primates and from this point it derives its general importance. At present we are far from a final solution; a definite answer cannot be expected before sufficient fossil records are available which document conclusively the historical paths of the origin of primates.

Animals↗
PubMed2007

New Paleocene skeletons and the relationship of plesiadapiforms to crown-clade primates.

Plesiadapiforms are central to studies of the origin and evolution of primates and other euarchontan mammals (tree shrews and flying lemurs). We report results from a comprehensive cladistic analysis using cranial, postcranial, and dental evidence including data from recently discovered Paleocene plesiadapiform skeletons (Ignacius clarkforkensis sp. nov.; Dryomomys szalayi, gen. et sp. nov.), and the most plesiomorphic extant tree shrew, Ptilocercus lowii. Our results, based on the fossil record, unambiguously place plesiadapiforms with Euprimates and indicate that the divergence of Primates (sensu lato) from other euarchontans likely occurred before or just after the Cretaceous/Tertiary boundary (65 Mya), notably later than logistical model and molecular estimates. Anatomical features associated with specialized pedal grasping (including a nail on the hallux) and a petrosal bulla likely evolved in the common ancestor of Plesiadapoidea and Euprimates (Euprimateformes) by 62 Mya in either Asia or North America. Our results are consistent with those from recent molecular analyses that group Dermoptera with Scandentia. We find no evidence to support the hypothesis that any plesiadapiforms were mitten-gliders or closely related to Dermoptera.

Animals↗