Literaturdatenbank
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Holroyd, P. A., & Parham, J. F. (2003). The antiquity of african tortoises. Journal of Vertebrate Paleontology, 23(3), 688–690.
Added by: Admin (22 Feb 2009 11:56:18 UTC) |
| Resource type: Journal Article BibTeX citation key: Holroyd2003 View all bibliographic details  |
Categories: General Keywords: Schildkröten = turtles + tortoises, Systematik = taxonomy Creators: Holroyd, Parham Collection: Journal of Vertebrate Paleontology |
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| Abstract |
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Testudinidae Tortoises (Testudinidae) are a diverse and highly specialized clade of terrestrial turtles that currently inhabit five continents. The global radiation of tortoises in the Paleogene, part of an explosive radiation of testudinoid turtles out of Asia, is poorly understood. The oldest known tortoises are from the late Paleocene of Mongolia (Parham, pers. obs. at PIN), and early in the Eocene they are known to have colonized North America and Europe (e.g., Hutchison, 1998; Lapparent de Broin, 2001). At some point in the early Paleogene they marched or floated to Africa. Today, the ancestors of those first invaders have evolved into the most diverse tortoise fauna in the world; Africa is home to 10 of the 13 extant genera (Iverson, 1992; Lapparent de Broin, 2000). One of the most poorly understood episodes in the early testudinid range expansion is the dispersal of tortoises into Africa. Fossil tortoises have been known from Africa since the beginning of the last century, when Andrews (1902) noted that a “gigantic land-tortoise” had been found by H. J. L. Beadnell. However, the age of these tortoises has never been firmly established, because early collecting records were not precise with regard to the specific quarries from which they were collected. Three species of Testudo were described (Andrews and Beadnell, 1903; Andrews, 1906) as having come from the upper Eocene “Fluvio-marine” deposits of the Jebel Qatrani Formation in the Fayum Province of Egypt. In the intervening years, the Jebel Qatrani Formation came to be regarded as early Oligocene in age (e.g., Simons, 1968), then partly late Eocene and partly early Oligocene (Kappelman, 1992; Kappelman et al., 1992). No further testudinids have been reported from Egypt, although fragmentary testudinid fossils possibly close to the Egyptian taxon have been recovered from lower Oligocene sediments in Oman (Thomas et al., 1989; Lapparent de Broin, 2000). Most recently, Lapparent de Broin (2000) reviewed the African fossil record of turtles and conservatively reported the age of the Fayum tortoises as early Oligocene. Resolution of the age of Africa’s oldest tortoises has been difficult because specimens housed in European institutions (Natural History Museum, London, and Staatliches Museum, Stuttgart) lack detailed locality data, and more recent fieldwork in the area by E. L. Simons and crews (materials housed at Yale Peabody Museum, Cairo Geological Museum, and Duke University Primate Center, Durham, North Carolina) has not yielded remains of these comparatively rare reptiles. Reevaluation of older collections from the Jebel Qatrani Formation has uncovered the only African tortoise with associated stratigraphic data indicating a late Eocene age, allowing us to place this taxon in an updated geochronologic context and providing us with the opportunity to resolve several taxonomic issues regarding these specimens.
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