Juan Rofes

Environmental change across the Early-Middle Pleistocene transition: small mammalian evidence from the Trinchera Dolina cave, Atapuerca, Spain

Abstract The sites of Atapuerca are well known for their hominin-bearing localities of Early to Middle Pleistocene age. Trinchera Dolina yields western Europe’s oldest fossil hominin, the 850 ka Homo antecessor; and at Sima de los Huesos there occurs the best collection of the Middle Pleistocene hominin Homo heidelbergensis. However, small mammals (Rodentia, Insectivora, Chiroptera and Lagomorpha) represent the largest number of species and greatest fossil abundance in the deposits of the Atapuerca cave complex. The small mammals are grouped by habitat categories, but because the ecology of mammals is complex, we base our study on the evolution of these categories throughout the sequence. The assemblage distribution at the Trinchera Dolina site reflects landscape and environmental changes during the past million years. Shifts between woodland, open land and moorland are indicated by the relative abundance of species based on diagnostic elements such as first lower molars. These data are combined with the distribution of large mammals, pollen, sediments and geological context of the Trinchera Dolina site. From this interdisciplinary approach, we conclude that the first hominins from western Europe (Homo antecessor) lived during a warm, wet and wooded interval, probably corresponding to Marine Isotope Stages 21 to 19. The transition from Early to Middle Pleistocene at Atapuerca is characterized by palaeoenvironmental changes recorded between levels TD5–6 and TD8–10, respectively. The general opening of the landscape at the beginning of the Middle Pleistocene could have favoured the dispersal of hominins (Homo heidelbergensis) across western Europe.

FIRST EVIDENCE OF THE SORICIDAE (MAMMALIA) ASORICULUS GIBBERODON (PETÉNYI, 1864) IN THE PLEISTOCENE OF NORTH IBERIA

The paper describes thirteen specimens of the extinct red-toothed shrew Asoriculus gibberodon (Petenyi, 1864) from the lower levels (8 to 14) of the Sima del Elefante cave (TE Lower Red Unit). These are the first bona fide examples of this taxon in the north of the Iberian peninsula. The Lower Red Unit of the Sima del Elefante dates from the early Pleistocene and contains evidence of the very first human activity in the European continent, in the form of lithic tools and large mammal bones with cutmarks. After a detailed discussion of systematic considerations, we focus on the palaeoecological and palaeobiogeographical implications of the presence of this species in the Sima del Elefantei¦s Lower Red Unit. In palaeoecological terms, as a member of the Neomyini, A. gibberodon would have had a mainly aquatic life and is taken as an indicator of humid environments with a permanent green covering. As for its palaeobiogeographical implications, on the basis of its geographical distribution and morphometric particularities we have reconstructed the biogeography of the genus Asoriculus from its very first record at the end of the Miocene to its extinction shortly before the beginning of the middle Pleistocene.

First evidence of poisonous shrews with an envenomation apparatus

Herein, we report evidence of an envenomation apparatus (EA) in two different species of extinct “giant” shrews, Beremendia and an indeterminate soricine (Mammalia, Eulipotyphla, Soricidae), documented by very well preserved fossil specimens recovered from two Early Pleistocene cave deposits of the Sierra de Atapuerca in Burgos, Spain. The two soricine taxa from Atapuerca have evolved specialized teeth as EAs, which differ from those of recently reported mammals of the Paleocene age, being more similar to the ones described in the modern Solenodon. This discovery reveals the first instance of shrews possessing what appears to be an EA, an evolutionary adaptation that, in these species, was probably related to an increase in body mass and hunting of a larger-sized prey. The Atapuerca specimens would have a highly specialized EA, one of the very few reported for an extinct or living mammal of any time. In addition to the presence of a gutter-like groove along the medial side of the crown of the lower incisors, these two species also present stout jaws and a modified mandibular symphysis with a conspicuous cavity, which in life would likely contain large amounts of connective tissue. The strong mandible architecture of these large shrews would be, in this way, reinforced by a more immovable symphysis, increasing the bite force exerted over a potential prey. This adaptation, together with the grooved incisors, would ensure a rapid and efficient transmission of the poisonous saliva to paralyze relatively large-sized prey.

A new species of water vole from the Early Pleistocene of Southern Europe

In the Early Pleistocene Red Lower Unit of the Sima del Elefante site (Sierra de Atapuerca karst complex, Burgos, Spain), levels TE9–TE13, dental and mandibular remains of an arvicoline are referred to as the new species Arvicola jacobaeus sp. nov. The new species has medium-sized hypselodont molars, with abundant cementum in the re-entrant folds, and thick enamel band with differentiation of the Mimomys-type. The occlusal morphology of M3 is simple. The dental morphology of the new species resembles that of Arvicola sapidus, though smaller. It is more derived, in size and morphology than the Middle Pleistocene species Arvicola mosbachensis. The morphologic affinities among Arvicola jacobaeus, Arvicola terrestris, and A. sapidus suggest a common ancestry. A preliminary phylogenetic analysis corroborates that Mimomys savini is the sister group of the Arvicola clade.

Nesiotites rafelinensis sp. nov., the earliest shrew (Mammalia, Soricidae) from the Balearic Islands, Spain

This paper describes a new species of shrew from a fossiliferous bone breccia near to Calo den Rafelino (Mallorca, Spain). The site is stratigraphically and palaeontologically dated to the earliest Early Pliocene (MN13-14). Nesiotites rafelinensis sp. nov. (Mammalia, Soricidae) is arguably the earliest representative of the Nesiotites known to date, a clade restricted to the Balearic Islands. The new species combines primitive dental traits with a relatively large size. The primitive features relate N. rafelinensis more with Asoriculus gibberodon, the possible ancestor of Nesiotites, than any other representative of the genus. The large size interrupts a, otherwise, regular trend of increase of size from the comparatively small A. gibberodon to the recent very large N. hidalgo. The faunal assemblage of Calo den Rafelino represents the earliest evidence of the fauna that arrived to the Mallorca Island during the Messinian Salinity Crisis.

Combining Small-Vertebrate, Marine and Stable-Isotope Data to Reconstruct Past Environments

Three very different records are combined here to reconstruct the evolution of environments in the Cantabrian Region during the Upper Pleistocene, covering ~35.000 years. Two of these records come from Antoliñako Koba (Bizkaia, Spain), an exceptional prehistoric deposit comprising 9 chrono-cultural units (Aurignacian to Epipaleolithic). The palaeoecological signal of small-vertebrate communities and red deer stable-isotope data (δ13C and δ15N) from this mainland site are contrasted to marine microfaunal evidence (planktonic and benthic foraminifers, ostracods and δ18O data) gathered at the southern Bay of Biscay. Many radiocarbon dates for the Antoliña’s sequence, made it possible to compare the different proxies among them and with other well-known North-Atlantic records. Cooling and warming events regionally recorded, mostly coincide with the climatic evolution of the Upper Pleistocene in the north hemisphere.

Late Miocene/Early Pliocene vertebrate fauna from Mallorca (Balearic Islands, Western Mediterranean): An update

The vertebrate fossil record from the Balearic Islands (western Mediterranean) has improved considerably over the past decade, especially in Mallorca and Menorca. In Menorca, the Pliocene terrestrial fauna was updated by the discovery and description of the large-sized leporid Nuralagus, several reptiles and an amphibian. In Mallorca, paleontological exploration yielded 2 deposits with a Late Miocene/Early Pliocene chronology, Caló den Rafelino (CdR) and Na Burguesa-1 (NB-1). So far, 4 new mammalian taxa and 2 new reptiles have been identified for the CdR deposit, whereas the faunal assemblage from the recently discovered deposit (Apr 2012) of NB-1 is currently composed of, at least, 6 terrestrial mammals, 8 reptiles and an amphibian. Its faunal composition and some primitive characteristics of the obtained taxa suggest that the chronology of this deposit is slightly earlier than the CdR. The terrestrial vertebrates recorded in these 2 Mallorcan deposits are changing the view of the paleofaunal assemblage previously known for the Plio-Pleistocene of the island. Morphological characteristics displayed by some of the taxa suggest that these faunas would be at the beginning of an isolated evolution. In this paper we present a preliminary report on the fossils recovered from the NB-1 deposit, as well as some unpublished data from CdR, and we analyze the whole fauna from both Mallorcan deposits, focusing on taxonomical and paleobiogeographical aspects.

Exceptional biting capacities of the Early Pleistocene fossil shrew Beremendia fissidens (Soricidae, Eulipotyphla, Mammalia): new taphonomic evidence

The discovery of small, very well-defined and perfectly preserved toothmarks on a humerus of a mole Talpa cf. europaea from level TE9 of Sima del Elefante (Sierra de Atapuerca, Burgos) with a chronology of the Early Pleistocene is extraordinary. In a previous paper, this bite was compared with current small carnivores such as Mustela nivalis molars and with fossil remains of Mustela palerminea and the soricid (Eulipotyphla and Mammalia) Beremendia fissidens with the purpose of identifying the predator. It was hypothesised that Beremendia fissidens could be the bite maker. However, it was not possible to rule out other predators due to the shortage of Beremendia fissidens remains. Recently, new fossil remains of this insectivore have been found in Sima del Elefante levels, allowing the upper dentition to be measured. These new data suggest that effectively Beremendia fissidens may have had the capacity to bite prey larger than itself, even though it did not possess morphological characteristics specialised for the consumption of small mammals. The addition of small vertebrates (like talpids) to complement a diet based on insects could have been a way of responding to the needs of the high metabolic rate characteristic of Beremendia fissidens.

Radiocarbon dating minute amounts of bone (3–60 mg) with ECHoMICADAS

Because hard tissues can be radiocarbon dated, they are key to establishing the archaeological chronologies, palaeoenvironmental reconstructions and historical-biogeographical processes of the last 50,000 years. The advent of accelerator mass spectrometers (AMS) has revolutionized the field of archaeology but routine AMS dating still requires 60–200 mg of bone, which far exceeds that of small vertebrates or remains which hold a patrimonial value (e.g. hominid remains or worked bone artefacts). Here, we present the first radiocarbon dates obtained from minute amounts of bone (3–60 mg) using a MIni CArbon DAting System (MICADAS). An optimized protocol allowed us to extract enough material to produce between 0.2 and 1.0 mg of carbon for graphite targets. Our approach was tested on known-age samples dating back to 40,000 BP, and served as proof of concept. The method was then applied to two archaeological sites where reliable dates were obtained from the single bones of small mammals. These results open the way for the routine dating of small or key bone samples.

Proportions, characters and chronologies: Their contribution to systematic paleontology. A rebuttal to Furió and Pons-Monjo

The comment by Furio and Pons-Monjo is an attempt to invalidate the new species Nesiotites rafelinensis recently described by Rofes et al. and to place it in synonymy with N. ponsi or a closely related form (N. aff. ponsi and/or N. cf. ponsi). Through detailed argumentation, the use of proportions instead of lengths, the re-analysis of the characters questioned by Furio and Pons-Monjo, and the consideration of the chronology and the evolution of ecological communities, we rebut Furio and Pons Monjo’s conclusions and confirm the status of N. rafelinensis as a valid and distinct species represented by the specimen of Calo den Rafelino (Mallorca, Spain).