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Alcheringa: an Australasian Journal of Palaeontology the Worm This article was downloaded by: [García-Bellido, Diego C.] On: 21 December 2010 Access details: Access Details: [subscription number 931324548] Publisher Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37- 41 Mortimer Street, London W1T 3JH, UK Alcheringa: An Australasian Journal of Palaeontology Publication details, including instructions for authors and subscription information: http://www.informaworld.com/smpp/title~content=t770322720 The worm Palaeoscolex from the Cambrian of NW Argentina: extending the biogeography of Cambrian priapulids to South America Diego C. García-Bellidoa; Guillermo F. Aceñolazab a Departamento de Paleontología, Instituto de Geología Económica (CSIC-UCM), Facultad de Ciencias Geológicas, Madrid, Spain b Instituto Superior de Correlación Geológica (CONICET-UNT), Facultad de Ciencias Naturales e IML, Tucumán, Argentina First published on: 17 December 2010 To cite this Article García-Bellido, Diego C. and Aceñolaza, Guillermo F.(2010) 'The worm Palaeoscolex from the Cambrian of NW Argentina: extending the biogeography of Cambrian priapulids to South America', Alcheringa: An Australasian Journal of Palaeontology,, First published on: 17 December 2010 (iFirst) To link to this Article: DOI: 10.1080/03115518.2011.538907 URL: http://dx.doi.org/10.1080/03115518.2011.538907 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.informaworld.com/terms-and-conditions-of-access.pdf This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, re-distribution, re-selling, loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. The worm Palaeoscolex from the Cambrian of NW Argentina: extending the biogeography of Cambrian priapulids to South America DIEGO C. GARCI´A-BELLIDO AND GUILLERMO F. ACEN˜ OLAZA GARCI´A-BELLIDO, D.C. & ACEN˜ OLAZA,G.F.iFirst article. The worm Palaeoscolex from the Cambrian of NW Argentina: extending the biogeography of Cambrian priapulids to South America. Alcheringa, 1–8. ISSN 0311-5518. Over one hundred years of palaeontological research in northwestern Argentina has provided extensive knowledge of Andean lower Palaeozoic fossil assemblages, with trilobites, graptolites, brachiopods and echinoderms being among the most prominent groups. This record is enriched by the recent discovery of soft-bodied worms in Cambrian outcrops of northwestern Argentina. Palaeoscolex sp. cf. P. ratcliffei from the Furongian Lampazar Formation in Jujuy is described, considerably expanding the biogeographical range of this genus and filling the distributional gap, between the well-known early–middle Cambrian occurrences of Palaeoscolex and those of its Ordovician species. Diego C. Garcı´a-Bellido [[email protected]], Departamento de Paleontologı´a, Instituto de Geologı´a Econo´mica (CSIC-UCM), Facultad de Ciencias Geolo´gicas, Jose´ Antonio Nova´is 2, 28040 Madrid, Spain; Guillermo F. Acen˜olaza [[email protected]], Instituto Superior de Correlacio´n Geolo´gica (CONICET-UNT), Facultad de Ciencias Naturales e IML. Miguel Lillo 205, 4000 Tucuma´n. Argentina. Received 14.9.2010, revised 28.10.2010, accepted 5.11.2010. Key words: soft-bodied biota, priapulids, Palaeoscolecida, Furongian, Argentina. STUDIES of Argentinean lower Palaeo- Soft-bodied fossils constitute an excep- zoic fossil assemblages have been based tional source of information on past life primarily on sclerotized and mineralized particularly with respect to functional mor- remains; few have dealt with soft-bodied phology, life habits and biodiversity than organisms. Non-mineralized organisms are more common skeletal fossils. The deposits assumed to have existed in Argentina’s containing these special fossils, known as Downloaded By: [García-Bellido, Diego C.] At: 09:32 21 December 2010 Palaeozoic seas, even though few are Konservat-Lagersta¨tten, are very scarce, and preserved in this region. Palaeoecological among the best-known suites of early evaluations of the biota largely overlook Palaeozoic age are the Cambrian assem- the range of soft-bodied elements, which blages of the Burgess Shale in Canada, were probably very important in lower Chengjiang and Kaili in China, and Sirius Palaeozoic trophic chains. Perception of Passet in Greenland. Studies carried out at these ‘ghost taxa’ has increased via the these localities show that organisms lacking description of ichno-assemblages, which a mineralized skeleton constitute over 80% record the activities of a varied and of the assemblages (Conway Morris 1986, abundant soft-bodied fauna, while the Zhao et al. 2009). Soft-bodied vermiform latter provides data critical for phyloge- organisms, such as those described herein, netic evaluation and autecological apprai- are important constituents of the faunas sal. that arose between 540 and 520 million years ago, during the Cambrian ‘explosion’. ISSN 0311-5518 (print)/ISSN 1752-0754 (online) Ó 2010 Association of Australasian Palaeontologists In the latest complete surveys of the DOI: 10.1080/03115518.2011.538907 Chengjiang biota (Steiner et al. 2005), about 2 D. C. GARCI´A-BELLIDO and G. F. ACEN˜ OLAZA ALCHERINGA 9% of the genera correspond to priapulids, (2004) to Sphenothallus? sp., has been whereas in the younger Burgess Shale, they reassigned to the priapulid worm Selkirkia constitute about 4% of the total diversity sp. (Acen˜ olaza & Acen˜ olaza 2007, fig. 3.5). (Caron & Jackson 2008). Many components An additional soft-bodied organism re- of these groups suffered an important cently described by Vaccari et al. (2004), setback during the Ordovician, as was the consists of a single specimen of a new case for the palaeoscolecids. euthycarcinoid arthropod, Apankura ma- The palaeontological literature of north- chu, collected from a pebble in the Huasa- western Argentina includes several other mayo River in Tilcara, Jujuy Province. This putative soft-bodied fossils, but these have unique specimen is interpreted to come from mostly been reinterpreted as trace fossils, shales of the Casa Colorada Formation, sedimentary structures associated with mi- which is partially equivalent to the Lampa- crobial mats, or are still regarded as incertae zar Formation and crops out extensively in sedis. An example of the first case is that of the area of Tilcara (Jujuy). The presence of a medusoid (‘Brooksella’) from the Casa soft-bodied arthropods, together with the Colorada Formation at the Quebrada de worm described here, suggests that further Humahuaca in Jujuy Province (Moya et al. research in northwest Argentina may reveal 1986), which was synonymized with the a greater diversity of Cambrian forms, ichnofossil Gyrophyllites. Similarly, forms apparently unrivalled in South America. assigned to Squamodictyon and Protopa- laeodictyon are now interpreted to be structures associated with microbial mats (Acen˜ olaza & Acen˜ olaza 2001, 2003, 2005, Geological setting and 2007). The presence of subcircular bodies provenance of material with a central knob (Durand & Acen˜ olaza The material examined here derives from a 1990, and references therein), had been unit in the Neoproterozoic–lower Palaeo- assigned to Tiernavia, Sekwia and Beltanel- zoic succession of northwestern Argentina, liformis, with some of them recently syno- the Furongian Lampazar Formation. The nymized with Beltanelloides (Acen˜ olaza Lampazar Formation in the Sierra de Cajas, et al. 2005). A fossil from the Puncoviscana Jujuy Province (Fig. 1), has produced two Formation at Choromoro in Tucuma´n specimens of the worm Palaeoscolex sp. cf. Downloaded By: [García-Bellido, Diego C.] At: 09:32 21 December 2010 Province, originally assigned by Acen˜ olaza P. ratcliffei. Fig. 1. Regional and local maps of the area of Jujuy Province (northwestern Argentina) where Palaeoscolex sp. cf. P. ratcliffei was collected. ALCHERINGA CAMBRIAN PALAEOSCOLEX FROM ARGENTINA 3 The Lampazar Formation (Harrington 1957) was originally described near the locality of Ingeniero Maury (Salta Province), and consists of grey to green, banded mudstones and sandstones with a total thickness of almost 100 m (Harrington 1957, Tortello & Rao 2000). Additional exposures of this formation have since been recognized to the north (Fig. 1), in the Sierra de Cajas (Jujuy Province), where it is 178 m thick (Fig. 2) and conformably overlies the sandstones and quartzites of the Padrioc Formation and underlies the quartz-rich sandstones of the Cardonal Formation. The Lampazar Forma- tion contains a rich fossil record consisting of trilobites and other arthropods, conodonts, brachiopods, echinoderms, ichnofossils (Ace- n˜ olaza 1968, Benedetto 1977, Rao 1999 and references therein), and the two specimens of the worm Palaeoscolex sp. cf. P. ratcliffei described here (Figs 3A–D). The Palaeoscolex specimens come from the pelitic and sandy levels in the upper part of the unit on the western slope of the Sierra de Cajas (Fig. 1). Although the material is fragmentary,
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