Extinct foraminifera figured in Brady’s <i>Challenger</i> Report

Abstract

Abstract. Brady’s (1884) widely available monograph on foraminifera from the Challenger Expedition is generally assumed to illustrate hundreds of living species from modern seafloor sediment from around the world. This assumption may have contributed to the delay in recognizing the youngest extinction ‘episode’ in the deep sea, which occurred during the mid-Pleistocene Climate Transition. At least 18 of the species illustrated by Brady are part of the group of c. 70 elongate, benthic foraminifera now known to have died out globally between 1.2 and 0.6 million years ago. The figured specimens were sampled from just seven stations that presumably contain relict or reworked sediment, possibly mixed in with Holocene. The majority (14 species) come from two stations (191A, 192) off Kei Islands, Banda Sea, Indonesia. Station 192, from c. 250 m depth, is considerably shallower than the established fossil bathymetric ranges of the extinct species and therefore tectonic uplift is inferred. Additional pre-Holocene or even extinct species may also be among those illustrated by Brady, especially from the seven stations so far identified.

Late Paleocene‐middle Eocene benthic foraminifera on a Pacific seamount (Allison Guyot, ODP Site 865): Greenhouse climate and superimposed hyperthermal events

“…However, both infaunally positioned suspension feeders anchored by spines and attached epifaunal suspension feeders may be common. We suggest that the spinose cylindrical taxa most common throughout the studied interval (stilostomellid species of the genus Strictocostella ) [ Hayward et al ., ] may have been shallow infaunally living species, according to their shape, distribution, and carbon isotope signature [ Hayward and Kawagata , ; Hayward et al ., ; Mancin et al ., ], anchored in the sediment by their spines [ Hottinger , ] and suspension feeding in the water column using their pseudopods extended through the complex aperture [e.g., Hottinger, , ; Mancin et al ., ]. Such a lifestyle would be in agreement with suggestions that they were infaunal, k‐strategist taxa with low metabolic rates [ Mancin et al ., ], and rules out the possibility of reworking as the cause of their high numbers in the sediment.…”

Methods

“…Neogene planktonic foraminiferal taxonomy largely follows that of Kennett and Srinivasan (1983). For benthic foraminiferal taxonomic identification, the Ellis and Messina online catalogue (Ellis and Messina, 1940), Barker (1961), Poag (1981), Hayward and Kawagata (2005), and the generic classification scheme of Loeblich and Tappan (1988) were used. Paleodepth estimates were determined using depth ranges presented by Poag (1981) and Galluzzo et al (1990).…”

Mid-Pleistocene Stilostomella extinction event off northern Chile (25ºS)

“…Schönfeld (1996) reviewed the Mid-Pleistocene Stilostomella extinction from known global records and summarized that the extinction of larger-sized specimens (>150 µm) occurred between 1.0 and 0.6 myr (predominantly from 0.8 to 0.7 myr), with highly variable timings. More recently, several studies (Hayward 2001(Hayward , 2002Hayward and Kawagata 2005;Hayward et al 2006; Kawagata indicó que la desaparición de los especímenes de mayor tamaño (>150 µm) ocurrió entre 1.0 y 0.6 ma (predominantemente de 0.8 a 0.7 ma) con un ritmo muy variable. Más recientemente, varios estudios (Hayward 2001(Hayward , 2002Hayward y Kawagata 2005;Hayward et al 2006;Kawagata et al 2005Kawagata et al , 2006Kawagata et al , 2007O'Neill et al en prensa) han mostrado que la transición climática del Plioceno tardío al Pleistoceno medio (3.0-0.55 ma) resultó ser un intervalo de mucho recambio con la extinción de 96 especies y 19 géneros (>63 µm) de foraminíferos bentónicos elongados y cilíndricos (de las familias Stilostomellidae, Pleurostomellidae y Nodosariidae).…”