A rich macroflora has been collected from eleven localities in the Lower Member of the Campo Chico Formation in the Cafto Colorado area of the Sierra de Perija, Western Venezuela. A new geological map of the area has been produced. The sediments were deposited in a deltaic environment. Faunal evidence suggests an age between early Givetian and Late Devonian. Palynological preparations suggest an age of Givetian or latest Eifelian for the lower plant-bearing horizons. The plants themselves indicate a latest Eifelian-early Frasniana age. Some nineteen plant taxa are recorded, including five new genera and ten new species. They occur principally as compression fossils, although fragmentary permineralised material was discovered The lycophyte flora is composed of at least eight species belonging to the genera Ledercqia, Colpodexylon, Haskinsia, Archaeosigillaria and Lycopodites. Zosterophylls include Sawdonia and Serrulacaulis. Axes of Taeniocrada'-like appearance have probable S-type water conducting cells. Two species belonging to two new genera are attributed to the Trimerophytina, the definition of this subdivision being broadened. A new cladoxylopsidh as fertile ultimate appendages branched in a three-dimensional dichotomous manner, and recurved pairs of terminal sporangia. A compression fossil is possibly related to Iridopteridales. One species remains incertae sedis. The progymnosperms(including ?Rellimia) and a number of types of sterile axes remain unworked. Contributions have been made to the knowledge of existing taxa, particularly Archaeosigillaria, Haskinsia, Colpodexylon and Serrulacaulis. Eifelian/Frasnian floras world-wide are discussed. The Venezuelan flora, particularly the lycophyte element, is most similar to Givetian and early Frasnian assemblages from New York State, and less so to the German and Belgian assemblages which lack diverse lycophytes. A brief investigation of the biogeography of the Devonian has suggested a palaeogeographic model which is relatively consistent with the biogeographical data, and that the Venezuelan assemblages may not be representative of other Gondwanan floras
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:492235 |
| Date | January 1993 |
| Creators | Berry, Christopher Mark |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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