Review of 'The Geographic, Environmental and Phylogenetic Evolution of the Alveolinoidea from the Cretaceous to the Present Day.'

This article has been reviewed by Johann Hohenegger

The article on Alveolinoids by Marcelle K. BouDagher-Fadel and Geoffrey D. Price continues their former works on larger benthic foraminifera in a very comprehensive manner. The outstanding knowledge of published articles about this group of larger, symbiont-bearing Foraminifera allows a comprehensive view about mutual phylogenetic relations between the three families Alveolinidae, Rhapidioninidae and Fabulariidae. These families are solely based on morphological characters, which determines the generic status of the different morphologically (not biologically) determined genera. Therefore, the stratigraphic gap between Cretaceous and Paleogene representatives within the same morphological genera (e.g. in the Periloculina-Lacazina lineage) will be explained by canalizing strongly the possibilities of genetic alterations leading to identical morphospecies starting from a ‘simple’ forerunner. The second and more common explanation for similar forms at different stratigraphic levels is by homoplasy, again canalizing the pathways in genetic alterations, but not in the strict form as explained above. Therefore, differences in the outer and inner morphology between Cretaceous and Paleogene genera explains this separation.

The important point based on these morphological differences is the environmental and paleogeographic aspect of these induced phylogenetic lineages based on sea-level stands, where low stands has led to migrations across oceans and high stands create different ecological niches in the oceans, where differentiations within genera occur. Four transatlantic migrations based on low sea level stands can be found from the Mid-Cretaceous to the end of Cretaceous (Fig. 11), especially from the East to the West, while one migration based on low sea-level stands can be found in the Paleogene. The migration from the Tethys Ocean to the Indo-Pacific is caused by the connections between these oceans in the Paleogene and the following disconnection in the Neogene due to tectonic events. This explains the today distributions of the two genera Borelis and Alveolinella, where the first can be found in shallow waters of the whole tropical Indo-Pacific, possibly spread by the open Inter-American gateway to the Caribbean, while Alveolinella is restricted to the tropical East Indian and West Pacific Ocean.
All distribution are coincident with the directions of the paleo-currents.

Summing up, this is a well-written paper, where the reader can clearly understand the intensions of the authors. We have to keep in mind, that this are the opinions of the authors. Some specialists will not agree with some interpretations, but this does not impair the value of this paper. Published in this form, it is great information and shows possible interpretations of the phylogeny in this remarkable group of organisms, especially by the interruption of phylogenetic lines and the restart from primitive forms to extremely similar high evolved forms.