The importance of fossil taxa in the knowledge of Neopterygian interrelationships

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 ).