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www.sciencedirect.com Revue de micropaléontologie 54 (2011) 239–240
Comments to
Palaeozoic Foraminiferal response to global change夽 La réponse des foraminifères paléozoïques aux changements globaux Daniel Vachard a,∗ , Lucie Pille b , Jérémie Gaillot c a
FRE 3298 du CNRS géosystèmes, université de Lille-1, 59655 Villeneuve-d’Ascq cedex, France b 52, boulevard Jules-Guesde, 93200 Saint-Denis, France c Total, CSTJF, 64018 Pau, France
The constructive criticism of D. Ruban (2011) allows to clarify a few topics developed in our paper (Vachard et al., 2010) and to take part in the definition of further projects that will deserve the undivided attention of future Palaeozoic foraminiferologists. Firstly, we would like to stress that we are not members of the happy few users of quantitative data, but such approaches are probably necessary when the systematic study is sufficiently mature. It is possibly the case for the Cenozoic and Mesozoic foraminifers, the study of which began as early as the 19th century, but it is not the case for the Palaeozoic foraminifers, the study of which was mainly initiated during the second half of the 20th century (Rauzer-Chernousova, 1948; Reitlinger, 1950). As pointed out by Ruban, the numerical analyses on foraminifers are principally based on the work of Tappan and Loeblich (1988). This article indeed represents the accounting version of the handbook of Loeblich and Tappan (1987). Although much less partial (in both meanings of the word: biased and incomplete) than their previous work (Loeblich and Tappan, 1964), the 1988’s handbook still adds some biases to the estimation of true Palaeozoic foraminifers as they are combined with the algospongia, a poorly known incertae sedis group (Vachard and Cózar, 2010). This group was extremely abundant and diverse during the Devonian and Early Carboniferous (especially during the Frasnian and the Viséan). This explains why the strong drop in the foraminiferal number at the Frasnian-Famennian boundary (due to the disappearance of the super-families Semitextularioidea and Eonodosarioidea and substitution by the Tournayelloidea and Quasiendothyroidea) does not appear on the curve of Loeblich and Tappan (1964). DOI of original article:10.1016/j.revmic.2011.10.001. Comment to article: Ruban D.A. Palaeozoic mass extinctions and foraminifers: a new insight? Revue de Micropaléontologie 54 (4), in press. ∗ Corresponding author. E-mail address:
[email protected] (D. Vachard). 夽
0035-1598/$ – see front matter © 2011 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.revmic.2011.10.002
Because Leven’s curve (2003) for the fusulinids seems to remain relatively accurate and up to date, this is the only one we showed in our paper. The curve should be re-assessed regarding the recent discovery of several homeomorph genera in the United States (Stevens and Stone, 2009; Wilde, 2006), where many schwagerinoid (keriothecal fusulinida) lineages may contain vicariant genera, as compared with the Tethyan and Uralian palaeobiogeographic provinces. Leven’s curve indicates that the oldest appearance of the fusulinida took place at the base of the Viséan stage and their last occurrence at the Permian-Triassic mass extinction event. Through this time interval, the evolution of the Palaeozoic foraminifers was driven by both intrinsic and extrinsic factors and events (sensu Jablonski, 2000). The latter are often regarded as closely associated to global environmental changes, although it is worth noting that some global change events, such as the LPIA (Late Palaeozoic Ice Age), did not particularly disrupt their evolutionary history (Leven, 2003; Groves and Lee, 2008; Groves and Yue, 2009). The intrinsic factors still remain unclear but are probably related to a distinctive evolutionary dynamics proper to benthic Foraminifera. Biotope substitution and/or modification of the chemical microenvironment seem to be the only external factors operating at a local level. This kind of evolution is not only illustrated by the Givetian revolution (i.e., the transition from the questionable Fusulinata to the true Fusulinata), but also by the appearance of other classes of foraminifers during the Palaeozoic which seem to originate at times of no significant environmental changes. For example, the class of Miliolata appeared during the Serpukhovian-Bashkirian interval, without any conspicuous connection with a major event of the Earth history. This is also the case for the class Nodosariata (also called Rotaliata), a monophyletic clade that appeared as early as the early Moscovian (Kashirian) and is still well-represented in the modern seas. Again, the Kashirian is not a critical period, apart
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from the fact that it corresponds to a late phase of the Hercynian orogenesis. Similarly, no obvious event has been a prelude to the appearance of the Fusulinida (base of Viséan) or to the disappearance of the important group of the archaediscoids (early Moscovian Vereian). The Givetian revolution of Foraminifera was probably due to intrinsic factors. The massive colonization of the shallow marine platforms by the foraminifers can probably be correlated with the first maximal development of reefs, of the first development of terrestrial plants (and consequently to a supplementary influx of phytodetritus in the oceans) and probably to an additional development of the phytoplankton (especially calcitarcha sensu Versteegh et al., 2009). The correlation with the Taghanic Event (House, 2002; Walliser, 1996) is probably not justified, because the two events do not appear to be strictly contemporaneous and because the Givetian revolution is not an extinction event. On the contrary, in the Givetian stratotype (Fromelennes Formation; Ardennes mountains, France) although the foraminiferal communities are stable they are accompanied by the appearance of the important incertae sedis group of Umbellidae, which diversified rapidly during the Frasnian and Famennian. Furthermore, in the Fromelennes Fm, it seems that no drastic change in sea level and sedimentation rate occurred, with the only exception of some very local variations (Vachard, unpublished data). In conclusion, the Palaeozoic foraminifers will probably significantly contribute to the study of the biodiversity curves. When their classification will be robust enough, it will be possible to quantify them properly. Nevertheless, an outstanding question for the next generation of systematicians remains the geochemical characterization of the tests (those with a “differentiated wall”), in order to avoid problems related to cases of homeomorphy (Miklukho-Maklay, 1957). Understanding the microstructural differences of the foraminiferal test is very important, especially for the simple forms. Then, the statistic treatment of Palaeozoic foraminiferal data will become a very objective and accurate task. References Groves, J.R., Lee, A., 2008. Accelerated rates of foraminiferal originations and extinction during the Late Paleozoic age. Journal of Foraminiferal Research 38 (1), 74–84. Groves, J.R., Yue, W., 2009. Foraminiferal diversification during the Late Paleozoic ice age. Palaeobiology 35 (3), 367–392.
House, M.R., 2002. Strength, timing, setting and cause of mid-Palaeozoic extinctions. Palaeogeography, Palaeoclimatology, Palaeoecology 181, 5–25. Jablonski, D., 2000. Chapter 2.3 Macroevolution; 2.3.1 Origin of evolutionary novelties. In: Briggs, E.G., Crowther, P.R. (Eds.), Palaeobiology II. Blackwell Publishing, pp. 162–166. Leven, E., 2003. The Permian stratigraphy and fusulinids of the Tethys. Rivista Italiana di Paleontologia e Stratigrafia 109 (2), 267–280. Loeblich, A.R., Tappan, H., 1964. Sarcodina, chiefly “Thecamoebians” and Foraminiferida. In: Moore, R.C. (Ed.), Treatise of Invertebrate Paleontology, Part C, Protista 2., 2. The Geological Society of America and the University of Kansas Press, pp. C1–900. Loeblich, A.R., Tappan, H., 1987. Foraminiferal genera and their classification. Van Nostrand Reinhold Company Publisher 2 volumes, 1 vol. text: X + 970 p., 1 vol. pls: VIII + 212 p. + 847 pl. Miklukho-Maklay, A.D., 1957. O gomeomorfii fuzulinid [On fusulinid homeomorphy]. Vses Paleont. Obshch., Ezhegodnik 16 (1955–1956), 48–57. (In Russian). Rauzer-Chernousova, D.M., 1948. Stratigrafiya vizeiskogo yarusa yuzhnogo kryla podmoskovnogo basseina po faune foraminifer [Stratigraphy of the Visean stage of southern border of Submoscovite basin by foraminiferal fauna]. Akademiya Nauk SSSR, Trudy Instituta Geologicheskikh Nauk 62, geologichevskaya seriya 19, 3–40. (In Russian). Reitlinger, E.A., 1950. Foraminifery srednekamennougolnykh otlozhenii tsentralnoi chasti Russkoi platformy (isklyuchaya semeistvo Fusulinidae) [Foraminifera from middle Carboniferous deposits of the central part of the Russian Platform (excepting the family Fusulinidae)]. Akademiya Nauk SSSR, Trudy Instituta Geologicheskikh Nauk 126, geologichevskaya seriya 47, 1–126. (In Russian, French translation BRGM no. 1456). Ruban, D.A., 2011. Palaeozoic mass extinctions and foraminifers: a new insight? Comment on Vachard et al. Revue de Micropaléontologie 54 (4), In press. Stevens, C., Stone, P., 2009. New Permian fusulinids from Conglomerate Mesa, southeastern Inyo Mountains, east-central California. Journal of Paleontology 83 (1), 9–29. Tappan, H., Loeblich, A.R., 1988. Foraminiferal evolution, diversification and extinction. Journal of Paleontology 62 (5), 695–714. Vachard, D., Cózar, P., 2010. An attempt of classification of the Palaeozoic incertae sedis Algospongia. Revista Espa˜nola de Micropaleontología 42 (2), 129–241. Vachard, D., Pille, L., Gaillot, J., 2010. Palaeozoic Foraminifera: systematics, palaeoecology and responses to the global changes. Revue de Micropaléontologie 53 (4), 209–254. Versteegh, G.J.M., Servais, T., Strenga, M., Munnecke, A., Vachard, D., 2009. A discussion and proposal concerning the use of the term Calcispheres. Palaeontology 52 (2), 343–348. Walliser, O.H., 1996. Global events in the Devonian and Carboniferous. In: Walliser, O.H. (Ed.), Global Events and Event Stratigraphy in the Phanerozoic. Springer, Berlin, pp. 225–250. Wilde, G.L., 2006. Pennsylvanian-Permian fusulinaceans of the Big Hatchet Mountains, New Mexico. New Mexico Museum Natural History and Science 38, 1–311.