Average rating: | Rated 5 of 5. |
Level of importance: | Rated 5 of 5. |
Level of validity: | Rated 5 of 5. |
Level of completeness: | Rated 5 of 5. |
Level of comprehensibility: | Rated 5 of 5. |
Competing interests: | None |
The paper presents a useful taxonomic, palaeoenvironmental and palaeogeographic summary of the Aptian to Cenomanian Orbitolinidae. The most recent significant works on this family include Schroeder et al. (2010), Boudagher-Fadel et al. (2017) and Boudagher-Fadel (2018). The present paper presents supplementary evidence to that presented in Boudagher-Fadel et al. (2017) to extend existing knowledge of the Tethyan and American forms to the flanks of the Western Pacific region. Studies of the orbitolinids from the Tibetan Plateau and South Kalimantan, stratigraphically calibrated with planktonic foraminifera, provide new evidence for the migration paths and their individual evolutionary lineage that will significantly assist the stratigraphic application of orbitolinids. The Tethys is maintained as the centre for orbitolinid development, from which one migration path extended west to the Americas and the other east to the Western Pacific, with subsequent evolution of local provincial forms.
The photomicrographs easily display the features of taxonomic importance. Figures 4 and 5 clearly illustrate the morphological changes of orbitolinid embryonic apparatus and test morphology, with reference to the evolutionary groups described in the text. Episodes of migration are explained as responses to eustatic sea-level changes, as well illustrated in Figure 6, with figures 7 and 11 succinctly explaining the geographic and stratigraphic distribution of the various genera in the three provinces.
The paper is important as it permits application of orbitolinid evolutionary stages to be better understood across the wide extent spanning the American to the Western Pacific. Calibration with the planktonic foraminiferal zones is an important tool for correlation at both regional and local levels. Links with eustatic controls on dispersal are highlighted as well as the tendency for provincial evolution in the three provinces respectively.