Rhodolith forming coralline algae in the Upper Miocene of Santa Maria Island (Azores, NE Atlantic): a critical evaluation

Abstract

The Late Miocene Malbusca outcrop is located in the southeastern coast of Santa Maria Island (Azores, NE Atlantic), interspersed in volcanic formations. At ~20 meters above present sea level, a prominent discontinuous layer of rhodoliths seizes with an extension of ~250 meters. This paper presents the first taxonomic record of fossil rhodolith forming coralline algae for the Miocene of the Azores. The preserved taxonomic features used were the following: (1) arrangement of basal filaments, (2) epithallial cells (when observable), (3) presence of cell fusions, (4) conceptacle type, (5) number of cells layers which conceptacle chamber floors are situated below the surrounding thallus surface and (6) for the sporangial pores, the orientation of the filaments around the conceptacle pores. Based on these characters, six taxa were identified encompassing three Corallinaceae (Lithophyllum prototypum, Lithophyllum sp., Spongites sp. and Hydrolithon sp.) and one Hapalidaceae (Phymatolithon calcareum and cf. Phymatolithon sp.). An unidentified coaxial thallus was also present, the coaxial construction ascribing the specimens to the genus Mesophyllum or Neogoniolithon. Taxonomic accounts for the identified taxa are described, illustrated and an identification key is provided. The report of L. prototypum represents the first Miocene record and the preservation of the specimens is very good. Miocene coralline algae seem very consistent among deposits but some species are relevant for particular areas, like in the Azores.

The Palaeontological Heritage of Santa Maria Island (Azores: NE Atlantic): a Re-evaluation of Geosites in GeoPark Azores and Their Use in Geotourism

“…The different Q-values assigned to the Figueiral outcrop by Lima et al (2014) and by this work are explained by the fact that the former authors failed to consider the recently published literature on this geosite (e.g. Kirby et al 2007;Winkelmann et al 2010;Madeira et al 2011;Ávila et al 2012;Rebelo et al 2014). For that reason, Lima et al (2014) used Eq.…”

“…Relevant publications were consulted concerning specific groups of fossils including the Mollusca, which is the most abundant fossil group on Santa Maria Island (Callapez and Soares 2000;Ávila et al 2002, b, 2010, Brachiopoda , Crustacea (Winkelmann et al 2010), Echinodermata (Madeira et al 2011), Ostracoda (Meireles et al 2012(Meireles et al , 2014 and Vertebrata (Estevens and Ávila 2007;Ávila et al 2012), as well as coralline algae (Amen et al 2005;Rebelo et al 2014;Johnson et al in press).…”

Comparing Methods of Evaluation of Geosites: The Fossiliferous Outcrops of Santa Maria Island (Azores, NE Atlantic) as a Case Study for Sustainable Island Tourism

“…These works led to detailed knowledge regarding the location of the most important fossiliferous outcrops (see , as well as the biological composition and ages of their palaeocommunities. Currently, 204 Pliocene and 146 Pleistocene (MIS 5e) species and at least 15 to 20 ichnospecies are reported for the island, ranging in size from megavertebrates (e.g., whales and sharks [24][25][26]) to macrovertebrates (e.g., ray fishes [27]), and from macroinvertebrates (e.g., molluscs, sea urchins, barnacles, annelids [28][29][30][31]) to microinvertebrates (e.g., molluscs, brachiopods, bryozoans, ostracods [32][33][34][35][36]), including marine algae as well [37][38][39]. For a recent review of the most significant fossiliferous outcrops of Santa Maria Island, please see [40].…”

“…Several relevant scientific publications were taken into account (cf. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]; for a review, see [19,40] and references therein) for the attribution of values to each criterion per geosite, and the quantitative evaluation attributed for each indicator was confirmed by experts on the geology and palaeontology of Santa Maria Island, mainly as a result of 14 annual sessions with international workshops on "Palaeontology in Atlantic Islands," held on the island since 2002 (see Tables S1-S4). These quantitative values were converted into rankings (Table 1), which were then compared with Q-values [19].…”

Fossil Mysticeti from the Pleistocene of Santa Maria Island, Azores (Northeast Atlantic Ocean), and the prevalence of fossil cetaceans on oceanic islands

“…These conditions favoured the incorporation in the marine sediments of abundant remains of marine vertebrates including fishes (Zbyszewski and Ferreira, 1962), cetaceans (Estevens and Ávila, 2007), and sharks (Ávila et al, 2012). There are also abundant invertebrate species, such as molluscs (Janssen et al, 2008), brachiopods , crustaceans (Winkelmann et al, 2010), echinoderms , ostracods (Meireles et al, 2012), as well as calcareous algae forming rhodoliths (Rebelo et al, 2014), whose fossils are nowadays exposed in 15 Late Miocene-Early Pliocene outcrops scattered in the island (Ávila et al, in press).…”