Platyrrhine Primates Research Articles

Sexual dimorphism and dental variability in platyrrhine primates

Leutenegger and Cheverud (1982, 1985) propose a hypothesis to explain why larger primates are more sexually dimorphic in body weight and canine size. Their hypothesis states that any factor selecting for an evolutionary increase in body size will produce an increase in sexual dimorphism in any character if either heritability or phenotypic variability is greater in males than in females for that character. They cite no evidence for heritability but give some data to suggest that males are, in fact, more variable than females. We test the latter proposition more fully using measurements on the dentitions of platyrrhine primates. Male and female phenotypic variances are not significantly different in most cases. Cases of greater male phenotypic variance are not limited to sexually dimorphic species. We conclude that the hypothesis of Leutenegger and Cheverud does not explain the observed patterns of dental sexual dimorphism, at least in platyrrhines.

Postcranial adaptations of the earliest platyrrhine

A model of the earliest platyrrhine primate is generated as the result of a cladistic analysis of platyrrhine relationships. The morphological features of the postcranium hypothesized as present in this model are analyzed in order to suggest the adaptations and behavioral repertoire of the first platyrrhine. A consistent pattern emerges indicating a grasping, arboreal quadruped, emphasizing walking and running on horizontal supports with only limited leaping or suspensory activities, approximately 1000 g in body mass. It is suggested that this pattern, with only minor changes, also characterized the earliest euprimates. The major derivations in the first platyrrhines were increased body size from a smaller euprimate ancestor, and improvements in stability as arboreal quadrupeds. The fossil record indicates that platyrrhines evolved as a distinct group before reaching South America, with possible relatives remaining behind in Africa.

New specimens of the primateBranisella bolivianafrom the early oligocene of Salla, Bolivia

ABSTRACT Two new specimens of the early Oligocene primate Branisella boliviana have been discovered recently in deposits at Salla, Bolivia. One specimen is a right mandibular fragment with M2 and roots of M3. The other, a right maxillary fragment, includes M1, M2 and the first known M3 for this primate. The M3 is substantially smaller than other upper molars, with a reduced protocone and metacone, and only an incipient hypocone. Three roots are present on all upper molars and two on all lower molars. Although M3 is more complex than M3 of Saimiri, considerable similarities support the assertion that Branisella boliviana is a platyrrhine primate.

Gradistic views and adaptive radiation of platyrrhine primates

Gradistic views and adaptive radiation of platyrrhine primates

Cranial anatomy and implications of Dolichocebus, a late Oligocene ceboid primate

THE very scarce fossil record of Cainozoic New World monkeys(1,2) has contributed little to knowledge of the history of platyrrhine primates, an important element of both the neotropical mammal fauna(3) and the pantropical primates, as a whole. Only the affinities of the Middle Miocene Colombian fossils Neosaimiri, Stirtonia and Cebupithecia seem reasonably well established(4), though not without dissent(5), and these are clearly linked with the modern squirrel, howler and sakiuakari monkeys, respectively. After completion of a survey of the morphology and interrelationships of the platyrrhines, to be detailed elsewhere (A. L. R., in preparation), it is now possible to discuss the evolutionary implications of the terminal Oligocene Dolichocebus gaimanesis of Patagonia, represented by a nearly complete cranium only recently prepared fully, although first described in 1942 (ref. 6). This specimen strongly suggests that Dolichocebus is a member of the Saimiri lineage, which thus becomes the oldest generic lineage known for the primates, dating from about 25 Myr ago(7). Its affinities also imply that the two major monophyletic divisions of Ceboidea were already established by late Oligocene times, as were the marmosets and tamarins.

The Phenetic Position of Pliopithecus and its Phylogenetic Relationship to the Hominoidea

Ciochon, R. L., and R. S. Corruccini (Department of Anthropology, University of California, Berkeley, CA 94720 and Division of Physical Anthropology, Smithsonian Institution, Washington, D.C. 20560) 1977. The phenetic position of Pliopithecus and its phylogenetic relationship to the Hominoidea. Syst. Zool. 26:290-299.-Problems of ascertaining affinities of fossil taxa are explored utilizing the European Miocene primate Pliopithecus vindobonensis as an example. Traditionally, Pliopithecus has been regarded as an ancestral gibbon, yet aspects of its postcranial anatomy contradict this. Current studies provide strong evidence that the forelimb complex of the extant Hominoidea represents a synapomorphic character complex. The shoulder joint of Pliopithecus was therefore compared with 17 species of anthropoid primates using 10 measurements emphasizing the glenohumeral articulation. Multivariate analysis indicates that Pliopithecus conforms in every way with the symplesiomorphic morphopattern shown by extant cercopithecoids and platyrrhine primates but contrasts markedly with extant hominoids, especially the gibbon. It is therefore unlikely that Pliopithecus and Hylobates are directly related. The great similarity of Pliopithecus to the African Miocene primate, Dendropithecus, also sheds doubt on its current hylobatine classification. [Phenetics; phylogenetics; shoulder; multivariate analysis; Pliopithecus.] The accurate assessment of the taxonomic and phylogenetic affinities of fossil taxa has always been a difficult task. Problems arise from inaccurately applied neontological systematics and the disparate usage of various taxonomic philosophies (Schaeffer, Hecht and Eldredge, 1972). The exact nature of the relationship of a particular fossil specimen to other fossil and recent taxa, be it phenetic, cladistic, evolutionary or otherwise, must be expressly stated. If not, misinterpretations may develop and later become the source of futile controversy. An appropriate example can be found in discussions of the European Miocene primate Pliopithecus vindobonensis. The first specimens allocated to the genus Pliopithecus were discovered as long ago as the early part of the middle 19th century (Lartet, 1837; Blainville, 1840; Gervais, 1845). Today, Pliopithecus ranks as perhaps the best known Neogene fossil primate, being represented by 3 partial skeletons and hundreds of isolated cranial and dental elements. Yet the phylogenetic affinities of this primate are still the subject of much recent speculation (Groves, 1972, 1974; Tuttle, 1972; Frisch, 1973; Simons and Fleagle, 1973; Morbeck, 1972, 1975; Feldesman, 1975; Delson, 1975, 1976; Delson and Andrews, 1975). When only dental remains of Pliopithecus were known, it was widely believed to be a small hominoid primate ancestral to the extant Hylobatinae (Lartet, 1837; Hiirzeler, 1954; Piveteau, 1957). Others who studied the dentition, however, did notice certain primitive features such as a strong buccal cingulum, frequent occurrence of a paraconid on M1, distal position of the metaconid, existence of a direct hypoconid-protoconid ridge and the tendency of the talonid to be broader than the trigonid (Ferembach, 1958; Remane, 1965; Groves, 1972). With the discovery of the 3 partial skeletons of Pliopithecus in the middle Miocene (Vindobonian or Badenian in current local terminology) deposits of Czechoslovakia, a reassessment of the genus took place. However, the outcome was very similar to the traditional long standing view (Zapfe, 1958, 1960; Simons, 1964, 1969) despite the presence of such primitive postcranial features as a low intermembral index, unspecialized hand pha-

Morphometric analysis of platyrrhine femora with taxonomic implications and notes on two fossil forms

Postcranial elements have been relatively neglected in primate evolutionary studies, especially for platyrrhine primates. We have analyzed 38 variables of the femur in 92 specimens of fossil and extant platyrrhines to determine patterns of shape affinity for comparison with other, more traditional information. Callitrichids ∗ and advanced cebids were separated along a morphological continuum bridged by the more generalized cebids ( Cebus, Callicebus, Saimiri, Aotus). Callitrichids were very closely interrelated and included Callimico as an integral member. Pithecines ( Pithecia, Chiropotes and Cacajao) and atelines ( Ateles, Brachyteles, Lagothrix plus Alouatta) form two clusters with considerably greater intra-group variability, inferentially related to the great adaptive radiation and changes undergone by these groups. Two fossil specimens, Homunculus and Cebupithecia, are significantly divergent from all extant ceboids but are nearest callitrichids, lying at the extreme callitrichid pole as that grade is contrasted with cebids.

Additional evidence for the Precolumbian migration of Black African peoples to the American continent

Evolutionary approaches to the identification of DNA sequences required for transcription of the genes of the β-globin cluster are reviewed. Sequence alignments of non-coding regions from widely divergent species revealed many conserved motifs (phylogenetic footprints) that were putative transcription factor binding sites and candidate binding proteins were identified. The differential timing of the prosimian and simian γ-globin genes was analyzed by identifying base changes in the vicinity of the phylogenetic footprints. These differential phylogenetic footprints were shown to bind different nuclear factors, and the behavior of constructs with human or galago γ-promoters in transgenic mice indicated that DNA motifs near the γ-globin genes are sufficient to determine the developmental stage of expression. Locus control region alignments have identified many conserved sequence differences outside of the hypersensitive sites. Globin protein and mRNA expression profiles during embryological development in a series of catarrhine (Old World monkeys and apes) and platyrrhine (New World monkeys) primates have been determined. While all catarrhines examined to date have globin expression patterns that are highly similar to the well-established human switching behavior, platyrrhines have inactivated their γ1 genes by a variety of mechanisms, and have an earlier γ–β switch.