摘要：Middle Devonian Chonetoidea (Brachiopoda) of the Amazon and Parnaíba basins, Brazil.
The systematic of Middle Devonian Chonetoidea brachiopods from the Amazon (Maecuru and Ererê Formations)
and Parnaíba (Pimenteira and Cabeças Formations) Basins was re-evaluated based on fossil specimens not yet
studied, and the type material already described for Amazon Basin and housed in the Department of Geology
and Paleontology at Museu Nacional, Rio de Janeiro, RJ. This study enable the choice of lectotypes and
paralectotypes for “Chonetes” freitasi Rathbun, 1879, Pleurochonetes comstocki (Rathbun, 1874), “Chonetes”
herbertsmithi Rathbun, 1874 and “Chonetes” onettianus Rathbun, 1874. “Chonetes” freitasi is found in the
Maecuru Formation while the remaining species are presently known to occcur in the Ererê Formation.
Pleurochonetes comstocki is also present and abundant in the Cabeças Formation. Further taxonomic occurrences
are representatives of the genus Montsenetes Rachebouef 1992, the species Montsenetes carolinae sp.nov.,
from the Maecuru Formation, and Montsenetes cf. Montsenetes boliviensis Racheboeuf, 1992 from the Pimenteira
Formation. The stratigraphic distributions of Montsenetes (Eifelian-Givetian) and Pleurochonetes Isaacson,
1977 (Emsian-Eifelian) are in agreement with recent palynological studies that suggest an Eifelian age for the
top of the Maecuru Formation and the base of the Ererê Formation. These findings also give support to
correlate beds in the Pimenteira and Cabeças Formations, both of these cropping out in the Eastern boarder
of the Parnaíba Basin, that bear brachiopods of the genera Montsenetes and Pleurochonetes
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