The geographic, environmental and phylogenetic evolution of the Alveolinoidea from the Cretaceous to the present day

Abstract

The superfamily Alveolinoidea is a member of the Order Miliolida, and comprises three main families, the Alveolinidae, the Fabulariidae and the Rhapydioninidae. They are examples of Larger benthic foraminifera (LBF), which are single-celled organisms with specific characteristic endoskeletons. Alveolinoids are found globally from the Cretaceous to the present day, and are important biostratigraphic index fossils in shallow-marine carbonates. They are often associated with hydrocarbon reservoirs, and exhibit provincialism with characteristic genera often confined to one of the American, Tethyan or Indo-Pacific provinces. Previously, the systematic study of the global interrelationship between the various alveolinoid lineages has not been possible because of the absence of biostratigraphic correlation between the geographically scattered assemblages, and the scarcity of described material from the Indo-Pacific province. Here we use the literature and new material from the Americas, the French Alps, Iran, Tibet, India and South East Asia, coupled with the use of the planktonic foraminiferal zonal (PZ) correlation scheme to propose a comprehensive, global, systematic analysis of the biostratigraphic, phylogenetic and paleogeographic evolution of the alveolinoids. The alveolinoids originated in the Cretaceous in the Tethyan province. During a global sea-level low stand, a westward migration of some alveolinoids species to the Americas occurred, a behaviour previously reported in contemporaneous orbitolinid LBF. After the Cretaceous/Palaeogene (K–P) event, which saw the extinction of all Cretaceous alveolinoids, rare new forms of alveolinoids evolved again, first in the Americas and later independently in Tethys. As was found in previous studies of rotalid LBF, sea-level low stands in the Paleocene also allowed some alveolinoid forms to migrate, but this time in an eastward direction from the Americas to Tethys, and from Tethys on to the Indo-Pacific province. Alveolinoids still exist today (Borelis and Alveolinella), the former of which is cosmopolitan, while the latter is restricted to the Indo-Pacific province. Throughout their phylogenetic history, alveolinoids characteristically exhibit convergent evolution, with the repeated re-occurrence of certain morphological features. Understanding this propensity to homoplasy is essential in understanding and constructing the phylogenetic relationships within the alveolinoid superfamily.

Evolution, Extinction, Homology and Homoplasy of the Larger Benthic Foraminifera from the Carboniferous to the Present Day, as Exemplified by Planispiral-Fusiform and Discoidal Forms

“…The adult form is typically characterized by numerous planispirally coiled chambers around an elongated axis with each chamber sliced into smaller tubular chamberlets by secondary septa that runs in the coiling direction. Importantly, the connectivity is maintained between the chambers by vertical septa carving out canals, which are positioned either in front of the septum (post-septal) or behind it (pre-septal) (see BouDagher-Fadel and Price, 2021;BouDagher-Fadel, 2018a).…”

“…In the Paleogene, the alveolinids re-appeared in the Late Paleocene seemingly independently from their Cretaceous relatives, but evolving from a common simple, long-ranging miliolid ancestor, e.g. the simple Pseudonummuloculina (see BouDagher-Fadel and Price, 2021;Hottinger, 2006;Hottinger et al, 1989). They subsequently develop lineages that are spherical to fusiform in shape, and planispiral in the adult part, exhibiting morphological convergence (homoplasy) with the fusiform/globular alveolinids of the mid-Cretaceous (e.g.…”

“…Two examples of this include the gradual stratigraphic evolution of species with a primitive nepionts to species with more advanced nepionts, and also the gradual evolution from thin-walled cubiculae/chamberlets to those with more numerous cubiculae in the swollen parts as observed in the test of Lepidocyclina (see BouDagher-Fadel, 2018a;BouDagher and Lord, 2010;BouDagher-Fadel and Price, 2010a). Other characteristics appear suddenly in the Cretaceous, such as alveoles (blind recesses separated by septula) in the miliolid Praealveolina, which seem to have evolved directly from a small, simple miliolid (BouDagher-Fadel and Price, 2021;BouDagher-Fadel, 2018a). These characteristics, however, re-appeared in the miliolids later on in the stratigraphic column, such as the alveoles in the Paleogene Alveolina, where they become an apomorphic characteristic.…”

“…Conversely to homoplasy, homology could also be a product of divergent evolution where the same common ancestor develops and accrues differences, resulting in the formation of new separate lineages of closely related but different species. Divergent evolution may take place in response to changes in biotic factors in the case of morphologically similar species appearing at different times within the stratigraphic column or may occur when two populations from the same species become separated by physical barriers, created for example by changing sea levels or tectonic changes (see BouDagher-Fadel and Price, 2021;2013;2010a).…”

“…These biological evolutionary processes probably reflect that LBF shared a genetic predisposition to develop mutations of specific, advantageous types, inherited from their last common ancestor (see BouDagher-Fadel and Price, 2021;2013;2010a) and a genetic predisposition to the repetition of these specific mutations that produce morphological characteristics that are used to define a genus. Many of these characteristics are gradual and linked to the timing of phases in growth and mode of reproduction.…”