CASSIO ANGELO DALCIN CERRI
Programa de pós-graduação, Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-900, São Paulo, [email protected]
JULIANA DE MORAES LEME
Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-900, São Paulo, SP. [email protected]
ABSTRACT - A systematic analysis of the Brachiopoda (Calciata) from Ponta Grossa Formation, Devonian, Apucarana Sub-basin, Paraná Basin, Paraná State, Brazil, is presented, which since 1913, were not the object of proper systematic revision. The studied material consists of fossil samples from Ponta Grossa Formation, Paraná State, Paraná Basin. The results have shown that, of the species previously described,
Australostrophia mesembria, Pleurochonetes falklandicus, Cryptonella baini and Australocoelia palmata are valid and remain unchanged; the species Coelospira (?) colona could only be identified up to a generic. Autralospirifer possesses five described
species for the Ponta Grossa Formation, although the diagnostic characters that differentiate them are susceptible to taphonomic modification and present high variability degree, which impedes the identification of those species. The genus
Schuchertella has undergone taxonomic revision, excluding the species from Ponta
Grossa Formation of the generic classification. Those species may belong in the
43 this hypothesis. Derbyina is very similar to Paranaia, but the lack of brachidia in the examined material, it was not possible to confirm the distinction between these genera. The present work has strengthened the idea that the designation of new species must be made in face of a considerable number of samples, so that the largest spectrum of taphonomic and morphological variations resulting from the fossilization process is identified, which diminishes the error margin.
Keywords: Brachiopoda, Calciata, Devonian, Ponta Grossa Formation, Paraná Basin
RESUMO- Uma análise sistemática dos braquiópodes (Brachiopoda, Calciata) da Formação Ponta Grossa, Devoniano, Sub-bacia Apucarana, Estado do Paraná, Bacia do Paraná, Brasil, é apresentada, os quais desde 1913 nunca foram o alvo de uma revisão sistemática apropriada. O material de estudo consiste de amostras fósseis provenientes da Formação Ponta Grossa, Estado do Paraná, Bacia do Paraná,. Os resultados
mostraram que, das espécies previamente descritas, Australostrophia mesembria,
Pleurochonetes falklandicus, Cryptonella baini e Australocoelia palmata são válidas e
permanecem sem modificação; a espécie Coelospira (?) colona pôde ser somente identificada a nível genérico. Autralospirifer possui cinco espécies descritas para a Formação Ponta Grossa, porém os caracteres diagnósticos que as diferem são passíveis de modificação tafonômica e de apresentam um grau de variação alto, o que impede a identificação dessas espécies. O gênero Schuchertella sofreu uma revisão taxonômica, excluindo as espécies da Formação Ponta Grossa da classificação genérica. Tais espécies poderiam pertencer ao gênero Floweria, porém a falta de dados nas amostras impede a validação desta hipótese. Derbyina é muito a Paranaia, mas a falta de braquídios no material examinado impede a distinção entre esses gêneros. O presente
44 trabalho fortaleceu a ideia de que a designação de novas espécies deve ser realizada perante a presença de diversos espécimes, para que o maior espectro possível de variações tafonômicas e morfológicas decorrentes do processo de fossilização seja identificado, com holótipos bem preservados, o que diminui a margem de erros.
Palavras-chave: Brachiopoda, Calciata, Devoniano, Formação Ponta Grossa, Bacia do Paraná.
INTRODUCTION
The sedimentary rock succession from the Devonian of Paraná Basin (Ponta Grossa Formation) encloses the richest and most diverse known fossil content of the Paraná Basin, in terms of marine macroinvertebrates. These fossils were initially described and illustrated by Clarke (1913). After the publishing of this classic
monograph, various groups of invertebrate fossils, due to their relatively good state of preservation, geological and paleoenviromental importance, were revised and/or revisited and described by Brazilian and foreign researchers alike, like the trilobites (Popp, 1985; Carvalho et al., 1987; Carvalho & Edgecombe 1991; Soares, 2007; Soares
et al., 2008; Simões et al., 2009; Leme et al., 2010a; Mori & Leme, 2012), bivalves
(Morsch, 1984a, b, 1986, 1987; Kotzian, 1995; Machado, 1999), tentaculites (Ciguel, 1989; Azevedo-Soares, 1999), conulariids (Leme, 2002, 2006; Leme et al., 2004, 2008, 2010b), and linguliids (Bosetti, 1989a, b, c, 2004; Zabini, 2007, 2011). An excellent historical review of the researches at the Devonian of Paraná Basin was presented by Melo (1985), while the paleobiogeographical and geochronological settings of the fauna
45 were discussed by Lange & Petri (1967), Boucot (1971) and Cooper (1977), especially in regard to the inclusion of the fauna in the Malvinokaffric Realm.
Mollusks, trilobites, brachiopods and conulariids preserved in Devonian strata from the Austral Continents (except Australia), display notable endemism (e.g., Clarke, 1913; Boucot, 1971; Richter & Richter, 1942; Eldredge & Ormiston, 1979; Melo, 1985; Kotzian, 1995; Machado, 1999; Leme, 2002, 2006; Leme et al., 2004; Soares, 2007). In Brazil, the best registry of the so-called Malvinokaffric Realm Fauna (Boucot, 1971; Cooper, 1977; Eldredge & Ormiston, 1979) are found in Ponta Grossa Formation, members Jaguariaíva, Tibagi and São Domingos, that occur in stratigraphic succession in Paraná State (Lange & Petri, 1967; Petri & Fúlfaro, 1983; Melo, 1988; Assine et al., 1994).
Studies about brachiopods from the Malvinokaffric Realm are numerous, mainly including the works of Sharpe (1856), Bernard (1895), Kayser (1897), Reed (1904, 1925), Thomas (1905), Schwarz (1906), Knod (1908), Clarke (1913), Kozlowski (1913, 1923), Douglas (1920), Ahlfeld & Branisa (1960), Boucot (1971), Isaacson (1977a, b), Boucot et al. (1980), Racheboeuf & Herrera (1994), etc.
The brachiopods of the Ponta Grossa Formation are diversified and can be locally abundant. They are represented by elements of the Lingulata and Calciata groups (Williams et al., 1997), in particular the genera Lingula and Australocoelia,
respectively. Clarke (1913) described eight genera of Calciata brachiopods from the Devonian of Paraná. In the decade of 1980 and in subsequent years, a variety of important studies were performed about the brachiopods of Ponta Grossa Formation, worth mentioning those of Quadros (1979, 1987); Bosetti (1989a,b,c; 2004); Marques (2006), and Zabini (2007, 2011); Zabini et al. (2010, 2012).
46 Quadros (1979, 1987) presented a detailed study about the paleontology of the Brachiopoda (Lingulida, Strophomenida, Spiriferida, Terebratulida) of the Devonian of Chapada dos Guimarães, Atimã Mountain Range and surroundings, Ponta Grossa Formation, Alto Garças Sub-basin, state of Mato Grosso. In those works, it was performed a systematic revision of the brachiopods (Lingulata and Calciata), together with the presentation of geographical relations of the fauna and chronostratigraphic distribution of the brachiopods at Chapada dos Guimarães. Marques (2006) performed a cladistic analysis of the spiriferids (Brachiopoda, Calciata) from Ponta Grossa
Formation, Alto Garças Sub-basin, in the region of Amorinópolis, state of Goiás, while also presenting a taxonomic study of other invertebrates of the same region.
The lingulids had their systematic broadly revised in the works of Bosetti (1989a, b, c). The work of Nunes (1999) introduces the application of taphonomy in the study of lingulids in the Devonian succession of the Paraná Basin. Bosetti (2004) applied a taphonomic approach in the study of the lingulids, presenting also a
correlation to the genesis of the strata, occurrence and distribution of the macrofauna. Zabini (2007, 2011); Zabini et al. (2010, 2012) performed a taphonomic and taphofacies analysis of the lingulid brachiopods of the Devonian of Paraná Basin, presenting models of deposition and life habitats.
On the other hand, the Calciata from Ponta Grossa Formation, Apucarana Sub- basin, state of Paraná, still remained poorly of inadequately studied, caressing of urgent revision, once no formal taxonomic study was published since Clarke (1913). The Devonian Calciata brachiopods were only properly revised in the Amazonas and Parbaíba Basins, in the works of Fonseca (2001; 2004). In contrary to other groups of invertebrates common to the Ponta Grossa Formation that were entitled to important revisions, the Calciata brachiopods from the Devonian of Paraná State remain
47 practically ignored and inadequately described. In the light of recent changes on the taxonomy of fossil brachiopods, mainly those on the revised edition of the Treatise on Invertebrate Paleontology (Williams et al., 1997), the purpose of this work is to provide a taxonomic review of this group, while taking in consideration the taphonomic
processes that may have interfered with the preservation of these fossils and may have influenced previous descriptions.
The present work had as objectives:
a- to revise the systematic of the Calciata brachiopods from the Ponta Grossa Formation, state of Paraná, through morphological study of the available fossil material;
b- to verify the diversity of the Calciata brachiopod fauna of this Formation, comparing it with works from the Ponta Grossa Formation, State of Mato Grosso (Quadros, 1987);
c- to verify if any morphological characters used in the diagnosis of genera and species of Calciata brachiopods from Ponta Grossa Formation are susceptible to
taphonomic alteration, particularly due to post-mortem compaction and exfoliation, as occurs with other fossil groups, like conulariids and trilobites (Leme et al., 2004; Rodrigues et al., 2003; Simões et al., 2003; Soares et al., 2008).
MATERIAL AND METHODS
The samples here described were collected in sedimentary rocks belonging to the Jaguariaíva Member (Lange & Petri, 1967) or to the B Sequence from Bergamaschi (1999) and from Bergamaschi & Pereira (2001) of Ponta Grossa Formation, state of Paraná (Figure 1). In Jaguariaíva County (Figure 2), the Ponta Grossa Formation is up to 80 m thick and consists predominantly of shales and siltstones. Shallow marine, fine-
48 grained sandstones bearing wavy structures and hummocky cross-stratification occur at the base of the unit (Petri, 1948; Lange & Petri, 1967; Melo, 1988). The remainder of the Jaguariaíva stratigraphic section is made up of fairly fossiliferous muddy shelf rocks, mainly light-grayish siltstones, strongly bioturbated, which are intercalated with massive, dark shales. These shales were deposited below storm wave base, and are a record of marine flooding surfaces (Bergamaschi, 1999). Stratigraphic intervals particularly suitable to brachiopods collecting are the railroad cuts at km 3.8, and km 4.5 of the railroad between the cities of Jaguariaíva and Arapoti, specifically 29 to 44 m from the base of the Ponta Grossa Formation (Figure 2). Pyritic, well-laminated, poorly fossiliferous dark shales enclose the Devonian sequence at the top of Jaguariaíva section (Petri, 1948; Lange & Petri, 1967; Melo, 1988; Bergamaschi, 1999; Bergamaschi & Pereira, 2001). According to Bergamaschi (1999), these rocks are recording the transgressive maximum in the area and they were deposited in dysaerobic bottom conditions, as indicated by the scarcity of burrowing fauna.
The analysis of additional material entailed collections from several institutes, including Departamento Nacional de Produção Mineral (DNPM-RJ), Museu Nacional (MN), Universidade Federal do Paraná (UFPR), Universidade Federal do Rio de Janeiro (UFRJ), Universidade de Guarulhos (UnG) and Universidade de São Paulo (IGc-USP). The correspondence between the acronyms used to number each fossil and the institute from which they derive is as follows: fossils identified with DGM are from DNPM-RJ; MN from Museu Nacional; GP/1E from IGc-USP; NR from UFPR; BrPg from UnG; Bq from UFRJ.
The samples consist of molds and casks from ventral and dorsal valves, both interior and exterior faces. The analyses were conducted using stereomicroscope, with a total of 990 samples analyzed. Also, a session using a SEM microscope was performed
49 on three samples, in order to achieve high enhancement of possible structures on the molds.
The photographs were taken with the help of Zeiss stereomicroscope, model SV6, digital camera, and the Axiovision software. Some of the specimens utilized for taking pictures were fumigated with magnesium oxide: a technique that accentuates the contrast between high and low surfaces, and therefore highlight important diagnostic characters.
The systematic description follows terms applied by Clarke (1913) and Fonseca (2001; 2004), together with the Treatise on Invertebrate Paleontology (Williams et al., 1997).
SYSTEMATIC PALEONTOLOGY
Phylum BRACHIOPODA Duméril, 1806
Subphylum RHYNCONELLIFORMEA Williams et al., 1997 Class STROPHOMENATA Williams et al., 1997
Order PRODUCTIDA Muir-Wood, 1955 Superfamily CHONETOIDEA Bronn, 1862 Family STROPHOCHONETIDEA Muir-Wood, 1962 Subfamily STROPHOCHONETINAE Muir-Wood, 1962
Genus Australostrophia Caster, 1939
50 Diagnosis: Medium, plano- to concavoconvex shell; maximum width at midlength; radial ornamentation parvicostellate, crossed by dense fila; median enlarged costa present in early stages only; spines orthomorph oblique, symmetric and low-angled (Caster, 1939; Williams et al., 1997).
Australostrophia mesembria Clarke, 1913
(Figure 3)
Diagnosis: same as genus.
Examined material: DGM 241(Syntype), 242(Syntype), 243(Syntype), 244(Syntype), 344, 370; Bq 026, 076, 124; BrPg 56, 57; GP/1E 3492, 7544a, b, c, 7545a, b, 7549a, b, 7591a, b, 7647, 7677, 7687, 7495, 7496, 7498, 7503, 7504a, b, 7505a, b, 7510, 7515, 7518a, b, 7519, 7521, 7523, 7526a, b, 7527, 7531, 7532, 7533a, b, 7536, 7540a,b,7541, 7546a, b, 7547a, b, c, 7563, 7573, 7575, 7580a, b, 7584, 7585, 7724, 7757, 7789, 7798. Occurrence: Ponta Grossa Formation.
Description: Medium sized shells, with outline subquadrangular to subrectangular, more rarely subcircular; hinge line straight, where can be seen divergent spines, more rarely preserved. On most samples, the cardinal angle is right and the major width is in the hinge line. A few samples show obtuse angles and major width on median portion of the valve. Shell plano-convex to resupinate, ventral valve planoconvex, showing most of its convexity on the umbonal region; dorsal valve flat with slight concavity on the anterior muscular portion. Ventral interarea apsacline, dorsal anacline. Delthyrium arranged in an angle of 60º and covered by big pseudodelthydium. Shell surface marked by fine costae, characteristic by its radial distribution, rounded in section, separated by fine concentric lines. They increase in number by bifurcation and intercalation.
51 Ventral valve interior: Dental lamellae very short or inexistent. Teeth prominent and diverging in obtuse angle. Muscular field is flabellate, occupying 1/3 of valve length, distant approximately 2/3 of anterior margin. A median myophragm separates the muscle field, becoming very prominent and large on the posterior region, like in a septum. Small myophragms visible in some specimens. Pseudopunctuations sparse by the entire valve, occupying intercostellar spaces.
Dorsal valve interior: cardinal process prominent and bilobate. Internal and external ridges of sockets present. Internal ridges diverge at a approximately 120º angle and have 3 to 4 mm length. Anderidia present, initiating 1mm after cardinal base process and diverging in a 10º to 15º angle. Muscle field showing two pairs of small adductor scars, the posterior ones being slightly visible and occupying a larger area, while the anterior ones are more visible and separated by a small myphragm. Costellae well defined at peripheral region.
Discussion: this species, while already revised by some authors (Caster, 1939; Boucot, 1975b), still remains with a minor issue in its classification, namely the absence of a holotype. Quadros (1987) already debated on this problem when studying samples from the Ponta Grossa Formation, Chapada dos Guimarães, Mato Grosso, comparing those with Clarke’s (1913) samples at the Departamento Nacional de Produção Mineral (DNPM), Rio de Janeiro. Quadros (1987) noticed that the latter samples were only casts of ventral valve interiors, thus concluding that the holotype should be chosen from one of Clarke’s samples deposited in the New York State Museum, where there were both ventral and dorsal valves, which would provide complete data for future comparisons. New analysis on Clarke’s samples at the DNPM corroborates that of Quadros (1987). Since no one has yet revised the samples at the New York State Museum with the objective of resolving this issue, the holotype problem still endures.
52 When analyzing the material collected from the Ponta Grossa Formation at Paraná State, under the light of the newest descriptions of the species (Racheboeuf and Branisa, 1985; Williams et al., 1997;), a complete match is observed, therefore no changes in the taxonomic description of the species is considered necessary.
Family CHONETIDAE Bronn, 1862
Subfamily NOTIOCHONETINAE Racheboeuf, 1992
Genus Pleurochonetes Isaacson, 1977
Type-species: Pleurochonetes lauriata Isaacson, 1977
Diagnosis: Differs from Notiochonetes in its dorsal valve interior; anderidia less developed, more divergent anteriorly; inner socket ridges shorter, posteriorly curved, more posteriorly situated, more divergent anteriorly; median septum supporting cardinal process; myophore projecting posteriorly; spines orthomorph oblique, symmetrically arranged (Isaacson, 1977; Williams et al., 1997).
Pleurochonetes falklandicus (Morris & Sharpe, 1846)
(Figure 3)
1846 Chonetes falklandica (Morris & Sharpe), p. 274-275, Pl. 10, figs. 4a c; Von Ammon, 1893, p. 360, fig. 5; Kayser, 1897, p. 299-300, Pl. 10, fig. 2.
1856 Chonetes sp. Sharpe, p. 209-210, Pl. 16, figs. 14-16.
53 1903 Chonetes cf. C. coronatus (Conrad). Reed, p. 172-173, Pl. 20, figs. 11, 12, Pl. 21, figs. 1, 2.
1913 Chonetes falklandicus (Morris & Sharpe). Clarke, p. 295-297, Pl. 24, figs. 1-25 (pars); Reed, 1925, p. 42-43; Mendez-Alzola, 1938, p. 24-25, Pl. 6, figs. 6-9.
1913 ?Chonetes falklandicus (Morris and Sharpe). Kozlowski, p. 7, Pl. 12, fig. 5. 1925 Chonetes sp. Reed, p. 45-46.
1962 "Chonetes" falklandicus (Morris and Sharpe). Muir-Wood, p. 12, 26. 1977 Chonetes (Pleurochonetes) lauriata Isaacson, p. 175-177, Pl. 6, figs. 1-13.
1977 (non) Notiochonetes falklandicus (Morris and Sharpe) Isaacson, p. 170-172, P1. 5, figs. 1-11; Racheboeuf & Branisa, 1985, p. 1446- 1448, fig. 9.7-9.14.
1987 Chonetes (Pleurochonetes) falklandicus (Morris & Sharpe) Hiller, p. 1149-1152, fig. 2, 1-16.
Diagnosis: same as genus.
Examined material: DGM 198-213, 341, 343, 365, 1531, 1532, 1602, 1609, 1610, 1654, 1655, 1715, 1721, 1724; MN 2754- 2756, 2759, 2760, 2761, 2787-2805, 3560, 4469, 4473, 4474; Bq 012, 115, 157; BrPg 572; GP/1E 4756a, b, c, d, 5604- 5612, 5614, 5628, 7524, 7553a, b, 7564, 7565, 7567, 7578a, b, 7621, 7706, 7707, 7732, 7746, 7747, 7778, 7785, 7920, 7921.
Occurrence: Ponta Grossa Formation.
Description: small to medium-sized shells, with outline subelliptical to
subquadrangular. Ventral valve slightly convex and dorsal valve varies from plane to concave. Shallow median ridge observed in some samples. The hinge line is straight, bearing spines in some samples, and represents the larger width of the shell. The spines are in number of two in each side. The cardinal angle varies from 60º to 80º. Frontal
54 commissure rectimarginate. Ventral interarea catacline to anacline, with dorsal interarea anacline. Separated chilidial plates cover most of the delthyrium. Fine, low, uniform ribs, in number of 15 to 20 in each side, that increase in size by bifurcation, rounded in section. Interspaces fine, V shaped in section. The ribs are most visible in the outer region, where there are pseudopunctuations following the radial disposition of the interspaces.
Ventral valve interior: Reduced dental lamellae, not visible in most samples. Prominent, elongated teeth, diverging in an obtuse angle. Median septum long, posteriorly ample, extending from 1/2 to 2/3 of the valve length. Muscle field disposed laterally, occupying 1/2 to 2/3 of the valve. Adductor muscle scar flabelliform, with longitudinal crests, diverging between each other in an obtuse angle. Poorly defined diductor. Muscle field divided by small myophragms.
Dorsal valve interior: bulbous cardinal process, stretched, ventrally projected. Distally quadrilobate. Deep and curved sockets, circumvented by internal and external crests. The external ones are smaller and lower than the internal ones, which are longer. Anderidia present, initiating at the base of the cardinal process platform, diverging in a very acute angle. Low septum, enlarged at the base of the cardinal process platform and narrowing anteriorly. Two pair of adductor muscles situated between the anderidia. The muscles have elliptic outline, being the posterior larger than the anterior.
Discussion: this species has undergone a few changes in its taxonomic classification over the course of its revisions. There were those made by Isaacson (1977), who classified it as belonging in the genus Notiochonetes Muir-Wood, 1962. In the same work, Isaacson established the genus Pleurochonetes, with P. lauriata Isaacson, 1977 as type-species. Hiller (1987), revising Isaacson’s work, suggests that C. falklandicus and
55 genus, a classification that endured in newer citations of this species (Racheboeuf, 1992).
While revising the works of these other authors about this species, it is noticeable the morphological variety that it possesses. For example, the outline goes from subelliptical to subquadrangular. Morphological details also occur variably, like the median septum or the spines in the hinge line. The same appears to be true with the samples analyzed here. Of all the samples, only a handful possesses those characters, the presence of spines being even rarer. The size of the shells is another variable character noticed in the species descriptions. It is possible that these variations are due to preservational issues, resulting from taphonomic alteration of the shell. That being said, it is safe to assume that Hiller’s (1987) revision of the species is a valid one and applicable to the Ponta Grossa Formation specimens, since the characters considered are matched in both descriptions.
Order TEREBRATULIDA Waagen, 1883 Suborder TEREBRATULIDINA Waagen, 1883 Superfamily CRYPTONELLOIDEA Thomsom, 1926
Family CRYPTONELLIDAE Thomsom, 1926 Subfamily CRYPTONELLINAE Thomsom, 1926
Genus Cryptonella Hall, 1861
Type-species: Terebratula rectirostra Hall, 1860
Diagnosis: Small to medium; subcircular to elongate; ventribiconvex; smooth or anteriorly faintly plicate; anterior commissure rectimarginate to sulciplicate; foramen
56 submesothyrid; dental plates short to obsolete; muscle field well impressed; free,
perforate or imperforate hinge plate extending unsupported between socket plates; adult loop teloform (cryptonelliform) (Williams et al., 1997).
Cryptonella baini Sharpe, 1846
(Figure 3)
Diagnosis: ventral valve interior with relatively short and slender dental plates with deep pedicle pit; muscle scar elongate and lateral umbonal parts occasionally showing pallial venation; dorsal valve crural plates consolidated with broad concave hinge plate, attached to the surface of the valve; dental sockets with very distinct grooves at the sides of hinge plate, with cross-striated surface (Sharpe, 1846; Clarke, 1913).
Examined material: DGM 218-221, 1537; NR 776, 778, 780, 6388; BrPg 231; GP/1E 7511, 7516a, b.
Occurrence: Ponta Grossa Formation.
Description: shell biconvex, smooth, without sulci or fold, outline subelliptical, oval, with length generally equal (in younger forms) or larger (in more senile forms) than width. Commissure line rectimarginate. The length/thickness ratio also changes with shell age, resulting in more obese forms in senile specimens.