53 he A Rei Series A/ Zitteliana An International Journal of Palaeontology and Geobiology Series A /Reihe A Mitteilungen der Bayerischen Staatssammlung für Paläontologie und Geologie 53 An International Journal of Palaeontology and Geobiology München 2013 Zitteliana Zitteliana A 53 (2013) 37 A Middle Cenomanian coral fauna from the Northern Calcareous Alps (Bavaria, Southern Germany) – new insights into the evolution of Mid-Cretaceous corals Hannes Löser1, Winfried Werner2* & Robert Darga3 Zitteliana A 53, 37 – 76 1Estación Regional del Noroeste, Instituto de Geología,Universidad Nacional Autónoma de México München, 31.12.2013 Blvd. Luis Donaldo Colosio S/N y Madrid 83250 Hermosillo, Sonora, Mexico 2SNSB – Bayerische Staatssammlung für Paläontologie und Geologie and GeobioCenterLMU, Manuscript received Richard-Wagner-Straße 10, D-80333 München, Germany 01.08.2013; revision 3Naturkunde- und Mammut-Museum Siegsdorf, Auenstraße 2, D-83313 Siegsdorf, Germany accepted 15.10.2013 *Author for correspondence and reprint requests: E-mail: [email protected] ISSN 1612 - 412X Abstract In the Northern Calcareous Alps, relics of a formerly widely distributed shallow marine facies belonging to the Branderfleck Formation (Upper Albian to Early Turonian) crop out and contain locally abundant corals. The fauna described here derives from Middle Cenomanian sediments. It encompasses 39 species in 25 genera, belonging to seven scleractinian and one octocorallian order. One genus and two species are described as new. The fauna that was formerly located at the northern part of the Apulian plate (Austroalpine unit), south of the Penninic ocean, shows palaeobiogeographic relationships to Cenomanian faunas from the Pelagonium, the Aquitanian Basin, and the Bohemian Basin, indicating stronger connections to Tethyan than Boreal faunas. The fauna also shares species with Aptian and Albian, as well as Late Cretaceous faunas. Ten genera experienced a range extension; five genera have their last occurrence in the Middle Ceno- manian fauna, and five genera their first occurrence. The fauna has an intermediate position between the Early Cretaceous and the post- Cenomanian corals showing that the faunal turnover at the Cenomanian/Turonian boundary was not marked by the sudden appearance of new faunal elements, but the disappearance of taxa. Many faunal elements that constitute post-Cenomanian faunas already existed in the Cenomanian but were very rare. Key words: Cretaceous, Hexacorallia, Octocorallia, Branderfleck Formation, Taxonomy, New taxa Zusammenfassung In den Nördlichen Kalkalpen sind Relikte der ursprünglich weiter verbreiteten flachmarinen Branderfleck Formation (Oberalb-Unter- turon) aufgeschlossen, die lokal häufig Korallen enthalten. Die hier beschriebene Fauna mittelcenomaner Sedimente erbrachte 39 Arten in 25 Gattungen, die zu sieben Unterordnungen der Scleractinia und einer Ordnung der Octocorallia gehören. Es werden eine neue Gattung und zwei neue Arten beschrieben. Die Fauna siedelte ursprünglich am nördlichen Rand der Apulischen Platte (Austroalpine Einheit), südlich des Penninischen Ozeans und zeigt paläobiogeographische Beziehungen zu cenomanen Korallenfaunen des Pelagoni- um, des Aquitanischen Beckens, und des Böhmischen Beckens mit ausgeprägteren Beziehungen zu tethyalen als borealen Faunen. Die beschriebene Vergesellschaftung hat auch Arten mit Faunen des Apts und Albs sowie der Oberkreide gemein. Zehn Gattungen erfuhren eine Erweiterung ihrer stratigraphischen Reichweite; fünf Gattungen hatten ihr letztes Auftreten im Mittelcenoman, und fünf Gattungen ihr erstes Auftreten. Die Korallenfauna nimmt eine Position zwischen Unterkreide- und post-cenomanen Faunen ein und zeigt, dass der Faunenwechsel an der Cenoman/Turon-Grenze nicht von einem plötzlichen Auftauchen neuer Faunenelemente gekennzeichnet war, son- dern eher von einem Verlust der Diversität. Viele Elemente post-cenomaner Faunen existierten bereits im Cenoman, aber waren offenbar sehr selten. Schlüsselwörter: Kreide, Scleractinia, Octocorallia, Branderfleck Formation, Taxonomie, Neue Taxa 1. Introduction 1998), conditions were more or less suitable for corals. With the Hauterivian, the Early Cretaceous The diversity and abundance of coral faunas va- presented an increasing amount of coral faunas (Lö- ried greatly throughout the Cretaceous period. De- ser 2013a; here, a fauna refers to an association of pending on the frequency of oceanic anoxic events species found in the same lithostratigraphical unit (OAE; Erba 2004; Bodin et al. 2006; Jenkyns 2010) of the same age, but not necessarily from the same and the variation of the sea level (Hardenbol et al. outcrop or sample point), but their number gradually Zitteliana A 53 (2013) 38 decreased in the central Tethys with the late Early higher latitude faunas clearly dominating (Tab. 1). Aptian, reaching a value as low as during the Berria- The Cenomanian was a rather short time period. sian during the Middle Albian (in the Western Tethys, Its coral distribution is characterised by two remar- Late Aptian to Albian faunas still persisted). During kable events: the Late Albian-Early Cenomanian sea the Late Albian, the number of faunas increased dra- level rise that led in various regions to transgressi- matically, resulting in a very high number of faunas on and the formation of highly diverse coral faunas. by the end of the Cenomanian. This large number is Species rich Late Albian to Early Cenomanian coral mainly due to increasing coral faunas at higher lati- faunas are known from the Boreal areas (Saxon and tudes. At the Cenomanian/Turonian boundary, a sea Westphalia in Germany, Löser 1989, 1994, 1998; level highstand followed by a sea level fall and OAE2 Devonshire in England, Jukes-Brown 1900), the We- caused a remarkable drop of faunas and genera. stern Tethys (Cobreces in Northern Spain, Wilmsen Recovery started with the Late Turonian throughout 1996; Rochefort in France, Beltremieux 1866; An- the Santonian. Hauterivian to Early Albian coral as- dalucia in Spain, Löser et al. in press), the Central sociations are uniform on the generic level, but Late Tethys (Kozani in Greece, Steuber & Löser 1997), the Cretaceous faunas from the Late Turonian on show Eastern Tethys (Tamil-Nadu in India; Stoliczka 1873) a different inventory: on the one hand the suborders and the Western Hemisphere (Texas, USA; Wells Amphiastraeina, Rhipidogyrina and Stylinina disap- 1932). peared completely and various families became re- The Middle Cenomanian was characterised by a duced in genera and species (Elasmocoeniidae, Mi- global sea level fall and an accompanied regression crosolenidae, Montlivaltiidae). On the other hand, the in many areas. There are only few Middle Cenomani- suborder Meandrinina achieved a very high diversity an coral faunas described. At the end of the Middle and families of other suborders emerged or show an Cenomanian, the sea level increased again leading increase in diversity (Agatheliidae, Columastraeidae, to a transgression in many areas, both Tethys and Placosmiliidae). The patterns of this faunal turnover Boreal. Important Boreal faunas ranging from the are poorly understood for several reasons. First, the late Middle Cenomanian to the Late Cenomanian are number of Albian coral faunas is very low (Löser et known from Belgium (Hainaut et al. 1975) the Czech al. in press) not allowing clear conclusions on co- Republic (Eliášová 1989, 1991, 1992, 1994, 1996, ral evolution. Second, the Cenomanian coral faunas 1997a,b, 2004), France (Sarthe, Thomel 1965) and differ in their taxonomic composition depending on Germany (Löser 1989, 1998). From more souther- their palaeolatitude: because of increasing sea water ly located areas, faunas are poorly reported, e.g. temperature (Johnson et al. 1996), Late Albian to Ce- Southern France (Aude, Var; Fromentel 1862–87). nomanian corals preferably colonized areas in Bo- The Boreal faunas are for the most part taxono- real regions. Cenomanian coral localities with more mically well studied. The taxonomy of the coral fau- than three species (and more than 50% of hermaty- nas from the Tethys is less well known, which ma- pic genera) total 58 localities (age assignments and kes comparison between Boreal and Tethyan faunas species counts according to Löser et al. 2005) with difficult, but several large coral faunas are under taxonomic revision by HL and were included in the Table 1: Percentage of the geographic distribution of Cenoma- taxonomic comparison with the present fauna. It is nian coral localities with more than three species (and more than at least known that Boreal and Tethyal faunas differ 50% of hermatypic genera). Total number of localities 58. in their general taxonomic composition (Löser 1998), but this difference is poorly quantified. Boreal (Belgium, Czech Republik, The present fauna comes from an area at the nort- 55% northern France, Germany) hern part of Apulia (Austroalpine unit) (Textfig. 1) that was separated from the Helvetic shelf by the ocean Aquitaine (central France) 14% waters of the Penninic Ocean (Dercourt et al. 2000). At that time a landmass connected parts of Apulia with Northern Calcareous Alps (Southern 2% the more eastern situated Moesia microplate (Pfiffner Germany) 2010). The study area in the north of this landmass had a central position within the Western Tethys and Northern Africa and Levante (Algeria, 7.5% its palaeogeographic position may therefore help to Egypt, Tunisia) understand the relation between Tethyan and Boreal faunas on