Palaeoniscoid remains from the Lower Permian Pedra de Fogo Formation (Parnaíba Basin): Insights from general morphology and histology

ABSTRACT

Fossil fish remains from the Pedra de Fogo Formation in Brazil are abundant and diversified, yet studies of fossils from this lithostratigraphic unit in the Tocantins State remain scarce. Here we describe the general morphology and histology of actinopterygian remains collected in Filadelfia municipality, Tocantins State. These new records comprise isolated teeth and scales found at about the same biostratigraphic level. Our morphologic analysis of scales reveals five distinct body regions. Comparative and histological analysis of the ganoid scales point to the palaeoniscoid type, confirming a palaeonisciform contribution. Additionally, teeth histology confirms the presence of simplexodont plicidentine, indicating a possible morphofunctional adaptation to predatory life. The discovery of more complete specimens is necessary to refine taxonomic assignment.

KEYWORDS:

• Palaeonisciformes
• teeth
• palaeoniscoid-type scales
• Csularian
• Tocantins State
• northern Brazil

Acknowledgments

We thank the three anonymous reviewers for their constructive comments and suggestions that greatly improved the manuscript. We are also grateful to the following: Dr A.C. Pedreira (NUTA/UNITINS) and Dr E.F. Pires (LABPALEOBIO/UFT) for providing access to the specimens; J. Machado (LABMEV/UERJ) for help in obtaining the scanning electron microscope images; and M.F. Belerique, Dr H. Araújo-Junior (Laboratório de Paleontologia/UERJ), Dr C.H. Callado (LABAVEG/UERJ) and Dr T.N.A. Pereira (LABSIST/UFT) for use of the stereoscope microscopes. The stereoscope microscope of the LABSIST/UFT was supported by the project “Mapeamento da biodiversidade do Estado do Tocantins” (process no. FINEP 01.18.0077.00). We are grateful to F.E.F. Souza (LABPALEOBIO/UFT) for assistance during fieldwork. Ground sections were made by N.M. da Silva and L. Melo (LGPA/UERJ). We especially thank Dr L.P. Bergqvist, L.O. Castro and I.D. Veiga (Laboratório de Macrofósseis/UFRJ), N. Moreira (Laboratório de Anatomia Vegetal/UERJ) and S. Morel (UMR 7207 CR2P MNHN– UPMC) for helpful feedback and comments with the histological methodology. Y.M.A. was supported by CNPq fellowship (process no. 15146/2018-3) and C.C. by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 (Programa Nacional de Pós-Doutorado/PNPD).

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

YMA was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico [CNPq PDJ fellowship/ proc. no. 15146/2018-3] and CC by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 (Programa Nacional de Pós Doutorado-PNPD).