Permo-Triassic fossil woods from the South African Karoo Basin

The Karoo Basin extends over more than half of the South African land surface and incorporates sediments deposited over a period of more than 100 million years, from the Upper Carboniferous to the Lower Jurassic. Biozones have been established on the basis of the abundant vertebrate fauna. Fossil plant deposits are numerous but best represented by the Lower Permian Glossopteris floras and Middle to Upper Triassic Dicroidium floras. Fossil woods occur throughout the sequence. In this paper previously described woods are discussed, newly collected woods are described and an attempt is made to correlate the woods with the Formations and vertebrate biozones. Prototaxoxylon africanum (Walton) Krausel and Dolianiti is common but restricted to the Permian (Ecca and Lower Beaufort Groups). Prototaxoxylon uniseriale Prasad has the same distribution but is rare. Australoxylon teixeirae Marguerier extends from the Ecca to the middle Beaufort. Araucarioxylon occurs throughout the Karoo but there are several species that have different ranges. Araucarioxylon africanum Bamford sp. nov. occurs throughout the Beaufort and into younger deposits. Araucarioxylon karooensis Bamford sp. nov. occurs in the Normandien Formation of the Beaufort Group. Woods with podocarpacean affinities, recognized as Mesembrioxylon, first occur in the uppermost Beaufort and extend into the Cretaceous. The woods can, therefore, be used as broadscale biostratigraphic indicators but further data need to be collected.The Council's Research Committe, University of the Witwatersrand; National Science Foundatio

Carboniferous pycnoxylic woods from the Dwyka Group of southern Namibia

Glacial deposits of the Dwyka Group between Keetmanshoop and Mariental in southern Namibia have been reinvestigated for palaeontological remains and associated tuff horizons in an attempt to accurately date the deposits. SHRIMP-based dating of juvenile zircons from these tuff horizons provide ages which cumulate in the latest Carboniferous (Gzelian). The pycnoxylic woods Megaporoxylon scherziKrausel and Megaporoxylon kaokense Krausel are described in detail for the first time and are compared with similar permineralised woods from Gondwana. Based on previous fossil wood studies covering the rocks of the main Karoo Basin, these species occur only in the Dwyka and lower Ecca Groups in southern Africa and do not extend to the upper Ecca Group.The Council's Research Committee, University of the Witwatersrand; National Research Foundation (NRF); Palaeo-Anthropology Scientific Trust (PAST); German Research Foundation (DFG) and the Postgraduate Research Program "Interdisciplinary Geoscience Research in Africa

Fossil wood of Cretaceous age from the Namaqualand continental shelf, South Africa

Fossil wood was collected from sediments on the Namaqualand shelf, West Coast, South Africa, between the Orange River mouth and just to the south of Kleinzee. Forty three of these samples are here described. All the woods are gymnospermous and have abietinian tracheid pitting. Nineteen of them are well enough preserved to be identified to species level: Podocarpoxylon cf. umzambense, Mesembrioxylon cf. stokesii, M. cf. sahnii, M. cf. woburnense and Protocupressinoxylon cf. purbeckensis. The remainder of the woods have been placed in the artificial genus Mesembrioxylon without species names. The woods are probably primitive members of the Podocarpaceae growing during the Lower Cretaceous. They indicate a seasonal climate and inhabited the extensive low-lying coastal regions.De Beer

More fossil wood from the Namaqualand coast, South Africa; onshore material.

Main articleFossil wood was collected from a palaeo-beach sequence on the farms Sandkop, Oubeep and adjacent State land, on the Namaqualand (west) coast of South Africa. Of the 14 samples sectioned only 5 were well enough preserved to describe and identify to species level. The woods are podocarpaceous and have been assigned to the taxa Podocarpoxylon cf. umzambense, Mesembrioxylon woburnense, M. stokesi and Mesembrioxylon sp. The samples are Lower Cretaceous in age and were most probably reworked a number of times into successively younger palaeoshoreline deposits. The same species occurred in the offshore sediments, therefore indicating a wider area of "woodland" and further evidence of extensive shelf erosion by subsequent marine transgressions and regressions.Non

Taxonomic description of fossil wood from Cainozoic Sak River terraces, near Brandvlei, Bushmanland, South Africa

Seven pieces of silicified wood are described from two sites near the Sak River, Bushmanland. The Miocene deposit yielded five specimens which can be assigned to the Dipterocarpaceae, Fagaceae, Myrtaceae, Oleaceae and Rutaceae. Of the two logs recovered from the Plio-Pleistocene deposit, only one was well enough preserved to be assigned to the Polygalaceae. All the woods indicate that the palaeoenvironment in that region was tropical to subtropical based on the wood structure, growth rings and from their modem counterparts.De Beer

Isotopic evidence for contrast diets of early hominins Homo habilis and Australopithecus boisei of Tanzania

Isotopic dietary studies of early hominins have hitherto been confined to specimens from South Africa. We are now able to report isotopic analyses of two species of early hominins from Tanzania : Homo habilis and Australopithecus boisei. The results show that these two species had very different diets. The isotopic analyses of three South African species of early hominins, in contrast, show considerable variation in individual diets, but no marked differences between species

A fossil peat deposit from the Late Triassic (Carnian) of Zimbabwe with preserved cuticle of Pteridospermopsida and Ginkgoales, and its geological setting

Well-preserved cuticular material of Pteridospermopsida and Ginkgoales from the Late Triassic of Zimbabwe is described here for the first time. It is preserved within a brown peat-like lens in the Upper Karoo Angwa Sandstone Formation. The locality is on the Manyima River in the lower portion of the mid-Zambezi Valley of Zimbabwe. Using SEM and light microscopy to identify the taxa, the fragmentary cuticles are of Pteridospermopsida type and have been assigned to Lepidopteris sp. (Peltaspermales) and Dicroidium sp. A, B, (Corystospermales). Cuticles of the ginkgoalean leaf genus, Sphenobaiera, are also described. Well-preserved ovules were found in close association with the cuticles, but as the stomata are not visible they cannot be assigned to any genus. Based on their close similarity to the Dicroidium flora of the South African Upper Karoo, the plants are considered to be equivalent to the South African Molteno Formation in age (Carnian). The palynoflora supports this age bracket, as does fauna preserved nearby. The taphonomic process was one of transport, sorting and deposition in a fluvial system.The CNRS-NRF agreement between France and South Afric

A Late Devonian refugium for Colpodexylon (Lycopsida) at high latitude

peer reviewedLocalities within strata of the Witpoort Formation (Witteberg Group, Cape Supergroup) of South Africa provide diverse new fossil material of Famennian plants from a high palaeolatitude marginal marine setting. Lycopsid axes with sterile leaves include material here diagnosed to two new species of Colpodexylon Banks 1944. C. pullumpedes sp. nov. from Waterloo Farm is a ‘short-tipped’ species, whereas C. mergae sp. nov. from Coombs Hill, is a ‘long-tipped’ species. The latter has leaves similar to those of the type species, C. deatsii Banks, yet differing in proportions. This provides the first definite high latitude records of the genus. Furthermore, these occurrences substantially extend the temporal range of Colpodexylon, formerly only known from lower Frasnian and older strata, indicating that the genus persisted at high-latitudes after its apparent disappearance from the palaeo-sub-tropics

X-rays and virtual taphonomy resolve the first Cissus (Vitaceae) macrofossils from Africa as early diverging members of the genus

PREMISE OF THE STUDY: Fossilized seeds similar to Cissus (Vitaceae) have been recognized from the Miocene of Kenya, though some were previously assigned to the Menispermaceae. We undertook a comparative survey of extant African Cissus seeds to identify the fossils and consider their implications for the evolution and biogeography of Cissus and for African early Miocene paleoenvironments. METHODS: Micro-computed tomography (µCT) and synchrotron-based X-ray tomographic microscopy (SRXTM) were used to study seed morphology and anatomy. Virtual taphonomy, using SRXTM data sets, produced digital fossils to elucidate seed taphonomy. Phylogenetic relationships within Cissus were reconstructed using existing and newly produced DNA sequences for African species. Paleobiology and paleoecology were inferred from African nearest living relatives. KEY RESULTS: The fossils were assigned to four new Cissus species, related to four modern clades. The fossil plants were interpreted as climbers inhabiting a mosaic of riverine woodland and forest to more open habitats. Virtual taphonomy explained how complex mineral infill processes concealed key seed features, causing the previous taxonomic misidentification. Newly sampled African species, with seeds most similar to the fossils, belong to four clades within core Cissus, two of which are early diverging. CONCLUSIONS: Virtual taphonomy, combined with X-ray imaging, has enabled recognition of the first fossil Cissus and Vitaceae from Africa. Early-divergent members of the core Cissus clade were present in Africa by at least the early Miocene, with an African origin suggested for the Cissus sciaphila clade. The fossils provide supporting evidence for mosaic paleoenvironments inhabited by early Miocene hominoids

Carbon, nitrogen, and oxygen stable isotopes in modern tooth enamel: A case study from Gorongosa National Park, central Mozambique

The analyses of the stable isotope ratios of carbon (delta C-13), nitrogen (delta N-15), and oxygen (delta O-18) in animal tissues are powerful tools for reconstructing the feeding behavior of individual animals and characterizing trophic interactions in food webs. Of these biomaterials, tooth enamel is the hardest, most mineralized vertebrate tissue and therefore least likely to be affected by chemical alteration (i.e., its isotopic composition can be preserved over millions of years), making it an important and widely available archive for biologists and paleontologists. Here, we present the first combined measurements of delta C-13, delta N-15, and delta O-18 in enamel from the teeth of modern fauna (herbivores, carnivores, and omnivores) from the well-studied ecosystem of Gorongosa National Park (GNP) in central Mozambique. We use two novel methods to produce high-precision stable isotope enamel data: (i) the "oxidation-denitrification method," which permits the measurement of mineral-bound organic nitrogen in tooth enamel (delta N-15(enamel)), which until now, has not been possible due to enamel's low organic content, and (ii) the "cold trap method," which greatly reduces the sample size required for traditional measurements of inorganic delta C-13(enamel) and delta O-18(enamel) (from >= 0.5 to <= 0.1 mg), permitting analysis of small or valuable teeth and high-resolution serial sampling of enamel. The stable isotope results for GNP fauna reveal important ecological information about the trophic level, dietary niche, and resource consumption. delta N-15(enamel) values clearly differentiate trophic level (i.e., carnivore delta N-15(enamel) values are 4.0 parts per thousand higher, on average, than herbivores), delta C-13(enamel) values distinguish C-3 and/or C-4 biomass consumption, and delta O-18(enamel) values reflect local meteoric water (delta O-18(water)) in the park. Analysis of combined carbon, nitrogen, and oxygen stable isotope data permits geochemical separation of grazers, browsers, omnivores, and carnivores according to their isotopic niche, while mixed-feeding herbivores cannot be clearly distinguished from other dietary groups. These results confirm that combined C, N, and O isotope analyses of a single aliquot of tooth enamel can be used to reconstruct diet and trophic niches. Given its resistance to chemical alteration, the analysis of these three isotopes in tooth enamel has a high potential to open new avenues of research in (paleo)ecology and paleontology.info:eu-repo/semantics/publishedVersio