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On-line version ISSN 1678-2690
An. Acad. Bras. Ciênc. vol.74 no.2 Rio de Janeiro June 2002
AN OVERVIEW OF THE LEPTOLEPIS-LIKE FISHES FROM THE SANTANA FORMATION, NORTHEASTERN BRAZIL
FRANCISCO J. DE FIGUEIREDO AND VALÉRIA GALLO
Departamento de Biologia Animal e Vegetal; Instituto de Biologia Universidade do Estado do Rio de Janeiro.
Presented by DIOGENES DE ALMEIDA CAMPOS
Silva Santos (1958, Not. Prel. e Estudos, DGM/DNPM, 108:1-15) described a small fish from the Santana Formation, "Leptolepis'' diasii, based on a few small-sized specimens preserved in carbonate concretions. At that time he included this new taxon in the genus Leptolepis which became a "waste-basket'' for several poorly known taxa. Later, Maisey (1991, Santana Fossils: An Illustrated Atlas. T.F.H. Publications, Neptune City, New Jersey, 459p.) described and illustrated an incomplete caudal skeleton and briefly discussed the validity of "Leptolepis'' diasii. Silva Santos (1991, Fósseis do Nordeste do Brasil: Paleoictiofáunula da Chapada do Araripe. UERJ, 64 p.) concluded that this genus does not occur in Brazilian strata, erecting Santanichthys as a substitute name for "Leptolepis'' diasii and proposed a different reconstruction of the caudal skeleton. Afterwards, Silva Santos (1995 An Acad Bras Cienc 67:249-258) reviewed Santanichthys ( = Leptolepis ) diasii, and based on new cranial and post-cranial elements, pointed out that the caudal skeleton figured by him in 1991 belongs to a new taxon. In this paper, Silva Santos did describe but did not illustrate the tail of Santanichthys, which appears to be the same as described previously by Maisey (1993, Am. Mus. Nov., 3076:1-15).
While reviewing the material of Santanichthys mentioned by Silva Santos in 1995, and based on new specimens from the Araripe and the Sergipe-Alagoas basins, we clearly distinguished this specimen as being a new taxon. It differs from Santanichthys in many anatomical features, such as the absence of skull fontanels and fenestrae, presence of teeth in certain dermal bones, and the pattern of the caudal skeleton. The presence of an extrascapular fused with the parietal, a large triangular `beryciform' foramen and a second hypural fused with first ural centrum suggest its inclusion within Clupeomorpha. Nevertheless, the new taxon lacks pleurostyle, recessus lateralis, and dorsal and ventral scutes, which are regarded as primitive features. ( December 20, 2001 ).