On a fossil lobster (Decapoda, Malacostraca, Crustacea) from the Riachuelo Formation, Albian of the Sergipe Basin, Brazil

Caio V.G Turbay,Eduardo A Koutsoukos,Pedro Cesero

doi:10.1590/s0001-37652002000200013

Caio V.G Turbay, Eduardo A Koutsoukos + Show 1 more

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https://doi.org/10.1590/s0001-37652002000200013

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Abstract

SUMMARY OF COMMUNICATIONS PALEONTOLOGICAL TOPICS AlexanderW.A.Kellner(Organizer) MODE OF LIFE OF THE MACROFOSSILS FROMTHE CABECAS FORMATION (DEVONIAN), PARNAIBABASIN, BRAZIL CleberF.daSilva 1 andDeusanaM.C.Machado 21 Estagiario do Laboratorio de Comunidades Paleozoicas, De-partamento de Ciencias Naturais, ECB, CCBS, UNI-RIO, Av.Pasteur 428, Urca, Rio de Janeiro – RJ. 2 Laboratorio de Comunidades Paleozoicas, Departamento deCiencias Naturais, ECB, CCBS, UNI-RIO, Av. Pasteur 428,Urca, Rio de Janeiro – RJ.Presented by DiogenesdeAlmeidaCampos The Cabecas Formation belongs to the CanindeGroup and corresponds to the Devonian depositional se-quence of the Parnaiba Basin. This unit is divided in twomembers, from base to top: Passagem and Oeiras. ThePassagem Member is of marine-deltaic origin and yieldedthe macrofossils studied here; the Oeiras Member is afos-siliferous and was deposited under ﬂuvio-deltaic condi-tions. Fifteen taxa of the twenty-ﬁve known from thePassagem Member were found in the studied samples, asfollows: six brachiopods, six bivalves, one trilobite andone tentaculitid. Besides those, ﬁve additional ones arereported for the ﬁrst time in this unit: two brachiopods(lingulid and Terebratulidae indet.), one inderminated bi-valve and two crinoids [Hexacrinites (?) sp. and Pen-tagonostipes (?) sp.]. These species fell under sevenmodes of life: (1) reclined epibenthic suspension feed-ers, represented by Pleurochonetes comstocki (Rathbun1874) and Mucrospirifer (?) pedroanus (Rathbun 1874);(2)attachedepibenthicsuspensionfeeders,representedbyPustulatia(?) curupira (Rathbun 1874), Mutationellinaeindet. D, Rhipidothyrididae sive Mutationellidae indet.B, Rhipidothyrididae sive Mutationellidae indet. D, Ter-ebratulidae indet., Hexacrinites (?) sp. and Pentagonos-tipes (?) sp.; (3) infaunal suspension feeders, representedby Grammysioidea lundi (Clarke 1899), Grammysioideasp. A and Tentaculites sp. (cf. T. eldregianus Rathbun1874); (4) semi-infaunal suspension feeders, representedby Spathella pimentana (Rathbun 1874); (5) infaunal de-positfeeders, representedbyCucullellatriquetra(Conrad1841), Nuculites (Nuculites) aff. N. (N) oblongatus (Con-rad 1841) and Palaeoneilo sp. A; (6) mobile epibenthicpredator, represented by Metacryphaeus meloi (Carvalhoet al. 1997); and (7) mobile epibenthic herbivore, repre-sented by Plectonotus derbyi (Clarke 1899). These habitsand their abundance agree with the previous suggestionthat the Cabecas Formation was deposited in a shallowmarine environment near the coast with moderated distur-bance from marine currents. — ( December 20, 2001 ).

Highlights

The Cabeças Formation belongs to the Canindé Group and corresponds to the Devonian depositional sequence of the Parnaíba Basin
The Passagem Member is of marine-deltaic origin and yielded the macrofossils studied here; the Oeiras Member is afossiliferous and was deposited under fluvio-deltaic conditions
The analyzed variables showed positive allometry between Mesosaurus and Stereosternum, and negative allometry for Brazilosaurus. These results suggest an heterochronic shift as the explanation of major evolutionary changes in the morphology of this group and provide additional support for the current hypothesis of phylogenetic relationships among the mesosaurids, that place Brazilosaurus sanpauloensis as the most distinct taxon in the family Mesosauridae. — ( December 20, 2001 ) . ∗ E-mail: maurobio@acd.ufrj.br

Summary

Introduction

The Cabeças Formation belongs to the Canindé Group and corresponds to the Devonian depositional sequence of the Parnaíba Basin. This unit is divided in two members, from base to top: Passagem and Oeiras. Fifteen taxa of the twenty-five known from the Passagem Member were found in the studied samples, as follows: six brachiopods, six bivalves, one trilobite and one tentaculitid. Five additional ones are reported for the first time in this unit: two brachiopods (lingulid and Terebratulidae indet.), one inderminated bivalve and two crinoids [Hexacrinites (?) sp. These species fell under seven modes of life: (1) reclined epibenthic suspension feeders, represented by Pleurochonetes comstocki (Rathbun 1874) and Mucrospirifer (?) pedroanus (Rathbun 1874);

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