Livro de Resumos - Dinossauros do Maranhão

Paleontologia 84
Guadalupian lycopsids from the Paraná Basin: Emendation of
Lycopodiopsis derbyi Renault and a new species of Lepidophylloides
1 Departamento de Geologia e Recursos Naturais, Instituto de Geociências, Universidade Estadual de Campinas
(Unicamp), Cidade Universitária Zeferino Vaz - Barão Geraldo - Caixa postal 6152, 13083-970, Campinas, SP,
Brasil.
2 Bolsista Produtividade em Pesquisa do CNPq.
E-mail: fresia@ige.unicamp.br
Rafael Souza de Faria 1 & Fresia Ricardi-Branco 1,2
Silicified lycopsids stems and microphylls from five localities containing Guadalupian
outcrops of the Paraná Basin, Southern Brazil show new features. Three localities are from
São Paulo State (in the municipalities of Piracicaba and Bofete and at kilometer 164 of the
State Highway SP 280) from strata of the Corumbataí Formation, one in Paraná State (Rio
Preto Quarry) and one in Santa Catarina State (municipality of Canoinhas) from strata of
the Teresina Formation. The stems belong to Lycopodiopsis derbyi Renault. The diagnosis
has been emended based on additional cortical traits found. Dichotomizing stems were
encountered and three different branch regions related to apoxogenesis can be
distinguished. The most proximal region has the larger leaf cushions, clearly rhomboid and
with their upper edges more protruding; the transitional region has leaf cushions also
rhombic but smaller and less longitudinally elongated than the previous ones; finally, the
most distal region has inconspicuous cushions interspersed among attached microphylls. A
well preserved branch representative of this most distal region was sectioned and
presented a siphonostelic cylinder similar to previous descriptions of L. derbyi. The cortex
however shows new traits such as a short portion of elongated cells between the periderm
and the external cortex (or leaf cushion tissue). The isolated microphylls will be described
as a new species of the lepidodendralean leaf genus Lepidophylloides. Their organization
of the xylem in arch-like or crescent-shaped bundles suggests a relation with Cathaysia
species. The close association with Lycopodiopsis derbyi stems (which have true leaf scars
and must have suffered leaf abscission) suggests that they are different organs from the
same species. These lycopsids remains were probably not transported for long distances.
The common alkalinity of a shallow marine environment in the Corumbataí and Teresina
Formations could have mobilized the silica and favoured the petrifaction.
Paleobotânica