[Papers in Palaeontology, 2017, pp. 1–41] A NEW CHONDRICHTHYAN FAUNA FROM THE LATE JURASSIC OF THE SWISS JURA (KIMMERIDGIAN) DOMINATED BY HYBODONTS, CHIMAEROIDS AND GUITARFISHES by LEA LEUZINGER1,5 ,GILLESCUNY2, EVGENY POPOV3,4 and JEAN-PAUL BILLON-BRUYAT1 1Section d’archeologie et paleontologie, Office de la culture, Republique et Canton du Jura, Hotel^ des Halles, 2900, Porrentruy, Switzerland 2LGLTPE, UMR CNRS ENS 5276, University Claude Bernard Lyon 1, 2 rue Rapha€el Dubois, F-69622, Villeurbanne Cedex, France 3Department of Historical Geology & Paleontology, Saratov State University, 83 Astrakhanskaya Str., 410012, Saratov, Russia 4Institute of Geology & Petroleum Technology, Kazan Federal University, Kremlevskaya Str. 4/5, 420008, Kazan, Russia 5Current address: Centro Regional de Investigaciones Cientıficas y Transferencia Tecnologica de La Rioja (CRILAR), Provincia de La Rioja, UNLAR, SEGEMAR, UNCa, CONICET, Entre Rıos y Mendoza s/n, (5301) Anillaco, La Rioja, Argentina; [email protected] Typescript received 27 November 2016; accepted in revised form 4 June 2017 Abstract: The fossil record of chondrichthyans (sharks, Jurassic, modern neoselachian sharks had overtaken hybo- rays and chimaeroids) principally consists of isolated teeth, donts in European marine realms, the latter being gradually spines and dermal denticles, their cartilaginous skeleton confined to brackish or freshwater environments. However, being rarely preserved. Several Late Jurassic chondrichthyan while the associated fauna of the Porrentruy platform indi- assemblages have been studied in Europe based on large bulk cates marine conditions, neoselachian sharks are surprisingly samples, mainly in England, France, Germany and Spain. rare. The chondrichthyan assemblage is largely dominated by The first study of this kind in Switzerland is based on con- hybodonts, guitarfishes (rays) and chimaeroids that are all trolled excavations in Kimmeridgian deposits related to the known to be euryhaline. This unexpected chondrichthyan construction of the A16 motorway in the Swiss Jura (Porren- faunal composition questions the presence of fresh to brack- truy, NW Switzerland). This study is based on more than ish water in the vicinity of the platform, and the occurrence 2000 isolated chondrichthyan remains (teeth, dental plates, of salinity fluctuations within a general context marine. This spines and dermal denticles) and adds to our knowledge of could explain the scarcity of neoselachian sharks and the the chondrichthyan distribution at a regional scale in Eur- extended success of hybodonts in the Porrentruy area as late ope. We describe and identify this new fauna, define a new as the Late Jurassic. species of hybodont with crushing-type dentition (Asteracan- thus udulfensis sp. nov.) and report for the first time the car- Key words: chondrichthyan, Swiss Jura, Kimmeridgian, hy- charhiniform Corysodon cirinensis in Switzerland. By the Late bodont, Asteracanthus, water salinity. R ECENTLY, numerous studies focusing on isolated chon- hybodont sharks in marine deposits (e.g. Duffin & Thies drichthyan remains (teeth, dermal denticles, spines) have 1997; Kriwet & Klug 2004) gradually replaced by the so- demonstrated their usefulness for faunal and palaeoenvi- called modern sharks and rays (Neoselachii) (Cuny & ronmental reconstructions (e.g. Underwood 2002, 2004; Benton 1999) that underwent a strong diversification in Rees 2005; Cuny et al. 2006; Klug & Kriwet 2013a). Until the Middle Jurassic, an epoch when most of their groups the second part of the twentieth century, studies of chon- emerged (Underwood 2006; Kriwet et al. 2009). Along drichthyans focused mainly on macroremains; but more with this neoselachian radiation and hybodont decline in recently the consideration of small-sized, sometimes sub- marine realms, a diversification and great abundance of millimetric fossils and of large bulk sampling have given a hybodonts is observed in restricted, reduced salinity and new dimension to the chondrichthyan picture (Under- freshwater environments, especially by the Cretaceous wood 2006; Underwood et al. 2016). (Cuny 2012). The Jurassic is thus a key period for the Late Jurassic chondrichthyan assemblages of Europe are understanding of the interrelationship between hybodonts generally characterized by the reduced presence of and neoselachians, both dominant at a certain point of © 2017 The Authors. doi: 10.1002/spp2.1085 1 Palaeontology published by John Wiley & Sons Ltd on behalf of The Palaeontological Association. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. 2 PAPERS IN PALAEONTOLOGY the chondrichthyan evolutionary history (Underwood & Reuchenette Formation. Chronostratigraphically, the sec- Ward 2004a). tion from the Banne Marls up to the Virgula Marls corre- With respect to Swiss chondrichthyan faunas from the sponds to the early Kimmeridgian to late Kimmeridgian Late Jurassic, large datasets from bulk samples had never respectively (Fig. 2) (Comment et al. 2015). Palaeogeo- been acquired, and few publications are available on the graphically, Porrentruy was a shallow-marine carbonate topic (Agassiz 1843 in 1833–1844; Peyer 1946; Muller€ platform, located at about 30°N (Marty 2008) and 2011). Swiss Late Jurassic chondrichthyan faunas were rimmed by the Rhenish and London–Brabant massifs to therefore poorly known until now and represent an the north, the Tethys to the south-east, the Central massif important missing piece in the chondrichthyan picture of to the south and the Paris basin to the north-west Europe (Kriwet & Klug 2008). Here we report over 2000 (Fig. 3). The platform was a complex system of bulges isolated chondrichthyan remains, discovered in Kim- and depressions locally inducing lateral changes in water meridgian shallow-water platform deposits, in the vicinity depth. Numerous theropod and sauropod dinosaur tracks of Porrentruy (Swiss Jura). The description and identifi- and hardgrounds indicate episodes of emergence (e.g. cation of this material, coming from a carbonate platform Marty 2008; Waite et al. 2013). A food source for the her- straddling Boreal and Tethyan ammonite provinces, will bivorous dinosaurs was presumably present, and thus firm add to the knowledge of the geographical distribution of ground and freshwater must have been present in the chondrichthyans in Europe during the Kimmeridgian, vicinity. Several lines of evidence suggesting that a palaeo- and qualify the general trend observed throughout the sol was present in the region, and subsequently eroded, Jurassic, namely the diversification of neoselachians to the were presented by Waite et al. (2013). The presence of detriment of hybodonts. Protocupressinoxylon purbeckensis is recorded, a tree that can grow as high as 13 m and forms closed forests (Phi- lippe et al. 2010) thus indicating a firm ground of consid- GEOGRAPHICAL AND GEOLOGICAL erable extent. The semi-arid climate was characterized by SETTINGS a high seasonality with long, dry summers and short, wet winters (Philippe et al. 2010; Waite et al. 2013). The This study is based on fossil material discovered by the study area presents affinities with the Boreal, as well as ‘Paleontologie A16’ team (PAL A16, Porrentruy, canton of with the Tethyan realm in its ammonite association, albeit Jura, NW Switzerland) in the framework of the building of with a stronger Boreal influence (Schudack et al. 2013). the A16 motorway. Between 2000 and 2011, numerous sites of palaeontological interest were uncovered in the Ajoie region, around the locality of Porrentruy (Fig. 1). MATERIAL AND METHOD The study region is part of the Tabular Jura (Marty et al. 2007) and is composed of a subhorizontal succes- The Mesozoic chondrichthyan material of Porrentruy is sion of limestone and more marly intervals of the the result of controlled excavations conducted by the FIG. 1. Geographical map of the erm 7°04’40”E G any Ajoie region, Canton Jura, Switzer- Canton A Jura u N Delle s € t land (modified from Puntener et al. - r ten i 5 km h a Belfort e Liec 2015). Excavation sites yielding c in n ste a chondrichthyan remains are marked, r Switzerland F most of them along the track of the 2 A16 motorway. See Site Abbrevia- tions in text for details of locality Italy names. 1, Bois de Montaigre (BDM); 2, Neu Bois (NBO); 3, Che- Montbéliard Porrentruy 47°25’05”N venez (CHV); 4, Bois d’Estai (BES); Courtedoux 9 4 10 Basel 5, Bois de Sylleux (BSY); 6, Creu- 8 11 A 5 61 1 genat CRE); 7, Sur Combe Ronde 7 6 m Delémont (SCR); 8, Tch^afoue (TCH); 9, V^a 3 o t o Tche Tch^a (VTT); 10, Roche de rw ay Mars (RDM); 11, Tunnel du Banne bs Dou (TLB). Colour online. Le Bienne LEUZINGER ET AL.: SWISS KIMMERIDGIAN CHONDRICHTHYANS 3 Paleontologie A16 team (PAL A16) and comprises a large Description of the cephalic spines. Posteriorly curved crown (c) dataset: 2264 fossils, of which 1941 are elasmobranch with enameloid coating (Fig. 4A–D) on a porous, three-lobed teeth, 34 chimaeroid tooth plates, 245 dermal denticles, basal plate (bp) (Fig. 4E–G). The posterior lobe (lp) of the basal 34 fin spines and three cephalic spines. Several centra are plate is broader than the lateral (ll) and mesial (lm) lobes and recorded but were not used for identification due to their shows a more rounded outline. One cephalic spine shows a partly preserved crown on an incomplete basal plate (Fig. 4A– poor taxonomic value compared to dental remains