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The environment 5-5.2 million years ago

During the course of her doctorate, Tamara Franz-Odendaal did stable isotope analyses on many of the teeth of the ungulates from Langebaanweg in order to identify the photosynthetic pathway used by the vegetation in the environment. This would indicate whether  C3 or C4 plants dominated at Langebaanweg, which would in turn indicate the prevailing climatic conditions at Langebaanweg 5 million years ago.
One of the issues Franz-Odendaal hoped to investigate was if the world-wide expansion in C4 grasslands which began between 8 and 6 million years ago (and continues to the present day) extended as far south as Langebaanweg during the Mio-Pliocene. C4 grasses dominate in areas where there is summer rainfall, and C3 grasses in areas of winter rainfall.

Franz-Odendaal’s (2002) research indicated that both grazing and browsing ungulate species showed δ13C values which indicated that Langebaanweg was a C3 dominated environment. As fynbos and the type of grasses found at Langebaanweg all had a C3 signature, it was impossible to tell if animals were grazers or browsers. If the grasses found at Langebaanweg had been C4 grasses it would have been easy to distinguish between grazing and browsing ungulate species as the browsers would have had a C3 signature, and the grazers a C4 signature, and mixed feeders something in between. This is not too much of a problem however as paleontologists have another trick up their sleeves and are able to distinguish between grazers, browsers and mixed feeders by looking at the microwear on the teeth of the various ungulate species. (Go to 'What fossil bones and teeth can tell us')

Prior to the research done by Franz-Odendaal there was no direct evidence to indicate whether the main rainfall season at Langebaanweg was in winter (as it is today) or in summer. The fact that Langebaanweg was dominated by C3 plants indicates that a winter rainfall pattern was established on the west coast by the Mio-Pliocene.

Charcoal, fossil wood, seeds and pollen grains can be used to identify the type of trees and plants that grew in an area thousands or millions years ago. Pollen grains are amazingly durable, despite their tiny size, and the earliest recovered fynbos pollen from the western Cape region was found in some of the Langebaanweg sediments.

The pollen spectrum from Langebaanweg indicates a variety of environments. Swamps/marshes were certainly present in the Langebaanweg area, as indicated by the dominance of pollen (92%) from the acquatic, or semi-acquatic Ranunculaceae. The existence of coastal plains were inferred from the presence of plant families such as the Ranunculacea, Cyperaceae, Asteraceae and Umbelliferae, and areas of relative dryness by the Asteraceae, Chenopodiaceae, and Amaranthaceae. The presence of trees in the area is indicated by the presence of Podocarpus, Olea and Proteaceae pollen. Very few diagnostic elements of open vegetation were found (Scott 1995).

Table 1 shows the vegetation suggested for various areas of southern Africa, as indicated by pollen studies from fossil sites in South Africa and Nambia.

Period Southern and southwestern Cape Namaqualand Interior plateau Marine area of Namibia off the west coast
Quaternary Fynbos (macchia) Succulent rich dwarf shrub-land or grassland Woodland savanna or upland grassland or moist mesic woodland Desert vegetation or dry grassland
Pliocene Fynbos - Similar to Quaternary vegetation Open desert or dry woodland or shrubland vegetation or dry grassland
Late Miocene/ Pliocene Transition from sub-tropical woodland to fynbos Karoid shrubland with fynbos and woodland elements - Development of desert elements like Chenopodiaceae
Miocene Subtropical woodland with swamps Subhumid subtropical woodland - -
Table 1: Vegetation in southern Africa during the Neogene according to the Pollen data (After Scott 1995, Table 5.2, page 75)

References:

Axelrod, D. I. and Raven, P. H. 1978. Late Cretaceous and tertiary vegetation history of Africa. In Werger, M.J.A (ed.) Biogeography and ecology of Southern Africa. 79-130. The Hague: Junk.

Coetzee, J. A. 1980. Tertiary environmental changes along the south-western African coast. Palaeontologica Africana. 23:197:203.

Coetzee, J. A. and Rogers, J. 1982. Palynological and lithological eveidence for the Miocene Palaeoenvironment in the Saldhana region (South Africa). Paleogeography, Paleoclimatology, Paleoecology. 39:71-85.

Franz-Odendaal, T. 2002. Analysis of dental pathologies in the Pliocene herbivores of Langebaanweg and their palaeoenvironmental implications. Unpublished Ph.D. thesis, University of Cape Town, South Africa.

Hendey, Q. B. 1983. Cenozoic geology and palaeoecology of the fynbos region. In Deacon, H. J., Hendey, Q.B. and Lambrechts J. J. N. (eds.) Fynbos palaeoecology: A preliminary synthesis. South African National Scientific Programmes Report no 75. 35-60. Mills Litho:Cape Town.

Matthews, T. 2004. The taphonomy and taxonomy of Mio-Pliocene and late Middle Pleistocene micromammals from the Cape west coast, South Africa. Unpublished Ph.D. thesis, University of Cape Town, South Africa.

Scott, L. 1995. Pollen evidence for vegetational and climatic change in Southern Africa during the Neogene and Quaternary. In Vrba, E. S., Denton, G. H., Partridge, T. C., and Burckle, L. H. (eds.) 65-76. Paleoclimate and evolution with emphasis on human origins. Yale:Yale University Press.

Siesser, W. G. 1980. Late Miocene origin of the Benguela upwelling system off northern Namibia. Science. 208: 283-285.