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- Andersson, Ki, 1975-
(author)
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Aspects of locomotor evolution in the Carnivora (Mammalia)
- 2003
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Doctoral thesis (other academic/artistic)abstract
- In this thesis, the shape of the distal humerus trochlea is analysed using landmark-based morphometrics and multivariate methods, with the aim of exploring locomotor evolution in carnivorans. Elbow joint morphology is used together with body size and craniodental morphology to characterize past and present carnivorans. Evolutionary implications are studied at the ordinal, familial, and species levels, testing specific hypotheses about scaling, morphological constraints, evolutionary trajectories, and potential for social pack-hunting behaviour. The circumference of the distal humerus trochlea is found to be highly correlated with body mass, and appears to scale similarly throughout the order Carnivora. A general predictive model for carnivoran bodymass is presented (a=0.601; b= 2.552; r2=0.952, SEE=0.136, p<0001, n=92), which removes the need for the investigator to actively choose between the diverging estimates that different predictors and their equations often produce. At the elbow joint, manual manipulation and locomotion appear to be conflicting functions, thus suggesting mutually exclusive lifestyles involving either forelimb grappling or pursuit. At large body sizes, carnivorans are distributed over a strongly dichotomised pattern (grappling or locomotion), a pattern coinciding with the postulated threshold in predator-prey size ratio at 21.5-25 kg. This pattern is compared to that of two carnivoran faunas from the Tertiary. In the Oligocene (33.7-23.8 Myr BP), the overall pattern is remarkably similar to that observed for extant Carnivora. In the Miocene (23.8-11.2 Myr BP) carnivores show a similarly dichotomised pattern as the Oligocene and Recent, although the whole pattern is shifted towards larger body sizes. This difference is suggested to be a reflection of the extraordinary species richness of browsing ungulates in the early Miocene of North America. Such an increase in prey spectrum would create a unique situation, in which large carnivores need not commit to a cursorial habitus in order to fill their nutritional requirements. Finally, the elbow joints and craniodental morphology (14 measurements) of fossil canids were examined with the aim of assessing the potential for pack-hunting in fossil canids. It is clear that small and large members of the Recent Caninae share similar craniodental morphologies. However, this pattern is not present in Borophaginae and Hesperocyoninae. In the latter, large representatives are characterized by being short-faced, with reduced anterior premolars and enlarged posterior premolars, thus approaching a “pantherine-like” craniodental configuration. These traits are interpreted as an adaptation for killing prey with canine bites. It is similarly determined that, unlike recent Caninae, all analyzed species of borophagines and hesperocyonines have retained the ability to supinate their forearms. It is therefore likely that manual manipulation was part of their hunting behaviour, thus removing an essential part of the argument for social pack-hunting in these forms, as the benefits of such a strategy become less obvious.
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| 2. |
- Werdelin, Lars, et al.
(author)
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A revision of the genus Dinofelis (Mammalia, Felidae)
- 2001
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In: Zoological Journal of the Linnean Society. - 0024-4082 .- 1096-3642. ; 132, s. 147-258
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Journal article (peer-reviewed)abstract
- This paper consists of a taxonomic and systematic revision of the extinct felid genus Dinofelis (Felidae, Machairodontinae) and an analysis of its ecomorphology and evolution. Dinofelis has a broad distribution, with material from all northern continents and Africa, the latter of which was the apparent centre of evolution of the genus. We describe new material of Dinofelis from a number of sites in eastern Africa and reconsider all previously described material. We name two new species and identify several other distinct species-level taxa but refrain from naming these due to a paucity of well-preserved material. At the same time, we synonymize the two named Asian species, D. cristata and D. abeli, of which the former has priority. There are few characters useful in systematic analysis, but we can suggest at least one migration from eastern to southern Africa. Ecomorphological analysis of both craniodental and postcranial characters suggests that Dinofelis in many respects converged on modern pantherine cats in morphology and behaviour, a trend culminating in the South African D. barlowi and the Asian D. cristata, which are the most pantherine-like of all machairodont felids. This trend is reversed in the evolution of the youngest species, D. piveteaui, which is also the most machairodont in its ecomorphology. The timing of the extinction of Dinofelis is difficult to determine. Outside Africa material is scarce at all times, while in Africa the apparent extinction of Dinofelis at about 1.4 Mya coincides with the end of the good, semi-continuous fossil record present in eastern Africa from about 4Mya onwards. Dating of Kanam East (with D. piveteaui) to the Jaramillo Subchron (1.070–0.990 Mya) suggests possible survival considerably later. Thus, the extinction datum for Dinofelis cannot at present be firmly established.
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| 3. |
- Werdelin, Lars, et al.
(author)
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Carnivora from the South Turkwel hominid site, northern Kenya
- 2000
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In: Journal of Paleontology. - 0022-3360 .- 1937-2337. ; 74, s. 1173-1180
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Journal article (peer-reviewed)abstract
- A small collection of carnivoran fossils from the South Turkwel hominid site is described. The fauna is composed of Megantereon ekidoit new species, Homotherium sp., Crocuta cf. dietrichi, cf. Pachycrocuta sp., Canis new species A., cf. Civettictis sp., Viverridae or Herpestidae indet., and Lutrinae indet. The record of Megantereon and Canis, as well as Pachycrocuta and Civettictis, if these genera are identified correctly, represents the earliest occurrences of their respective taxa in Africa. These specimens suggest a relatively rapid reorganization of the carnivore guild some time around 3.5 Ma, followed by a longer period of transition to a fauna more comparable in composition to the modern one.
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