News and Reviews – Comments on “New aragonite 87Sr/86Sr records of Mesozoic ammonoids and approach to the problem of N, O, C and Sr isotope cycles in the evolution of the Earth” by Yuri D. Zakharov, Sergei I. Dril, Yasunari Shigeta, Alexander M. Popov, Eugenij Y. Baraboshkin, Irina A. Michailova and Peter P. Safronov [Sedimentary Geology, 364 (2018): 1–13]

Abstract

Comments are provided on a published paper on 87Sr/86Sr records of Mesozoic ammonoids [Yuri D. Zakharov, Sergei I. Dril, Yasunari Shigeta, Alexander M. Popov, Eugenij Y. Baraboshkin, Irina A. Michailova, and Peter P. Safronov, New aragonite 87Sr/86Sr records of Mesozoic ammonoids and approach to the problem of N, O, C and Sr isotope cycles in the evolution of the Earth, Sedimentary Geology, 364 (2018): 1–13], where insufficiently or erroneously dated materials have been used. The names of the Jurassic ammonites used in the discussed article are erroneous, and these names are sometimes allocated wrong stratigraphic and geographic information. For example, “Procerites funatus” from the Callovian of the Ryazan region following its features and mode of preservation should be re-assigned to the Volgian Kachpurites cheremkhensis from the Yaroslavl area. These problems partly result from the study of specimens delivered from fossil dealers. Therefore, the interpretation of the differences in Lower Albian ammonite Sr isotope values as function of their habitat depths given by these authors should rather be explained by their different geologic age.