Primate Fossil Record Research Articles

EVOLUTIONARY DYNAMICS OF VERTEBRATE BODY MASS RANGE

Change in body mass with time has been considered for many clades, often with reference to Cope's rule, which predicts a tendency to increase in body size. A more general rule, namely increase in the range of body mass with time, is analyzed here for vertebrates. The log range of log vertebrate body mass is shown to increase linearly and highly significantly with the log of duration of clade existence. The resulting regression equations are used to predict the origin age, initial body mass, and subsequent dynamics of body mass range for primate clades such as the New World monkeys (Platyrrhini, 32 million years ago, initial mass of 1.7 kg) and the Anthropoidea (57 million years ago, initial mass of 0.12 kg), tested against the primate fossil record. Using these methods, other major primate clades such as Lemuriformes and Adapoidea are also estimated to have originated in the Tertiary (63 and 64 million years ago, respectively), with only the Plesiadapiformes originating in the Cretaceous (83 million years ago). Similarities of body mass range between primate and other vertebrate sister groups are discussed. Linear relationships of log range and log duration are considered with respect to Brownian processes, with the expected regression coefficients from the latter explored through simulations. The observed data produce regression coefficients that overlap with or are higher than those under Brownian processes. Overall, the analyses suggest the dynamics of vertebrate body mass range in morphologically disparate clades are highly predictable over many tens of million years and that the dynamics of phenotypic characteristics can assist molecular clock and fossil models in dating evolutionary events.

Correlates of body mass evolution in primates

Body mass is undoubtedly central to the overall adaptive profile of any organism. Despite this, very little is known of what forces drive evolutionary changes in body mass and, consequently, shape patterns of body mass distribution exhibited by animal radiations. The search for factors that may influence evolutionary processes in general frequently focuses on environmental parameters such as climate change or interspecific competition. With respect to body mass, there is also the suggestion that evolutionary lineages may follow an inherent trend toward increased body mass, known as Cope's rule. The present paper investigates whether overall directional trends of body mass change, or correlations between patterns of body mass evolution and environmental factors have influenced the evolution of body mass in plesiadapiforms and primates. Analyses of the global fossil record of plesiadapiforms and primates suggest that the former did indeed follow an overall trend toward increased body mass compatible with the predictions of Cope's rule. In contrast, neither primates as a whole, nor a number of individual primate radiations (Adapiformes, Omomyiformes, and Anthropoidea), show any indication of overall directional patterns of body mass change. No correlations of primate body mass change with either the latitudinal distribution of fossil species, or with estimates of global temperature trends, were found. There is evidence, however, that direct competition between omomyiforms and adapiforms (the two main primate radiations known from the Paleogene) influenced processes of body mass evolution in omomyiforms.

Deep Time and the Search for Anthropoid Origins

Recent fossil discoveries, phylogenetic analyses, revised reconstructions of continental drift, and accumulating molecular evidence have all yielded new information relating to anthropoid origins within the broader context of primate evolution. There is an emerging consensus among molecular studies that four superorders of eutherian mammals can be recognized: Afrotheria, Euarchontoglires (to which primates belong), Laurasiatheria, and Xenarthra. Overall, molecular phylogenies for mammals agree with some statistical analyses of the primate fossil record in indicating an early origin for primates around 85 Ma ago, and the divergence of haplorhines and strepsirrhines at ca. 77 Ma. Such an ancient date for the origin of haplorhines is some 17 Ma prior to the first known possible primate, and some 22 Ma before the earliest fossil evidence of undoubted euprimates. Because anthropoid fossils date back at least to the late Eocene and perhaps to the middle Eocene, and given indications of an early origin for primates, it is unlikely that ancestral anthropoids arose within any other currently known clade of fossil primates (adapiforms, omomyiforms, strepsirrhines, or tarsiiforms). Implications of new molecular, morphological, and biogeographic lines of evidence are explored with respect to the likely time and place of the origin of anthropoids. Four competing, testable hypotheses are reviewed in detail: 1) the Paratethyan hypothesis, 2) the continental Asian hypothesis, 3) the Indo-Madagascar hypothesis, and 4) the African hypothesis. A case is made that current evidence best supports a relatively ancient Gondwanan origin for primates, as well as a Gondwanan (African or Indo-Madagascan) origin for anthropoids at least as old as that of any other currently documented major primate clade. Available fossil evidence at present seems to be most compatible with the African hypothesis, but it is noteworthy that primates are included not in Afrotheria but in Euarchontoglires.

The primate fossil record

The primate fossil record

The Primate Fossil Record

W. C. Hartwig (ed.). 2002. The Primate Fossil Record. Cambridge University Press, Cambridge, United Kingdom, 530 + xiv pp. ISBN 0-521-66315-6, price (cloth), $175.00. This valuable new volume challenges significant components of the normal view of primate history. In Chapter 1, the editor briefly comments that “… fossil primates have always been interpreted in light of how they might relate to living ones. Whether this tendency stems from scientific insight or myopia, a framework of closely related forms and conservative phylogenies has persevered.” In the normal view (e.g., Clark 1959; Eisenberg 1981; Fleagle 1999), the earliest primates were Plesiadapiformes (or were closely related to them) that “took to the trees” at the end of the Cretaceous. The suborder Prosimii emerged in the Eocene, and ancestral Anthropoidea diverged in the Late Eocene in Africa. Derived African anthropoids of the Oligocene that retained only 2 premolars founded our infraorder Catarrhini. The super-family Hominoidea radiated in East Africa and Eurasia beginning in the early Miocene, but by the Pliocene, specialized Cercopithecoidea (Old World monkeys) had replaced most hominoids. A bipedal African hominoid begat the family Hominidae during climatic perturbations of the Plio-Pleistocene. Fieldwork and analysis by the contributors to this book over the last 2 decades have revised several key points of this view, but the editor (Chapter 1) makes it clear that the volume is not a new synthesis of fossil and living primate sys-tematics. Instead, multiple systematic inferences coexist, supported by conflicting interpretations of the same evidence. Following the brief introduction, Rasmus sen reviews current functional models for the origin of the primates by reprising his observations of Caluromys derbianus to address 2 competing hypotheses, that primates were initially successful “visual predators” (Cartmill 1972) and that primates initially exploited fruits at terminal branches of …

Review of “The Primate Fossil Record”

Review of “The Primate Fossil Record”

The primate fossil record

The primate fossil record

The Primate fossil record

Preface Acknowledgements 1. Introduction to the primate fossil record Walter Carl Hartwig 2. The origin of primates David Tab Rasmussen Part I. The Earliest Primates and the Fossil Record of Prosimians: 3. The earliest fossil primates and the evolution of prosimians Herbert H. Covert 4. Adapiformes: phylogeny and adaptation Daniel L. Gebo 5. Tarsiiformes: evolutionary history and adaptation Gregg F. Gunnell and Kenneth D. Rose 6. Fossil lorisoids Erica Phillips and Alan C. Walker 7. Quaternary fossil lemurs Laurie R. Godfrey and William L. Jungers Part II. The Origin and Diversification of Anthropoid Primates: 8. The origin and diversification of anthropoid primates - introduction Marian Dagosto 9. Basal anthropoids K. Christopher Beard 10. Platyrrhine paleontology and systematics: the paradigm shifts Alfred L. Rosenberger 11. Early platyrrhines of southern South America John G. Fleagle and Marcelo F. Tejedor 12. Miocene platyrrhines of the northern neotropics Walter Carl Hartwig and D. Jeffrey Meldrum 13. Extinct Quaternary platyrrhines of the Greater Antilles and Brazil Ross D. E. MacPhee and Ines Horovitz Part III. The Fossil Record of the Early Catarrhines and Old World Monkeys: 14. Early catarrhines of the African Eocene and Oligocene David Tab Rasmussen 15. The Pliopithecoidea David Begun 16. The Victoriapithecidae, Cercopithecoidea Brenda Benefit and Monte L. McCrossin 17. Fossil Old World monkeys: the Late Neogene radiation Nina G. Jablonski Part IV. The Fossil Record of Hominoid Primates: 18. Perspectives on the Miocene Hominoidea David R. Pilbeam 19. Late Oligocene to Middle Miocene catarrhines from Afro-Arabia Terry Harrison 20. European hominoids David Begun 21. The hominoid radiation in Asia Jay Kelley 22. Middle and Late Miocene African hominoids Steven C. Ward and Dana Duren Part V. The Fossil Record of Human Ancestry: 23. Introduction to the fossil record of human ancestry Henry M. McHenry 24. Earliest hominids Tim D. White 25. Early genus Homo Holly Dunsworth and Alan C. Walker 26. Migrations, radiations and continuity: patterns in the evolution of Middle and Late Pleistocene humans Fred Smith References cited Index.

Reconstructing behavior in the primate fossil record

Reconstructing behavior in the primate fossil record

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.

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.

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. Am J Phys Anthropol 109:33–40. © 1999 Wiley-Liss, Inc.

Turn back the clock

It’s easy to forget, as the universal currency of DNA sequence data continues to drive the field of molecular evolution, that the exchange rate between sequence differences and times of species divergence is ultimately set by that less fashionable commodity, the bone. Through the work of paleontologists and taxonomists, dates of divergence between pairs of animal groups are established; molecular divergence data between the groups’ living descendants then provide a reference by which other species splits can be dated. The validity of these reference dates is therefore crucial, and attention has now been turned to one that has implications for our own species, as it profoundly affects the timings of divergences among the primates. For over 30 years these have rested on an uncertain dating of ⩾30 MYBP (million years before present) for the split between Old World Monkeys (e.g. baboon), and apes and humans. The primate fossil record is particularly poor, so it makes sense to apply other references where it is better: these are the split between artiodactyls (e.g. cow) and cetaceans (whales), at 60 MYBP, and that between equids (e.g. horse) and rhinoceroses (50 MYBP). Contributing a baboon mtDNA sequence as molecular calibrator, Arnason et al.1xMolecular timing of primate divergences as estimated by two nonprimate calibration points. Arnason, U. et al. J. Mol. Evol. 1998; 47: 718–727Crossref | PubMed | Scopus (111)See all References1 recalculate the Old World Monkey – hominoid split at 50 MYBP, thus doubling the times of divergences among the primates: the human – chimp split increases from 5 MYBP to ⩾10 MYBP. All of the dates in human evolution that rely on this divergence will need extending accordingly.

Evolution of alpha 1,3galactosyltransferase and of the alpha-Gal epitope.

Most of the genes studied in humans have homologues in other mammals; however, theα1,3galactosyltransferase (α1,3GT) gene represents a unique exception. Whereas it is highly active in nonprimate mammals, prosimians and New World monkeys (i.e., monkeys of South America), producing one of the most abundant cell surface carbohydrate epitopes, the epitope Galα1–3Galβ1α4GlcNAc-R (termed the α-gal or α-galactosyl epitope), this gene is completely inactive in Old World primates (i.e., humans, apes and Old World monkeys). As discussed below, the inactivation of α1,3GT in ancestral primates was likely to be associated with a catastrophic evolutionary event that led primates of the Old World (i.e., primates of Asia and Africa) into almost complete extinction. Because of this event, humans, apes and Old World monkeys produce very large amounts of a natural antibody against the α-gal epitope. This antibody, termed anti-Gal, constitutes 1% of circulating immunoglobulins and it prevents transplantation of organs or tissues from nonprimate mammals (e.g., pigs) into humans because it readily binds to the α-gal epitopes on such xenografts. It is impossible to determine the actual evolutionary events which have led to inactivation of the α1,3GT gene and suppression of α-gal epitope expression in ancestral Old World primates. However, information on the expression of this epitope in various species, the structure of the α1,3GT pseudogene in primates and the fossil record of primates, enable us to speculate on both the evolutionary period in which α1,3GT gene inactivation occurred, as well as possible causes for this event.

The Cambridge Encyclopedia of Human Evolution

1. Introduction: what makes us human? 2. Patterns of primate evolution 3. The life of primates 4. The brain and language 5. Primate social organisation 6. Human evolution in geological context 7. The primate fossil record 8. Primate genetics and evolution 9. Genetic clues of relatedness 10. Early human behaviour and ecology 11. Human populations, past and present 12. Conclusion: the evolutionary future of humankind.

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.

Soils, time, and primate paleoenvironments

AbstractSoils are the skin of the earth. From both poles to the equator, wherever rocks or sediment are exposed at the surface, soils are forming through the physical and chemical action of climate and living organisms. The physical attributes (color, texture, thickness) and chemical makeup of soils vary considerably, depending on the composition of the parent material and other variables: temperature, rainfall and soil moisture, vegetation, soil fauna, and the length of time that soil–forming processes have been at work. United States soil scientists1 have classified modern soils into ten major groups and numerous subgroups, each reflecting the composition and architecture of the soils and, to some extent, the processes that led to their formation. The physical and chemical processes of soil formation have been active throughout geologic time; the organic processes have been active at least since the Ordovician.2 Consequently, nearly all sedimentary rocks that were deposited in nonmarine settings and exposed to the elements contain a record of ancient, buried soils or paleosols. A sequence of these rocks, such as most ancient fluvial (stream) deposits, provides a record of soil paleoenvironments through time.Paleosols are also repositories of the fossils of organisms (body fossils) and the traces of those organisms burrowing, food–seeking, and dwelling activities (ichnofossils). Indeed, most fossil primates are found in paleosols. Careful study of ancient soils gives new, valuable insights into the correct temporal reconstruction of the primate fossil record and the nature of primate paleoenvironments.

Rates of evolution in the Carnivora (Mammalia): the importance of phylogeny and fossils

Calculations of “rates of evolution” have been applied to a variety of indicators of change within populations, species, or higher taxa. This has led to confusion about taxonomic and temporal scaling, particularly when rates are calculated for supposedly “equivalent” taxonomic ranks, or “higher-level” taxa that are not monophyletic groups. All calculations of rates of evolutionary change require accurate temporal calibration. Even in studies of molecular evolution that assume a “molecular clock”, the rate at which any clock ticks must be calibrated empirically by fossil data on the age of divergence of some taxa.Molecular clock rates for all Mammalia generally have been calculated from the primate fossil record and phylogeny. However, rates of molecular evolution have been shown to vary both within and among different clades. Given a preference for a more rigorous system in which molecular divergence is not assumed to occur at a constant rate, the time of divergence should be determined directly for all clades in studies of molecular “rates of evolution”.The mammalian order Carnivora is a monophyletic group widely cited in studies of evolutionary tempo, and mode. However, few of those rate studies have considered explicitly the roles of fossil taxa and rigorously tested phylogenies. For example, phylogenetic placement of early Cenozoic Carnivora (generally placed in the paraphyletic “stem-group” “Miacoidea”), relative to the two major clades of living Carnivora (Caniformia and Feliformia), profoundly influences estimates of the age of cladogenetic divergence for clades of living carnivorans. If all the taxa placed within the “Miacoidea” lie outside a restricted clade of Carnivora (defined as the most recent common ancestor of extant Carnivora, and all of its descendants), then the oldest Carnivora (“neocarnivorans”) are late Eocene (about 35–40 Ma). However, if miacid “miacoids” are caniforms and viverravid “miacoids” are feliforms, then the Caniformia/Feliformia (=Carnivora) clade is at least as old as the oldest “miacoid” (middle Paleocene, or >60 Ma). The implications for calculations of rates of evolution within Carnivora are obvious. Similarly, many fossil Carnivora taxa have been assigned to living families, although the phylogenetic relationships of both fossil and living taxa within most of these families has been poorly understood. This presentation will consider: 1) minimum estimates of clade divergence time, based on current hypotheses of carnivoran phylogeny (emphasizing placement of fossil taxa) and oldest occurrence of fossils within a clade or its sister group- traditional taxonomies both underestimate (e.g. Caniformia/Feliformia) and overestimate (e.g. some living families, such as Viverridae) clade divergence times; and 2) calculation of rates of evolution within Carnivora, focusing on taxonomic diversification and molecular divergence, comparison of rates calculated using traditional taxonomies and artificial “higher-taxa” categories versus those using phylogenetic clades (“unranked”), and the effects of fossil taxa.

Primate origins and evolution: a phylogenetic reconstruction

A survey of living primates the primate fossil record classification and phylogenetic reconstruction adaptive radiation of mammals are tree-shrews primates? primate diets and dentitions the skull and major sense organs evolution of the primate central nervous system primate reproductive biology primate locomoter patterns evidence from chromosomes and proteins a provisional synthesis.

Problems of body-weight estimation in fossil primates

Body-weight estimates of fossil primates are commonly used to infer many important aspects of primate paleobiology, including diet, ecology, and relative encephalization. It is important to examine carefully the methodologies and problems associated with such estimates and the degree to which one can have confidence in them. New regression equations for predicting body weight in fossil primates are given which provide body-weight estimates for most nonhominid primate species in the fossil record. The consequences of using different subgroups (evolutionary “grades”) of primate species to estimate fossil-primate body weights are explored and the implications of these results for interpreting the primate fossil record are discussed. All species (fossil and extant) were separated into the following “grades”: prosimian grade, monkey grade, ape grade, anthropoid grade, and all-primates grade. Regression equations relating lower molar size to body weight for each of these grades were then calculated. In addition, a female-anthropoid grade regression was also calculated for predicting body weight infernales of extinct, sexually dimorphic anthropoid species. These equations were then used to generate the fossil-primate body weights. In many instances, the predicted fossil-primate body weights differ substantially from previous estimates.