Livro de Resumos - Dinossauros do Maranhão

Paleontologia 131
Crinoidea from eastern border of the Parnaíba Basin
(Cabeças Formation, Middle Devonian)
Sandro Marcelo Scheffler 1 , Cleber Fernandes da Silva 2 , Antonio Carlos Sequeira Fernandes 2,3 ,
& Vera Maria Medina da Fonseca 2
This article presents a description of Cabeças Formation (Middle Devonian, Parnaíba
Basin)crinoids found until the present, collected in Km 305 outcrop, Municipality of Picos,
in Piauí state. The material consist of isolated and sparsely arranged columnals in samples
of fine sandstone. The specimens are not well preserved, but it was possible to describe
three morphotypes (PB/Cb-01, PB/Cb-02 and PB/Cb-03). Two of them (PB/Cb-01 and
PB/Cb-02) are represented by only one specimen, and the third morphotype (PB/Cb-03) is
the most abundantly found and probably represent the most common crinoid in ancient
sedimentation environments of 305 Km outcrop. The characteristics which crinoids occur
(probably parautochthonous) suggest that after their death, they‟ve remained in watersediment
interface for a fairly time before their burial. This fact is a further indication to
corroborate with the model suggested to Cabeças Formation in this region, represented by
a mouth-bar environment in a flood-dominated fluvio-deltaic system.
1 Programa de Pós-graduação em Geologia, Instituto de Geociências, Universidade Federal do Rio de Janeiro
(UFRJ), Avenida Brigadeiro Trompowsky, s/n 0 , Cidade Universitária - Ilha do Fundão - 21949-900, Rio de
Janeiro, RJ, Brasil.
2 Departamento de Geologia e Paleontologia, Museu Nacional (MN/UFRJ), Quinta da Boa Vista s/n 0 - São
Cristóvão - 20940-040, Rio de Janeiro, RJ, Brasil.
3 Bolsista de Produtividade em Pesquisa do CNPq.
E-mails: schefflersm@yahoo.com.br, cleberfer@uol.com.br, fernande@acd.ufrj.br,
vmedina@acd.ufrj.br
Paleoinvertebrados