Gloria Cuenca-Bescós Small mammals from Sima de los & César Laplana Huesos Conesa Paleontología. F. Ciencias, Universidad A small collection of rodents from Sima de los Huesos helps to clarify the de Zaragoza, 50009 Zaragoza, Spain, stratigraphic position of this famous human locality. The presence of Allocricetus and U.A. CSIC-U. Zaragoza, Museo bursae and Pliomys lenki relictus and the size of A. bursae, Apodemus sylvaticus and Nacional de Ciencias Naturales, Eliomys quercinus suggest a Middle Pleistocene age (Saalian) to the Clays where 28002 Madrid, Spain humans have been found. ? 1997 Academic Press Limited Jose Ignacio Canudo Museo de Paleontología, Universidad de Zaragoza, 50009 Zaragoza, Spain Juan Luis Arsuaga Dpto. de Paleontología, Universidad Complutense, 28006 Madrid, Spain Received 24 April 1996 Revision received 1 November 1996 and accepted 22 March 1997 Keywords: rodents, Middle Pleistocene, Atapuerca, Sima de los Huesos, Spain, micromammal biochronology. Journal of Human Evolution (1997) 33, 175–190 Introduction In 1974, René Lavocat wrote in this journal: ‘‘It may be rather surprising to read in a journal devoted to human evolution a paper on rodents. This contribution is justified by the fact that the study of rodents can provide excellent arguments’’ . of correlation and relative age assignment of fossil hominid sites (e.g., Lavocat, 1956; Chaline, 1971; Repenning & Fejfar, 1982; Carbonell et al., 1995) and can also tell us a great deal about past environments (Bishop, 1982; Andrews, 1990a,b). The Sima de los Huesos cave locality is one of the sites containing Pleistocene humans in the Sierra de Atapuerca (Burgos, Spain) karst system (Aguirre, 1995; Arsuaga et al., 1993; Bischoff et al., 1997; Carbonell et al., 1995 and references therein). In the past 5 years, the paleontological team from the Complutense University of Madrid has sieved the clays where the human fossils are recovered (about 250 kg of matrix) by means of modern sieving techniques (Daams & Freudenthal, 1988a). This yielded 43 concentrates containing a small collection of microvertebrates that helps to clarify the stratigraphic position of Sima de los Huesos locality. Collecting is continuing, and further additions to the fauna may be expected. When the small mammals were unknown in Sima de los Huesos, the carnivores were the best tool for correlation (García et al., 1997). Cuenca-Bescos´ et al. (1994) presented a preliminary report of biostratigraphical correlation based on the small mammal fossil remains. This work studies the small mammal assemblage found in the Sima de los Huesos cave site, and attempts to make biostratigraphical correlation with other Pleistocene faunas on the basis of its small mammal fauna contents. The biostratigraphy from the Gran Dolina site is still in progress of determination. It requires an enormous amount of work, partially because of the large number of small mammal fossil remains found in every stratigraphical 0047–2484/97/080175+16 $25.00/0/hu970153 ? 1997 Academic Press Limited 176 . -´ ET AL. level (Gil & Sesé, 1991; Cuenca-Bescós et al., 1995), and partially because of the discovery, in level TD 6, of the supposed oldest human remains in the Pleistocene of Europe (Carbonell et al., 1995). This brings the problem into a wider forum of discussion than merely the small mammal paleontologists. It opens the question of which level of the Gran Dolina site the Sima de los Huesos lower unit correlates. The scarcity and poor diversity of fossil rodents and the short stratigraphical sequence of Sima de los Huesos makes difficult the most common practice applicable in mammalian correlation, the so-called first or last appearance datum. Thus, an accurate correlation, requires detailed morphological and biometrical comparative analysis of the species present in the locality. This analysis is pertinent for Allocricetus bursae from Sima de los Huesos and Gran Dolina. For the same reasons, we have compared the size of A. bursae from Sima de los Huesos with these species in other European localities. The small vertebrate fauna Gil & Sesé (1991) give a faunal list of small mammals whose stratigraphical position in the Sima de los Huesos is unknown. This list includes the following taxa: Insectivora indet., Quiroptera indet., and Allocricetus bursae, Microtus/Pitymys sp. and Apodemus sp. among Rodentia. The cricetid Allocricetus bursae has been the object of a more complete study by Cuenca-Bescós et al. (1994) and those authors provide the following faunal list: Miniopterus schreibersi, Myotis myotis/blythi, Allocricetus bursae cf. correzensis, Pliomys sp., Arvicolidae indet., Eliomys quercinus cf. quercinus and Apodemus sp. from the layers where the human remains were excavated. In this work, the authors concluded that the Sima de los Huesos’ small mammal assemblage was correlated with the upper levels of Gran Dolina site, also in the Atapuerca karst system, and they indicate a Middle Pleistocene age for this faunal assemblage. It is beyond the scope of the present work to describe the stratigraphy of the cave at Sima de los Huesos in any detail (see Bischoff et al., 1997). Nevertheless, for the sake of clarity when correlating and the stratigraphical position of the small mammal faunas, the salient features of the stratigraphic succession will be briefly outlined. The lower sediments, or lower unit, consist of clays with macrofossils designated ‘‘Clays with macrofossils’’ and it consists of ‘‘Arcilla roja’’ and ‘‘Yellow brown mud’’ as is described in Bischoff et al. (1997). Here, this was designated as lower unit of ‘‘Clays with human and bear bones’’ and it is labelled CH&B in text and figures. In Figure 4, SH indicates Allocricetus bursae specimens from this layer. The faunal list of this lower unit, with minimum number of individuals (MNI) for rodents in brackets, is: Rodentia, Allocricetus bursae Schaub, 1930 (3), Apodemus sylvaticus (Linnaeus, 1758) (6), Pliomys lenki relictus Bartolomei et al., 1975 (1), Microtinae indet. (3), Eliomys quercinus (Linnaeus, 1766) (1); Chiroptera, Rhinolophus mehelyi Matschie, 1901, Myotis myotis/M. blythi (sensu Sevilla, 1988), Miniopterus schreibersi (Kuhl, 1819); Insectivora, Crocidura sp. These sediments have also yielded other vertebrates such as fish vertebrae and teeth (Salmo sp. and Leuciscus sp.), and undetermined small reptile bones. Fragments of gastropods and arthropods, charophytes and plant remains are also present. The samples from the lower layer are labelled after the excavation abbreviations provided by the excavation team: Q, R, S, T, SR An, SRMS, SRM(a), SRM(r), SRM(ar), SRM, SRA, SRB. The plan of the Sima de los Huesos with the small mammal samples from the lower unit (CH&B) is given in Figure 1. 177 S/T 12/13 S/T 15/16 Allocricetus bursae Allocricetus bursae Apodemus sylvaticus Myotis myots/ M. blythi S13 y R13 Crocidura sp. Allocricetus bursae Q 25 SRMS Apodemus sylvaticus Myotis sp. Apodemus sylvaticus Myotis myotis/ M. blythi Rhinolophus mehelyi Miniopterus schreibersi Myotis myotis/ M. blythi Rhinolophus sp. U SR An T Apodemus sylvaticus SRM S Eliomys quercinus Miniopterus schreibersi Apodemus sylvaticus R Myotis myotis/ M. blythi Sorex sp. Miniopterus schreibersi Q CPV SRB Insectivora indet. P O SRM 9 11131517 SRA 1 m Eliomys quercinus Apodemus sylvaticus Apodemus sylvaticus Allocricetus bursae Microtinae indet. Microtinae indet. Apodemus sylvaticus Myotis myotis/ M. blythi Myotis myotis/ M. blythi Eliomys quercinus Rhinolophus sp. Rhinolophus sp. SRM (a) Pliomys lenki relictus Miniopterus schreibersi Myotis sp. SRM (r) Miniopterus schreibersi SRM (ar) Figure 1. Location map of the Middle Pleistocene in Sima de los Huesos, small mammals. Redrawn from Arsuaga et al. (1993). Above these deposits is a speleothem which appears to cover the lower unit. The upper part of the sequence in Sima de los Huesos consist of dark clays with bat guano, known as the ‘‘Brown mud and bat guano’’ in Bischoff et al. (1997), and here labelled ‘‘Dark clays with bat guano’’ (DCBG). The sediments from this layer and the lower layer share the species of Chiroptera and one rodent species: Apodemus sylvaticus. No other fossil remains appear in the Bat Guano layer. This paper describes the morphological and biometrical characters of the teeth of the rodents, mainly Cricetidae and Muridae, and comparison is made to European cricetids and murids of similar age. Tooth abbreviations and dental measurements 1 2 3 M ,M,M are used for the upper molars and M1,M2,M3for the lower molars. The teeth were measured using a calibrated micrometer eyepiece in an Olympus SZH binocular microscope. The measurements are the maximum length (L) and width (W) of the occlusal surface of the molars, and the method of taking measurements and the nomenclature of parts of the cheek teeth of the Cricetidae follows Daams & Freudenthal (1988b). Nomenclature of the teeth of the Arvicolidae is after van der Meulen (1973) and of the Gliridae after Daams (1981). The Muridae and Gliridae were measured in the same way as Cricetidae. Re-examination of the nomenclature of the elements of murid teeth has been given by Michaux (1971) and Pasquier (1974); however, the classical nomenclature is followed in the present paper (it is the most applied; e.g. van de Weerd, 1976; Martin Suárez & Mein, 1991). Measurements are given in mm (L#W). 178 . -´ ET AL. Figure 2. Occlusal view of the lower cheek teeth of Allocricetus bursae from Sima de los Huesos: left mandible with M1,M2,M3: SH Clays with human and bear bones (CH&B) T15/16. Bar 1 mm. Repository The small mammal specimens described are provisionally housed in the Museo Paleontológico de la Universidad de Zaragoza. Systematic palaeontology Family, Cricetidae Rochebrune, 1883; species, Allocricetus bursae Schaub, 1930; Figure 2. Material and measurements M1: 2·03#1·28; 2·08#1·26; M2: 1·65#1·26; 1·58#1·32; 1·58#1·25; M3: 1·50#1·20; 1·47#1·23; 1·65#1·28; M1:-#1·34; M2: 1·47#1·38.