Banca de DEFESA: Alex Gabriel Cajado Ferreira

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Alex Gabriel Cajado Ferreira
DATE: 12/12/2023
TIME: 14:00
LOCAL: Sala de videoconferência e Teams
TITLE:

 Crocodylomorph oteoderm microstructure from the Bauru Group (Upper Cretaceous).

KEY WORDS:

Cretaceous, Notosuchia, histology, Adamantina Formation

PAGES: 76
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The living crocodylomorphs are part of the monophyletic group Crocodylia, which currently includes more than 20 species distributed in the intertropical regions around the world. In addition to the extant species such as crocodiles, alligators, and gharials, Crocodylomorpha also encompasses various extinct lineages. In Brazil, post-Paleozoic continental sedimentary deposits are notable for the abundance of Crocodylomorpha fossils. A common feature among all crocodylomorphs, whether living or extinct, is the presence of the dermal skeleton. This covering is composed of bones known as osteoderms or dermal plates, which are interconnected by fibrous tissues. These dermal plates play essential roles in protection, flexibility, energy absorption, and mineral storage, varying in size, shape, ornamentation, and functions according to the species. This study aims to analyze the dermal plates of fossil species belonging to the taxa Baurusuchidae, Peirosauridae, Sphagesauridae, and Mariliasuchus, kept in the collection of the University of Brasília, Planaltina Campus. Thin sections were prepared for the histological analysis of the specimens to compare their morphological differences and similarities with other living and extinct lineages. During the research, osteoderms from an individual of Baurusuchidae (cervical, anterior dorsal, and posterior dorsal regions) and dermal plates from Sphagesauridae, both from the parasagittal row and ventral shield, were examined. Osteoderms of juvenile Baurusuchidae were also analyzed. For comparison purposes, thin sections of osteoderms attributed to Candidodontidae and Caimaninae (associated with Purussaurus) were also made. Although the dermal plates analyzed come from crocodylomorphs of different crocodylomorph groups (Peirosauridae, Baurusuchidae, Sphagesauridae, and Mariliasuchus), they exhibit distinct external morphologies at a macroscopic level. However, histological analysis revealed notable similarities, especially regarding the structure of the bone tissue. The bone tissue shows fibers arranged in a matrix of parallel and interwoven fibers, secondary osteons are much larger than the primary ones, indicating bone resorption processes, and the presence of growth lines in some of the analyzed histological slides.

COMMITTEE MEMBERS:
Externa ao Programa - 2285268 - JULIA KLACZKO - nullExterno ao Programa - 1805604 - RICARDO LOURENCO PINTO - nullInterno - 2520585 - RODRIGO MILONI SANTUCCI
Externo à Instituição - THIAGO DA SILVA MARINHO - UFTM