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| 12. |
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| 13. |
- Werdelin, Lars, et al.
(författare)
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A comparison of two methods to study correlated discrete characters on phylogenetic trees
- 1996
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Ingår i: Cladistics. - 0748-3007 .- 1096-0031. ; 11, s. 265-277
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Tidskriftsartikel (refereegranskat)abstract
- We use a simulation approach to study two methods proposed for the analysis of correlated discrete characters on cladograms, the concentrated changes test (CCT) and the contingent states test (CST). Both of these consider the case where there is an independent and a dependent character and assign probabilities to various events in the dependent character given one or the other state of the independent character. The CCT gives different results for symmetric and asymmetric cladograms. In the latter case, the proportion of branches reconstructed as having the derived state has less influence on the resulting probabilities. The CST is only sensitive to the proportion of derived branches, regardless of whether the tree is symmetric or asymmetric. The CCT calculates probabilities by considering character state reconstructions which are not allowed by parsimony algorithms, thereby increasing the probability of rejecting a true null hypothesis (type I error rate). We discuss some alternative questions that could be studied using these tests and also derive equations for calculating the number of possible events in the dependent character for unresolved parts of the phylogeny.
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| 14. |
- Werdelin, Lars, et al.
(författare)
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Allohyaena (Mammalia: Carnivora): giant hyaenid from the Late Miocene of Hungary
- 1999
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Ingår i: Zoological Journal of the Linnean Society. - 0024-4082 .- 1096-3642. ; 126, s. 319-334
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Tidskriftsartikel (refereegranskat)abstract
- The topotypic material of the giant Late Miocene hyaenid Allohyaena kadici Kretzoi is described. New data on the deciduous dentition shows unambiguously that A. kadici is a hyaenid and not a percrocutid as reported by some previous authors. A. kadici is compared to the large hyaenids Adcrocuta eximia and Crocuta crocuta. These comparisons show that A. kadici has a mixture of primitive characters such as dp4 morphology, retention of m2, long and slender premolars and a large protocone on P4, and derived characters such as a preparastyle on P4, an internal root on P3 and a uniquely derived talonid structure of m 1. This combination of features makes A. kadici difficult to classify, but it is considered to probably be most closely related to derived, bone-cracking hyaenids such as Pachycrocuta and Crocuta. A. kadici is rare in the fossil record, being found at only two sites. We suggest that the reason for this rarity is that it had a geographic and stratigraphic range which is poorly sampled in the Miocene fossil record of Europe.
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| 19. |
- Werdelin, Lars
(författare)
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Community-wide character displacement in the lower carnassials of Late Miocene hyenas
- 1996
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Ingår i: Lethaia. - 0024-1164 .- 1502-3931. ; 29, s. 97-106
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Tidskriftsartikel (refereegranskat)abstract
- Recent studies have found regularities in the pattern of distribution of dental parameters such as canine or carnassial length among sympatric carnivores. These regularities are taken to be indicative of community-wide character displacement. This study documents similar pattern in late Miocene and earliest Pliocene hyaenids from several localities in Eurasia and Africa. Statistical tests show ratios of lower carnassial total lengths and blade lengths between species to be suggestively equal among sympatric late Miocene hyaenas. Other measurements do not show this regular pattern. This finding mirrors that regarding modern canids in the Middle East, suggesting that a process leading to community-wide character displacement was in effect among these hyaenid taxa. Their response to this pattern suggests that they occupied a similarecological role to modern canids. The causal basis for such a process is unknown but is suggested to lie in direct interspecific competition between carnivores rather than being a response to regularly spaced features of the environment.
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| 20. |
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