Apatite U-Pb dating of Cretaceous vertebrate fossils from Bauru Basin, Brazil: insights into geochronology and fossildiagenesis

• Grant number: 24/22536-4
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: May 01, 2025
• End date: October 31, 2025
• Field of knowledge: Biological Sciences - Zoology - Paleozoology
• Principal Investigator: Max Cardoso Langer
• Grantee: Fellipe Pereira Muniz
• Supervisor: Sandra Kamo
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Institution abroad: University of Toronto (U of T), Canada
• Associated to the scholarship: 24/03599-5 - Life, death and preservation of vertebrates in desert environments: an integrative taphonomic approach to the Cruzeiro do Oeste bonebeds (Bauru Basin, Paraná), BP.PD

Abstract

Absolute dating of many fossiliferous units from the Mesozoic is hampered by the lack or rarity of igneous minerals. Recent advances in U-Pb dating have shown that fossil vertebrate apatite can yield reliable depositional ages if late diagenetic processes did not overprint the primary U and Pb compositions acquired during late diagenesis. The Bauru Basin, in central-south Brazil, hosts one of the most well-documented continental faunas from the Cretaceous of South America. However, the age of several units within the basin is uncertain due to the scarcity of radiometric dating. As a consequence, important geological and biological events are still poorly time-constrained. This project aims to test the feasibility of using LA-ICPMS U-Pb dating on fossil apatite from vertebrates collected in several units of the Bauru Basin and evaluate potential implications for understanding their geochronology and fossildiagenesis. The proposed combination of the U-Pb analysis and Raman microscopy will allow the assessment of the latter as a possible screening tool for identifying less altered samples. Additionally, the sampling selection might help evaluate the potential influence of age, lithology, and skeletal tissue type on recovered U-Pb ages. The anticipated results are expected to improve the temporal framework of the Bauru Basin and refine the understanding of the taphonomic processes affecting fossil apatite during early and late diagenesis.