Shark (Chondrichthyes) microremains from the Lower Cretaceous Quiricó Formation, Sanfranciscana Basin, Southeast Brazil

ABSTRACT

The first chondrichthyan teeth, dermal and oropharyngeal denticles from the Lower Cretaceous lacustrine Quiricó Formation (Sanfranciscana Basin), in southeastern Brazil are described. Eight microremains morphologies have been recovered from lower levels of this formation, dated as possibly Valanginian with basis on ostracods. The dermal denticles belongs to indeterminate Hybodontiformes; some teeth are ascribed to ?Lonchidiidae. The presence of Tribodus is suggested by some dermal denticles, but this assignment requires confirmation with more complete material. The new specimens indicate a much greater diversity of chondrichthyans in the Quiricó Formation than previously thought. The associated occurrence of hybodontiforms, the coelacanthiform Mawsonia and early neopterygians observed in the Sanfranciscana Basin is not uncommon for the Cretaceous sedimentary strata of Brazil and Africa. However, the use of the Quiricó Formation shark remains as biostratigraphic tool is limited, due to their current poor taxonomic and relatively broad temporal distribution.

KEYWORDS:

• Hybodontiformes teeth
• dermal denticles
• oropharyngeal teeth
• Tribodus
• Valanginian

Acknowledgments

We thank André Vasconcelos (UFMG, Belo Horizonte) for field assistance and Paulo Brito (UERJ, Rio de Janeiro) for previous discussions on the fossil record of the Sanfranciscana Basin. Scanning electron microscopy was undertaken at the Centro de Pesquisas Professor Manoel Teixeira da Costa (CPMTC-IGC-UFMG) and the Center of Microscopy at the Federal University of Minas Gerais (UFMG) in Belo Horizonte. We thank the reviewers for suggestions that greatly improved the final version of the paper. This research was funded by Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG, grants APQ-01110-15 and PPM-00304-18 to JSB).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Fundação de Amparo à Pesquisa do Estado de Minas Gerais [APQ-01110-15,PPM-00304-18].