Ultrastructure, composition, and 87Sr/86Sr dating of shark teeth from lower Miocene sediments of southwestern Peru

Taphonomy of a Mysticete Whale from the Lower Pliocene of the Coast of Cádiz (Spain)

“…87 Sr/ 86 Sr corrected values were converted into ages using the LOESS Table 6 calibrated to the GTS2020 timescale [75]. To estimate the age of the stratigraphic layer, a mean 87 Sr/ 86 Sr value was calculated from the better-preserved oysters and then converted to age [76,77]. The uncertainty was calculated as 2 s.e.…”

A new platyrostrine sperm whale from the Early Miocene of the southeastern Pacific (East Pisco Basin, Peru) supports affinities with the southwestern Atlantic cetacean fauna

“…Along the western side of the Ica River, including the thoroughly investigated Ullujaya area (Fig. 1B), the Chilcatay strata have been shown to consist of two distinct sequences or allomembers, namely, Ct1 and Ct2 (in ascending stratigraphic order), plus an older sequence (Ct0) that has recently been identified at the remote Media Luna locality, in the southern portion of the basin (DeVries & Jud 2018; Di Celma et al 2018, 2019; DeVries et al 2021; Bosio et al 2022). During the deposition of the Chilcatay strata, the East Pisco Basin was shaped as a shelfal embayment whose seaward border was marked by an archipelago of basement islands (Bianucci et al 2018b; DeVries & Jud 2018).…”

“…E , Simplified stratigraphic section of the Chilcatay Formation in Zamaca, showing the exact position of the holotype of R. valenciae in the Ct1 allomember, Ct1a facies association. Both sections D and E include positions of ash layers dated with 40Ar/39Ar and shell-rich beds dated with 87Sr/86Sr along with the corresponding age estimates (after Bosio et al 2022). Maps and sections modified from Bianucci et al (2018b), Di Celma et al (2018, 2019), Bosio et al (2020, 2022), and Lambert et al (2020).…”

“…Both sections D and E include positions of ash layers dated with 40Ar/39Ar and shell-rich beds dated with 87Sr/86Sr along with the corresponding age estimates (after Bosio et al 2022). Maps and sections modified from Bianucci et al (2018b), Di Celma et al (2018, 2019), Bosio et al (2020, 2022), and Lambert et al (2020).…”

“…This part of the Ct1 allomember has been dated to the late Early Miocene (Burdigalian, between c. 19 and 18 Ma, and probably close to 18.4 Ma) based on biostratigraphic data (Craspedodiscus elegans diatom zone and the upper part of the Naviculopsis ponticula silicoflagellate zone) (Di Celma et al 2018). Radiometric dating of two volcanic ash layers and the application of Strontium Isotope Stratigraphy to selected shell-rich beds (Bosio et al 2020(Bosio et al , 2022 allow the age of the studied cetacean specimen to be constrained to the 18.8-18.3 Ma interval (Fig. 1D).…”