Banca de DEFESA: LUCIA HELENA DE SOUZA ELEUTERIO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LUCIA HELENA DE SOUZA ELEUTERIO
DATE: 11/02/2022
TIME: 14:00
LOCAL: Remotamente
TITLE:
KEY WORDS:

Paleohistology; Reptiles; PALEOANTAR; Cretaceous; Antarctica.

PAGES: 155
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

Fossil vertebrates from Antarctica are considerably rare, presenting a fragmented and disjointed aspect, which makes it difficult to understand the evolutionary history of the fossil biota of that continent. In this sense, osteohistological analyzes constitute an important tool in the identification of these records, since the preservation of the bone microstructure keeps information about the life history of organisms. Despite this, few studies have been carried out involving the osteohistology of specimens from Antarctica. Aiming to improve the knowledge about this fossil biota, the objective of this study was to identify the groups of Cretaceous vertebrates preserved in the James Ross Sub-basin (Antarctic Peninsula) through their osteohistological characteristics. The material consists of 20 vertebrate bone fragments collected during Antarctic Operation XXXV, carried out in 2016 by the PALEOANTAR project. The histological features observed from thin sections showed a predominance of aquatic reptiles in the sample, although terrestrial and flying animals were also recorded. Osteoporotic, pachyostotic, osteosclerotic and pachytosclerotic bone patterns were associated with Plesiosauria indet. (Reptilia, Sauropterigia) and Mosasauridae indet. (Reptilia, Squamata). These are microstructures related to the various adaptations for swimming, previously described for these animals. The presence of structural fibers in the secondary bone tissue in slides made of osteoderm allowed the identification of dinosaurs of the infraorder Ankylosauria (Dinosauria, Ornithischia), as they constitute microstructures exclusive to this group. The presence of a thinner cortex, composed of fibrolamellar tissue, longitudinal vascular channels of similar diameters, without signs of anastomoses and composed only of primary osteons, with a free medullary cavity, allowed the confirmation of the first record of pterosaurs in the Cretaceous of Antarctica (MN 7800-V). This study proved that the use of bone microstructure represents an effective tool for the identification of fragmented material. Thus, contributing to the knowledge of the evolutionary history, diversity and paleobiology of the fossil fauna in the Antarctic Peninsula.

BANKING MEMBERS:
Interno - 053.518.267-80 - GUSTAVO RIBEIRO DE OLIVEIRA - UFRPE
Presidente - 073.131.737-84 - JULIANA MANSO SAYAO - UFRJ
Externa à Instituição - MARIANA VALERIA DE ARAUJO SENA
Externa à Instituição - MARINA BENTO SOARES - UFRJ
Externo à Instituição - RENAN ALFREDO MACHADO BANTIM - URCA