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| Author(s): |
Alberto Barbosa de Carvalho
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2006-11-17 |
| Examining board members: |
Hussam El Dine Zaher;
Luiz Eduardo Anelli;
Célio Fernando Baptista Haddad;
Claudio Riccomini;
Hélio Ricardo da Silva
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| Advisor: | Hussam El Dine Zaher |
| Abstract | |
The fossil record of mesozoic anurans is rare in most sedimentary basins worldwide. In South America, these records are even more scarce, particularly in Brazil. Among the findings of this group in Brazilian basins, there are records of Arariphrynus placidoi (Leal and Brito 2006), from the Lower Cretaceous of the Araripe Basin and Baurubatrachus pricei Báez and Peri, 1989, Upper Cretaceous of the Bauru Basin. The Bauru Basin (sensu Fernandes & Coimbra, 1996) deposit began in the Upper Cretaceous (Senonian) and is composed of two Groups: Caiuá and Bauru. The climate during the deposit of these sediments was hot and arid/semi-arid. Moreover, in the eastern areas, the intrusion of streams and rivers and a greater abundance of water favored the presence of fauna and flora. In the area of the municipality of Marília, are found sediments from the Adamantina Formation, Bauru Group, Upper Cretaceous of the Bauru Basin. The finding of anuran fossil material in this region has demonstrated a great potential for fossils regarding vertebrates, with a peculiar fauna within the Bauru Basin context. In this study, the anuran material found in the nearby areas of the municipality of Marilia is described. To test its relations with the other groups of modern anurans, a phylogenetic analysis according to the principles of the cladistic methodology was applied. A matrix of 45 taxa of modern genus of different families of Anura and 86 osteological characters was analyzed. This resulted in a single, more parsimonious tree with 582 steps, consistency index (CI) 0,239, and a retention index (RI) 0,435. As a result of the analysis of the characters matrix, the modern taxa, although well defined in the cladogram, present inconsistencies with the morphological and molecular phylogenies proposed to date. This most likely occurs due to the lack of a more significant number of samples and of non-osteological characters which support some clades. However, the groups of characters found for each of the taxons studied can be used in comparative analyses and osteological identification. In the result of the analysis, the anuran fossil appears within the clades leptodactilids". Its relations with Eleutherodactylinae (Brachycephalidae sensu Frost et al., 2006) are also reinforced due to its position near representatives of this group. Thus, the anuran fossil from Marília currently represents the most well preserved specimen among the leptodactilid fossils from South America. Moreover, it is the first fossil of cretaceous anuran formally described for the State of São Paulo and the oldest anuran from the Bauru Basin (± 83 to 70 m.y.a.). The presence of an older record of Leptodactylidae in Cretaceous sediment in South America reinforces the hypothesis of this groups origin on this continent. (AU) | |