Inventory and review of the Mio–Pleistocene São Jorge flora (Madeira Island, Portugal): palaeoecological and biogeographical implications

<p>The occurrence of plant fossils on Madeira Island has been known since the mid-nineteenth century. Charles Lyell and George Hartung discovered a leaf bed rich in Lauraceae and fern fossils at São Jorge in 1854. The determinations were controversial but a full review was never performed. Here we propose possible geological settings for the fossiliferous outcrop, and present an inventory and a systematic review of the surviving specimens of the São Jorge macroflora. The São Jorge leaf bed no longer outcrops due to a landslide in 1865. It was possible to establish the two alternative volcano-stratigraphical settings in the sedimentary intercalations from the Middle Volcanic Complex, ranging in age from 7 to 1.8 Ma. The descriptions of Heer (<a href="#cit0036" target="_blank">1857</a>), Bunbury (<a href="#cit0013" target="_blank">1859</a>) and Hartung & Mayer (<a href="#cit0032" target="_blank">1864</a>) are reviewed based on 82 surviving specimens. From the initial 37 taxa, we recognize only 20: <i>Osmunda</i> sp., <i>Pteridium aquilinum</i>, <i>Asplenium</i> cf. <i>onopteris</i>, aff. <i>Asplenium</i>, cf. <i>Polystichum</i>, cf. <i>Davallia</i>, <i>Woodwardia radicans</i>, Filicopsida gen. et sp. indet. 1 and 2, <i>Ocotea foetens</i>, <i>Salix</i> sp., <i>Erica arborea</i>, cf. <i>Vaccinium</i>, <i>Rubus</i> sp, cf. <i>Myrtus</i>, Magnoliopsida gen. et sp. indet. 1 to 3, Liliopsida gen. et sp. indet. 1. Magnoliopsida gen. et sp. indet. 4 is based on one previously undescribed flower or fruit. The floristic composition of the São Jorge fossils resembles the current floristic association of temperate stink laurel (<i>Ocotea foetens</i>) forest, suggesting a warm and humid palaeoclimate and indicating that laurel forests were present in Macaronesia at least since the Gelasian, a time when the palaeotropical geofloral elements were almost extinct in Europe.</p>