Nanaichthys longipinnus, um peixe fóssil baiano.

Nanaichthys longipinnus, um peixe fóssil baiano.

Um fóssil de peixe encontrado nos sedimentos da Bacia do Recôncavo que originalmente estava descrito como “Dastilbe minor”, passa a ser enquadrado como um novo gênero, dos Chanidae. É o Nanaichthys longipinnus.

Com esta descoberta realça-se uma relação entre a fauna de águas então regidas pelo mar Tethys e a nossa Bacia do Recôncavo.

DO artigo:

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“A New Chanidae (Ostariophysii: Gonorynchiformes) from the Cretaceous of Brazil with Affinities to Laurasian Gonorynchiforms from Spain.”

Cesar R. L. Amaral, Paulo M. Brito*
* - Instituto de Biologia Roberto Alcântara Gomes, Universidade do Estado do Rio de Janeiro, São Francisco Xavier, Maracanã, Brazil

Abstract:
“Based on specimens originally referred to as “Dastilbe minor”, a nomem-nudum, we describe a new genus of Chanidae †Nanaichthys longipinnus nov. gen. and sp. which exhibits several diagnostic characters such as the absence of orbitosphenoid and basisphenoid, anteriorly displaced quadrate-mandibular articulation, laterally expanded supraneurals, an acute angle between the preopercular limbs, expansion at the angle between the preopercular limbs, and a curved maxillary articular process. Its occurrence and supposed relationship within the Chanidae reinforce the influence of the Mediterranean Tethys over the Gondwanan main rift system prior to the Aptian/Albian highstands.”
Conclusion:

"Nanaichthys longipinnus nov. gen. and sp. exhibits several characters that support its inclusion within the Gonorynchiformes as well as its placement in Chanidae. These include the absence of an orbitosphenoid and basisphenoid, an antero-ventral expansion in the hyomandibula, a quadrate-mandibular articulation anterior to the orbit, an elongated symplectic, a concave-convex premaxilla, laterally expanded anterior supraneurals not in contact with each other, and the expanded opercle at about one-third of the head length.
Our results support the affinities between †Nanaichthys longipinnus and the Laurasian rubiesichthyns from Spain, mainly based on the small and curved articular process of the maxilla, the acute angle formed by the preopercular limbs, and posterior expansion at the angle between the preopercular limbs.
†Nanaichthys longipinnus differs from other †Rubiesichthyinae (cf. †Rubiesichthys gregallis and †Gordichthys conquensis) by presenting a combination of characters such as a gently (not strongly) curved maxillary process and the possession of eleven anal fin rays; from †Gordichthys in the body depth, vertebral count (39 for †Nanaichthys against 37 for †Gordichthys), and edentulous parasphenoid and vomer; and from †Rubiesichthys in body proportions, position of the dorsal, pelvic, and anal fins; and shape of the head, triangular in †Nanaichthys and elongated in †Rubiesichthys. The proximity of †Nanaichthys longipinnus with the †Rubiesichthyinae from Spain reinforces the influence not only from the Caribbean Tethys but also from the Mediterranean Tethys and Laurasia prior to the Aptian/Albian marine transgressions over the continental terrains of Western Gondwana. This was probably influenced by the tectonically interconnected drainages that developed over the main rift axis prior to the well documented Aptian/Albian highstands."
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. Citation: Amaral CRL, Brito PM (2012) A New Chanidae (Ostariophysii: Gonorynchiformes) from the Cretaceous of Brazil with Affinities to Laurasian Gonorynchiforms from Spain. PLoS ONE 7(5): e37247. doi:10.1371/journal.pone.0037247 Editor: Andrew A. Farke, Raymond M. Alf Museum of Paleontology, United States of America
Received: December 9, 2011; Accepted: April 16, 2012; Published: May 21, 2012 Copyright: © 2012 Amaral, Brito. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This study was supported by the Brazilian National Counsel of Technological and Scientific Development and Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.