title: Spectroscopic studies of the fish fossils (Cladocyclus gardneri and Vinctifer comptoni) from the Ipubi Formation of the Cretaceous Period.
abstract: Fossils are mineralized remains or traces from animals, plants and other organisms aged to about 10(8)years. The chemical processes of fossilization are dated back from old geological periods on Earth. The understanding of these processes and the structure of the fossils are one of the goals of paleontology and geology in the sedimentary environments. Many researches have tried to unveil details about special kinds of biological samples; however, a lack of data is noticed for various other specimens. This study reports the investigations through infrared spectroscopy, X-ray fluorescence and X-ray diffraction measurements for two types of fish fossils from the Cretaceous Period. The sample of Cladocyclus gardneri and Vinctifer comptoni fossils were collected from the Ipubi Formation, being one of the less studied, among the formations that constitute the important Santana group in the Araripe Basin, Brazil. The results obtained through different techniques, showed that the C. gardneri fish fossil contains hydroxyapatite and calcite as constituents whereas its rock matrix was formed by calcite, quartz and pyrite. Regarding the V. comptoni, the measurements confirmed the presence of hydroxyapatite in the fossil and its rock matrix gypsum, pyrite, quartz and calcite. The above scientific data contributed to the understanding the fossil formation in the Ipubi Formation, an important environment of the Cretaceous Period, which is rich in well-preserved fossils from different species.
authors.affiliation: Departamento de Física, Universidade Regional do Cariri, Avenida Leão Sampaio S/N, 63010-970 Juazeiro do Norte, CE, Brazil.
authors.forename: F E
authors.initials: FE
authors.lastname: Sousa Filho
authors.affiliation: Universidade Federal do Cariri, 63000-000 Juazeiro do Norte, CE, Brazil; Departamento de Física, Universidade Federal do Ceará, 60455-970 Fortaleza, CE, Brazil.
authors.forename: J H
authors.initials: JH
authors.lastname: da Silva
authors.affiliation: Faculdade de Educação Ciências e Letras do Sertão Central, Universidade Estadual do Ceará, CEP 63, 900-000 Quixadá, CE, Brazil.
authors.forename: G D
authors.initials: GD
authors.lastname: Saraiva
authors.affiliation: Campus Bacabal, Universidade Federal do Maranhão, 65700-000 Bacabal, MA, Brazil.
authors.forename: B T O
authors.initials: BTO
authors.lastname: Abagaro
authors.affiliation: Laboratório de Paleontologia da Universidade Regional do Cariri-Rua Cel., Antônio Luiz, 1161, 63105-000 Crato, CE, Brazil.
authors.forename: O A
authors.initials: OA
authors.lastname: Barros
authors.affiliation: Laboratório de Paleontologia da Universidade Regional do Cariri-Rua Cel., Antônio Luiz, 1161, 63105-000 Crato, CE, Brazil.
authors.forename: A A F
authors.initials: AAF
authors.lastname: Saraiva
authors.affiliation: Departamento de Física, Universidade Federal do Piauí, Campus Universitário Ministro Petrônio Portella-Bairro Ininga, 64049-550 Teresina, PI, Brazil.
authors.forename: B C
authors.initials: BC
authors.lastname: Viana
authors.affiliation: Departamento de Física, Universidade Federal do Ceará, 60455-970 Fortaleza, CE, Brazil. Electronic address: tarso@fisica.ufc.br.
authors.forename: P T C
authors.initials: PTC
authors.lastname: Freire
mesh_terms: D000818:Animals; D001938:Brazil; D053476:Extinction, Biological; D005399:Fishes / Q000033:anatomy & histology; D005580:Fossils / Q000033:anatomy & histology; D013052:Spectrometry, X-Ray Emission / Q000379:methods; D013055:Spectrophotometry, Infrared / Q000379:methods; D014961:X-Ray Diffraction / Q000379:methods
keywords: Cretaceous Period; Fish fossils; Infrared spectroscopy; X-ray diffraction