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The Taxonomic and Phylogenetic Affinities of Bunopithecus sericus, a Fossil Hylobatid from the Pleistocene of China.

Ortiz A, Pilbrow V, Villamil CI, Korsgaard JG, Bailey SE, Harrison T - PLoS ONE (2015)

Bottom Line: Our results show that differences in M2 and M3 discriminate extant hylobatids fairly well, at least at the generic level, and that AMNH 18534 is not attributable to Hylobates, Nomascus or Symphalangus.In most multivariate analyses, Bunopithecus presents a unique morphological pattern that falls outside the range of variation of any hylobatid taxon, although its distance from the cluster represented by extant hoolocks is relatively small.Our results support the generic distinction of Bunopithecus, which most likely represents an extinct crown hylobatid, and one that may possibly represent the sister taxon to Hoolock.

View Article: PubMed Central - PubMed

Affiliation: Center for the Study of Human Origins, Department of Anthropology, New York University, New York, New York, United States of America; New York Consortium in Evolutionary Primatology (NYCEP), New York, New York, United States of America.

ABSTRACT
Fossil hylobatids are rare, but are known from late Miocene and Pleistocene sites throughout East Asia. The best-known fossil hylobatid from the Pleistocene of China is a left mandibular fragment with M2-3 (AMNH 18534), recovered from a pit deposit near the village of Yanjinggou in Wanzhou District, Chongqing Province. Matthew and Granger described this specimen in 1923 as a new genus and species, Bunopithecus sericus. Establishing the age of Bunopithecus has proved difficult because the Yanjinggou collection represents a mixed fauna of different ages, but it likely comes from early or middle Pleistocene deposits. Although the Bunopithecus specimen has featured prominently in discussions of hylobatid evolution and nomenclature, its systematic status has never been satisfactorily resolved. The present study reexamines the taxonomic and phylogenetic relationships of Bunopithecus by carrying out a detailed comparative morphometric study of its lower molars in relation to a large sample of modern hylobatids. Our results show that differences in M2 and M3 discriminate extant hylobatids fairly well, at least at the generic level, and that AMNH 18534 is not attributable to Hylobates, Nomascus or Symphalangus. Support for a close relationship between Bunopithecus and Hoolock is more equivocal. In most multivariate analyses, Bunopithecus presents a unique morphological pattern that falls outside the range of variation of any hylobatid taxon, although its distance from the cluster represented by extant hoolocks is relatively small. Our results support the generic distinction of Bunopithecus, which most likely represents an extinct crown hylobatid, and one that may possibly represent the sister taxon to Hoolock.

No MeSH data available.


Related in: MedlinePlus

Plot of the first two discriminant functions (DF1 and DF2) of the M3 analysis using linear measurements, cusp angles and absolute areas.Eigenvalues: 40.22 (DF1) and 0.31 (DF2); variance: 87.07% (DF1) and 6.80% (DF2).
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pone.0131206.g004: Plot of the first two discriminant functions (DF1 and DF2) of the M3 analysis using linear measurements, cusp angles and absolute areas.Eigenvalues: 40.22 (DF1) and 0.31 (DF2); variance: 87.07% (DF1) and 6.80% (DF2).

Mentions: Figs 3 and 4 illustrate the plots of the first two discriminant functions for individual molars showing the relative placement of B. sericus using linear measurements, cusp angles and absolute areas. S4 Table provides the average Mahalanobis distances between hylobatid taxa for each analysis. For M2, the first function is responsible for 84.4% of the variance, while the following two functions explain 10.4% and 4.1%, respectively. Similar values were obtained for M3, as the first three functions account for the 87.1%, 6.8% and 4.1% of the variance, respectively. The DFAs performed on M2 and M3 independently reveal that the greatest degree of overlap among hylobatids occurs between Nomascus and Hylobates. As expected, given their larger dentitions, siamangs are the most distinctive of the hylobatids. As illustrated in Fig 3, the M2 of B. sericus falls within the range of overlap among Nomascus, Hoolock and Hylobates, but when all axes are considered, the average pair-wise Mahalanobis comparisons indicate a closest distance to hoolock gibbons (S4 Table). In contrast, data for M3 for the first two discriminant functions show that B. sericus does not cluster with any extant group, although distances between B. sericus and the cluster represented by hoolock gibbons are relatively small (Fig 4). Although Bunopithecus' average Mahalanobis distance is smaller to Hylobates (1.3104) than to Hoolock (1.3159), the average Mahalanobis distance within Hylobates is much smaller (1.2086) than within Hoolock (1.3828), which places B. sericus well within the possible spread of Hoolock but not within the spread of Hylobates (S4 Table). The likelihood of individuals being accurately classified ranges between 80.15% (not jackknifed) and 71.76% (jackknifed) for M2 and between 79.05% (not jackknifed) and 62.86% (jackknifed) for M3.


The Taxonomic and Phylogenetic Affinities of Bunopithecus sericus, a Fossil Hylobatid from the Pleistocene of China.

Ortiz A, Pilbrow V, Villamil CI, Korsgaard JG, Bailey SE, Harrison T - PLoS ONE (2015)

Plot of the first two discriminant functions (DF1 and DF2) of the M3 analysis using linear measurements, cusp angles and absolute areas.Eigenvalues: 40.22 (DF1) and 0.31 (DF2); variance: 87.07% (DF1) and 6.80% (DF2).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4495929&req=5

pone.0131206.g004: Plot of the first two discriminant functions (DF1 and DF2) of the M3 analysis using linear measurements, cusp angles and absolute areas.Eigenvalues: 40.22 (DF1) and 0.31 (DF2); variance: 87.07% (DF1) and 6.80% (DF2).
Mentions: Figs 3 and 4 illustrate the plots of the first two discriminant functions for individual molars showing the relative placement of B. sericus using linear measurements, cusp angles and absolute areas. S4 Table provides the average Mahalanobis distances between hylobatid taxa for each analysis. For M2, the first function is responsible for 84.4% of the variance, while the following two functions explain 10.4% and 4.1%, respectively. Similar values were obtained for M3, as the first three functions account for the 87.1%, 6.8% and 4.1% of the variance, respectively. The DFAs performed on M2 and M3 independently reveal that the greatest degree of overlap among hylobatids occurs between Nomascus and Hylobates. As expected, given their larger dentitions, siamangs are the most distinctive of the hylobatids. As illustrated in Fig 3, the M2 of B. sericus falls within the range of overlap among Nomascus, Hoolock and Hylobates, but when all axes are considered, the average pair-wise Mahalanobis comparisons indicate a closest distance to hoolock gibbons (S4 Table). In contrast, data for M3 for the first two discriminant functions show that B. sericus does not cluster with any extant group, although distances between B. sericus and the cluster represented by hoolock gibbons are relatively small (Fig 4). Although Bunopithecus' average Mahalanobis distance is smaller to Hylobates (1.3104) than to Hoolock (1.3159), the average Mahalanobis distance within Hylobates is much smaller (1.2086) than within Hoolock (1.3828), which places B. sericus well within the possible spread of Hoolock but not within the spread of Hylobates (S4 Table). The likelihood of individuals being accurately classified ranges between 80.15% (not jackknifed) and 71.76% (jackknifed) for M2 and between 79.05% (not jackknifed) and 62.86% (jackknifed) for M3.

Bottom Line: Our results show that differences in M2 and M3 discriminate extant hylobatids fairly well, at least at the generic level, and that AMNH 18534 is not attributable to Hylobates, Nomascus or Symphalangus.In most multivariate analyses, Bunopithecus presents a unique morphological pattern that falls outside the range of variation of any hylobatid taxon, although its distance from the cluster represented by extant hoolocks is relatively small.Our results support the generic distinction of Bunopithecus, which most likely represents an extinct crown hylobatid, and one that may possibly represent the sister taxon to Hoolock.

View Article: PubMed Central - PubMed

Affiliation: Center for the Study of Human Origins, Department of Anthropology, New York University, New York, New York, United States of America; New York Consortium in Evolutionary Primatology (NYCEP), New York, New York, United States of America.

ABSTRACT
Fossil hylobatids are rare, but are known from late Miocene and Pleistocene sites throughout East Asia. The best-known fossil hylobatid from the Pleistocene of China is a left mandibular fragment with M2-3 (AMNH 18534), recovered from a pit deposit near the village of Yanjinggou in Wanzhou District, Chongqing Province. Matthew and Granger described this specimen in 1923 as a new genus and species, Bunopithecus sericus. Establishing the age of Bunopithecus has proved difficult because the Yanjinggou collection represents a mixed fauna of different ages, but it likely comes from early or middle Pleistocene deposits. Although the Bunopithecus specimen has featured prominently in discussions of hylobatid evolution and nomenclature, its systematic status has never been satisfactorily resolved. The present study reexamines the taxonomic and phylogenetic relationships of Bunopithecus by carrying out a detailed comparative morphometric study of its lower molars in relation to a large sample of modern hylobatids. Our results show that differences in M2 and M3 discriminate extant hylobatids fairly well, at least at the generic level, and that AMNH 18534 is not attributable to Hylobates, Nomascus or Symphalangus. Support for a close relationship between Bunopithecus and Hoolock is more equivocal. In most multivariate analyses, Bunopithecus presents a unique morphological pattern that falls outside the range of variation of any hylobatid taxon, although its distance from the cluster represented by extant hoolocks is relatively small. Our results support the generic distinction of Bunopithecus, which most likely represents an extinct crown hylobatid, and one that may possibly represent the sister taxon to Hoolock.

No MeSH data available.


Related in: MedlinePlus