SEARCH · PubMed Health

Results for “Primate fossil record”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed1993

Primate origins: plugging the gaps.

Recent discoveries of fossil primate specimens have produced several surprises and challenged prevailing views of early primate evolution. Plesiadapiformes, long regarded as 'archaic primates', may perhaps be linked to the peculiar colugos instead. Inferred relationships of the earliest known undoubted primates (adapids and omomyids) are in turmoil. Both groups have been proposed as sources for the simian primates. Although the origin of the simian primates is obscure, new fossil evidence could push it further back by at least 10 million years. Such uncertainties reflect the low sampling level of the primate fossil record, which can potentially also lead to underestimation of times of origin within the primate tree.

Animals↗

PubMed2000

Estimation of primate speciation dates using local molecular clocks.

Protein-coding genes of the mitochondrial genomes from 31 mammalian species were analyzed to estimate the speciation dates within primates and also between rats and mice. Three calibration points were used based on paleontological data: one at 20-25 MYA for the hominoid/cercopithecoid divergence, one at 53-57 MYA for the cetacean/artiodactyl divergence, and the third at 110-130 MYA for the metatherian/eutherian divergence. Both the nucleotide and the amino acid sequences were analyzed, producing conflicting results. The global molecular clock was clearly violated for both the nucleotide and the amino acid data. Models of local clocks were implemented using maximum likelihood, allowing different evolutionary rates for some lineages while assuming rate constancy in others. Surprisingly, the highly divergent third codon positions appeared to contain phylogenetic information and produced more sensible estimates of primate divergence dates than did the amino acid sequences. Estimated dates varied considerably depending on the data type, the calibration point, and the substitution model but differed little among the four tree topologies used. We conclude that the calibration derived from the primate fossil record is too recent to be reliable; we also point out a number of problems in date estimation when the molecular clock does not hold. Despite these obstacles, we derived estimates of primate divergence dates that were well supported by the data and were generally consistent with the paleontological record. Estimation of the mouse-rat divergence date, however, was problematic.

Animals↗

PubMed1999

Cranial capacity and performance on delay-response task correlated with principal sulcus length in monkeys.

During the process of evolution, a selective advantage may have been gained by organisms that had the ability to utilize mentally stored information of a stimulus rather than the stimulus itself. The ability to temporarily store and mentally operate on stimulus information is often termed "working memory." Within the neocortex of primates, the functional anatomic subdivision surrounding the principal (rectus) sulcus plays an important role in modulating the performance of delay-response tasks in monkeys (representing working memory). However, it appears that no study has investigated the direct relationship between the length of the principal sulcus and performance on a delay-response task. Therefore, this paper investigates the relationships between principal sulcus length and performance on delay-response tasks. However, to control for the effect of overall brain size on this relationship, cranial capacity is analyzed with both principal sulcus length and delay-response performance. Results support a consistent and significant correlation between principal sulcus length and performance on delayed-response tasks in a variety of Old World and New World monkeys. Principal sulcus length is also significantly correlated with cranial capacity; however, cranial capacity is not significantly correlated with performance on delayed-response tasks. The results of this investigation provide a method for analyzing cranial capacity and working-memory abilities in select primates based on principal sulcus length, and may prove useful for interpreting endocasts in the primate fossil record.

Animals↗

PubMed1997

A new Late Eocene anthropoid primate from Thailand.

The fossil record of anthropoid primates from the Middle Eocene of South Asia is so far restricted to two genera (Pondaungia cotteri Pilgrim, 1937 and Amphipithecus mogaungensis Colbert, 1937 from the Eocene Pondaung deposits of Burma) whose anthropoid status and phylogenetic position have long been under debate because they represent the oldest highly derived fossil primates of anthropoid grade. Moreover, several new African taxa, some of which are even older, have been recently included in the suborder Anthropoidea, suggesting an African origin for this group. Conversely, new fossil primates recently discovered in China (Eosimias) have been related to the most primitive representatives of Anthropoidea, alternatively suggesting an Asian origin and a probable Asian radiation centre. We report here the discovery of a new anthropoid from the Thai Late Eocene locality of Krabi, which displays several additional anthropoid characters with regard to those of the Eocene Burmese genera. This species, which is about the size of the Fayum Aegyptopithecus, can be related to the Burmese forms, and it further provides strong additional evidence for a southeast Asian evolutionary centre for anthropoids.

Animals↗

PubMed2026

Parting ways: Pan-Homo divergence revisited.

The timing of divergence between hominins and the bonobo-chimpanzee clade has been at the core of palaeoanthropological debate for over a century. The earliest molecular studies indicated divergence times ranging from 5 Ma to as recently as 1.3 Ma. This study critically reviews the trends of time estimates published between 1967 and 2023, and analyses how these are supported or rejected by the current molecular and fossil records. We compiled 202 divergence estimates and defined three distinct thresholds based on fossil evidence at 4.4 Ma (Australopithecus anamensis and Ardipithecus ramidus), 6.2 Ma (Orrorin tugenensis and Ardipithecus kadabba), and 7.2 Ma (Sahelanthropus tchadensis). We then used these thresholds to filter out molecular estimates that are too young to fit the fossil record. Overall, the data suggests a divergence event within the late Miocene, with each threshold pushing it further back, 8.63-6.38, 10.33-7.81, and 10.95-8.81 Ma, respectively. We use a quadratic regression to demonstrate that estimates have been slowly shifting from ~ 6 Ma to ~ 8.5 Ma over the past 56 years. A Bayesian meta-analysis of genomic estimates filtered by our most consensual threshold (i.e., assuming Australopithecus belongs to Hominini) indicates that the split must have occurred early in the late Miocene, most likely before 7 Ma (~ 99.5% posterior probability) with a pooled effect of 8.69-7.28 Ma. We conclude that, despite an initial bias towards younger estimates, the molecular timing for the last common ancestor (LCA) of Pan-Homo has been progressively approaching the intervals suggested by the current fossil record.

Animals↗

PubMed1986

Temporal scaling of molecular evolution in primates and other mammals.

Molecular clocks are routinely tested for linearity using a relative rate test and routinely calibrated against the geological time scale using a single or average paleontologically determined time of divergence between living taxa. The relative rate test is a test of parallel rate equality, not a test of rate constancy. Temporal scaling provides a test of rates, where scaling coefficients of 1.0 (isochrony) represent stochastic rate constancy. The fossil record of primates and other mammals is now known in sufficient detail to provide several independent divergence times for major taxonomic groups. Molecular difference should scale negatively or isochronically (scaling coefficients less than 1.0) with divergence time: where two or more divergence times are available, molecular difference appears to scale positively (scaling coefficient greater than 1.0). A minimum of four divergence times are required for adequate statistical power in testing the linear model: scaling is significantly nonlinear and positive in six of 11 published investigations meeting this criterion. All groups studied show some slowdown in rates of molecular change over Cenozoic time. The break from constant or increasing rates during the Mesozoic to decreasing rates during the Cenozoic appears to coincide with extraordinary diversification of placental mammals at the beginning of this era. High rates of selectively neutral molecular change may be concentrated in such discrete events of evolutionary diversification.

Amino Acid Sequence↗

PubMed1997

Anthropoid origins.

Recent fossil discoveries have greatly increased our knowledge of the morphology and diversity of early Anthropoidea, the suborder to which humans belong. Phylogenetic analysis of Recent and fossil taxa supports the hypotheses that a haplorhine-strepsirrhine dichotomy existed at least at the time of the earliest record of fossil primates (earliest Eocene) and that eosimiids (middle Eocene, China) are primitive anthropoids. Functional analysis suggests that stem haplorhines were small, nocturnal, arboreal, visually oriented insectivore-frugivores with a scurrying-leaping locomotion. A change from nocturnality to diurnality was the fundamental adaptive shift that occurred at the base of the tarsier-eosimiid-anthropoid clade. Stem anthropoids remained small diurnal arborealists but adopted locomotor patterns with more arboreal quadrupedalism and less leaping. A shift to a more herbivorous diet occurred in several anthropoid lineages.

Adaptation, Biological↗

PubMed1991

Intraspecific variation and sexual dimorphism in cranial and dental variables among higher primates and their bearing on the hominid fossil record.

The extent and nature of dental and cranial sexual dimorphisms in extant hominoids have been investigated using reliably sexed samples of Homo sapiens (n = 75), Pan troglodytes (n = 51), Gorilla gorilla (n = 64) and Pongo pygmaeus (n = 43). Seventy nine measurements (35 dental, 16 mandibular and 28 cranial) formed the basis of the study. The patterns of mean differences and dispersions between the taxa were compared across the anatomical regions and the group structures of the separate sex samples were analysed using multivariate (PCA and CVA) analysis. Within and between group variations were compared across the taxa to investigate whether any variables were consistently effective sex or taxonomic discriminators. The study confirmed that there were differences in degree and pattern of sexual dimorphism between the extant higher primates, but the results did not substantiate the distribution of patterns as suggested by Oxnard et al. (1985); in particular there was no evidence of the dispersion differences noted by those authors. There were sufficient consistencies in the behaviour of variables across the four taxa to suggest that all canine dimensions, postcanine crown buccolingual dimensions and mandibular and cranial breadths are generally good sex discriminators, whereas some incisor dimensions, postcanine crown mesiodistal dimensions and facial heights are more effective at discriminating between the four extant taxa included in this study.

Animals↗

PubMed1998

Diversity components of impending primate extinctions.

Many extant species are at risk to go extinct. This impending loss of species is likely to cause changes in future ecosystem functions. Ecological components of diversity, such as dietary or habitat specializations, can be used to estimate the impact of extinctions on ecosystem functions. As an approach to estimate the impact of future extinctions, we tested interdependency between ecological and taxonomic change based on current predictions of extinction rates in primates. We analyzed the ecological characteristics of extant primate faunas having species in various categories of endangerment of extinction and forecasted the future primate faunas as if they were paleontological faunas. Predicting future faunas combines the wealth of ecological information on living primates with large, fossil record-like changes in diversity. Predicted extinction patterns of living primates in Africa, Asia, Madagascar, and South America show that changes in ecology differ among the regions in ways that are not reducible to taxonomic measures. The ecological effects of primate extinctions are initially least severe in South America and larger in Asia and Africa. Disproportionately larger ecological changes are projected for Madagascar. The use of taxonomy as a proxy for ecology can mislead when estimating competence of future primate ecosystems.

Animals↗

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

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↗

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↗