Acta Geologica Leopoldensia XXIII(51): 21-31, 2000
ACTINOPTERYGIAN REMAINS FROM THE RIO DO RASTO FORMATION, UPPER PERMIAN OF THE PARANÁ BASIN, BRAZIL
Cristina Vega-Diasl, Eliseu Vieira Diasl,2, Martha Richter3
1 Curso de Pós-Graduação - Doutorado em Geociências - UFRGS - Inst. de Geociências - Av. Bento Gonçalves, 9500. CEP. 91509-900. Porto Alegre, RS. e-mail: cvega@if.ufrgs.br /
evdias@if.ufrgs.br
2 Universidade Regional Integrada do Alto Uruguai e das Missões - Campus de Erechim - Av. Sete de Setembro, 1621 - Erechim, RS – CEP. 99700-000.
3UFRGS - Inst. de Geociências - Av. Bento Gonçalves, 9500. CEP. 91509-900. Porto Alegre, RS. e-mail: richter@vortex.ufrgs.br;richter@nhi.lead.org.br
ABSTRACT: A few chondrichthyan, sarcopterygian and actinopterygian fishes are known from the Upper Permian formations of the Paraná Basin. This paper reports on three previously unknown actinopterygian, species A, B and C, from the Rio do Rasto Formation of the Passa Dois Group. Comparisons are made with Tholonotus braziliensis (Dunkle & Schaeffer, 1956) (Corumbataí Formation) and other lower actinopterygians in the literature. Most of the skull bones are very poorly preserved in our material, which precludes a secure comparison with other lower actinopterygians of the world. Species A, B and C can not be ascribed to any species known for the Paraná Basin up to date.
Key words: Actinopterygii, Rio do Rasto Formation, Paraná Basin, Upper Permian.
RESUMO: Poucos Chondrichthyes, Sarcopterygii e Actinopterygii são conhecidos nas formações do Permiano Superior da Bacia do Paraná. Este trabalho descreve três espécies de Actinopterygii (A, B e C), previamente desconhecidas, da Formação Rio do Rasto do Grupo Passa Dois. Comparações foram feitas com Tholonotus braziliensis (Dunkle & Schaeffer, 1956) (Formação Corumbataí) e outros actinopterígios basais encontrados na literatura. Em nosso material, grande parte dos ossos do crânio está mal preservada, o que impossibilita a sua comparação segura com outros actinopterígios basais do mundo. As espécies A, B e C não podem ser designadas a nenhuma espécie conhecida, até o momento, para a Bacia do Paraná.
Introduction One of these samples, collected in the 1980' s, was preliminarily presented by Vega et aI. (1997) and is described here.
The Upper Permian Passa Dois Group comprises many geological formations, including the Corumbataí and the Rio do Rasto Formations. Chondrichthyes (Würdig- Dr. Evaldo W. Ragonha collected
many samples of fossil fishes at outcrops of the Rio do Rasto Formation, along the margin of the highway BR-153, km 42 in Santo Antônio da Platina, Paraná State (Figure 1).
Maciel, 1975; Ragonha, 1984, 1985, 1986, 1987, 1989a; Ragonha e Silva Santos, 1987), Sarcopterygii (Würdig-Maciel, 1975; Ragonha, 1991) and a single species of Actinopterygii, namely Tholonotus
braziliensis Dunkle & Schaeffer, 1956,
represent the paleoichthyofauna of the Corumbataí Formation. In the Rio do Rasto Formation, the paleoichthyofauna is similar,
22
with remains of Chondrichthyes (Würdig-Maciel, 1975) and Sarcopterygii (Ragonha, 1989b). Dias (1995, 1996) reported the occurrence of a new species of deep-bodied Actinopterygii in this formation. However, the description and formal proposition of the new taxon is in preparation.
Material and methods
The material comprises seven fishes on a single slab of sandstone, deposited at the Museu de Ciências e Tecnologia of Pontifícia Universidade Católica do Rio Grande do Sul, in Porto Alegre (MCP-3765-PV) (Figure 2).
The study of these specimens was based on camara lucida drawings, reconstructions and thin section of some scales.
The comparison with Tholonotus
braziliensis Dunkle & Schaeffer 1956 and
other lower actinopterygians was based only on data from the literature.
Description
It was possible to distinguish three species among the seven specimens.
Class OSTEICHTHYES Huxley, 1880 Subclass ACTINOPTERYGII Klein, 1885
Species A
The species A (Figures 2B a-e, 3 and 4) is about 12.5 cm long, with maximum height around 2.5 cm. It has a fusiform body. The dorsal fin is right above the pelvic, both being placed in the second third of the trunk; the anal fin is at the end of the posterior third,
placed 2 cm ahead of the caudal fino. The caudal fin is heterocercal, with an elongate chordal lobe and the caudal peduncle height is about 1.1 cm. The scales are small, changing in size and shape according to their location on the body, as in fishes described by Blot (1966). Near the lateral line (Figure 3A, D), below the dorsal fin, the scales are ornamented with approximately 7 longitudinal and sub-parallel furrows. The trunk scales present a peg-and-socket articulation (Figure 3D). In the caudal peduncle, the scales show approximately 4 furrows, some of them bifurcated; those are without peg-and-socket. Since we have only a few scales preserved in external view, it is difficult to define if their posterior border is smooth or serrated. There are 24 dorso-ventral scale rows on the trunk and 16 on the caudal peduncle as well as 26 longitudinal scale rows anterior to the dorsal fin, 17 rows anterior to the pelvic fin, 43 rows anterior to the anal fin and 61 rows anterior to the caudal fino In the skull, which is not well preserved, it was identified the opercular and subopercular, both incomplete, the first branchiostegal ray and some indeterminated teeth-bearing elements from the oral cavity. Of the shoulder girdle, it was identified the cleithrum and supracleithrum, also incomplete. Species A is represented by five specimens (Figure 2a-e), and the reconstruction (Figure 4) is a composite drawing based mainly on specimens a and b.
The scales show three tissues: externally the ganoine, the intermediate dentine and the isopedine basely. The ganoine layer is about a tenth of the thickness of the isopedine layer.
Species B
Species B (Figures 2B f and 5) shows 4.7 cm of the anteriormost part of the trunk preserved, with its maximum height of about 2.5 cm. This species has a series of 12 well developed sagittal scales (basal fulcra),
23
anterior to the dorsal fin. Although the position of this fin is similar in species A, these sagittal scales are not present in the last. The cranial region is represented by the opercular, subopercular and the first branchiostegal, besides some isolated bones with teeth. The shoulder girdle is made up of the supracleithrum, postcleithrum and cleithrum, all incomplete. No histological sections of the scales of this species were made because most of the specimen is only an impression, and the ornamentation of the scales are not visible.
Species C
The species C (Figures 2B g and 6) is represented by an incomplete segment of the trunk, lacking the pectoral and pelvic fins and measuring 5 cm in length. It can be distinguished from species A and B by the position of the dorsal fin, which is opposite to the anal fin, both being placed in the posterior region of the trunk, near the caudal fin. The trunk is covered with big, square scales preserved in internal view, without visible ornamentation; they bear a peg-and-socket articulation and the posterior border is not serrated. In the reconstruction drawing (Figure 6C) we reversed the specimen to show an hypothetical external view. They are distributed in about 12 dorso-ventral rows; the caudal peduncle has 10 small dorso-ventral scale rows and is 0.8em in height. There are at least 22 longitudinal scale rows anterior to the dorsal fin, 17 rows anterior to the anal fin and 30 rows anterior to the caudal fin. The anteriormost region of the trunk and the skull are missing. The maximum height of the body is about 2.0 cm.
The histological sections show a typical paleoniscoid structure. The ganoine is thin, covering the dentine and isopedine layers. Apparently, the dentine layer is not continuous underneath the ganoine layer. The isopedine is about seven times as thick as the ganoine layer.
Discussion
Tholonotus braziliensis Dunkle &
Schaeffer 1956, the only actinopterygian known so far from the Passa Dois Group (apart from desarticulated scales and bones), shows the closest similarities with the species
A, considering the position of the dorsal fin in
relation to the skull and the size of the opercular and subopercular. However, the species A differs from T. braziliensis in other aspects. The position of the pelvic fin in T.
braziliensis is anterior to the dorsal fin, while
in the species A it is posteriorly placed. The anal fin of T. braziliensis is almost below the dorsal fin, contrary to the species A, where the anal fin is far behind the dorsal, while the pelvic fin is below the dorsal. Another difference is the number of scales. There are 46 rows on the trunk in T. braziliensis and 61 in the species A. Besides, the species A does not have enlarged sagittal scales anteriorly to the dorsal fin, a feature observed in T.
braziliensis. Comparisons with African
species described by Jubb & Gardiner (1975), show that Mentzichthys differs from species A in having a posteriorly placed dorsal fin and also by the presence of a series of sagittal scales anterior to the dorsal fin. Species A differs from Aestuarichthys, Willomorichthys,
Adroichthys in the body shape, which is
slender in the Brazilian species. It also differs from Sundayichthys in the size of the subopercular and in the position of the dorsal fin, which is more posterior in the African species.
The species B differs from T.
braziliensis in showing a series of enlarged
sagittal scales (basal fulcra) covering all of the 29 flank scale rows anterior to the dorsal fin, while in T. braziliensis these sagittal scales cover the 6 anteriormost scale rows. The shoulder girdle of the species B bears a postcleithrum, which is absent in T.
braziliensis. Moreover, in the species B, the
opercular is smaller than the subopercular. In
T. braziliensis it is the opposite. Species B
24
shares with African lower actinopterygians the presence of sagittal scales between the skull and dorsal fin, like in Mentzichthys,
Aestuarichthys, Willomorichthys and Adroichthys. This feature is also seen in other
lower actinopterygians (Gardiner 1984).
The species C differs from T.
braziliensis in the position of the dorsal and
anal fins, that are located in the posterior third of the fish, while in T. braziliensis they are in the second third. Moreover, the body of the species C is longer and slimer than in T.
braziliensis. The trunk scales of the species C
are relatively wider than those of T.
braziliensis. Three species of the African
genus Helichthys share similarities with species C in the position of the dorsal and anal fins and in the size of the scales. Another African species, Daedalichthys formosa, also shows these similarities, but differs from species C in the presence of basal scales ahead of the dorsal and anal fins.
Species A, B and C do not correspond to any species described for the Paraná Basin to date, and comparisons with other known fossil fishes is flawed by the lack of crucial information on the skull anatomy of our specimens.
Acknowledgements
The study was carried out in the Laboratório de Paleontologia, Museu de Ciências e Tecnologia of Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), and the Departamento de Paleontologia e Estratigrafia, Universidade Federal do Rio Grande do Sul (UFRGS). We are thankful to Dr. Evaldo Weimuth Ragonha who collected the material and kindly gave it to us for study. We also thank Mr. Luís Flávio Lopes, photographer at UFRGS. The authors acknowledge the CNPq support through fellowships.
________., 1996. New Fish (Actinopterygii, Platysomidae) from the Upper Permian of Paraná Basin, Brazil. In: JORNADAS ARGENTINAS DE PALEONTOLOGÍA DE VERTEBRADOS, 12, Santa Rosa, Argentina, 1996. Resúmenes... Santa Rosa, 33: p. 463.
DUNKLE, D.H. and SCHAEFFER, B., 1956. Preliminary Description of a Paleoniscoid Fish from the Late Paleozoic of Brazil. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, 193, série Geologia, 13: 1-22.
JUBB, R. A. and GARDINER, B. G., 1975. A preliminary catalogue of identifiable fossil fish material from Southern Africa. Annals of South African Museum, 67 (11): 381-440.
GARDINER, B.G., 1984. The relationships of the palaeoniscid fishes, a review based on new specimens of Mimia and Moythomasia form the Upper Devonian of Western Australia. Bulletin of the British Museum of Natural History, (Geology), 37(4): 173-428.
RAGONHA, E.W., 1984. Taxionomia de Dentes e Espinhos de Xenacanthodii (Chondrichthyes, Elasmobranchii) da Formação Corumbataí. Considerações Cronológicas e Paleoambientais. São Paulo, SP. Tese de Doutoramento.
_______., 1989b. Placas Dentárias de Dipnoi no Grupo Passa-Dois (P-Tr) da Bacia do Paraná. Apreciações Ambientais, Climáticas, Cronológicas e estratigráficas. In: CONGRESSO BRASILEIRO DE PALEONTOLOGIA, 11, Curitiba, 1989. Anais... Curitiba, SBP. 1: 195-206
________., 1991. Peixes pulmonados triássicos de Rio Claro, Estado de São Paulo. In: CONGRESSO BRASILEIRO DE PALEONTOLOGIA, 12, São Paulo, 1991. Resumos... São Paulo, SBP.
RAGONHA, E.W. and SILVA SANTOS, R., 1987. Nova Classificação de Dentalium florencei Moraes Rego, 1936 (Mollusca, Scaphopoda) para Hybodus (Chondrichthyes, Elasmobranchii). In: CONGRESSO BRASILEIRO DE PALEONTOLOGIA, Rio de Janeiro, 1987. Anais...
Rio de Janeiro, SBP 1: 1-6. References
25
Universidade de São Paulo - USP, 166 p.
________., 1986. Espinho Cefálico de Xenacanthus (Chondrichthyes, Elasmobranchii) da Formação Corumbataí, Bacia do Paraná, Estado de São Paulo. In: CONGRESSO BRASILEIRO DE GEOLOGIA, 34, Goiânia, 1986. Anais... Goiânia, SBG. 1: 533-538.
_______., 1987. "Coprólitos Espiralados" da Formação Corumbataí. In: CONGRESSO BRASILEIRO DE PALEONTOLOGIA, 8, Rio de Janeiro, 1987. Anais... Rio de Janeiro, SBP: 307-317.
_______., 1989a. Ictiodorulite de Base Bulbosa. Evidências de um Possível Processo Articulatório. In: CONGRESSO BRASILEIRO DE PALEONTOLOGIA, 11, Curitiba, 1989. Anais... Curitiba, SBP, 1: 177-181.
BLOT, J., 1966. Étude des Palaeonisciformes du Bassin hoiller de Commentry (Allier, France). Cahier de Paléontologie: Paris. 1-99, pls. I-XVIII. DIAS, E. V., 1995. Nova Espécie de Peixe
(Actinopterygii, Platysomidae) do Permiano-Triássico da Bacia do Paraná, Brasil. Porto Alegre, RS. Dissertação de Mestrado. Universidade Federal do Rio Grande do Sul - UFRGS, 88 p., VIII estampas.
______., 1985. Nova Espécie de Xenacanthodii (Chondrichthyes, Elasmobranchii) - Formação Corumbataí, Taquarituba (SP). In: CONGRESSO BRASILEIRO DE PALEONTOLOGIA, Fortaleza, 1985. SBP: 5p.
WÜRDIG-MACIEL, N.L., 1975. Ichthyodontes e Ichthyodorulitos (Pisces) da Formação Estrada Nova e sua Aplicação na Estratigrafia do Grupo Passa- Dois.
Pesquisas, 5: 7-85, est. 1-14.
VEGA, C. S., DIAS, E. V. and RAGONHA, E. W., 1997. Ocorrência de novos Actinopterygii da Formação Rio do Rasto, Permo-Triássico da Bacia do Paraná, Brasil. In: CONGRESSO BRASILEIRO DE PALEONTOLOGIA, 15, São Pedro, 1997.
Boletim de Resumos, São Pedro, SBP. p. 87.
Recebido em 18 de dezembro de 2000 Revisão aceita em 15 de maio de 2001
