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9 - Allometric and Phylogenetic Diversity in Lorisiform Orbit Orientation
- from Part I - Evolution, Morphology and the Fossil Record
- Edited by K. A. I. Nekaris, Oxford Brookes University, Anne M. Burrows, Duquesne University, Pittsburgh
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- Book:
- Evolution, Ecology and Conservation of Lorises and Pottos
- Published online:
- 29 February 2020
- Print publication:
- 19 March 2020, pp 113-128
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Summary
There is a rich history of work on paramasticatory and masticatory adaptations underlying phenotypic diversity in the feeding apparatus of lorisiform primates (Dumont, 1997; Nash, 1986a; Ravosa et al., 2010; Vinyard, 2007; Vinyard et al., 2003, 2007; Williams et al., 2002). Related studies have addressed the ontogenetic underpinnings of size-related patterns of craniomandibular covariation in lorisids and galagids, which constitute the two extant families of lorisiforms (Ravosa, 1998, 2007; Ravosa et al., 2010). Despite longstanding interest in the unique circumorbital region of taxa such as the slender loris (Cartmill, 1972), less well known is the role of allometry on variation in the circumorbital form of lorisiform and lemuriform strepsirrhines (Ravosa et al., 2006).
11 - Jaw adductor force and symphyseal fusion
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- By William L. Hylander, Department of Biological Anthropology and Anatomy, Duke University Medical Center, P.O. Box 3170, Durham, NC 27710, USA, Christopher J. Vinyard, Department of Biological Anthropology and Anatomy, Duke University Medical Center, P.O. Box 3170, Durham, NC 27710, USA, Matthew J. Ravosa, Department of Cell and Molecular Biology, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA, Callum F. Ross, Department of Anatomical Sciences, School of Medicine, Health Sciences Center, Stony Brook University, Stony Brook, NY 11794-8081, USA, Christine E. Wall, Department of Biological Anthropology and Anatomy, Duke University Medical Center, P.O. Box 3170, Durham, NC 27710, USA, Kirk R. Johnson, Department of Biological Anthropology and Anatomy, Duke University Medical Center, P.O. Box 3170, Durham, NC 27710, USA
- Edited by Fred Anapol, University of Wisconsin, Milwaukee, Rebecca Z. German, University of Cincinnati, Nina G. Jablonski, California Academy of Sciences, San Francisco
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- Book:
- Shaping Primate Evolution
- Published online:
- 10 August 2009
- Print publication:
- 20 May 2004, pp 229-257
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Summary
Introduction
Research over the last 25–30 years has revealed a considerable amount about the basic mechanisms of mammalian mastication (e.g., van Eijden and Turkawski, 2001; Türker, 2002). This progress has been largely due to the development of new experimental procedures and techniques. On the other hand, there has been relatively little emphasis on employing these procedures and techniques so as to facilitate adaptive explanations for the evolution of the mammalian masticatory apparatus (Herring, 1993). It has been our intent over the last several years to do just that (Ross and Hylander, 1996; Hylander et al., 1998, 2000, 2002, 2003; Ravosa et al., 2000; Vinyard et al., 2001, in press a; Wall et al., 2002; Williams et al., 2003). In recent years the functional morphology of the craniofacial region of primates and other mammals has attracted a significant amount of research interest (Weijs, 1994; Ross and Hylander, 1996, 2000; Spencer, 1998; Anapol and Herring, 2000; Daegling and Hylander, 2000; Dechow and Hylander, 2000; Herring and Teng, 2000; Hylander et al., 2000; Lieberman and Crompton, 2000; Ravosa et al., 2000). This is simply because there continue to be many unanswered research questions or problems. One persistent problem that has received a considerable amount of attention is related to the adaptive significance of symphyseal fusion in mammals. As noted by many, the ossification or fusion of the left and right sides of the lower jaw or dentaries has occurred independently in many different mammalian lineages (e.g., Beecher, 1977).
9 - Evolutionary morphology of the skull in Old World monkeys
- Edited by Paul F. Whitehead, Clifford J. Jolly, New York University
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- Book:
- Old World Monkeys
- Published online:
- 08 October 2009
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- 04 May 2000, pp 237-268
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Summary
Introduction
In an early review of Old World monkeys, Schultz (1970: 41) comments that “In most of their basic morphological characters … Old World monkeys are much more uniform than the other major groups of primates”. On the other hand, cercopithecid subfamilies clearly evince divergent functional specializations of the skull. “Colobines apparently have optimized biteforce magnitudes at the expense of a reduction in jaw gape in order to masticate leaves more efficiently. An increase in jaw gape is … advantageous to more frugivorous and/or terrestrial primates since they eat large food objects, which require extensive incisal preparation, and/or because of canine displays or canine slashing” (Hylander, 1979b:229).
Experimental studies have been instrumental in characterizing dynamic functional determinants of skull form in Old World monkeys and other primates (Luschei and Goodwin, 1974; McNamara, 1974; Hylander, 1979a–c, 1984, 1985; Bouvier and Hylander, 1981; Hylander et al., 1987, 1991a,b, 1992, 1998; Dechow and Carlson, 1990). In turn, morphological studies of cercopithecid subfamilies have greatly enhanced our knowledge of the functional bases of such craniodental variation (Hylander, 1975; Walker and Murray, 1975; Kay, 1978; Kay and Hylander, 1978; Bouvier, 1986a,b; Ravosa, 1988, 1990, 1991a–c, 1996; Lucas and Teaford, 1994).
Some research on the cercopithecid skull emphases the role of phylogeny in channeling morphological variation at the inter-and intra-specific level (Freedman, 1962; Fooden, 1975, 1988, 1990; Cochard, 1985; Cheverud and Richtsmeier, 1986; Leigh and Cheverud, 1991; Ravosa, 1991a,c; Shea, 1992; Richtsmeier et al., 1993; Profant and Shea, 1994; Ravosa and Shea, 1994; Profant, 1995).
Orbit orientation and the function of the mammalian postorbital bar
- Vivian E. Noble, Erica M. Kowalski, Matthew J. Ravosa
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- Journal:
- Journal of Zoology / Volume 250 / Issue 3 / March 2000
- Published online by Cambridge University Press:
- 01 March 2000, pp. 405-418
- Print publication:
- March 2000
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The visual predation hypothesis of primate origins was introduced by M. Cartmill in the 1970s. In outlining a series of predictions regarding changes in orbital orientation, he further posits that the formation of a bony postorbital bar is correlated with greater orbital convergence, which in turn appears to be linked to selection for increased stereoscopic visual acuity in a nocturnal milieu. A series of predictions related to this model is tested in living analogues that vary in postorbital bar formation: felid and herpestid carnivorans and the pteropodid megabats. Bivariate correlations and regressions, ANOVA and ANCOVA are used to assess the intrinsic allometric and non-allometric factors thought to affect two aspects of orbital orientation, convergence and frontation. These angles of orbital orientation are then examined in an effort to determine how they are associated with the development of a postorbital bar. Cartmill suggested that convergent orbits develop from changes in relative orbit diameter and relative interorbital breadth. This study indicates that felids show only weak support for these predictions, while herpestids do not provide support and pteropodids show some support. Instead, in response to natural selection, convergence seems to develop to improve stereoscopic vision and depth perception in nocturnal predators. As predicted, felids show a significant positive relationship between orbital frontation and relative brain size. Analyses in herpestids, however, do not show significant relationships between frontation and relative palate length or relative brain mass. Pteropodids also do not support the model regarding intrinsic frontation factors. In both carnivoran groups, convergence and frontation are positively correlated, whereas they are not correlated in Pteropodidae. In partial contrast to Cartmill's predictions, we found that orbital convergence and/or orbital frontation are generally higher in carnivorans and bats with postorbital bars. Therefore, a greater emphasis on nocturnal stereoscopic visual predation and increased relative brain size both move the orbital aperture out of the plane of the temporal fossa and a postorbital bar thus provides adequate rigidity to the lateral orbital margin. In the more encephalized Felidae, orbital frontation is positively correlated with relative brain size; as smaller mammals have relatively larger brains, this explains why postorbital bars tend to be found in smaller felids. In herpestids and pteropodids, postorbital bars tend to occur in larger taxa which are more convergent than smaller forms.