Oriol Oms

A calibrated mammal scale for the Neogene of Western Europe. State of the art

Abstract A magnetobiostratigraphically calibrated mammal scale for the Neogene of Western Europe is presented in this paper. The Mammal Neogene (MN) units originally proposed by Mein [Report on activity RCMNS-Working groups (1975)] have been re-defined here on the basis of first appearances of selected small and large mammal taxa. The chronology of the lower boundaries of each unit had been established mostly after the significant magnetobiostratigraphic framework developed in the last decade in a number of Spanish basins: Ebro, Calatayud–Daroca, Valles–Penedes, Teruel, Fortuna, Cabriel and Guadix–Baza. In the case of the early and middle Miocene (particularly, MN 1, MN 2 and MN 3), the authors have also taken into account the magnetobiostratigraphic framework developed in the North Alpine Foreland Basin. Some alternative correlations of the magnetostratigraphic data from this last basin are proposed in order to achieve a higher degree of consistence with the data from the Iberian basins. A quite well established magnetostratigraphic calibration of the MN boundaries can be proposed for most of the Neogene, from Middle Miocene to Late Pliocene. On the other hand, the chronological boundaries of the Early Miocene MN units are still poorly constrained due to: (1) scarcity of well-studied, continuous, thick magnetostratigraphic sections; (2) the difficulty in defining the boundaries of the MN zones for this time-span due to the relative homogeneity and persistence of the fossil rodent faunas and the absence of significant large mammal dispersal events. Some of the troubles which arise with the application of the MN units strengthen the need to take into account the palaeobiogeographical meaning of these units and their real suitability to date and correlate through extensive geographic areas.

Earliest human occupations at Dmanisi (Georgian Caucasus) dated to 1.85–1.78 Ma

The early Pleistocene colonization of temperate Eurasia by Homo erectus was not only a significant biogeographic event but also a major evolutionary threshold. Dmanisis rich collection of hominin fossils, revealing a population that was small-brained with both primitive and derived skeletal traits, has been dated to the earliest Upper Matuyama chron (ca. 1.77 Ma). Here we present archaeological and geologic evidence that push back Dmanisis first occupations to shortly after 1.85 Ma and document repeated use of the site over the last half of the Olduvai subchron, 1.85–1.78 Ma. These discoveries show that the southern Caucasus was occupied repeatedly before Dmanisis hominin fossil assemblage accumulated, strengthening the probability that this was part of a core area for the colonization of Eurasia. The secure age for Dmanisis first occupations reveals that Eurasia was probably occupied before Homo erectus appears in the East African fossil record.

A new key locality for the Pliocene vertebrate record of Europe: the Camp dels Ninots maar (NE Spain)

A new Pliocene Konservat-Lagerstatte in north-eastern Spain is described here for the first time. It is referred to as Camp dels Ninots. The particular geological conditions of the site, which correspond to lacustrine sedimentation in a maar, made it ideal for the preservation of fossils. At present, five large mammal skeletons in anatomical connection have been recovered: three individuals of Alephis tigneresi, one of Stephanorhinus jeanvireti and one of Tapirus arvernenis, as well as isolated remains. A minimum of five individuals of the chelonian Mauremys leprosa have been recovered, some of them in anatomical connection. The rodent Apodemus atavus, the amphibians cf. Pleurodeles sp., Lissotriton aff. helveticus and Pelophylax cf. perezi and freshwater fishes (Leuciscus ?) complete the vertebrate assemblage uncovered up to the present time. The coexistence of Stephanorhinus jeanvireti and Alephis tigneresi suggests an age of about 3.2Ma for the Camp dels Ninots, near the MN15-MN16 transition. The Camp del Ninots fossil record enables one to extend the biogeographic range of some vertebrate taxa, such as Stephanorhinus jeanvireti, Tapirus arvernensis or Mauremys leprosa to the Iberian Peninsula. Taphonomic evidences of the skeletal remains indicates minimal (if any) weathering. Deposition at the lake bottom seems to have taken place in oxygen depleted layers. In this way, Camp dels Ninots is comparable to other remarkable maar sites such as Messel, the Eocene site situated in Germany.

High-resolution LiDAR and photogrammetric survey of the Fumanya dinosaur tracksites (Catalonia): implications for the conservation and interpretation of geological heritage sites

Increasing political and social awareness of the importance of protecting the geological heritage is compelling geoscientists to consider new methods for reconciling conservation and exploration of their research sites. Terrestrial Light Detection And Range (LiDAR) imaging is an accurate method of collecting 3D spatial data that has so far been under-utilized in the geological sciences. This aim of this paper is to assess the value of integrated LiDAR and photogrammetric imaging as a tool for synchronizing scientific exploration with conservation of geological heritage sites.   Fumanya (Catalonia) is one of the most important Cretaceous tracksites in Europe, but the nature of exposure of the track-bearing surface has hindered quantitative documentation of the ichnites. Using integrated Light Detection And Range (LiDAR) imaging and photogrammetry it has been possible to construct high-resolution Digital Outcrop Models (DOM) of the tracksites. Photo-textured DOMs are a powerful visualization tool and function as fully 3D interactive databases that preserve information about the site that would otherwise be lost to erosion. LiDAR-derived DOMs have the potential to contribute profoundly to future geoconservation projects, particularly as a tool for documenting and monitoring heritage sites and promoting education and tourism. LiDAR scanning also provides sufficient resolution to perform robust quantitative analysis of dinosaur tracks.

Lithostratigraphical correlation of micromammal sites and biostratigraphy of the Upper Pliocene to Lower Pleistocene in the Northeast Guadix-Baza Basin (southern Spain)

The Plio-Pleistocene non-marine sequence in the northeast Guadix–Baza Basin (southern Spain) comprises alluvial and lacustrine deposits (Baza Formation). The results of a revised lithostratigraphical correlation between sections from the middle and upper members of the Baza Formation in the northeast part of the basin, supported by detailed mapping, is presented. The position of micromammal sites in the lithostratigraphical scheme, together with the results of intensive palaeontological sampling for small mammal remains, has allowed us to develop a high-resolution biostratigraphical framework for the area. This provides an opportunity to refine the biozonation for the Plio-Pleistocene micromammal faunas, and to define faunal events from the late Villanyian (late Pliocene) to the early Pleistocene. On the basis of the lithostratigraphical and biostratigraphical approaches we obtain the following sequence of biozones for the late Pliocene to early Pleistocene: Kislangia gusii, Mimomys cf. reidi, M. oswaldoreigi, Allophaiomys pliocaenicus and A. burgondiae. Copyright

The Latest Succession of Dinosaur Tracksites in Europe: Hadrosaur Ichnology, Track Production and Palaeoenvironments

A comprehensive review and study of the rich dinosaur track record of the Tremp Formation in the southern Pyrenees of Spain (Southwestern Europe) shows a unique succession of footprint localities prior to the end-Cretaceous mass extinction event. A description of some 30 new tracksites and data on sedimentary environments, track occurrence and preservation, ichnology and chronostratigraphy are provided. These new track localities represent various facies types within a diverse set of fluvial environments. The footprint discoveries mostly represent hadrosaurian and, less abundantly, to sauropod dinosaurs. The hadrosaur tracks are significantly smaller in size than, but morphologically similar to, those of North America and Asia and are attributable to the ichnogenus Hadrosauropodus. The track succession, with more than 40 distinct track levels, indicates that hadrosaur footprints in the Ibero-Armorican region occur predominantly in the late Maaastrichtian (at least above the early Maastrichtian–late Maastrichtian boundary). The highest abundance is found noticeably found in the late Maastrichtian, with tracks occurring in the C29r magnetochron, within about the latest 300,000 years of the Cretaceous.

Manus-only titanosaurid trackway from Fumanya (Maastrichtian, Pyrenees): further evidence for an underprint origin

The origin of manus-only and manus dominated sauropod trackways has been a matter of intense debate since two hyphothesis exist: (a) manus-only and manus-dominated trackways result from a ‘swimming’ sauropod, and (b) they result from a selective underprint phenomenon that only leaves the manus recorded. Several new sauropod trackways are reported in the Fumanya tracksite area (Maastrichtian), in SE Pyrenees, where both tracks and undertracks are found on the same stratigraphic bedding surface. In one of the trackways, footprint morphology together with the trackway pattern displays a clear succession of manus-only impressions attributed to a sauropod dinosaur in a walking gait. The ichnological comparison between the manus-only trackway with the other complete trackway (manus-pes) display an identical distribution of the manus pattern. This fact clearly points towards an underprint phenomenon as the origin for manus-only trackways, since it is rather unlikely that the same pattern would completely match different locomotion behaviours such as walking and swimming. Therefore, we suggest an interpretation based on the differential loading between the hindfoot and the forefoot on an upper stratigraphic track-level, for the studied manus-only trackway. □ Fumanya tracksite, manus-only trackways, titanosaurs, trackway pattern, underprint, Upper Cretaceous.

Calibration of the Early-Middle Pleistocene transition in the continental beds of the Guadix–Baza Basin (SE Spain)

Abstract The magnetostratigraphic and palaeontologic studies carried out in two sections in the Guadix–Baza Basin (SE Spain) have enabled an accurate calibration of the Early-Middle Pleistocene boundary in the continental beds of this basin. The palaeontological record (rodents) in the Cortes de Baza section indicates an age ranging from the earliest Pleistocene (latest Villanyian or early Biharian) to the late Early Pleistocene (late Biharian). The whole Cortes de Baza Section is placed in a reversed magnetic interval identified as the upper part of the Matuyama Chron. In the Guadix–Baza Basin, the Middle Pleistocene (early Toringian) was already known at the locality of Cullar–Baza I, but new studies in the area have resulted in the recognition of Early Pleistocene deposits in the lower part of the section. Thus, the locality of Cullar–Baza B is placed in a reversed magnetozone correlated with the uppermost Matuyama, while the locality of Cullar–Baza C is placed in a normal magnetozone correlated to the lower Bruhnes Epoch. Therefore, the Biharian–Toringian boundary (based on the presence of Arvicola cantiana ) falls well within the Bruhnes epoch. This result is consistent with what is found in other Early–Middle Pleistocene sections of Spain (Atapuerca Gran Dolina).

On the age of the last hipparionine faunas in western Europe

Abstract In this paper, a survey on the dating of the hipparionine fauna in the site of Villarroya (Spain) is provided. Recently, the age of Villarroya has been the subject of controversy, and an age close to the Reunion chron has been proposed. However, a detailed analysis of Kislangia ischus from this site and its comparison with samples of this species in the magnetostratigraphically well calibrated section of Zujar (Guadix–Baza basin), enables one to propose an alternative dating for the short Vill-2 section where the fossiliferous locality occurs. Therefore, the normal event present in this section is correlated to chron 2An.1n (Upper Gauss). Thus, the last hipparionine faunas can be placed in the upper part of the Gauss chron, shortly before the first evidence of Equus in Europe.

Marine-continental magnetobiostratigraphic correlation of the Dolomys subzone (middle of Late Ruscinian): implications for the Late Ruscinian age

Abstract Lacustrine deposits, which form part of a continental unit cropping out in many localities of the Jerez Basin (SW Spain), have for the first time been dated. These deposits are attributed to the lower part of the Dolomys subzone, the upper part of the MN 15 Neogene Mammal Unit (late Ruscinian). This continental unit unconformably overlies a marine unit. Since the isochrony of the unconformity is not precisely established, the biostratigraphic results and palaeomagnetic data give two possibilities in correlating the Dolomys subzone with the marine magnetobiostratigraphy: (1) it can be correlated with the C2Ar reversed-polarity chron, or (2) with the C2An.2r reversed-polarity subchron (or C2An.1r ?). Therefore, the lower boundary of the MN 15 would be at the base of the C2Ar or at the very top of the Early Pliocene, respectively. In any case, considering the magnetobiostratigraphy correlation carried out in other Pliocene continental basins of the southeastern Spain, the top of MN 15 seems to be within the Late Pliocene.