[Palaeontology, 2013, pp. 1–20] DIVERSITY AND PALAEOECOLOGY OF THE ENIGMATIC GENUS KNEBELIA (EUCRUSTACEA, DECAPODA, ERYONIDAE) FROM UPPER JURASSIC PLATTENKALKS IN SOUTHERN GERMANY by DENIS AUDO1*, GUNTER€ SCHWEIGERT2, JOACHIM T. HAUG3, CAROLIN HAUG3, JEAN-PAUL SAINT MARTIN1 and SYLVAIN CHARBONNIER1 1Museum National d’Histoire Naturelle, Departement Histoire de la Terre, CP38, UMR 7207 MNHN, UPMC, CNRS, 8 rue Buffon, 75005, Paris, France; e-mails: [email protected], [email protected], [email protected] 2Staatliches Museum fur€ Naturkunde, Rosenstein 1, 70191, Stuttgart, Germany; e-mail: [email protected] 3Zoological Institute and Museum, Department of Cytology and Evolutionary Biology, University of Greifswald, Soldmannstraße 23, 17487, Greifswald, Germany; e-mails: [email protected], [email protected] *Corresponding author. Typescript received 7 March 2013; accepted in revised form 24 June 2013 Abstract: For a long time, the genus Knebelia Van Strae- new species, K. totoroi sp. nov. This new species and a len, 1922 has comprised two species of eryonid lobster, review of K. bilobata have furnished new insights into the K. bilobata (Munster,€ 1839) and K. schuberti (Meyer, 1836), origin and function of the frontal lobes, which are expan- both recorded exclusively from Late Jurassic Lagerst€atten in sions articulated to the front of the carapace. They probably southern Germany. Recently, the latter has been suggested to functioned as rudders facilitating ‘tail-flip swimming’ as represent a juvenile individual of Cycleryon propinquus observed in the paddle-like antennae of extant scyllarids (Schlotheim, 1822). A re-examination of the type and new (Eucrustacea, Decapoda, Scyllaridae). The rudder-like lobes material has led to our rejection of that interpretation and identified in Knebelia may therefore represent a case of con- confirmation of assignment of this species to Knebelia. Two vergent evolution. specimens, both possessing short frontal lobes, from plat- tenkalks at Nusplingen (late Kimmeridgian) and at Solnho- Key words: polychelidan lobsters, lithographic limestones, fen (early Tithonian), respectively, are here assigned to a Lagerst€atten, Kimmeridgian, Tithonian, palaeoecology. T HE Upper Jurassic plattenkalks in southern Germany (Galil 2000). Among eryonids, Knebelia bilobata probably comprise a wide array of Konservat-Lagerst€atten deposited ranks among the more enigmatic species. It is rather rare in small restricted lagoons near the Kimmeridgian–Titho- and typically possesses a pair of frontal lobes whose unique nian boundary (Fig. 1). These Lagerst€atten are often structure was interpreted by Knebel (1907), who consid- lumped as ‘Solnhofen Lithographic Limestones’ (Garassino ered them to be an anterior portion of the carapace, while and Schweigert 2006). They are renowned for their excep- Van Straelen (1925) thought that they were a pair of flat- tionally preserved fossils including many delicate organ- tened antennae similar to those of scyllarids. isms such as articulated vertebrates, echinoderms, insects, The aim of the present study was to review the genus jellyfish and eucrustaceans. For a review, reference is made Knebelia and describe a new species based upon new to Frickhinger (1994, 1999; references therein). Among the specimens recorded from the Solnhofen and Eichst€att decapod crustaceans are diverse polychelidan lobsters that (early Tithonian, Bavaria) and Nusplingen (late Kimme- have been assigned by Garassino and Schweigert (2006) ridgian, Baden-Wurttemberg)€ Lagerst€atten. Our observa- and Audo et al. (2013a) to the families Eryonidae Haan, tions on Knebelia present new insights into the origin and 1841 (seven species), Coleiidae Van Straelen, 1925 (one function of the peculiar frontal lobes, and new palaeoeco- species) and the genus Palaeopentacheles Knebel, 1907 logical implications are put forward. (one species). All these taxa have well-developed eyes and are associated with both shallow-water and terrestrial Institutional abbreviations. BSPG, Bayerische Staatssammlung fur€ organisms. Extant representatives of the Polychelida, how- Pal€aontologie und Geologie (Munich, Germany); FSL, Universite ever, are blind and restricted to deep-water environments Claude Bernard Lyon 1 (Villeurbanne, France); JME, Jura-Museum © The Palaeontological Association doi: 10.1111/pala.12071 1 2 PALAEONTOLOGY (Eichst€att, Germany); MHNL, Musee des Confluences limestones; for an overview, reference is made to, for (Lyon, France); MNHN.F, Collection de Paleontologie du example, Barthel et al. (1990), Viohl (1994, 1998) and Museum national d’Histoire naturelle (Paris, France); NHM, Keupp et al. (2007). In general, the Solnhofen Litho- The Natural History Museum (London, UK); SMCU, Sedgwick graphic Limestones are almost devoid of bioturbation, Museum of Earth Sciences, Cambridge University (Cambridge, and because of their excellent preservation, it is assumed UK); SMF, Senckenberg Naturmuseum (Frankfurt am Main, that a fully marine environment existed, albeit with stag- Germany); SMNS, Staatliches Museum fur€ Naturkunde (Stuttgart, Germany). nant conditions due to a depletion of oxygen at least at the sea floor. Bedding planes often show typical structures related to microbial mats, and biostratinomy occasionally GEOLOGICAL SETTINGS points to rapid sedimentation (Keupp et al. 2007). It seems that most of these limestones were laid down in Solnhofen lithographic limestones moderately deep (<200 m) lagoonal settings situated along the northern Tethyan shelf. A serious problem, These strata constitute a world-famous Fossillagerst€atte of however, is that such environmental models need to Late Jurassic age in Bavaria, comprising laminated or explain observations from different localities. Historically, thin-bedded, very pure limestones with intercalated thin localities have often been simplified as ‘Solnhofen’, but marly layers, which occur especially in the vicinity of the fossils labelled ‘Solnhofen’ may in fact have come from village of Solnhofen and the town of Eichst€att. In the the Eichst€att area or elsewhere and may even be of vary- past, they have been quarried mainly for lithographic ing ages (Schweigert 2007b). The classic early Tithonian stone and roof tiles, but nowadays they are used as wall Solnhofen Limestone, the ‘Oberer Schiefer Member’ of and paving tiles or for cement production. During their Solnhofen and Langenaltheim, is quarried west of Solnho- exploitation, thousands of excellently preserved fossils, fen. This unit has a thickness of 20–50 m (Meyer and including the ancient bird Archaeopteryx lithographica Schmidt-Kaler 1994). Hitherto, only a few attempts have Meyer, 1861, have been recovered and have found their been made to differentiate the various localities; for the way to numerous palaeontological collections across the Solnhofen area (sensu stricto), only Walther (1904) pro- world. They are also illustrated in many popular science vided a faunal list. Contrary to what might be expected books (Frickhinger 1994, 1999). Numerous environmental on the basis of museum collections, fossils are extremely models have been suggested for the formation of these rare in the field, except for mass occurrences of the tiny FIG. 1. Geological map of southern Germany, with grey areas corresponding to the Upper Jurassic of the Swabian and Franconian albs. Abbreviations: E, Eichst€att Lagerst€atte; G, Germany; N, Nusplingen Lagerst€atte; S, Solnhofen Lagerst€atte. AUDO ET AL.: DIVERSITY AND ECOLOGY OF KNEBELIA 3 planktonic crinoid Saccocoma tenella (Goldfuss, 1831), oxygenation. The turbidites yield angular lithoclasts and which is the most typical fossil of the Solnhofen Litho- other components such as calcareous ooids, sponge spic- graphic Limestones. Occasionally, small bony fish occur ules and sponges, and even some fragments of hermatypic in mass mortality assemblages. Numerous decapod crusta- corals from shallower areas surrounding the lagoon. For ceans have been recorded (e.g. Garassino and Schweigert detailed sections, reference is made to Dietl et al. (1998) 2006; Charbonnier and Garassino 2012; references and Bantel et al. (1999). General overviews of this fossil therein). The lithographic limestones in the Solnhofen– site are those of Dietl and Schweigert (2001a, b, 2004, Langenaltheim area have yielded prawns such as Antrim- 2011) and Schweigert et al. (2012); a list of older publica- pos speciosus Munster,€ 1839, Aeger spinipes (Desmarest, tions can be found in Schweigert (1997). 1817) and Acanthochirana cordata (Munster,€ 1839), as The Nusplingen Lithographic Limestone is well exposed well as lobsters including Mecochirus longimanatus (Schlot- at two small quarries (Nusplingen and Egesheim). New heim, 1820), Glyphea pseudoscyllarus (Schlotheim, 1822), excavations by the Staatliches Museum fur€ Naturkunde, Palaeastacus fuciformis (Schlotheim, 1822), Eryma modes- Stuttgart (SMNS) at these localities have provided a tiforme (Schlotheim, 1822), Pustulina minuta (Schlotheim, wealth of new data on sedimentology, palaeoecology, 1822) and numerous eryonoids. The last-named are rep- taphonomy and biostratinomy, as well as the overall fossil resented by Cycleryon propinquus, Cycleryon orbiculatus content of this unit. Since 1993 more than 8000 fossils (Munster,€ 1839), Eryon cuvieri Desmarest, 1817 (of which have been recovered, comprising in excess of 400 taxa, E. arctiformis is a synonym; see Charbonnier et al. 2012), many of them new. Decapod crustaceans, in particular