The fossil history of palms (Arecaceae) in Africa and new records from the Late Oligocene (28–27 Mya) of north-western Ethiopia

Abstract

The African palm fossil record is limited but the data provide an outline of palm evolution from the Late Cretaceous through the Neogene. Pollen attributed to palms is reported from the Aptian (125–112 Mya), but the earliest unequivocal record in Africa is Campanian (83.5–70.6 Mya). Palms diversified 83.5–65.5 Mya and became widespread, although most records are from the west and north African coasts. Many taxa were shared between Africa and northern South America at that time, but a few were pantropical. Extirpations occurred throughout the Palaeogene, including a notable species turnover and decline at the Eocene–Oligocene boundary (33.9 Mya), a change that resulted in the elimination of nypoid palms from Africa. The Neogene plant macrofossil record is better sampled than the Palaeogene, although few palms are documented. Thus, the low diversity of African palms today is more likely the result of Palaeogene, rather than Neogene extinctions. Newly discovered palm fossils of leaves, petioles and flowers from the Late Oligocene (27–28 Mya) of north‐western Ethiopia document the abundance and dominance of palms in some communities at that time. The fossils represent the earliest records of the extant genera Hyphaene (Coryphoideae) and Eremospatha (Calamoideae). © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society, 2006, 151, 69–81.

Forest refugia in Western and Central Africa as ‘museums’ of Mesozoic biodiversity

“…Climate change may have depleted diversity after the separation of Africa and South America, with subsequent stable refugia acting as 'museums' for ancient lineages. In this respect, the data are largely congruent with the fossil record, which suggests that entire lineages of Neotropical palms were present in Africa until at least the Late Oligocene (27-28 Ma) [7]. Such models [5] may have received little support from molecular studies until now (but see [6]), because few phylogeographic studies have been conducted on old lineages with high endemism and low population density (see electronic supplementary material).…”

“…On the other hand, past climatic changes could have depleted rather than augmented biodiversity, suggesting that refugia might have acted as 'museums' for ancient lineages, and divergence between sister species might predate climatic fluctuations [6]. Whereas fossil evidence for plants has long suggested an ancient diversity followed by cycles of extinction owing to climatic fluctuation [7], most molecular studies (see the electronic supplementary material, Table 1. Tissue sample numbers, provenance data, GenBank accession numbers and voucher repositories for Ricinulei and outgroup taxa from which DNA sequence data were generated for the present study.…”

Low genetic diversity and recovery implications of the vulnerable Bankoualé Palm Livistona carinensis (Arecaceae), from North-eastern Africa and the Southern Arabian Peninsula

“…Fossils of Livistona affinity appear in India dated to the mid Eocene (Prakash and Ambwani 1980), although specimens of Livistona affinity have been excavated from European and North American sites dated to the late Cretaceous (Read and Hickey 1972) and the Eocene (Chandler 1978). Fossil fruits with affinity to Livistona have been reported from early Palaeocene deposits of Egypt (Gregor and Hagn 1982;Pan et al 2006). Based on fossil pollen records, palms appear to have been much more widespread across Africa than they are at present (Jacobs 2004).…”

Cenozoic imprints on the phylogenetic structure of palm species assemblages worldwide

“…3B). The African fossil record of palms indicates severe Tertiary extinction (51). It is therefore likely that decreasing speciation and increasing extinction rates due to dramatic rainforest decline have caused an overall random phylogenetic structure of African palm assemblages (Fig.…”