Hypsodont Myomiminae (Gliridae, Rodentia) from five new localities in the Lower Miocene Tudela Formation (Bardenas Reales, Ebro Basin, Spain) and their bearing on the age of the Agenian-Ramblian boundary Francisco J. RUIZ-SÁNCHEZ Departament de Geologia, Àrea de Paleontologia, Universitat de València, Doctor Moliner 50, E-46100 Burjassot (Spain) [email protected] Xabier MURELAGA Departamento de Estratigrafía y Paleontología, Universidad del País Vasco, Aptdo. 644, E-48080 Bilbao (Spain) [email protected] Juan C. LARRASOAÑA Instituto Geológico y Minero de España, Oficina de Proyectos de Zaragoza, C/ Manuel Lasala 44, 9B, E-50006 Zaragoza (Spain) [email protected] Matthijs FREUDENTHAL Departamento de Estratigrafía y Paleontología, Universidad de Granada, E-18071 Granada (Spain) and Netherlands Centre for Biodiversity Naturalis, 2333 CR Leiden (The Netherlands) [email protected] Miguel GARCÉS Grup de Geodinàmica y Anàlisi de Conques, Universitat de Barcelona, Zona Universitaria de Pedralbes, E-08028 Barcelona (Spain) [email protected] Ruiz-Sánchez F. J., Murelaga X., Larrasoaña J. C., Freudenthal M. & Garcés M. 2012. — Hypsodont Myomiminae (Gliridae, Rodentia) from five new localities in the Lower Mio- cene Tudela Formation (Bardenas Reales, Ebro Basin, Spain) and their bearing on the age of the Agenian-Ramblian boundary. Geodiversitas 34 (3): 645-663. http://dx.doi.org/10.5252/ g2012n3a10 ABSTRACT The hypsodont Myomiminae Daams, 1981 (Gliridae) from the lower part of the Tudela Formation (Ebro Basin) are described. Five localities (CH1, CA2, CA3, CA4 and CC1) of this formation contain remains of the hypsodont genus Armantomys GEODIVERSITAS • 2012 • 34 (3) © Publications Scientifiques du Muséum national d’Histoire naturelle, Paris. www.geodiversitas.com 645 Ruiz-Sánchez F. J. et al. de Bruijn, 1966 and CC1 has also yielded Praearmantomys de Bruijn, 1966. De- spite the poor material, we can identify the taxa A. cf. bijmai, A. daamsi (de Visser KEY WORDS Rodentia, in Álvarez-Sierra, Daams, Lacomba, López Martínez, Van Der Meulen, Sesé & Gliridae, De Visser, 1991), A. cf. parsani, A. cf. jasperi and cf. P. crusafonti, which are character- Agenian, istic of the Agenian and Ramblian continental stages. These data allow identification Ramblian, Lower Miocene, of the Agenian-Ramblian boundary in the Tudela Formation, and provide a calibra- Spain. tion of this boundary on the basis of available magnetostratigraphic information. RÉSUMÉ Myomiminae hypsodontes (Gliridae, Rodentia) de cinq gisements nouveaux du Mio- cène inférieur de la Formation Tudela (Bardenas Reales, bassin de L’Èbre, Espagne) et leur rapport avec l’âge de la limite Agénien-Ramblien. Ce travail décrit la faune de gliridés hypsodontes de la sous-famille Myomiminae Daams, 1981 de la partie inférieure de la Formation Tudela (Bassin de l’Èbre). Cinq nouvelles localités de cette formation (CH1, CA2, CA3, CA4 et CC1) contiennent des restes du genre Armantomys de Bruijn, 1966, la dernière (CC1) contenant également des restes de Prae armantomys de Bruijn, 1966. Malgré la pauvreté du matériel, les taxons suivants ont pu être identifiés : A. cf. bijmai, A. daamsi (de Vis- MOTS CLÉS Rodentia, ser in Álvarez-Sierra, Daams, Lacomba, López Martínez, Van Der Meulen, Sesé & Gliridae, De Visser, 1991), A. cf. parsani, A. cf. jasperi et cf. P. crusafonti, caractéristiques de Agénien, l’Agénien et du Ramblien. Ces données, qui permettent l’identification de la limite Ramblien, Miocène inférieur, Agénien-Ramblien dans la Formation Tudela, fournissent un étalonnage prélimi- Espagne. naire de cette limite basée sur l’information magnétostratigraphique disponible. INTRODUCTION Larrasoaña et al. (2006) provided magnetostratig- raphy-based ages for the fossil bearing sediments of Over the last years we have been carrying out a the Tudela Formation, ranging from chron C6r to detailed paleontological survey of the Lower and C5Cr (19.65 to 17.5 Ma after recalibration to the Middle Miocene continental successions of the ATNTS of Lourens et al. 2004). This chronology Tudela Formation in the Bardenas Reales de Nav- is coherent with the estimated age of the Tardienta arra region (western sector of the Ebro Basin) (see mammal site, found to represent the boundary of lo- Murelaga 2000). This ongoing survey has resulted cal zones Y2 and Z, within chron C6r (Pérez-Rivarés in the recovery of fossil remains that include a et al. 2002). The first 39Ar/40Ar dates of an ash-layer rich variety of vertebrates, such as small and large found at Tardienta gave an age of 19.3 ± 0.7 Ma mammals (Murelaga et al. 2004a, b), amphibians (Odin et al. 1997), which was later recalculated to and reptiles (Murelaga et al. 2002), and birds 19.7 ± 0.3 (Dam et al. 2006), in better agreement (Murelaga 2000). Among the small mammals, with the magnetostratigraphic data. rich glirid faunas found at several localities in the Some of our localities, like CH1 and CC1, are Units 2 and 3 of the formation (Larrasoaña et al. correlated with local zones Y1 and Y2 (Upper 2006) have permitted the identification of zones Z Agenian), but unfortunately these localities are and A of the Ramblian (Murelaga 2000; Murelaga not directly related with paleomagnetic sections. et al. 2004a). The combination of small and large If it were possible to find a mammal locality in mammal faunas allows attribution of these locali- the lowest part of the Tudela Formation or in the ties to MN3. Lerín Fm. this would allow to define a boundary 646 GEODIVERSITAS • 2012 • 34 (3) Hypsodont Gliridae and the age of the Agenian-Ramblian boundary 1°35’W 1°30’ CJ1 Pamplona FRANCE CC Pyrenees CC1 s Iberian range Zaragoza Pinsor Valtierra EBRO BASIN Barcelona SPAIN Mediterranean 100 km Arguedas Catalan CoastalSea Range CA2 42°10’N CH1 CA3 CA4 Ebro River N1 CM RB1 Valareña CA N2 N3 CM1 Zaragoza Navarra BT3 CV1 42°05’ Tudela Fustiñana BF1 Ribaforada PF1 42° 5 km Quaternary river Unit 5 road Unit 4 peak Unit 3 (Fustiñana Gypsum) new mammal locality Unit 2 Miocene previous mammal locality (Murelaga, Undifferentiated Tudela Formation Unit 1 2000; Murelaga et al. 2004a, b) Lerín Formation studied sections FIG. 1. — Geological map of the Lower-Middle Miocene continental sediments from the Tudela Formation at the Bardenas Reales de Navarra area, with location of the sections and fossil localities presented in this study. Abbreviations: CA, Cuesta Agujeros section; CC, Cabezo Carboneras section; CM, Cabezo Marijuán section. The location of other fossil localities studied previously by Murelaga (2000) and Murelaga et al. (2004a, b) is also shown. GEODIVERSITAS • 2012 • 34 (3) 647 Ruiz-Sánchez F. J. et al. TABLE 1. — Fossil localities set of the Units 2 and 3 from the Tudela Ranges fold-and-thrust belts (Fig. 1). From the late Formation containing micromammalian remains (Murelaga et al. 2004a; Larrasoaña et al. 2006). *, localities described in this paper. Eocene to the late Miocene, the Ebro Basin consti- tuted an endorrheic depression where alluvial and fluvial systems originating from the Pyrenean, the Code Section UTM (30T) Iberian and the Catalan Coastal margins converged BF1 Barranco Fraile X = 631237; Y = 4651913 into a central lacustrine system through a palustrine BT3 Barranco Tudela X = 621841; Y = 4660732 CA2* Cuesta Agujeros X = 625012; Y = 4667147 transitional zone (Alonso-Zarza et al. 2002; Costa CA3* Cuesta Agujeros X = 624598; Y = 4666392 et al. in press). The Tudela Formation is composed CA4* Cuesta Agujeros X = 624726; Y = 4666596 of 605 m of distal alluvial, fluvial, palustrine and CC1* Cabezo Carboneras X = 614540; Y = 4676819 CH1* Cabezo Hermoso X = 623670; Y = 4667338 lacustrine sediments accumulated in the western CJ1 Cabezo de la Junta X = 615491; Y = 4677985 part of the central Ebro Basin during the Lower- CM1 Cabezo Marijuán X = 619370; Y = 4664885 Middle Miocene (Larrasoaña et al. 2006). These CV1 Cabezo Vaquero X = 628833; Y = 4661506 N1 La Nasa X = 631111; Y = 4667198 sediments crop out extensively at the Bardenas Reales N2 La Nasa X = 630423; Y = 4664558 de Navarra, a semi-arid steppe region located in the N3 La Nasa X = 630315; Y = 4664320 vicinity of Tudela (Fig. 1). The Tudela Formation PF1 Pico Fraile X = 634468; Y = 4651105 is made up of red, brown, pink, ochre, yellow and RB1 Rincón del Bu X = 628059; Y = 4667019 grey mudstones with intercalations of frequent sandstones and limestones and some occasional gypsum bed. Sandstones appear either as thin (cm), stratotype for the Agenian/Ramblian, a question sheet-like levels distributed throughout the section that is particularly important because the Agenian or as thick (dm to m) channel-like beds that are has never been defined properly. In this paper we commonly associated to red and brown mudstones. use the term Agenian for the time and the corre- Limestone beds can be up to 2 m thick, and often sponding sediments between the Oligocene-Miocene appear in clusters associated to pink, ochre, yellow boundary and the base of the Ramblian. and grey mudstones. Limestones are often massive In the past years we have located five new locali- and bioturbated, and contain abundant gastropods, ties in the lower part of the Tudela Formation. In ostracods, charophytes, fish teeth and other fossil this paper we provide a detailed description of the fragments. Gypsum beds appear occasionally in material of Armantomys de Bruijn, 1966 and Prae- the lowermost and upper parts of the formation. armantomys de Bruijn, 1966. This new material, The sedimentary facies of the Tudela Formation are combined with a reevaluation of previously studied similar to those described elsewhere in the central remains from the Tudela Formation (Murelaga 2000; Ebro Basin (see Arenas & Pardo 1999). Distal fluvial Murelaga et al. 2004a, b) and from other areas in and alluvial muddy flood plains that drained the the Ebro Basin (Lacomba & Martínez-Salanova Pyrenean and Iberian Range margins are charac- 1988; Álvarez-Sierra et al. 1991; Daams 1990), terized by brown-red mudstones and sandstones.