The Paleozoic

 
The Paleozoic  
 
Biostratigraphy and phylogenetic evolution 
 
As discussed on the Paleozoic page, the foraminifera belonging to the suborder Fusulinina are the most important foraminifera that existed during the Paleozoic. They are the only major group of foraminifera without any living representatives (Groves et al, 2005). The Fusulinoidea are an important superfamily in the suborder Fusulinina and their complexity makes them one of the most stratigraphically useful fossils today. The evolution of the Fusulinoidea is shown in the figure to the left (after BougDagher-Fadel, 2008).  Abbreviations: A, Asselian; S, Sakmarian; Ar, Artinsskian; K, Kungurian; R, Roadian; W, Wordian; C, Capitanian; W, Wuchiapingian; Ch, Changhsingian.
 
 
The morphology of the fusulinine can be interpreted from external observation and their mode of coiling can aid in their identification and determine when they lived. Wall structure of the fusulinines, especially the Late Carboniferous and Permian fusulinines, provides a diagnostic identification tool. Evolutionary events are clearly indicated by the pre-keriotheca phase, the keriotheca phase, and the post-keriotheca phase. Please refer to the Paleozoic sub-page, which details the five types of wall structure indicated by these events and the figure below for these select biostratigraphic ranges of the Fusulinidae superfamily. The The stratigraphic occurrences of the keriotheca, anthotheca and stalactotheca stages (modified after Vachard et al., 2004) are shown in the figure above.
 
Paleoecology of the fusulinines 
 
Proxy evidence from morphologically similar faunal and floral groups from the Holocene must be used to determine the paleoecology of the fusulinines as they became extinct in the late Permian. The suborder Fusulininina most likely  required normal marine salinity and thrived in shallow warm well-oxygenated, nutrient-rich waters.  Fusulinine fossils are typically found in grey, shallow water limestones or calcareous shales. Because of their associations with some corals and crinoids which live in shallow, oligotrophic, warm and sunlit environments with minimal siliclastic input, it is inferred that the fusulines thrived under similar conditions.
 
The wide range of shapes of the fusulinines indicates that they were highly adaptive to their environment.  Ross (1992) found that shape was critical factor in the distribution of the fusulinines. For example, large forms of Triticites are associated with shallow-water algal meadows and banks of crinoidal fragments; elongate forms of Triticites are associated with environments of shallow bays, lagoons and wave-built bars and terraces; subglobose Triticites suggest an adaptation to more energetic environments due to the thicker shell and small fusiform Triticites are associated with deeper shelf waters (BouDagher-Fadel, 2008). Only rare fusulinines occur in sediments from deep water environments. It is clear that the fusulinines were a group that were well adapted to a number of distinct ecological and environmental conditions. A schematic drawing to the left shows localized paleoecological distribution of the Fusulinoidea
 
Paleogeography of the fusulinines
 
The geographic distribution of the fusulinines covers the late Paleozoic basins and adjacent marine shelves of Eurasia and the Western Hemisphere (Ross, 1967).  Faunal phases used to group and recongnize fusulinine faunal associations include:
  • The Tethyan realm
  • The East European basin realm
  • The North American realm
  • The peri-Gondwana part of the Tethys 
Global cooling that occurred at the Devonian-Carboniferous boundary is associated with a black shale facies (globally correlated). There were two phases of extinctions in the Late Devonian; one lasting 400 thousand years and a second lasting 50 thousand years (BouDagher-Fadel, 2008). These events resulted in extinctions of diverse marine groups, anoxia and rapid sea-level fluctuations. The collapse of the reef ecosystems occurred during these events (Copper, 2002; Bambach, 2006). While sea-level and climate changes have been blamed for the extinctions, massive volcanism that occurred during this time or an impact event (McLaren and Goodfellow, 1990) may have played a role.  A palaeogeogrpahic and tectonic reconstruction of the Late Devonian is shown above (R. Blakey: http://jan.ucc.nau.edu/~rcb7/paleogeographic.html), indicating the location of the Tethys during the Late Devonian.
 
Small, resilient foraminifera survived the Devonian extinctions (referred to as 'disaster forms') but it took 14 million years for the benthic forams to fully recover and begin to fill vacant ecological niches left by the mass extinctions of the Late Devonian. 
 
The northward drift of Gondwana and Euramerica and, later, their collision, during the Early Carboniferous led to the Variscan-Hercynian orogeny which brought about major changes in ocean circulation and led to the diversification of ammonoids, gastropods and foraminifera.  The figure to the left depicts the number of new fusulinine genera throughout the Carboniferous and Permian.  Recovery of shallow reef environments is indicated by the first appearance of fusulinine in the Visean. The largest increase in fusulinine genera diversity was seen during the Moscovian in East Europe, North America and Tethys.  
 
Fusulinine have been found on all continents except Australia, India and Antarctica as these land masses were at southern latitudes during the Carboniferous and fusulinines could not survive.  The diversity of genera decreased in the North American basin as the connection with the Tethyan and East European basins became limited from the Late Visean to Permian. The Tethys region was the main fusulinine breeding ground, with more than 900 species described from this region alone (Haynes, 1981). 
 
The figures below indicate how the continents were situated during the Paleozoic (after Blakey; http://cpgeosystems.com/globaltext2.html). The early Mississippian (Visean) foramifera were dominated by the endothyrides (common in algal limestones) but the final orogeny in the Variscan Belt resulted in declining populations of endothyrids, changes in ocean circulation and led to the closing of the equatorial seaway, resulting in the partial thermal isolation of the Paleotethys. Diversity increased during the Pennsylvanian in Eastern Europe, Tethys and the Americas and new fusulinines with complicated internal structures rapidly evolved (Fusulina, Fusulinella).  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Paleogeographic and tectonic reconstructions of the world from early to late Paleozoic
 
During the Pennsylvanian,  fusulinines were common in shallow-water carbonate banks on the edges of land masses along the Tethyan seaway (i.e., N. Spain, N. China, Korea, N. America). At thh end of the Moscovian, there was a partial extinction event possibly caused by large-scale volcanism (the Jutland basalt event) that affected Europe and North Africa (Smyth et al., 1995) and the Tethyan during the late Carboniferous contained relatively few fusulinine genera. Fusulinine assemblages recovered in the early Permian when the atmospheric oxygen level reached a peak and fusulinines became diverse and cosmopolitan.  The tectonic closure of the East European basins during the Asselian isolated the fusulinines and the East European foraminifera disappeared.
 
The End Permian extinction resulted in the extinction of all large fusulinine. In fact, 90%-96% of all marine invertebrate species went extinct (Sepkoski, 1986) along with all but one of 90 genera of reptiles, most corals, and brachiopods (McLaren and Goodfellow, 1990; Benton, 2002).  The cause of this massive extinction event is under investigation and many theories have been proposed (e.g., climate change, tectonic processes, volcanic activity).The fusulinines never recovered and, therefore,  a niche was developed for new fauna and ecosystems to develop in the Mesozoic.
 
References

Bambach, R.K., 2006. Phaenerozoic biodiversity mass extinctions. Annu. Rev. Earth Pl. Sci. 34, 117–155.

Benton, M.J., 2002. Cope’s rule. In: Pagel, M. (Ed.), Encyclopedia of Evolution. Oxford University Press, New York, pp. 209–210.

BouDagher-Fadel, M.K., 2008. Evolution and Geological Significance of Larger Benthic Foraminifera. Developments in Paleontology and stratigraphy, v. 21, 540p.

Copper, P., 2002. Reef development at the Frasnian/Famennian mass extinction boundary. Palaeogeogr. Palaeoclimatol. Palaeoecol. 28, 1–39.

Groves, J.R., Altiner, D., Rettori, R., 2005. Decline and recovery of lagenide foraminifers in the Permian–Triassic boundary interval (Central Taurides, Turkey). Paleontological Society Memoir 62 [supplement to J. Paleontol., 79(4)], 38.

Haynes, J.R., 1981. Foraminifera. MacMillan, London, 433p.

McLaren, D.J., Goodfellow, W.D., 1990. Geological and biological consequences of giant impacts. Annu. Rev. Earth Planet. Sci. 18, 123–171.

Ross, C.A., 1967. Eoparafusulina from the Neal Ranch formation (Lower Permian), West Texas. J. Paleontol. 41, 943–946.

Ross, C.A., 1992. Paleobiogeography of Fusulinacean Foraminifera. Studies in Benthic Foraminifera. Proceedings of the Fourth International Symposium on Benthic Foraminifera, Sendai, 1990, Tokyo, Tokai University Press, pp. 23–31.

Smythe, D.K., Russell, M.J., Skuce, A.G., 1995. Intracontinental rifting from major late carboniferous quartz-dolorite dyke swarm of NW Europe. Scott. J. Geol. 31, 151–162.

Vachard, D., Munnecke, A., Servais, T., 2004. New SEM observations of keriothecal walls implications for the evolution of the fusulinida. J. Foraminiferal Res. 34, 232–242.

 

 
 
** Page generated by Kerry McCarney-Castle; text summarized from BouDagher-Fadel (2008)**
 
 
 
 
 
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