Swiss J Geosci (2011) 104 (Suppl 1):S107–S114 DOI 10.1007/s00015-011-0075-z A new Jurassic cow shark (Chondrichthyes, Hexanchiformes) with comments on Jurassic hexanchiform systematics Ju¨rgen Kriwet • Stefanie Klug Received: 3 August 2011 / Accepted: 13 September 2011 / Published online: 12 November 2011 Ó Swiss Geological Society 2011 Abstract A new taxon, Crassodontidanus gen. nov. of ranging from the Sinemurian (Early Jurassic) to the Hauterivian Hexanchiformes (cow sharks) from the Jurassic of Germany (Early Cretaceous). is described. It is characterized by peculiar teeth combining apomorphic (serrated mesial cutting edge of the main cusp) Keywords Notidanus serratus Á Hexanchus? and plesiomorphic features (deep root with convex mesial wiedenrothi Á Crassodontidanus gen. nov. Á Crassonotidae and distal margins in labial and lingual views; protruding fam. nov. Á Jurassic Á Nusplingen Plattenkalke lingual root bulge). This character combination readily dis- tinguishes members of the new taxon from all other known Institutional abbreviations extant (Heptranchias, Hexanchus, Notorynchus) and extinct SMNS State Museum of Natural History Stuttgart, ( Gladioserratus, Notidanodon, Notidanoides, Pachyh- Germany exanchus, Paraheptranchias, Weltonia) hexanchiforms. GPIT Palaeontology Department and Museum, Currently, two species, C. serratus (type species; Late Institute of Geosciences, Eberhard-Karls Jurassic, Late Kimmeridgian of Nusplingen, South Germany) University Tu¨bingen, Germany and C. wiedenrothi (Early Jurassic, Early Pliensbachian of NHMUK PV Natural History Museum, London, Gretenberg (Hanover), North Germany) are assigned to this United Kingdom taxon. Crassodontidanus gen. nov. is member of Crasso- notidae fam. nov. and sister to Notidanoides MAISEY, 1986 and Pachyhexanchus CAPPETTA, 1990. We consider Not- Introduction idanus amalthei OPPEL, 1854 from the Pliensbachian of South Germany, Notidanus insignis SEGUENZA, 1887 from the Cow sharks (the Hexanchiformes) form a monophyletic Oxfordian of Sicily (Italy) and Notidanus wagneri AGASSIZ, group of plesiomorphic squalomorph neoselachians. The 1843 from the Early Tithonian of Solnhofen (South Germany) three living oceanic genera, which represent mid-water nomina dubia and nomina nuda, respectively. The family predators, are conspicuously characterized by additional Crassonotidae comprises plesiomorphic hexanchiforms gill arches (one in Hexanchus;twoinHeptranchias and Notorynchus), a single dorsal fin, imperfectly calcified vertebral centra and very characteristic dignathic dentitions comprising labio-lingually flattened saw-like teeth in the Editorial handling: Daniel Marty. lower jaws. Their fossil record is dominated by isolated teeth extending back into the Jurassic (e.g., Thies 1983; J. Kriwet (&) Department of Palaeontology, University of Vienna, Kriwet and Klug 2004; Underwood 2006). Articulated Althanstr. 14, 1090 Vienna, Austria skeletal remains only occur in the Late Jurassic of southern e-mail: [email protected] Germany (e.g., Maisey 1986; Kriwet and Klug 2004) and Late Cretaceous of Lebanon (e.g., Cappetta 1980). S. Klug Department of Earth Sciences, University of Bristol, The earliest fossil occurrences consisting of few isolated Wills Memorial Building, Queen’s Road, Bristol BS8 1RJ, UK teeth are from the Early Jurassic of Switzerland S108 J. Kriwet, S. Klug ( Notidanus arzoe¨nsis BEAUMONT, 1960), SW Germany needs further analyses of teeth assigned to these taxa, ( Notidanus amalthei OPPEL, 1854) and NW Germany which is not the focus of this study. ( Hexanchus? widenrothi THIES, 1983). A single species, Ward and Thies (1987) assigned Hexanchus? wie- Notidanus contrarius MU¨ NSTER, 1843, was reported from denrothi from the Early Jurassic and Notidanus serratus the Middle Jurassic (Bajocian) of Bavaria (Cappetta 2006). from the Late Jurassic to a new genus, Paranotidanus. Underwood and Ward (2004) additionally figured a partial Both taxa are represented by isolated teeth only, which are hexanchid tooth from the Bathonian of England. characterized by serrations at the base of the mesial cutting Late Jurassic records are more numerous and different edge of the principle cusp. This name, however, represents species have been described mainly based on isolated teeth. a nomen nudum according to the rules of zoological Two species, Notidanus huegeliae MU¨ NSTER, 1843 and nomenclature (ICZN, paragraphs 10, 11, and 15), because Notidanus serratus FRAAS, 1855 were reported from the no holotype and diagnosis was represented despite the Kimmeridgian of Baden-Wu¨rttemberg (SW Germany). assumption of Underwood and Ward (2004). Conse- Cappetta (1990) tentatively assigned Notidanus huegeliae quently, Kriwet and Klug (2004) continued to use to Pachyhexanchus. However, the holotype of Notidanus ‘‘Eonotidanus’’ for N. serratus and two hexanchiforms in huegeliae deposited in the State Museum of Natural His- the Late Jurassic of South Germany and northern Swit- tory Stuttgart, Germany under collection number SMNS zerland can be distinguished: Notidanoides muensteri 86237 represents a very incomplete tooth lacking useful from the Oxfordian of Switzerland, Kimmeridgian of characteristics for its taxonomic assignment. Tithonian Baden-Wu¨rttemberg and Tithonian of Bavaria, and species represented by isolated teeth only are Notidanus ‘‘Eonotidanus’’ serratus from the Kimmeridgian of eximius WAGNER, 1862 and N. intermedius WAGNER, 1862, Nusplingen. The intention of this paper is to establish a which were recovered from the Lithographic Limestones of new genus for Jurassic hexanchiforms characterized by Bavaria. The latter species is based on a symphyseal tooth teeth with serrated mesial cutting edges and a new family, that most likely belongs to Notidanoides. The only Crassonotidae fam. nov., to discuss its systematic Jurassic species represented by an articulated skeleton is composition. Notidanoides muensteri (AGASSIZ, 1843) from the Late Kimmeridgian of Nusplingen (SW Germany). However, isolated teeth of the same species occur in the Oxfordian of Systematic palaeontology Switzerland, and in Germany in the Kimmeridgian of Baden-Wu¨rttemberg and Tithonian of Bavaria. The dental terminology used herein follows that of App- Different taxonomic and systematic concepts of extinct legate (1965) and Kemp (1978). The taxonomic scheme and extant hexanchiforms were presented in the last adopted here is based on Kriwet and Klug (2004), Cappetta decades. For instance, Pfeil (1983) introduced the genus (2006) and Cione and Medina (2009). However, we use the Eonotidanus based on Notidanus contrarius to include term ‘main cusp’ instead of ‘acrocone’. N. muensteri and all other Jurassic hexanchids. This Class Chondrichthyes HUXLEY, 1880 taxonomic concept, however, was refuted by Maisey Subclass Elasmobranchii BONAPARTE, 1838 (1986), Ward and Thies (1987), and Cappetta (1990) due Cohort Euselachii HAY, 1902 to the incompleteness of the holotype of N. contrarius. Subcohort Neoselachii COMPAGNO, 1977 Maisey (1986) consequently transferred N. muensteri to Superorder Squalomorphii COMPAGNO, 1973 Notidanoides based on skeletal aspects. Additional Order Hexanchiformes BUEN, 1926 skeletal fossil selachians from the Tithonian of Bavaria Family Crassonotidae nov. subsequently were assigned to this species based on the presence of a single dorsal fin as it occurs in extant forms (e.g., Kriwet and Klug 2004). A comprehensive revision Etymology of Jurassic sharks and rays, however, provided sound evidence that the hitherto known Bavarian specimens Derived from the genus name Crassodontidanus gen. characterized by a single dorsal fin mostly (if not all) nov., which displays the characteristic tooth root mor- belong to synechodontiforms (Klug, pers. obser.). Con- phology of members of this family and the subfamily name sequently, the number and arrangement of paired and Notidanini BONAPARTE, 1838. unpaired fins and the number of gill arches in Jurassic hexanchiforms remain ambiguous. The Late Jurassic Remarks taxa N. arzoe¨nsis, N. eximius, N. huegeliae and N. daviesi were considered to be junior synonyms of Bonaparte (1838, p. 208) introduced the subfamily Not- N. muensteri by Kriwet and Klug (2004). This, however, idanini (family Squalidae) for the extant hexanchiforms New Late Jurassic cow shark S109 Heptranchias (type) and Notidanus (=Hexanchus). The well-developed; root thick and high with convex outline in name Notidanini subsequently often was used incorrectly labial and lingual views; lingual root bulge prominent; as family name Notidanidae (=Notodanidae; Owen (1846)) basal root face oblique in profile views forming an acute for extinct and/or extant hexanchiforms in the past. Gray angle; basal root face broad and slightly convex. (1851) allocated both living hexanchiforms to the family Hexanchidae, which is the correct systematic assignment. Differential diagnosis Consequently, no appropriate family name is available to comprise only extinct hexanchiforms, which do not belong The character combination of a main cusp with serrated to any extant taxon. mesial cutting edge and deep and rounded root with obli- que basal face readily distinguishes Crassodontidanus Included taxa gen. nov. from all other hexanchiform sharks although great similarities to other taxa exist (e.g., serrated mesial Crassodontidanus gen. nov. (syn. Notidanus CUVIER, cutting edge of main cusp in Gladioserratus, Hexanchus 1816 in partem), Notidanoides MAISEY, 1986 (syn. and Notorynchus spp.; root morphology similar in Not- Aellopus