sign in sign up
<<
Home , Pterotrigonia, Trigonia, Trigoniidae

THE SYSTEMATIC POSITION OF NEPOS PAULCKE, 1903, ANO PAULCKELLA, A NEW FOR THE APTIAN OF

MICHAEL R. COOPER Department 01 Geology, University 01 Durban-Westvi lle, Durban 4000, Soulh Africa ERNESTO PEREZ Servicio Nacional de Geolog ía y Minería, Casilla 10465, Santiago, Chile RENATO REYES Diego Portales 936, Viña del Mar. Chile

ABSTRACT

Trigonia nepos Paulcke is a poorly known bivalve lrom the late Aptian 01 northern Chile. Although the syntypes are lost, believed destroyed, topotype material shows it to represent a new genus 01 Pterotrigoniinae lor which the name Paulcke/la gen. nov. is proposed. A neotype is designated and the systematic position 01 Paulcke/la gen . nov. dis­ cussed. At present it is a South American endemic bivalve.

Key words: Systematics, , Trigoniídae, Pterotrigoniínae, Paulckellagen. nov., Aptian, Chile.

RESUMEN

Trigonia nepos Paulcke es un bivalvo poco conocido, recolectado en estratos del Aptiano superior, norte de Chile. El análisis de la descripción original, complementado con el estudio de topotipos reveló que , si bien pertenece a la sublamilia Pterotrigoniinae, posee características morfológicas ausentes en los géneros conocidos. Se propone la creación de un taxón nuevo, Paulcke/la gen . nov., hasta ahora endémico de Sudamérica, basado en T. nepos como es­ pecie tipo. Se designa un neotipo y se discute la posición sistemática del nuevo género.

Palabras claves: Sistemática, Bivalvia, Trigoniídae, Pterotrigoniinae, Paulckellagen. nov., Aptiano, Chile.

INTRODUCTION

Trigoniacean bivalves are characteristic ele­ , that has a peculiar anterior Ilank orn a­ ments 01 most shallow-marine deposits. mentation, a neotype is chosen based on a topo­ Whereas their hinge morphology has remained type. Three specimens, besides the neotype, col­ unchanged, they display a bewildering and unsur­ lected from the type locality by one 01 the authors passed diversity 01 external ornament as an ad­ (E . P.) have served to make a complementary des­ aptation to shallow burrowing. External morphol­ cription of T nepas and to discuss the lorms com­ ogy, therelore, is the prime character on which the ing lrom other localities 01 Chile, which have been 01 the group is based. identilied as T nepos by previous authors. The In this paper, the late early Trigania presence 01 the ammonite genus Parahap/ites in nepas, coming lrom Pabellón Formation strata, in the associated fauna allows to postulate a late Ap­ the Molle Alto locality (text-Fig. 1), is analyzed, tian age for this species (Pérez and Covacevich, and a new genus 01 trigoniid bivalve, with T nepos 1988). as type species, is described. Unlortunately, the T nepos Paulcke has been cited in northern syntypes 01 T nepas are lost, presumed destroy­ Chile, out 01 Molle Alto, in Quebrada El Way and ed by lire in the Strassburg Museum after World Calizas La Viuda, Antofagasta Region, and il Que­ War 11. Due to the systematic importance 01 this brada de Los Cóndores, Atacama Region (Reyes

Revista Geológica de Chile. Vol. 16. No. 1. p. 51·59. 2 Figs .. 1 Lám. 1989. 52 SYSTEMATIC posmoN OF TRIGONIA NEPOS

Co. AZU~~~9 coP;>

- Logunodel Negro Froncisco I I

Nv. JOI~beChe ) 5880 ,r I -1 I

CJ~"'~/)/ /~~ (./~~ \ ,?,Q:-

I O 10 20 km I

27056 ' L------~~~--~~~----JL~~~~~~~==~ ____~ From ' COPIOPÓ Sheet (2700-6900) Sccle I 250000 Insllluto Geográfico Mililor, Chile Conlour Ilne equldlstance 200 m A Itllude meters

Text-FI3. 1. Maps showing the type locality (Molle Alto: 27°50'S; 70 0 19'W) 01 Paulckella nepos (Paulcke), sited about 50 km south 01 Copiapó city, Atacama Region, northern Chile. M.R. Cooper, E. Pérez and R. Reyes 53

and Pérez, 1978, p. 13); besides Chile, it has only stratigraphic importance of in Chile' been mentioned in the Neocomian of Cerro de Pas­ sponsored by the Servicio Nacional de Geología y eo, Central Perú (Salfeld, 1911, p. 219). Minería (Chile). This study forms part of the project 'Chrono-

SYSTEMATICS Subclass Newell, 1965 Order Trigonioida Dall, 1899 Superfamily T rigoniacea Lamarck, 1819 Family Trigoniidae Lamarck, 1819 Subfamily Pterotrigoniinae van Hoepen, 1929

Diagnosis. Shell small to moderately large, sent only in nepionic stages. Area narrow. bipart­ strongly inequilateral, club shaped to lunate, with ite, usually unornamented in maturity. Middle umbones commonly prominent; anteriorly inflated, and adult growth stages with eonspicuously tuber­ posteriorly produced and often rostrate; respirato­ culate, oblique flank costae, which may be divided ry margin commonly rounded. Escutcheon wide, into a robust, coarsely tuberculate anterior set and sunken, with transverse costellae. Carinae pre- a more gracile posterior set.

Genus Paulckella gen. nov.

Type species: Trigonia nepos Paulcke, 1903, but its characters are not those of the type p. 293, PI. 17, Figs. 7, 8, by original designation species. P. cristata van Hoepen (1929, p. 10, PI. herein. 4, Figs. 3-6) (PI. 1, Figs. 9-15) differs in being club­ Etymology. In honour of W. Paulcke, the Ger­ shaped and strongly rostrate posteriorly, so that it man paleontologist who described the type spe­ is relatively much longer and narrower. It also has cies. a narrowly rounded respiratory margin, transverse Diagnosis. A Pterotrigoniinae with weakly eon­ eostellae to the escutcheon, and lacks the cave to straight posterodorsal margin and obli­ characteristic bifurcating anterior costae found in quely truncate respiratory margino Shell anteriorly Paulckella gen. nov., a diagnostic feature that has inflated with prominent umbones and strongly in­ not been previously described in any known curved prosogyrous beaks. Escutcheon wide, with Pterotrigonia species. oblique costellae. Area moderately narrow, smooth Pisotrigonia van Hoepen (1929, p. 20) (type spe­ except in early growth stages. Flank costae con­ cies: P. salebrosa van Hoepen) is widely regarded spicuously tuberculate, with subumbonal ribs as a synonym of Rinetrigonia van Hoepen (type bifurcating and curving upwards on the flattened species : Lyrodon ventricosa Krauss) (Kobayashi anterior face. and Nakano, 1957; Skwarko, 1966; Nakano, Discussion. The presence of oblique, strongly 1974); but, in fact, has page priority over the latter tuberculate flank costae, and strong anterior infla­ genus. Paulckella resembles Pisotrigonia in being tion places Paulckella gen. nov. in the Pterotrigonii­ strongly inflated anteriorly, with a tendency for the nae. Kobayashi and Nakano (1957, p. 230) put T. anterior face to be flattened and subvertical, and nepos with doubts in the subgenus Rinetrigonia in having prominent umbones and strongly incurv­ van Hoepen, pointing out that the flank branching ed beaks. Al! known species of Pisotrigonia. how­ anterior costae could place this species in a genus ever, are relatively higher. with a deeply concave not yet defined. In the same eontext, Levy (1967, posterodorsal margino and have simple anterior p. 102) preferred to emend the diagnosis of Rine­ ribs which never bifurcate. Typically. Pisotrigonia trigonia instead of proposing a new genus. Trigonia shows better discrimination between the anterior nepos Paulcke was also assigned to Pterotrigonia and posterior sets of flank costae. with coarser, van Hoepen (1929, p. 9) (type species: P. cristata more robust anterior costae bearing fewer. larger van Hoepen) by Reyes and Pérez (1978, 1979), nodes. 54 SYSTEMATIC posmoN OF TRIGONIA NEPOS

In shell outline, tuberculation and rigidity of phorella Nakano. The similarities seem to be due to flank costation, Paulckella gen. nov. is close to A­ convergence and Arabitrigonia has to be consid­ canthotrigonia van Hoepen (1929, p. 14) (type spe­ ered a good Pterotrigoninae. cies: Trigonia shepstonei Griesbach). The latter In its bifurcating anterior costae Pau/ckella gen. ':axon is a Late Cretaceous (Coniacian to Maas­ nov. closely resembles some forms of Apiotrigonia trichtian) genus known only from , Cox, e.g. A. (Microtrigonia) postonodosa Nakano and . It differs from Pau/ckella (Tashiro, 1972, PI. 40, Figs. 20-23). Mhough the gen. nov. in being weakly inflated anteriorly, with in­ similarities are the result of convergence, bifurcat­ conspicuous umbones and simple anterior flank ing anterior flank costae are also encountered in costae wh ich do not bifurcate. species of Heterotrigonia Cox (Tashiro, 1979) and Scabrotrigonia Dietrich (1933, p. 330) (type spe­ this character is thus widespread within the Apiotri­ cies: Trigonia scabra Lamarck) differs from Pau/­ goniinae. Pau/ckella differs from Apiotrigonia in its ckella gen. nov. in being less inflated anteriorly, prominent umbones and strongly incurved beaks, with denser, more finely tuberculate flank costae its unornamented area in maturity, and its strongly which curve anteriorly and are not separated into oblique flank costae with coarse tuberculation. At an anterior and posterior se!. In addition, the cos­ all growth stages it lacks the V-shaped flank cos­ tae of the flank and escutcheon are continuous tae of typical Apiotrigonia. In all these characters onto the area of Scabrotrigonia, forming a chevron it is closer to the Pterotrigoniinae. Another trigoniid at the median longitudinal groove. which displays bifurcating anterior flank costae is Ptilotrigonia van Hoepen (1929, p. 22) (type spe­ the Scaphorella Leanza, Pérez and Re­ cies : P. /auta van Hoepen) differs from Pau/ckella yes (1987, p. 83) (type species: Trigonia /eanzai gen. nov. in being less inflated anteriorly, with less Lambert), but the latter is a Myophorellinae and the prominent umbones and a rounded respiratory mar­ similarities are due to convergence. gin. In addition, it has curved flank costae which The upward curvature of the anterior flank cos­ do not bifurcate and are ornamented by crowded tae seen in Pau/ckella gen. nov. is also found in Bu­ nodes besides having a deeply concave poste ro­ chotrigonia Dietrich. The latter genus differs in be­ dorsal margino ing subovate and relatively higher, with a very Arabitrigonia Nakano (1973, p.66) (type spe­ short posterodorsal margino It also lacks the cies: Trigonia pseudocrenu/ata Noetling) is an Ap­ coarse tuberculation of Pau/ckella gen nov. and is tian taxon known only from the Middle East. It re­ less inflated anteriorly with the result that the sembles Pau/ckella gen . nov. in its prominent um­ strong curvature of anterior costae is conspicuous bones, strong ribs and obliquely truncate respira­ in lateral view. tory margin, but has sinuous flank costae which do Large individuals of Paulckella gen . nov. (e.g. not bifurcate anteriorly and have finer tubercula­ Paulcke, 1903, PI. 17, Fig. 7) bear a marked resem­ tion. In addition, Arabitrigonia has radial costellae blance to Permo- Costatoria Waagen to the area, a feature which led Nakano (1973) to (Newell and Boyd, 1975, p. 153, Figs. 94, 95) but place it in the Myophorellinae, close to Pseudomyo- the similarities are due to convergence.

Paulckella nepas (Paulcke, 1903) (PI. 1, Figs. 1-8; text-Fig . 2)

Trigonia nepos Paulcke, 1903, p. 293, PI. 17, Figs. rez, 1979, PI. 3. 7-8 Neotype. Specimen SNGM-7146 (PI. 1, Figs. 1,2). non Trigonia nepos Paulcke, 1903. Leanza and Paulcke (1903, p. 193-195, PI. 17, Figs. 7, 8) Castellaro, 1955, p. 186-188, PI. 1, Fig. 9, PI. 2, based his description of T nepos on five syntypes Figs. 1, 5. (text-Fig. 2) deposited in the Strassburg Collec­ non Trigonia nepos Paulcke, 1903. Tavera in Alar­ tion . This collection is missing, presumably des­ cón and Vergara, 1964, p. 114, PI. 4, Fig . 9. troyed by fire after World War 11 . Due to the sys­ Pterotrigonia nepos (Paulcke). Reyes and Pérez, tematic importance of T nepos, the specimen 1978, p. 13, PI. 2, Fig. 4. SNGM-7146, of the topotype material, is here desig­ Pterotrigonia (P.) nepos (Paulcke). Reyes and Pé- ned as the neotype . M.R. Cooper, E. Pérez and R. Reyes 55

8b

Text-FIG. 2. Reproductions of!he original illustrations of T. nepos Paulcke, 1903 (PI. 17, Figs. 7, 8), x 1.

Type locality. Molle Alto (ca. 2r50'S; 70°19' gin, shallowly concave to straight. W), 50 km south of Copiapó city, Atacama Region The escutcheon is concave, slightly narrower (text-Fig. 1). than the area, and ornamented with finely tubercu­ Complementary material and occurrence. late costellae which are twice narrower than the in­ The silicified topotype material studied here (PI. 1, terspaces, with four costellae in a centimeter on Figs. 1-8) was collected from the type locality Mo­ the central portion of the neotype. The costellae lle Alto (by E.P., 1965, samples FCH-45-A) (text­ are oblique, cutting the growth striae at nght and Fig. 1), from the upper part of the Pabellón Forma­ oblique angles, and meet the posterodorsal com­ tion (Biese in Hoffstetter et al., 1957). It includes missure to form an obtuse, posteriorly directed specimens SNGM-7147 (PI. 1, Figs. 4, 8), SNGM- chevron. The position of the inner carina is marked 7148 (PI. 1, Fig. 3) and SNGM-7149 (PI. 1, Figs. 5-7). in the nepionic stages by a row of spaced tuber­ Repository. Museo Geológico, Servicio Nacio­ cles, one for each costella of the escutcheon. nal de Geología y Minería (SNGM), Santiago, Chile. The area is moderately narrow, almost flat, and Associated fauna. This includes Parahoplites broadens posteriorly. It is ornamented with fine, re­ gr. nutfieldiensis (J. Sowerby), Steinmannella gr. gular, transverse costellae in the nepionic stages, transitoria (Steinmann), Paulckella sp. nov., Chla­ but later only by growth striae. There is a distinct mys d. discors (Philippi) [non Pecten discors Phili­ median longitudinal furrow which persists to the ppi], Idonearca sp., and Ptychomya sp., together respiratory margin, and is situated closer to the with indeterminate bryozoans, serpulids and gas­ escutcheon than the flank. The marginal carina is tropods. fine and sharp near the umbo, becoming rounded Age. The presence of the ammonite Parahoplites later. In both valves the flank costae join this gr. nutfieldiensis (J. Sowerby) at the type locality carina at acute angles. of P. nepos dates this species, and also the upper The flan k costae are rigid, about as wide as the part of the Pabellón Formation, as late Aptian, in­ interspaces, and broaden ventrally. Close to the stead of late Barremian (Corvalán 1974, p. 33). are a they are finely crenulated by small po nted tu­ Description. The shell is medium to moderately bercles which may develop into spines (text-Fig. large, thick, trigonally ovate, very inequilateral, 2). Distally, however, the tubercles becol1e well and posteriorly produced. It is strongly inflated an­ spaced, exaggerated, and bluntly rounded, resem­ teriorly, with prominent subterminal umbones and bling the condition observed in Acanthotrigonia. strongly incurved, prosogyrous beaks. The anteri­ Although the flank costae are separated into an or margin is steep, weakly convex to flat; the ven­ anterior and posterior set, this is not as marked as tral margin is strongly convex; the respiratory mar­ Pisotrigonia. The first 3-4 umbonal costae are gin, obliquely truncate; and the posterodorsal mar- concentric to subconcentric, after which they be- 56 SYSTEMATIC PosmON OF TRIGONlA NEPOS come strongly oblique. The subumbonal 3-4 cos­ 2, Figs. 1, 5) from Quebrada El Way, Antofagasta tae bifurcate at the anterolateral shoulder (text­ Region, northern Chile, represents another spe­ Fig. 2) and curve upwards, extending across the cies of Pau/ckalla. It differs from P. napos in hav­ anterior face to meet the commissure in an acute ing a more acute umbonal angle, a more steep ante­ angle. The posterior 3-4 ribs of the anterior set are rior region, and flank subumbonal costae with finer straight, and posteriorly inclined. The posterior set branches that fail to reach the anterior commis­ eomprises 11-12 straight, simple costae which are sure (Pérez and Reyes, in prep.). narrower than those of the anterior. They are in­ Among the assocíated fauna of T. napos neo­ clined strongly to the posterior and are crowded type (Molle Alto locality) there are some speci­ and finer at their contact with the carina, forming mens considered, in this paper, as Paulckalla sp. an angla which beco mes progressivelly acute pos­ nov. (Pérez and Reyes, in prep.). The new species teriorly. bears a superficial resemblance to P. napos (Paul­ Measurernents (In mm) cke) but differs in being elongated pyriform; with the anterior border strongly eonvex and the dorsal, No. L H T H/L T/L slightly concave. Moreover, the area is very nar­ row and convex and the flank posterior costae are SNGM·7146 (RV) 45 " 41 " 21 " 0,91 " 0,47" fairly thin and not tuberculated. (neotype) The other mentions of T. napos Paulcke, Que­ SNGM·7147 (RV) 70 50 " 21 0,71 " 0,30 brada de Los Cóndores, Atacama Region (Corva­ SNGM·7148 (RV) 74 " 54 " 0,73 " lán in Reyes and Pérez, 1978, p. 13) and Cerro de SNGM-7149 (RV) 52 " 42 21 0,81 " 0,40 Paseo, Central Perú (Salte Id, 1911, p. 219) do not RV: right valve; L: length; H: height; T: thickness. give enough information, about the ornarnentatJon " Approximate values. of the flank anterior region, to evaluate if the identi­ fication as T. napos corresponds to the diagnosis Dlscussion. Trigonia nepos Leanza and Castel­ of species. laro (non Paulcke) (1955, p. 186, PI. 1, Fig. 9, PI.

ACKNOWlEDGEMENTS

The authors wish to thank José Corvalán and nal de Historia Natural) for constructive criticism of Vladimir Covacevich (Servicio Nacional de Geolo­ the manuscript. They are also greatful to Osear gía y Minería) and Daniel Frassinetti (Museo Nacío- Alfaro for the photographic work.

REFERENCES

Alarcón, B.; Vergara, M. 1964. Nuevos antecedentes so­ nae. Japanese Journal 01 Geology and Geography, bre la geologla de la quebrada El Way. Universidad de Vol. 28, No. 4, p. 219-238, Láms. 16-17. Chile, Instituto de Geología,Publicaciones, No. 26, p. Leanza, A.; Castellaro, H. 1955. Algunos fósiles cretáci­ 101-128,4 Láms. cos de Chile. Asociación Geológica Argentina, Revis­ Corvalán, J. 1974. Estratigrafía del Neocomiano marino ta, Vol. 10, No. 3, p. 178-213, 4 Láms. de la región de Copiapó, provincia de Atacama. Revis­ Leanza, H.; Pérez, E.; Reyes, R. 1987. Scaphorella, un ta Geológica de Chile, No. 1, p. 13-36. nuevo género de Trigoniidae (Bivalvia) del Jurásico Dietrich, W. 1933. Das Münster der Gattung Trigonia Medio de Argentina, Chile y Estados Unidos de Amé­ (MoII. Lam.). Sitzungsbericht Gesellschaft der Natur­ rica. Ameghiniana, Vol. 24, Nos. 1-2, p. 81-88,1 Lám. forschung Freunde 1933, p. 325-332. Levy, R. 1967. Revisión de las Trigonias de Argentina. 3. Hoffstetter, R.; Fuenzalida, H.; Cecioni, G. 1957. Lexique Los Pterotrigoniinae de Argentina. Ameghiniana, Vol. stratigraphique International. Amerique Latine, Vol. 5, No. 3, p. 101-108. 15, No. 7, Chile, Centre National de la Recherche Nakano, M. 1973. A new genus Arabitrigonia. Hiroshima Scientilique, 144 p. Paris. University, Journal 01 Science, Series C, Vol. 7. No. 1. Kobayashi, R.; Nakano, M. 1957. On the Pterotrigonii- p.65-67. M.R. Cooper, E. Pérez and R. Reyes 57

Nakano, M. 1974. Rinetrigonia and its allies. Hiroshima to de la familia Trigoniidae (Molusca: Bivalvia) en Chi­ University, Journal of Science, Series C, Vol. 7, No. 2, le.Revista Geológica de Chile, No. 8, p. 13~4, 6 Láms. p.101-111. Salfeld, H. 1911. Versteinerungen aus dem Devon von Newell, N.D.; Boyd, D.w. 1975. Parallel evolution in early Bolivien, dem Jura und der Kreide von Perú. In Reisen trigoniacean bivalves. American Museum of Natural in Bolivien und Perú (Hauthal, R.; editor). Wissen­ History, Bulletin, Vol. 154, No. 2, p. 55-162, 98 Figs. schaftliche Veroffent. Gesellschaft für Erdkunde, Vol. Paulcke, W. 1903. Ueber die Kreideformation in Südameri• 7, p. 207-220, 4 Láms. ka und ihre Beziehung zu anderen Gebieten. Neues Skwarko, S.K. 1966. Cretaceous stratigraphy and paleon­ Jahrbuch für Mineralogie und Geologie, Vol. 17, p. 252- tology of !he Northern Territory. , Bureau of 312, Láms. 15-17. Mineral Resources, Geology and Geophysics, Bul­ Pérez, E.; Covacevich, V. 1988. Presencia de Parahopli­ letin, No. 73, p. 1-55,6 Láms. tes sp. (Ammonoidea) en la Formación Pabellón y su Tashiro, M. 1979. A study of the 'pennatae lrigoniids' significado cronoestratigráfico. In Congreso Geológi• from . Paleontological Society of Japan, Trans­ co Chileno, No. 5, Resúmenes, p. 104, Santiago. actions Proce9ding, N.S., No. 116, p. 179-222, Láms. Reyes, R.; Pérez, E. 1978. Las Trigonias del Titoniano y 25-26. Cretácico Inferior de la cuenca andina de Chile y su va­ Van Hoepen, E.C.N. 1929. Die Krytfauna van Soeloeland. lor cronoestratigráfico. Instituto de Investigaciones 1. Trigoniidae. Paleontologiese Navorsing Nasionale Geológicas, Boletln, No. 32, 105 p., 5 Láms. Museum, Bloemfontein, Vol. 1, No. 1,38 p., 7 Láms. Reyes, R.; Pérez, E. 1979. Estado actual del conocimien- 58 SYSTEMATIC POSITION OF TRIGONIA NEPOS

PLATE 1 (AII ligures in natural size)

Figures 1-8 Pau/ckella nepos (Paulcke) p.54

Molle Alto, about 50 km south 01 Copiapó city, Atacama Region, northem Chile. Pabellón Formation, upper partoLate Aptian.

1,2 Lateral and anterior view 01 the neotype, SNGM 7146. Note the bilurcating subumbonal costae. 3 Lateral view 01 SNGM 7148. 4,8 Dorsal and lateral views 01 SNGM7147 5-7 Lateral, anterior and umbonal views 01 SNGM 7149.

Figures 9-15 Pterotrigonia cristata van Hoepen

Zululand, South Alrica; all in the South Alrican Museum.

9,10 The holotype, SAM 01404. 11,12 A paratype, SAM 01409. 13 A plesiotype, SAM 0533. 14, 15 A paratype, SAM 01410. M,R. Cooper, E. Pérez and R. Rey es PLATE 1

9 12

Pau/ckella Cooper et al.