The Quaternary plant fossil record from the volcanic Azores Archipelago (Portugal, North Atlantic Ocean): a review

Abstract

Plant fossils are known from the Azores Islands, yet poorly studied. We present a comprehensive bibliographical review for the archipelago. A first pre-scientific reference dates from late fifteenth century, while the first scientific description was reported in 1821, accounting for trunks in pyroclastic units and silicified plants within hydrothermal deposits. Throughout the second-half of the nineteenth century and the first-half of the twentieth century, prospection by naturalists and geological mapping work, led to the discovery and description of plant fossils in most islands. From the 1970s onwards, the taxonomic interest ceased, and plant fossils were used mainly for 14 C dating. Recently, sediment cores from lakes and peatlands were used for palaeoecological reconstructions and to measure anthropogenic impacts. Generally, plant fossils are younger than 50 ka, although older fossils may exist. Azorean plant fossils include somatofossils of leaves, stems, logs and seeds preserved as impressions, compressions, adpressions, permineralizations, lava tree casts and mummifications. The taphonomy of macrofloral elements is usually related to explosive volcanic activity, while palynological record is associated with lake sediments and peat bogs. The persistence in palaeobotanical and palaeopalynological studies will decisively contribute to disentangle the paleodiversity, palaeoecology, and add crucial information on insular plant phylogeny and biogeography.

Colonization time on island settings: lessons from the Hawaiian and Canary Island floras

“…In these cases, island colonization is expected to have been rapidly followed by diversification within the island setting (Kim et al, 2008). Such a pattern of diversification is often triggered by inter-island dispersal, but it may also occur within single islands over short time intervals (Garot et al, 2019;Saro et al, 2019). When all extant populations/taxa are island Yan et al, 2018), the stem age estimate (8.0 Myr, 95% HPD = 6.8-10.3) suggests an old split between a mainland East Asian clade and the island lineage.…”

Description and systematic affinity of flower and seed fossils of Erica sect. Chlorocodon (Ericaceae) from the early Pleistocene of Madeira Island, Portugal

“…Immigration to Madeira Island from the Azores seems less probable since geochronological data shows that 1.3 Ma ago, most Azorean islands had not emerged yet. The only subaerial edifices available as source were Santa Maria Island and, less probably, the coeval São Jorge (1.3 Ma) or Corvo (1.5-1.0 Ma) islands (see Góis-Marques & al., 2019b and references therein). Désamoré & al.…”

“…To date, no macrofossils attributable to the WPBH are known from the Macaronesian islands. This is mostly due to the infrequent palaeobotanical research performed in these islands (Góis‐Marques & al., 2019b; Góis‐Marques, 2020), due to the supposed idea that volcanic islands lack a well‐preserved and palaeobiological informative terrestrial fossil record (Anderson & al., 2009). However, other Erica fossils such as E. arborea L. were described from Madeira Island (Góis‐Marques & al., 2018) and a doubtful mention of E. arborea does exist for São Miguel Island (Góis‐Marques & al., 2019b).…”

Phylogeographical Analyses of a Relict Fern of Palaeotropical Flora (Vandenboschia speciosa): Distribution and Diversity Model in Relation to the Geological and Climate Events of the Late Miocene and Early Pliocene

“…This would place H-III in the Azores before that date, although a more recent origin of these private haplotypes cannot be ruled out. Góis-Marques et al [ 111 ] concluded a Pleistocene–Holocene age for all plant fossils described in the Azores. Vandenboschia speciosa could have arrived to the Azores at Santa Maria Island (~6 Ma), the only island older than 1.5 Ma (reviewed by [ 108 ]).…”