| 1. |
- Andersson, Ki, et al.
(författare)
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Sabertoothed carnivores and the killing of large prey
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:10, s. e24971-
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Tidskriftsartikel (refereegranskat)abstract
- Sabre-like canines clearly have the potential to inflict grievous wounds leading to massive blood loss and rapid death. Hypotheses concerning sabretooth killing modes include attack to soft parts such as the belly or throat, where biting deep is essential to generate strikes reaching major blood vessels. Sabretoothed carnivorans are widely interpreted as hunters of larger and more powerful prey than that of their present-day nonsabretoothed relatives. However, the precise functional advantage of the sabretooth bite, particularly in relation to prey size, is unknown. Here, we present a new point-to-point bite model and show that, for sabretooths, depth of the killing bite decreases dramatically with increasing prey size. The extended gape of sabretooths only results in considerable increase in bite depth when biting into prey with a radius of less than ~10 cm. For sabretooths, this size-reversed functional advantage suggests predation on species within a similar size range to those attacked by present-day carnivorans, rather than “megaherbivores” as previously believed. The development of the sabretooth condition appears to represent a shift in function and killing behaviour, rather than one in predator-prey relations. Furthermore, our results demonstrate how sabretoothed carnivorans are likely to have evolved along a functionally continuous trajectory: beginning as an extension of a jaw-powered killing bite, as adopted by present-day pantherine cats, followed by neck-powered biting and thereafter shifting to neck-powered shear-biting. We anticipate this new insight to be a starting point for detailed study of the evolution of pathways that encompass extreme specialisation, for example, understanding how neck-powered biting shifts into shear-biting and its significance for predator-prey interactions. We also expect that our model for point-to-point biting and bite depth estimations will yield new insights into the behaviours of a broad range of extinct predators including therocephalians (gorgonopsian + cynodont, sabretoothed mammal-like reptiles), sauropterygians (marine reptiles) and theropod dinosaurs.
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| 4. |
- Hartstone-Rose, Adam, et al.
(författare)
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A new species of fox from the Australopithecus sediba type locality, Malapa, South Africa
- 2013
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Ingår i: Transactions of the Royal Society of South Africa. - 0035-919X .- 2154-0098. ; 68, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- The 1.977 Ma site of ‘Malapa’ (Gauteng, South Africa) has yielded important new fossils, including the type specimens of the new hominin species Australopithecus sediba. Recently, we reported the first Carnivora specimens to have been recovered from the site. That sample included members of Felidae, Herpestidae and Hyaenidae. That first report also included three associated small canid specimens (an M2, a rib and a posterior mandibular fragment including the P4, M1, coronoid, condylar and angular processes) that we attributed to Vulpes cf. V. chama. In this paper, we compare these specimens to a broad sample of modern and fossil foxes and conclude that these specimens are distinct enough to be referred to a new species, here described and named Vulpes skinneri.
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| 5. |
- Hartstone-Rose, Adam, et al.
(författare)
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The Plio-Pleistocene ancestor of wild dogs, Lycaon sekowei n. sp.
- 2010
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Ingår i: Journal of Paleontology. - 0022-3360 .- 1937-2337. ; 84, s. 299-308
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Tidskriftsartikel (refereegranskat)abstract
- African wild dogs (Lycaon pictus) occupy an ecological niche characterized by hypercarnivory and cursorial hunting. Previous interpretations drawn from a limited, mostly Eurasian fossil record suggest that the evolutionary shift to cursorial hunting preceded the emergence of hypercarnivory in the Lycaon lineage. Here we describe 1.9–1.0 ma fossils from two South African sites representing a putative ancestor of the wild dog. The holotype is a nearly complete maxilla from Coopers Cave, and another specimen tentatively assigned to the new taxon, from Gladysvale, is the most nearly complete mammalian skeleton ever described from the Sterkfontein Valley, Gauteng, South Africa. The canid represented by these fossils is larger and more robust than are any of the other fossil or extant sub-Saharan canids. Unlike other purported L. pictus ancestors, it has distinct accessory cusps on its premolars and anterior accessory cuspids on its lower premolars–a trait unique to Lycaon among living canids. However, another hallmark autapomorphy of L. pictus, the tetradactyl manus, is not found in the new species; the Gladysvale skeleton includes a large first metacarpal. Thus, the anatomy of this new early member of the Lycaon branch suggests that, contrary to previous hypotheses, dietary specialization appears to have preceded cursorial hunting in the evolution of the Lycaon lineage. We assign these specimens to the taxon Lycaon sekowei n. sp.
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| 6. |
- Kuhn, Brian F., et al.
(författare)
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Carnivoran remains from the Malapa hominin site, South Africa
- 2011
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:11, s. e26940-
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Tidskriftsartikel (refereegranskat)abstract
- Recent discoveries at the new hominin-bearing deposits of Malapa, South Africa, have yielded a rich faunal assemblage associated with the newly described hominin taxon Australopithecus sediba. Dating of this deposit using U-Pb and palaeomagnetic methods has provided an age of 1.977 Ma, being one of the most accurately dated, time constrained deposits in the Plio-Pleistocene of southern Africa. To date, 81 carnivoran specimens have been identified at this site including members of the families Canidae, Viverridae, Herpestidae, Hyaenidae and Felidae. Of note is the presence of the extinct taxon Dinofelis cf. D. barlowi that may represent the last appearance date for this species. Extant large carnivores are represented by specimens of leopard (Panthera pardus) and brown hyaena (Parahyaena brunnea). Smaller carnivores are also represented, and include the genera Atilax and Genetta, as well as Vulpes cf. V. chama. Malapa may also represent the first appearance date for Felis nigripes (Black-footed cat). The geochronological age of Malapa and the associated hominin taxa and carnivoran remains provide a window of research into mammalian evolution during a relatively unknown period in South Africa and elsewhere. In particular, the fauna represented at Malapa has the potential to elucidate aspects of the evolution of Dinofelis and may help resolve competing hypotheses about faunal exchange between East and Southern Africa during the late Pliocene or early Pleistocene.
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| 7. |
- Leakey, Meave G., et al.
(författare)
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Early Pleistocene Mammals of Africa: Background to dispersal
- 2011
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Ingår i: Out of Africa 1: Who, When and Where?. - New York : Springer-Verlag New York. ; , s. 3-11
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Bokkapitel (refereegranskat)abstract
- The initial dispersal of humans out of Africa was a significant event in human evolution raising many questions. Why did this happen at this particular time? Was it part of a major migration of mammals out of Africa and did any species move into Africa at the same time? Were climate and habitat changes taking place that might have been contributing factors? With the advent of culture at 2.6 Ma, hominins moved from the primate to the carnivore feeding niche, thus avoiding constraints that had previously determined their distribution. Here we look at fossil carnivores and cercopithecids for factors that provide a background to this significant event in our evolutionary history and we also look at herbivore diversity as a potential source of prey for meat-eating hominins.
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| 8. |
- Lewis, Margaret E., et al.
(författare)
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Carnivoran dispersal out of Africa during the Early Pleistocene: relevance for hominins?
- 2010
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Ingår i: Out of Africa 1: Who, When and Where?. - New York : Springer. ; , s. 13-26
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Bokkapitel (refereegranskat)abstract
- Carnivorans and hominins share a long history of interactions. This paper examines some of the evidence for carnivoran migration out of Africa at the same time as the earliest hominin dispersals. Of the two relevant taxa, Crocuta and Megantereon , Megantereon is the focus of this paper due to increased interest in this taxon in recent years and to the nature of the earliest records of dispersal of these two taxa, raising several questions related to Megantereon and its possible influence on hominins. To answer these questions, a brief summary of the literature on Megantereon in Eurasia and Africa is provided. While researchers do not agree on the number of species of Megantereon or the evolutionary relationships among those species, most would agree that Megantereon is a hypercarnivorous predator capable of grappling with relatively large prey for its body size. Despite the fact that carcasses generated by Megantereon were probably of value to hominins, the hypotheses that these carcasses were a major source of food or that they were a major force enabling hominins to migrate out of Africa are rejected. As indicated in the literature on extant carnivorans, kleptoparasitism (= food theft) by dominant members of a carnivore guild exacts a heavy price on lower ranking carnivores. In addition, there is nothing in the African fossil record to suggest a special relationship between Megantereon and hominins that did not exist between hominins and other large-bodied carnivorans. The hypothesis that a species of Megantereon migrated out of Africa at roughly the same time as early hominins is also considered. While this hypothesis cannot be rejected, alternative hypotheses to explain similarities between later African and Eurasian forms of Megantereon are proposed (e.g., shared characters are due to convergence or are symplesiomorphies). In the end, the small number of diverse African species (including hominins) who disperse into Eurasia at the Plio- Pleistocene transition may have been part of a sweepstakes dispersal where the factors permitting (or driving) dispersal may have differed from species to species.
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| 9. |
- Raia, Pasquale, et al.
(författare)
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Rapid action in the Palaeogene. The relationship between phenotypic and taxonomic diversification in Cenozoic mammals
- 2012
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954.
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Tidskriftsartikel (refereegranskat)abstract
- A classic question in evolutionary biology concerns the tempo and mode of lineage evolution. Considered variously in relation to resource utilization, intrinsic constraints or hierarchic level, the question of how evolutionary change occurs in general has continued to draw the attention of the field for over a century and a half. Here we use the largest species-level phylogeny of Coenozoic fossil mammals (1031 species) ever assembled and their body size estimates, to show that body size and taxonomic diversification rates declined from the origin of placentals towards the present, and very probably correlate to each other. These findings suggest that morphological and taxic diversifications of mammals occurred hierarchically, with major shifts in body size coinciding with the birth of large clades, followed by taxonomic diversification within these newly formed clades. As the clades expanded, rates of taxonomic diversification proceeded independently of phenotypic evolution. Such a dynamic is consistent with the idea, central to the Modern Synthesis, that mammals radiated adaptively, with the filling of adaptive zones following the radiation.
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