Name: Lays Stheffânny de Oliveira Silva
Type: MSc dissertation
Publication date: 02/05/2023
Advisor:
Name |
Role |
|---|---|
| Taissa Rodrigues Marques da Silva | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| Carlos Roberto dos Anjos Candeiro | External Examiner * |
| Richard Santos Buchmann de Oliveira | Internal Alternate * |
| Rodrigo Miloni Santucci | External Examiner * |
| Taissa Rodrigues Marques da Silva | Advisor * |
Summary: Sauropods are a very diverse group, with a wide
biogeographical and geochronological distribution. However, only
punctual occurrences were registered in the Brazilian Northeast
and in Aptian-Cenomanian (Cretaceous) deposits. The present work
reports a new occurrence of sauropods in the Povoado de Santo
Izídio (municipality of Coroatá, Maranhão), in outcrops of the
Itapecuru Formation of the Parnaíba Basin, allowing a review of
the fauna present in the State of Maranhão. The material has
limited diagnostic value and consists of dissociated fragments of
tibia, fibula and vertebral centers isolated from indeterminate
Neosauropoda, two caudal vertebrae related to Rebbachisauridae
and one caudal vertebra identified as Titanosauria. The
identification is mainly based on characteristics comparable with
other specimens described in the literature and not on
synapomorphies, which is why the elements of the tail and tibia
of the main groups of neosauropods present, mainly, during the
end of the Lower Cretaceous and the beginning of the Late
Cretaceous in South America. With the exception of the caudal
vertebra identified as Titanosauria because it is strongly
procoelic and has developed spongy tissue, the others show a
combination of characteristics widely distributed by most of the
Neosauropoda, including basal titanosaurids and rebachysaurids,
such as: amphicellic condition, position of the neural arch in
the anterior portion of the proximal caudals and absence of
spongy tissue. Vertebrates related to Rebbachisauridae exhibit
hourglass-shaped caudal centers and, in only a single specimen,
faint lateral ridges. Although the bone elements do not allow
identification at the species level, the age of the deposits and
the morphological characteristics identified in the review and in
the present work are congruent with the presence of basal
titanosaurs and rebachisaurids in northeastern Brazil, making the
Itapecuru Formation deposits a one of the few regions WHERE both
groups are represented in all of northern South America during
the Albian-Cenomanian.
