Eric J. Sargis

Yale University | YU · Department of Anthropology

Multiple unlinked genetic loci often provide a more comprehensive picture of evolutionary history than any single gene can, but analyzing multigene data presents particular challenges. Differing rates and patterns of nucleotide substitution, combined with the limited information available in any data set, can make it difficult to specify a model of...

Genetic studies have shown that New York City white-footed mouse (Peromyscus leucopus) populations exhibit substantial genetic structure and high levels of allelic diversity and heterozygos-ity. These studies have also identified mutations and genes involved in the divergence of urban and rural P. leucopus populations. To investigate whether morpho...

Morphometric analyses of the manus skeleton have proven useful in understanding species limits and morphological divergence among tupaiid treeshrews (Scandentia: Tupaiidae). Specimens in these studies are typically limited to mature individuals with fully erupted permanent dentition, which eliminates potentially confounding variation attributable t...

Diverse metatherian and eutherian tarsal remains from the Late Cretaceous (middle-late Turonian) Bissekty Formation, Kyzylkum Desert, Uzbekistan (ca 90 MYA) are described. Their functional and taxonomic properties, along with those of other tarsal evidence, led to a reassessment of polarity hypotheses of therian, metatherian, and eutherian cruroped...

Studies of the effects of habitat fragmentation and degradation on primate positional behavior, strata use, and substrate utilization offer valuable insights into the behavioral and ecological flexibility of primates whose habitats have undergone extensive anthropogenic disturbance. In this study, we evaluated how positional behavior, strata use, a...

Two of the most-studied ecogeographical rules describe patterns of body size variation within species. Bergmann’s rule predicts that individuals have larger body sizes in colder climates (typically at higher latitudes), and the island rule predicts that island populations of small-bodied species average larger in size than their mainland counterpar...

The Lesser Treeshrew, Tupaia minor Günther, 1876, is a small mammal from Southeast Asia with four currently recognized subspecies: T. m. minor from Borneo; T. m. malaccana from the Malay Peninsula; T. m. humeralis from Sumatra; and T. m. sincepis from Singkep Island and Lingga Island. A fifth subspecies, T. m. caedis, was previously synonymized wit...

Tree hyraxes (Dendrohyrax) are one of only three genera currently recognized in Procaviidae, the only extant family in the mammalian order Hyracoidea. Their taxonomy and natural history have received little attention in recent decades. All tree hyrax populations of Guineo-Congolian forests of Africa are currently treated as a single species, Dendro...

The living guenons (Cercopithecini, Cercopithecidae) are speciose and widely distributed across sub-Saharan Africa but are poorly represented in the fossil record. In addition, the craniodental and skeletal similarity of the guenons has hampered the identification of fragmentary material, likely obscuring the taxonomic diversity represented in the...

The Pen-tailed Treeshrew, Ptilocercus lowii Gray, 1848, is a small arboreal mammal from Southeast Asia. It is the only extant species of Ptilocercidae and includes two subspecies: P. l. lowii from Borneo and offshore islands, and P. l. continentis from the Malay Peninsula, Sumatra, and smaller islands, including the Batu and Mentawai Islands. Intra...

The Cretaceous-Paleogene (K-Pg) mass extinction 66 million years ago was characterized by a worldwide ecological catastrophe and rapid species turnover. Large-scale devastation of forested environments resulting from the Chicxulub asteroid impact likely influenced the evolutionary trajectories of multiple clades in terrestrial environments, and it...

The Large Treeshrew, Tupaia tana Raffles, 1821, is a small mammal (~205 g) from Southeast Asia with a complicated taxonomic history. Currently, 15 subspecies are recognized from Borneo, Sumatra, and smaller islands, and many were originally differentiated based on minor pelage differences and small sample sizes. We explored intraspecific variation...

Age is a basic demographic characteristic vital to studies of mammalian social organization, population dynamics, and behavior. To eliminate potentially confounding ontogenetic variation, morphological comparisons among populations of mammals typically are limited to mature individuals (i.e., those assumed to have ceased most somatic growth). In ou...

Objectives: The little known guenon Cercopithecus dryas has a controversial taxonomic history with some recognizing two taxa (C. dryas and C. salongo) instead of one. New adult specimens from the TL2 region of the central Congo Basin allow further assessment of C. dryas morphology and, along with CT scans of the juvenile holotype, provide ontogene...

When sociality evolved and in which groups remain open questions in mammalian evolution, largely due to the fragmentary Mesozoic mammal fossil record. Nevertheless, exceptionally preserved fossils collected in well-constrained geologic and spatial frameworks can provide glimpses into these more fleeting aspects of early mammalian behaviour. Here we...

Treeshrews are small, Indomalayan mammals closely related to primates. Previously, three-dimensional geometric morphometric analyses were used to assess patterns of treeshrew lower second molar morphology, which showed that the positions of molar landmarks covary with intraordinal systematics. Another analysis used dental topographic metrics to tes...

Pencil-tailed Tree Mice (Muridae: Chiropodomys) are small arboreal mammals endemic to the rainforests of Southeast Asia. They are capable of manual and pedal grasping and have nails rather than claws on their pollex and hallux, but their limb morphology has never been analyzed from functional, ecogeographic, or taxonomic perspectives. We compared t...

Objectives: The guenons (tribe Cercopithecini) are a diverse and primarily arboreal radiation of Old World monkeys from Africa. However, preliminary behavioral observations of the lesula (Cercopithecus lomamiensis), a little-known guenon species described in 2012, report it spending substantial amounts of time on the ground. New specimens allow us...

Molar morphology plays a key role in the systematics and behavioral interpretation of fossil taxa, so understanding the developmental patterns that shape occlusal morphology in modern taxa is of central importance to informing analysis of the fossil record. The shape of the outer enamel surface (OES) of a tooth is largely the result of the forming...

The ecology, and particularly the diet, of treeshrews (order Scandentia) is poorly understood compared to that of their close relatives, the primates. This stems partially from treeshrews having fast food transit times through the gut, meaning fecal and stomach samples only represent a small portion of the foodstuffs consumed in a given day. Moreov...

There are a number of ecogeographical “rules” that describe patterns of geographical variation among organisms. The island rule predicts that populations of larger mammals on islands evolve smaller mean body size than their mainland counterparts, whereas smaller-bodied mammals evolve larger size. Bergmann's rule predicts that populations of a speci...

The living guenons (Tribe Cercopithecini) are largely an arboreal radiation, but the recognition of patas, vervets, and L’Hoest’s monkeys as a clade suggests a single evolutionary transition to terrestriality within the tribe. Recently, a new guenon species was discovered in the TL2 region of the Democratic Republic of the Congo, the lesula (Cercop...

Palaechthonid plesiadapiforms from the Palaeocene of western North America have long been recognized as among the oldest and most primitive euarchontan mammals, a group that includes extant primates, colugos and treeshrews. Despite their relatively sparse fossil record, palaechthonids have played an important role in discussions surrounding adaptiv...

Electronic Supplementary Material: Oldest skeleton of a plesiadapiform provides evidence for an exclusively arboreal radiation of stem primates in the Paleocene

Treeshrews (order Scandentia) include 23 currently recognized species of small-bodied mammals from South and Southeast Asia. The taxonomy of the common treeshrew, Tupaia glis, which inhabits the Malay Peninsula south of the Isthmus of Kra, as well as a variety of offshore islands, has an extremely complicated history resulting from its wide distrib...

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009;...

This plot is not part of the published stance but derives from it. The plot shows the number of authors by geographic region (courtesy of Dr. Diego Astua).

Significance Madagascar is a conservation priority because of its unique and threatened biodiversity. Lemurs, by acting as seed dispersers, are essential to maintaining healthy and diverse forests on the island. However, in the past few thousand years, at least 17 lemur species, many of which were inferred seed dispersers, have gone extinct. We out...

Accounts of woolly mammoths (Mammuthus primigenius) preserved so well in ice that their meat is still edible have a long history of intriguing the public and influencing paleontological thought on Quaternary extinctions and climate, with some scientists resorting to catastrophism to explain the instantaneous freezing necessary to preserve edible me...

The authenticity of the fossil horse purportedly served at the 1969 ECAD. (DOCX)

There are five major scenarios that have been advanced to account for the early events in the origination of the order Primates: a transition from terrestriality to arboreality, the adoption of a grasp-leaping mode of locomotion, the evolution of features for visual predation, an adaptation to terminal branch feeding occurring during angiosperm div...

Small-bodied, insectivorous Nyctitheriidae are known in the Palaeogene fossil record almost exclusively from teeth and fragmentary jaws and have been referred to Eulipotyphla (shrews, moles and hedgehogs) based on dental similarities. By contrast, isolated postcrania attributed to the group suggest arboreality and a relationship to Euarchonta (prim...

The Mentawai and Batu Island groups off the west coast of Sumatra have a complicated geological and biogeographical history. The Batu Islands have shared a connection with the Sumatran 'mainland' during periods of lowered sea level, whereas the Mentawai Islands, despite being a similar distance from Sumatra, have remained isolated from Sumatra, and...

The taxonomy of treeshrews (Order Scandentia) has long been complicated by ambiguous morphological species boundaries, and the treeshrews of the Palawan faunal region of the Philippines are no exception. Four named forms in the genus Tupaia Raffles, 1821, have been described from four island groups based on subtle qualitative morphological characte...

Tree-building with diverse data maximizes explanatory power. Application of molecular clock models to ancient speciation events risks a bias against detection of fast radiations subsequent to the Cretaceous-Paleogene (K-Pg) event. Contrary to Springer et al., post–K-Pg placental diversification does not require “virus-like” substitution rates. Even...

The common treeshrew, Tupaia glis, represents a species complex with a complicated taxonomic history. It is distributed mostly south of the Isthmus of Kra on the Malay Peninsula and surrounding islands. In our recent revision of a portion of this species complex, we did not fully assess the population from Java (T. ‘‘glis’’ hypochrysa) because of o...

Pika species generally fall into two eco- types, meadow-dwelling (burrowing) or talus-dwelling, a classification that distinguishes a suite of different eco- logical, behavioral, and life history traits. Despite these differences, little morphological variation has previously been documented to distinguish among ecotypes. The aim of this study was...

To discover interordinal relationships of living and fossil placental mammals and the time of origin of placentals relative to the Cretaceous-Paleogene (K-Pg) boundary, we scored 4541 phenomic characters de novo for 86 fossil and living species. Combining these data with molecular sequences, we obtained a phylogenetic tree that, when calibrated wit...

Treeshrews (order Scandentia) comprise 2 families of squirrel-sized terrestrial, arboreal, and scansorial mammals distributed throughout much of tropical South and Southeast Asia. The last comprehensive taxonomic revision of treeshrews was published in 1913, and a well-supported phylogeny clarifying relationships among all currently recognized exta...

In June 2007, a previously undescribed monkey known locally as "lesula" was found in the forests of the middle Lomami Basin in central Democratic Republic of Congo (DRC). We describe this new species as Cercopithecus lomamiensis sp. nov., and provide data on its distribution, morphology, genetics, ecology and behavior. C. lomamiensis is restricted...

Maximum likelihood tree, TSPY. Phylogram and bootstrap support values (500 replicates) were inferred using GARLI 0.951. The topology is identical to that inferred using a Bayesian approach (Fig. S2). Cercopithecus lomamiensis and C. hamlyni are reciprocally monophyletic. The scale at the bottom is in units of nucleotide substitutions per site. (PDF...

Bayesian tree, TSPY. Phylogram and clade credibility scores were obtained using MRBAYES 3.11. The topology is identical to the ML tree. The scale at the bottom is in units of nucleotide substitutions per site. (PDF)

Maximum likelihood tree, Xq13.3 homolog. The scale at the bottom is in units of nucleotide substitutions per site. (PDF)

Bayesian tree, Xq13.3 homolog. The scale at the bottom is in units of nucleotide substitutions per site. (PDF)

Specimens of Cercopithecus lomamiensis and Cercopithecus hamlyni examined for this study. (PDF)

Genetic samples list. (PDF)