Banca de DEFESA: Patricia Fabiana Rodrigues Costa

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Patricia Fabiana Rodrigues Costa
DATE: 13/12/2023
TIME: 09:00
LOCAL: Sala de videoconferência e Teams
TITLE:

Description and taphonomy of the paleoichthyofauna from the Araçatuba and Adamantina formations (Upper Cretaceous), Bauru Group of Presidente Prudente, São Paulo State.

KEY WORDS:

Lepisosteidae; Teleostei; Cretaceous, Bauru Group; Taphonomy

PAGES: 116
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The paleoichthyofauna of the Bauru Group comprises fish remains, usually isolated such as scales, vertebrae, teeth, and cranial bones. The diversity of fish includes Actinopterygians such as Lepisosteidae, Amiidae, Osteoglossiformes, Characiformes, and Perciformes, with some records of dipnoi. However, due to the scarcity of more complete specimens, the understanding of the components of the paleoichthyofauna in this unit is still unknown. The material was collected in the Presidente Prudente region, near Pirapozinho and General Goulart, and it is deposited in the paleontological collection of LaPaDA-FUP. It has been prepared and described based on specific literature, with some specimens analyzed using computerized microtomography and morphometric analysis of ganoid scales. In this study, the material is associated with lacustrine deposits, preserved in fine to medium sandstones with intercalations of mudstone and frequent carbonate cementation, as well as mudcracks associated with lake dry periods (Araçatuba Formation). Additionally, fluvial deposits are preserved in fine to medium sandstones with carbonate cementation, planar stratification, climbing ripples, and invertebrate burrows indicating shallower water conditions (Adamantina Formation). The similarity between the Araçatuba and Adamantina Formations studied in this work suggests a transitional area from lacustrine to fluvial conditions. In both formations, levels with various turtle bone remains and fish fossils associated with calmer to more turbulent water conditions and carbonate cementation were identified. At the top of both sequences, there are fossils strongly associated with high levels of transport, abrasion, and packing, indicating larger water body energy flows. In the Adamantina Formation, at the base, there are numerous gyrogonites of charophyte algae. It was concluded that the paleoichthyofauna of these two units are quite similar, with sympatric species such as Lepisosteidae and Atractosteus cohabiting the region. Both units show records of cycloid scales of Characiformes and pectoral spines of Siluriformes with similar morphologies. Cycloid scales have not been adequately studied in the Bauru Group, and their records are brief and vague due to the incompleteness of the material. Therefore, this study aimed to better characterize the morphological description of these cycloid scales based on recent scale studies and comparisons with current morphotypes and subtypes, possibly attributing them to cycloid scales of Characiformes. The most common records undoubtedly belong to Lepisosteidae, indicating either a greater abundance of these individuals or that they simply have more easily preserved remains in the fossil record, such as ganoid scales than elasmoid scales. This work reports for the first time in the Bauru Group a left dentary of a juvenile Atractosteus, based on its unique characteristics such as three robust conical teeth with strong plicidentine, the absence of a row of smaller lateral teeth, and mandibular canal morphology indicating an ontogenetic stage of a juvenile.

COMMITTEE MEMBERS:
Externo à Instituição - ELISEU VIEIRA DIAS - UNIOESTE
Externo ao Programa - 1805604 - RICARDO LOURENCO PINTO - nullPresidente - 2520585 - RODRIGO MILONI SANTUCCI
Externa ao Programa - 3125063 - VERONICA DE BARROS SLOBODIAN MOTTA - null