Evolution of the extinct Sabretooths and the American cheetah-like cat
2005; Elsevier BV; Volume: 15; Issue: 15 Linguagem: Inglês
10.1016/j.cub.2005.07.052
ISSN1879-0445
AutoresRoss Barnett, Ian Barnes, Matthew J. Phillips, Larry D. Martin, C. R. Harington, Jennifer A. Leonard, Alan Cooper,
Tópico(s)Bat Biology and Ecology Studies
ResumoThe sabretooths (Smilodon and Homotherium) and the American cheetah-like cat (Miracinonyx) were the top predators in Late Pleistocene America, but became extinct about 13 thousand years ago [1Turner A. Anton M. The Big Cats and Their Fossil Relatives. Columbia University Press, New York1997Google Scholar]. As the evolutionary history of these taxa remains poorly understood [1Turner A. Anton M. The Big Cats and Their Fossil Relatives. Columbia University Press, New York1997Google Scholar, 2Herrington, S.J. (1986). Phylogenetic relationships of the wild cats of the world. Ph.D thesis, University of Kansas.Google Scholar], we analysed their phylogenetic relationship to extant felids. In contrast to previous molecular studies [3Janczewski D.N. Yuhki N. Gilbert D.A. Jefferson G.T. O’Brien S.J. Molecular phylogenetic inference from saber-toothed cat fossils of Rancho La Brea.Proc. Natl. Acad. Sci. USA. 1992; 89: 9769-9773Crossref PubMed Scopus (52) Google Scholar], our results show that the sabretooths diverge early and are not closely related to any living cats. This supports their morphological placement in a separate subfamily (Machairodontinae) [1Turner A. Anton M. The Big Cats and Their Fossil Relatives. Columbia University Press, New York1997Google Scholar]. Despite its remarkable morphological similarity to the African cheetah (Acinonyx jubatus), Miracinonyx appears to have evolved from a puma-like ancestor, presumably in response to similar ecological pressures [4Adams D.B. The Cheetah: Native American.Science. 1979; 205: 1155-1158Crossref PubMed Scopus (32) Google Scholar, 5Hemmer H. Kahlke R.D. Vekua A.K. The Old World puma - Puma pardoides (Owen, 1846) (Carnivora: Felidae) - in the Lower Villafranchian (Upper Pliocene) of Kvabebi (East Georgia, Transcaucasia) and its evolutionary and biogeographical significance.Neues Jahrbuch für Geologie und Paläontologie. 2004; 233: 197-231Google Scholar]. Even though the evolutionary relationships within the cat family (Felidae) have been analysed using morphological, molecular and palaeontological data [1Turner A. Anton M. The Big Cats and Their Fossil Relatives. Columbia University Press, New York1997Google Scholar], many proposed relationships remain contentious, including those of recently extinct species. For example, the sabretooth catsare known from plentiful Late Pleistocene fossil materialand have been placed, based on morphological criteria, outside of all extant cats (subfamily Felinae) as a separate subfamily, the Machairodontinae [1Turner A. Anton M. The Big Cats and Their Fossil Relatives. Columbia University Press, New York1997Google Scholar]. In contrast, an early ancient DNA study tentatively suggested that Smilodon was a member of the Felinae and thus part of the modern cat radiation [3Janczewski D.N. Yuhki N. Gilbert D.A. Jefferson G.T. O’Brien S.J. Molecular phylogenetic inference from saber-toothed cat fossils of Rancho La Brea.Proc. Natl. Acad. Sci. USA. 1992; 89: 9769-9773Crossref PubMed Scopus (52) Google Scholar]. The relationships of the American cheetah-like cat, Miracinonyx trumani, are similarly confused as it had previously been mistaken for an ancestral or modern puma (e.g. Puma trumani). It was only recognised as a truly distinct group after abundant post-cranial fossil material became available [6Martin L.D. Gilbert B.M. Adams D.B. A Cheetah-like cat in the North American Pleistocene.Science. 1977; 195: 981-982Crossref PubMed Scopus (14) Google Scholar]. Morphologically, M. trumani strongly resembles the modern African cheetah (Acinonyx jubatus) [4Adams D.B. The Cheetah: Native American.Science. 1979; 205: 1155-1158Crossref PubMed Scopus (32) Google Scholar], which has led to uncertainty about whether it is more closely related to the Old World cheetah or the New World puma [2Herrington, S.J. (1986). Phylogenetic relationships of the wild cats of the world. Ph.D thesis, University of Kansas.Google Scholar, 4Adams D.B. The Cheetah: Native American.Science. 1979; 205: 1155-1158Crossref PubMed Scopus (32) Google Scholar, 6Martin L.D. Gilbert B.M. Adams D.B. A Cheetah-like cat in the North American Pleistocene.Science. 1977; 195: 981-982Crossref PubMed Scopus (14) Google Scholar, 7van Valkenburgh B. Grady F. Kurten B. The Plio-Pleistocene Cheetah-like Cat Miracinonyx inexpectatus of North America.Journal of Vertebrate Palaeontology. 1990; 10: 434-454Crossref Scopus (56) Google Scholar]. To address these questions, we used ancient DNA techniques, including independent replication, to generate mitochondrial DNA sequences from several specimens of Smilodon populator from Patagonia and a M. trumani specimen from Wyoming. In total, 1302 bp of cytochrome b (cytb), NADH5, ATP8, as well as 12S and 16S ribosomal RNA genes were recovered (Supplemental Data). We also obtained a short fragment of cytb from a Yukon scimitar-toothed cat (Homotherium serum), another recent member of the Machairodontinae. Phylogenetic analyses (Figure 1; Supplemental Data) show that Smilodon and Homotherium fall outside the extant cats, the Felinae. This is in agreement with their traditional morphological placement [1Turner A. Anton M. The Big Cats and Their Fossil Relatives. Columbia University Press, New York1997Google Scholar]. The deep genetic split between the two sabretooth taxa is also consistent with morphological analyses [1Turner A. Anton M. The Big Cats and Their Fossil Relatives. Columbia University Press, New York1997Google Scholar]. These phylogenetic analyses also reveal that M. trumani is the sister taxon to the puma, rather than the African cheetah. Another endemic American cat, the jaguarundi, groups with Miracinonyx and the puma. This result corroborates the first morphological studies using complete specimens of Miracinonyx [6Martin L.D. Gilbert B.M. Adams D.B. A Cheetah-like cat in the North American Pleistocene.Science. 1977; 195: 981-982Crossref PubMed Scopus (14) Google Scholar, 7van Valkenburgh B. Grady F. Kurten B. The Plio-Pleistocene Cheetah-like Cat Miracinonyx inexpectatus of North America.Journal of Vertebrate Palaeontology. 1990; 10: 434-454Crossref Scopus (56) Google Scholar], but also raises questions about the anatomical structures used to classify Miracinonyx as a cheetah [4Adams D.B. The Cheetah: Native American.Science. 1979; 205: 1155-1158Crossref PubMed Scopus (32) Google Scholar]. Re-analysis of these characters [2Herrington, S.J. (1986). Phylogenetic relationships of the wild cats of the world. Ph.D thesis, University of Kansas.Google Scholar, 7van Valkenburgh B. Grady F. Kurten B. The Plio-Pleistocene Cheetah-like Cat Miracinonyx inexpectatus of North America.Journal of Vertebrate Palaeontology. 1990; 10: 434-454Crossref Scopus (56) Google Scholar] has emphasised that many of them are associated with a highly cursorial lifestyle, such as elongated limbs and enlarged nares [2Herrington, S.J. (1986). Phylogenetic relationships of the wild cats of the world. Ph.D thesis, University of Kansas.Google Scholar, 4Adams D.B. The Cheetah: Native American.Science. 1979; 205: 1155-1158Crossref PubMed Scopus (32) Google Scholar], which increase running speed and air-intake efficiency, respectively. In contrast, other limb characters, such as a well-developed anteriorly projecting flange on the head of the fibula, link Miracinonyx, puma and jaguarundi [2Herrington, S.J. (1986). Phylogenetic relationships of the wild cats of the world. Ph.D thesis, University of Kansas.Google Scholar, 7van Valkenburgh B. Grady F. Kurten B. The Plio-Pleistocene Cheetah-like Cat Miracinonyx inexpectatus of North America.Journal of Vertebrate Palaeontology. 1990; 10: 434-454Crossref Scopus (56) Google Scholar]. It has been suggested that the cheetahs originated in the New World [4Adams D.B. The Cheetah: Native American.Science. 1979; 205: 1155-1158Crossref PubMed Scopus (32) Google Scholar] and later migrated to the Old World. However, the mitochondrial sequence analysis together with recent fossil data (Supplemental Data) suggests that they originated in the Old World and that a puma-like cat then invaded North America around six million years ago [5Hemmer H. Kahlke R.D. Vekua A.K. The Old World puma - Puma pardoides (Owen, 1846) (Carnivora: Felidae) - in the Lower Villafranchian (Upper Pliocene) of Kvabebi (East Georgia, Transcaucasia) and its evolutionary and biogeographical significance.Neues Jahrbuch für Geologie und Paläontologie. 2004; 233: 197-231Google Scholar, 7van Valkenburgh B. Grady F. Kurten B. The Plio-Pleistocene Cheetah-like Cat Miracinonyx inexpectatus of North America.Journal of Vertebrate Palaeontology. 1990; 10: 434-454Crossref Scopus (56) Google Scholar, 8Zhanxiang Q. Chapter 2: Dispersals of Neogene Carnivorans between Asia and North America.Bull. Am. Mus. Nat. Hist. 2003; 279: 18-31Crossref Google Scholar]. Around 3.2 million years ago, this ancestor diverged into Miracinonyx and Puma, which is broadly contemporaneous with increasing prairie in North America [9Janis C.M. Damuth J. Theodor J.M. The origins and evolution of the North American grassland biome: the story from the hoofed mammals.Palaeogeogr. Palaeoclimatol. Palaeoecol. 2002; 177: 183-198Crossref Scopus (135) Google Scholar]. The expansion of this habitat and its effect on ungulate prey, e.g. the pronghorn antelope (Antilocapra americana), may have driven the evolution of cursoriality in Miracinonyx, allowing it to excel in high-speed pursuit [1Turner A. Anton M. The Big Cats and Their Fossil Relatives. Columbia University Press, New York1997Google Scholar]. We thank P.J.H. van Bree (Zoological Museum Amsterdam) for access to Smilodon samples, Lars Werdelin (Swedish Museum of Natural History) for helpful information on specimens, Andrew Kitchener (National Museum of Scotland) for modern felid samples and Trish McLenachan and David Penny (Massey University) for access to mongoose data. Work at UCLA on Homotherium was supported by an NSF grant to Robert Wayne and Blaire Van Valkenburgh (OPP-9617068). This research was supported by NSF (AC, JAL), NERC (RB and AC), Leverhulme (AC), BBSRC (RB), and Wellcome (IB and AC). We also thank Mauricio Anton for use of his artwork. Download .pdf (.07 MB) Help with pdf files Document S1
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