Cainozoic Research, 3-18, 2006 4(1-2), pp. February An Early Miocene elasmobranch fauna from the Navidad Formation, Central Chile, South America ³* Mario+E. Suarez Alfonso Encinas² & David Ward ¹, 'Museo Paleontoldgico de Caldera, Cousino, 695, Caldera, Atacama, Chile, [email protected] 2 Departamento de Geologia. Universidad de Chile, Plaza Ercilla 803, Santiago Chile. [email protected] J David J. Kent ME4 4AW UK. Ward, School of Earth Sciences, University of Greenwich, Chatham Maritime, Address for correspon- dence: Crofton Court, 81 Crofton Lane, Orpington, Kent BR5 1HB, UK. E-mail: [email protected]. [* corresponding author] Received 5 March 2003; revised version accepted 12 January 2005 A rich elasmobranch assemblage is reported from the Early Neogenemarine sediments ofthe lower member of the NavidadFormation, Central Chile. The fauna comprise Squalus sp., Pristiophorus sp., Heterodontus sp., Megascyliorhinus trelewensis. Carcharias cuspi- data, Isurus hastalis, Carcharoides and Cal- Odontaspisferox, oxyirinchus,Isurus hastalis, Cosmopolitodus totuserratus, Myliobatis sp. for the the Miocene The of lorhinchus sp., all ofwhich are reported first time in Early ofChile. presence Carcharoides totuserratus sup- the Miocene for the lower ofthe basal Navidad Formation. The Chilean fossil elasmobranch fauna is ports Early age part representedby deep water and shallow water taxa, which probably were mixed in a submarine fan. Certain taxa suggest warm-temperate waters. The Early Miocene fauna from the Navidad Formation show affinities with other faunas previously reported from the Late Paleogene and Neogene of Argentina and New Zealand. Se describe rica asociacion de fosiles veniente de los sedimentos marines del Inferior de la Formación una elasmobranquios pro Neogeno central. La fauna Navidad, Chile comprende Squalus sp., Pristiophorus sp., Heterodontus spp., Megascyliorhinus trelewensis, Carcha- rias cuspidata, Odontaspis ferox, hums oxirinchus, Cosmopolitodus hastalis, Carcharoides totuserratus, Myliobatis sp. and Cal- lorhinchus todos los cuales el Mioceno de Chile. La de Carcharoides sp., son reportados por primera vez para Temprano presencia to- edad miocena la basal del miembro inferior de la Formatión Navidad. Los tuserratus permite proponer una tempranapara parte compo- de la fauna de fósiles formas de habrían sido mezcladas al nentes elasmobranquios incluyen agua profunda y somera que depositarse en abanico submarino. la de La fauna de la Formatión Navidad un Algunos taxones sugieren presencia aguas temperadas-cálidas. presenta afmidades faunísticas faunas de el tardfo de con otras elasmobranquios previamente reportadas para Paleógeno y Neógeno Argentina y Nueva Zelandia. Key words:: Miocene, Elasmobranch, Teeth, Chile Navidad Formation. from Introduction shark remains this formation, commenting briefly on a large tooth, which had been recovered from the Matanzas First described by Darwin (1900), the Navidad Formation locality. That toothwas described as Carchariasgiganteus also similar from is one of the largest onshore exposures of Tertiary sedi- Philippi and compared with a one La Her- These fos- radura Both teeth mentary successions in western South America. locality (Coquimbo Formation). were “ siliferous have been known since the last illustrated in classic work Los outcrops century Phillipi’s (Phillipi, 1887) Covacevic & through the work of a number of authors; Phillipi (1887), fosiles cuaternarios y terciarios de Chile". (1942, 1968),Osorio (1976), Tav- Frassinetti cited the of in their Darwin (1900), Tavera (1980) presence Lanina sp. Valenzuela Covacevic & invertebrate fauna recovered from the Punta Alta era (1979), Martinez & (1979), locality Frassinetti (1980), Martinez-Pardo (1990), Troncoso and recently Suarez and Encinas (2002) yielded a brief fossil (1991), Troncoso & Romero (1993), who described the report about the vertebrate assemblage from the lower member of the Navidad Formation. presence ofbivalves, gastropods, scaphopods, brachiopods, echinoids, Bryozoa, barnacles, cephalopods, corals, fo- The present contribution is the result of several field trips raminifera, discoasters, ostracods, leaves, tree trunks and carried out in the Navidad Formation during the years plant pollen. Fossil vertebrates such as fish are, however, 1998-2002.These trips allowed us to gather a significant collectionoffossil vertebrates, fish teeth, scarce or absent judgingfrom the major part of the litera- mainly including ture cited. Philippi (1887)provided the first description of an unexpectedly rich elasmobranch assemblage. -4- Figure 1. Location of study area. A,B- Location of study area; C- Distribution ofthe Navidad Formation along the coast of Central Chile; D- The Early Miocene Punta Perro and La Boca sections (indicated by T’ and ‘2’ respectively). The material reported in this paper comprises sharks’ teeth, Historia Natural (MNHN) in Santiago, Chile. dental of and All plates rays, holocephalians. are new re- cords for the Navidad Formation. Geological setting Materialand methods The Navidad Formation was first described by Darwin (1900). He assigned the term “sandstone formation at The material described in this paper was obtained by sur- Navidad” to all the sedimentary rocks exposed between face collecting from two sites located along the sea cliffs Estero Yali to the north and Punta Topocalma to the south. between Punta Perro and the town ofLa Boca (Figure Id). It consists of approximately 500 m of mudstones, silt- isolated dental of and sandstones and which form It comprises shark teeth, plates rays, stones, conglomerates a succes- holocephalians. Additionalassociated vertebrate remains, sion of relatively undeformed strata. The Formation crops comprising both osteichthyan and cetacean teeth,were also out between 33° 45' S and 34° 15’ S latitude and 71° 30’ W lh outside the All in the 6 collectedbut fall the scope of present work. longitude, 130kilometres southwest ofSantiago, in for km north and the specimens described this paper have been deposited region ofChile, and extends 70 to south in the Seccion Paleontologla, of the Museo Nacional de 30 km east to west (Figure 1c). The Navidad Formation -5 - crops out extensively along the coastal cliffs ofthe Navidad town of Rapel (M. Suarez, personal observation). During region, the eroded banks of the Rapel River and the hill- the field trips we carried out in this area we found fossil sides inland It (Chambers, 1985). rests unconformably vertebrates at several sea cliff sites between Estero upon the Permo-Carboniferous crystalline basement, the Maitenlahue and the town of Pupuya. Cretaceous Punta Topocalma Formation, or the Eocene Rfo In the northern extreme ofPunta Perro, fossil sharks’ teeth Formation foundin the sandstone of intertidal Topocalma (Cecioni, 1978). are grey-green the zone, Etchart (1973), Tavera (1979) and Ceccioni (1978) studied immediately above the basal conglomerate. At the southern the ofthe Navidad Formation in detail.Etchart of Punta fossil teeth become stratigraphy part Perro, more common divided the Miocene succession into the Middle (1973) along the sea cliffs, within thin, discontinuous lenses of Miocene La Boca Formation and the Late Miocene Navi- varying lithology such as conglomerates and coquina beds dadFormation. Tavera (1979) divided the Navidad Forma- with gastropods, bivalves and scaphopods. SouthofPunta tion into three from oldest in the Punta Alta and the of members, to youngest being: Perro, locality near town Ma- Lincancheo and Ceccioni Navidad, Rapel. (1970, 1978) tanzas (Figure Id), fossil teeth are scarcer and are associ- defined the Navidad Group as formed by different units of ated with lithologies similar to those of Punta Perro (Tav- Cretaceous-Pleistocene Within this he defined age. group era, 1979; Covacevic and Frassinetti, 1980; this paper). the Miocene-Pliocene Punta Perro-La Era Two mainfossiliferous sites Formation, were recognised which yielded which is the Navidad Formation of Tavera. the elasmobranch equivalent to assemblages (Figure 1c). These are lo- Ceccioni divided this formationin four members: I, II, III cated along the sea cliffs between Punta Perro and La Boca and IV. town and belong to the base of this formation. The first and richest assemblage was recovered from a locality named “La Boca,” to the northofLa Boca town. The second local- of the Navidad Formation is referred Age ity to as “Punta Perro”, which is at the south of Punta Perro. Two sections, where we have found the most There is the of the Navidad some disagreement over age representative fossil assemblages, are describedin detail in Formation. It has been described as Early Miocene based this section. on macrofossils (Tavera, 1979) who suggested that the ob- served palaeontological differences among members could be attributedto facies variations.Osorio (1979) suggested a Stratigraphic sections maximum of 11.5 Ma age based on ostracods. Martinez- Pardo (1990) suggested a 19-10 Ma age based on plank- La Boca Section tonic foraminifera. Frassinetti & Covacevic (1981) sug- Miocene for the 1 gested an Early-Middle age Navidad This site is located about km north ofLa Boca town and member and based and is on stratigraphical correlation, as- shown as point 1 (Figure 2a). The section was measured Late-Middle Late Miocene for the Lin- from the intertidal signed a to age zone to the top ofthe cliff. cacheo member. These authors proposed the same Late- BASE: Base ofsection lies below sea level. Middle Miocene for to Late age