Blythe A. Williams

Anthropoid origins : a phylogenetic analysis

Living Anthropoidea—the group that includes monkeys, apes, and humans—has long been recognized as a monophyletic group among primates diagnosed by a suite of features of the skull, dentition, and postcranium. Likewise it is agreed that there are two monophyletic groups of living anthropoids—the Central and South American Platyrrhini (New World monkeys) and African and Eurasian Catarrhini (Old World monkeys, “apes,” and humans). As well, most paleontologists and neontologists agree that Tarsius is the closest living relative of anthropoids and that strepsirrhines, lemurs and lorises, are more distantly related (but see Eizirik et al., this volume for a different view). Paleontologists also generally accept the following “facts”: The oldest Tarsius relatives occur in the Asian middle Eocene. The oldest undisputed fossil record of anthropoids is from the late Eocene localities in Afro-Arabia. Platyrrhines first appear in the late Oligocene in South America and the catarrhine record is acknowledged by all to include Propliopithecidae from the early Oligocene of Egypt and Oman.

New perspectives on anthropoid origins.

Adaptive shifts associated with human origins are brought to light as we examine the human fossil record and study our own genome and that of our closest ape relatives. However, the more ancient roots of many human characteristics are revealed through the study of a broader array of living anthropoids and the increasingly dense fossil record of the earliest anthropoid radiations. Genomic data and fossils of early primates in Asia and Africa clarify relationships among the major clades of primates. Progress in comparative anatomy, genomics, and molecular biology point to key changes in sensory ecology and brain organization that ultimately set the stage for the emergence of the human lineage.

The oldest Asian record of Anthropoidea

Undisputed anthropoids appear in the fossil record of Africa and Asia by the middle Eocene, about 45 Ma. Here, we report the discovery of an early Eocene eosimiid anthropoid primate from India, named Anthrasimias, that extends the Asian fossil record of anthropoids by 9–10 million years. A phylogenetic analysis of 75 taxa and 343 characters of the skull, postcranium, and dentition of Anthrasimias and living and fossil primates indicates the basal placement of Anthrasimias among eosimiids, confirms the anthropoid status of Eosimiidae, and suggests that crown haplorhines (tarsiers and monkeys) are the sister clade of Omomyoidea of the Eocene, not nested within an omomyoid clade. Co-occurence of Anthropoidea, Omomyoidea, and Adapoidea makes it evident that peninsular India was an important center for the diversification of primates of modern aspect (euprimates) in the early Eocene. Adaptive reconstructions indicate that early anthropoids were mouse–lemur-sized (≈75 grams) and consumed a mixed diet of fruit and insects. Eosimiids bear little adaptive resemblance to later Eocene-early Oligocene African Anthropoidea.

Dental Evidence for Anthropoid Origins

Over the past decade, many new finds of African Eocene and Oligocene monkeys and Holarctic Eocene primates have rekindled long-standing debates concerning the origins and early diversification of the Anthropoidea. These debates have centered around several related questions: 1. Is Anthropoidea a monophyletic group, and, if so, what did the last common ancestor of the anthropoids look like? 2. From which known group of Holarctic primates (if any) did anthropoids evolve? 3. How do known Eocene and Oligocene anthropoids of Africa [Para-pithecidae, Propliopithecidae (Propliopithecus and Aegyptopithecus), Oli-gopithecidae] relate to the Miocene—Recent Platyrrhini and Catarrhini of the New and Old World, respectively?

Levels of Homoplasy in the Evolution of the Mammalian Skeleton

It is commonly believed that there are differences in the evolutionary lability of the crania, dentition, and postcrania of mammals, the latter two being more prone to homoplasy because of strong selective pressures for feeding and locomotion, respectively. Further, because of the fragmentary nature of fossils, phylogenetic analyses of extinct taxa often must utilize characters based on only one of these systems. In this paper the levels of homoplasy (as measured by the consistency index; CI) were compared in characters based on these three anatomical systems in therian mammals. No statistically significant differences were found in the overall CIs of 41 data sets based on dental, cranial, or postcranial characters. Differences in homoplasy within data sets with two or three kinds of data were not statistically significant. These findings suggest that dental, cranial, and postcranial characters can be equally prone to homoplasy and none should be automatically dismissed, disregarded, or systematically weighted in phylogenetic analyses. The level of homoplasy in characters derived from a given region of the skeleton may differ depending on the taxonomic level of the taxa considered. Dental, cranial, and postcranial characters may not constitute “natural” classes, yet examination of the phylogenetic signal of these subsets of data previous to a simultaneous analysis can shed light on significant aspects of the evolutionary process.

The Adaptations of Branisella boliviana, the Earliest South American Monkey

One of the goals of paleoprimatology is to provide adaptive explanations for the origins of evolutionary novelties of the order and its major groups. For such scenarios to be more than,“just-so stories,” like Kipling’s story of how the leopard got its spots, we need to develop and test ideas about the adaptive significance of particular morphological character states that are likely to be preserved in the fossil record. Once the adaptive context of the morphology is fully appreciated, we can go on to make inferences about the behavior of extinct primate species that possessed similar character states. But even when we know with some confidence the adaptive “meaning” of a particular morphological character state and use it to infer the behavior of an extinct species, we must be able to place that extinct species into its phylogenetic context. What is the distribution of the newly identified morphological peculiarity? Is it found in just one extinct species or does it characterize some larger group of species? And what does the distribution of the character state tell us about the ancestral morphological (and inferred behavioral) pattern of primate clades? Therefore, in parallel with the effort to understand adaptation of character states, there must be an effort to reconstruct the phylogenetic pattern of primates.

Darwinius masillae is a strepsirrhine—a reply to Franzen et al. (2009)

* Corresponding author. E-mail address: blythe.williams@duke.edu (B.A. W 1 Crown groups include the common ancestor of liv and all descendants (both living and fossil) of that members of a clade include those taxa that are more c group than they are to its extant sister taxon (Wible 2 In this context, they note that ‘‘Darwinius masillae with early tarsioids, could represent a stem group primates evolved, but we are not advocating this here, n winius or adapoids to be anthropoids’’ (2009:24). We are Franzen et al. are advocating with this statement, but it

Recently Recovered Specimens of North American Eocene Omomyids and Adapids and Their Bearing on Debates about Anthropoid Origins

Most recent reviews of primate evolution recognize that modern primates can be divided into two monophyletic suborders, the Strepsirhini (lemuriforms and lorisiforms) and the Haplorhini (tarsiers, monkeys, apes, and humans). It is also accepted by most researchers that the radiation of modern primate taxa dates to at least the beginning of the Eocene. The earliest occurring animals that appear to be seeded within this radiation belong to the families Adapidae and Omomyidae, the Eocene euprimates (Hoffstetter, 1974; Szalay and Del-son, 1979; Covert, 1986; MacPhee and Cartmill, 1986; Martin, 1986; Wible and Covert, 1987; and Szalay et al., 1987).

New Uintan primates from Texas and their implications for North American patterns of species richness during the Eocene.

New omomyid fossils from the Purple Bench locality of the Devils Graveyard Formation, middle Eocene (Uintan) of southwest Texas, are described. One specimen represents a new genus and species, herein named Diablomomys dalquesti. This new species is allocated to the tribe Omomyini, sister taxon to Omomys and Chumashius. A second specimen represents a range extension of the Utah species Mytonius hopsoni to the Trans-Pecos region of Texas. Previously, only one omomyid species (Omomys carteri) had been documented from Purple Bench and other late Uintan localities in the Devils Graveyard Formation. These new omomyid fossils are of particular significance because Purple Bench is stratigraphically intermediate between the older late Bridgerian/early Uintan localities and the younger Duchesnean localities of Trans-Pecos Texas. With a more southerly location in the continental United States, the Devils Graveyard Formation amplifies our understanding of patterns of North American primate richness at a time when the higher-latitude sites of the western interior were undergoing significant climatic cooling and increases in seasonality with commensurate faunal reorganization. Although the Uintan (approximately 46.5-40Ma) was a time in which anaptomorphine richness decreased dramatically, the results of this analysis suggest that Uintan omomyine richness is higher than was previously appreciated, particularly at lower latitudes.

Fossil Papio Cranium From !Ncumtsa (Koanaka) Hills, Western Ngamiland, Botswana

Three fossils, a cranium of Papio, a cercopithecid frontal bone, and a mandible of juvenile Papio, have been recovered from cave deposits in the !Ncumtsa (Koanaka) Hills of western Ngamiland, Botswana. These specimens are significant because well-preserved crania of Papio are extremely rare in the fossil record outside of South Africa and because this is the first report of fossil primate cranial remains from Botswana. Thermoluminescence dating of surrounding cave matrix indicates an age of ≥317 ± 114 ka, within the Middle Pleistocene, although it may be older. Based on univariate and multivariate analyses, the adult !Ncumtsa specimen falls within the range of variation seen in extant forms of Papio, yet is distinct from any living species/subspecies and represents a new taxon, named here as a new subspecies of Papio hamadryas-Papio hamadryas botswanae.