UMR AMAP

ABSTRACT [fre] Nous rapportons les principaux sujets en débat autour de la biodiversité, dans le cadre des réunions internationales qui ont eu lieu depuis 1990 à la FAO, au PNUE, à la CEE et au Conseil de l'Europe. [eng] We have reported the main controversal topics in the field of the biodiversity emerging from international conferences held under the auspices of FAO, UNEP, EEC and the Council of Europe since 1990.

A preliminary account is presented herein of the revision of 473 slabs containing macrofossil plant remains from the Domenico Lovisato plant Collection. The latter is housed in the Museo Sardo di Geologia e Paleontologia “D. Lovisato” of the Università
di Cagliari. The material examined encompasses palaeobotanical remains collected from the Genna Selole Formation and from the basal part of the Dorgali Formation, both of Jurassic age at a variety of localities in Barbagia and Sarcidano, eastern Sardinia. A reconstruction is given of the history of the collection, initiated in 1888, and the scientific studies of the flora by a variety of palaeobotanists. Based on a preliminary revision of the specimens the following genera are recognized: Phlebopteris Brongniart, 1836, Hausmannia Dunker, 1846, Coniopteris Brongniart, 1849, Cladophlebis Brongniart, 1849, Sagenopteris Presl in Sternberg, 1838, Cycadeospermum Saporta, 1875, Ptilophyllum Morris in Grant, 1840, Williamsonia Carruthers, 1870 emend. Harris, 1969, Weltrichia Braun, 1847 emend. Harris, 1969,
Taeniopteris Brongniart, 1828, Czekanowskia Heer, 1876 emend. Harris et al., 1974, Brachyphyllum Brongniart, 1828, Elatocladus Halle, 1913 emend. Harris, 1979 and Carpolithes Brongniart, 1822. Some plant remains have been putatively assigned to the following genera: Ptilozamites Nathorst, 1878 emend. Antevs, 1914, Nilssonia Brongniart, 1825, Pterophyllum Brongniart, 1828 and Geinitzia Endlicher, 1847.
Several of these genera are known also from the Jurassic flora of Yorkshire and from other Jurassic floras of Italy.

The Middle Jurassic flora of Sardinia has been studied, and 24 taxa (19 genera) belonging to horsetails, ferns (Phlebopteris, Hausmannia, Coniopteris, Todites, Cladophlebis), seed ferns (Sagenopteris, Ptilozamites), cycadophytes (Nilssonia, Pterophyllum, Cycadeospermum, Ptilophyllum, Williamsonia, Weltrichia, Taeniopteris), ginkgophytes (Czekanowskia), conifers (Geinitzia, Brachyphyllum, Elatocladus) and seeds (Carpolithes), have been identified.  The flora of Sardinia is the southernmost of all Middle Jurassic European floras.  The coeval European and North African floral assemblages (112 genera) are present in a wide variety of environments and different palaeogeographic positions, which is reflected in a wide variety of taxa. A comparison between the coeval floras of Middle Jurassic age reveals a higher degree of dissimilarity than similarity between the various assemblages, which is in disagreement with the general picture of the homogeneity in the Jurassic floras given by previous authors.