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

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posted on 2017-11-21, 03:31 authored by Carlos A. Góis-Marques, José Madeira, Miguel Menezes de Sequeira

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 (1857), Bunbury (1859) and Hartung & Mayer (1864) are reviewed based on 82 surviving specimens. From the initial 37 taxa, we recognize only 20: Osmunda sp., Pteridium aquilinum, Asplenium cf. onopteris, aff. Asplenium, cf. Polystichum, cf. Davallia, Woodwardia radicans, Filicopsida gen. et sp. indet. 1 and 2, Ocotea foetens, Salix sp., Erica arborea, cf. Vaccinium, Rubus sp, cf. Myrtus, 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 (Ocotea foetens) 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.

Funding

ARDITI – Regional Agency for the Development of Research, Technology and Innovation, project M1420- 09-5369-FSE-000001- PhD grant; Patrícia Santos, Bruno Aveiro, Ricardo José and Paul Felber for field assistance, and the latter also for the original Heer (1857) paper. This research received support from the SYNTHESYS Project (GB-TAF-3203; http://www.synthesys.info/), which is financed by European Community Research Infrastructure Action under FP7 Integrating Activities Programme.

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