Functional anatomy of the cervical region in the late Miocene amphicyonid Magericyon anceps (Carnivora, Amphicyonidae): implications for its feeding behaviour

We describe the skull and neck morphology of the late Miocene amphicyonid Magericyon anceps, focusing on aspects related to functional anatomy. This species, recorded only from the Vallesian sites of Batallones-1 and Batallones-3 (Madrid, Spain), is the last known amphicyonid in the fossil record of Western Europe, with the Batallones populations being one of the best-known of the family. The morphology of its skull and cervical vertebrae allows us to infer aspects of its associated musculature, such as muscle strength and range of movement. Magericyon anceps had well-developed neck muscles, suited for providing the head with a high capacity for lateral and rotatory movements, as well as for playing an important role in the extension and stabilization of the head and neck, improving its efficiency in killing and consuming prey. Magericyon anceps shared its habitat with other large carnivorans, which would have strongly influenced its behaviour. Rapid killing and processing of prey would have been an advantage for avoiding kleptoparasitism by other large predators, as well as reducing consumption time, during which M. anceps would have been more vulnerable to attack from competitors.MJS and JM belong to the research groups UCM-BSCH-910607, CSIC-641534, CSIC-641538 and IDL-RG2 (Coast, Water, and Earth surface processes). This study is part of the research projects CGL2008-00034, and CGL2011-25754 (Ministerio de Economía y Competitividad, Spanish Government).Peer Reviewe

Historia de dos poblaciones: los félidos “dientes de sable” de Batallones 3

De todos los yacimientos del Cerro de losBatallones, dos son especialmente relevantes para el estudio de los carnívorosdel Mioceno superior: Batallones-1 y Batallones-3. En ambos la proporción defósiles recuperados de este grupo se sitúa en torno al 98% (Morales et alii, 2000, 2004; Abella et alii, 2011, Monescillo et alii,2014, Siliceo et alii, 2014), existiendopor tanto un predominio abrumador de éstos sobre los restos de otrosmacromamíferos. Este elevado porcentaje de carnívoros indica que ambos yacimientos funcionaron comotrampas naturales, formados como cavidades en las cuales los animales entrabanactivamente, atraídos principalmente por el olor a carroña de animales atrapadospreviamente, y no podían salir (Antón y Morales, 2000; Salesa, 2002; Antón et alii. 2004; Morales et alii.,2000, 2004). Las similitudes entre estos dos yacimientos son muchas: tantoel alto porcentaje de carnívoros (cercano al 98%), como su diversidad, y laexcelente preservación de los fósiles es comparable en ambos. Sin embargo, pesea sus semejanzas y proximidad espacial (se hallan separados por menos de 180 m),un estudio sobre la dentición del cricétido Hispanomysmoralesi (presente en ambos yacimientos) reveló una morfología más derivadaen la población de Batallones-3 respecto de la de Batallones-1, estableciéndosepor tanto una edad relativa más antigua para este último yacimiento (López-Antoñanzaset alii, 2010).Fil: Siliceo, Gema. Universidad de Alcalá; EspañaFil: Fernández García, Marcos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Functional and Systematic Implications of the Postcranial Anatomy of a Late Miocene Feline (Carnivora, Felidae) from Batallones-1 (Madrid, Spain)

The Spanish late Miocene locality of Batallones-1 yielded a rich sample of large carnivorans, including saber-toothed felids, amphicyonids, and ailurids, but also of smaller species, with the small cats being especially interesting. Two species are known from Batallones-1, one of them the size of a wildcat, Felis silvestris, the other one the size of a caracal, Caracal caracal. The former is represented by skulls, mandibles, and postcranial bones, whereas the latter is known from a collection of long bones. Both species are less abundant than their larger relatives, the saber-toothed felids Promegantereon ogygia and Machairodus aphanistus, but the available sample allows us to assess body proportions and adaptations of the smallest species, and to propose a new genus for this feline, Leptofelis vallesiensis. Its limb bones are remarkably gracile compared to fossils of the earlier genera Pseudaelurus, Miopanthera, and Styriofelis, and comparable in cursorial adaptations to the wildcat, very different from extant arboreal cats. While middle Miocene felids were likely semi-arboreal forest dwellers, L. vallesiensis would be mostly terrestrial, climbing essentially for protection. This indicates an adaptation to a mosaic of habitats, including relatively open terrain, and may be related to the climatic changes detected in Eurasia during the late Miocene.This study is part of the research projects CGL2015-68333-P (MINECO/FEDER, UE) and IF/00351/2014/CP1216/CT0003 (Fundação para a Ciênciae a Tecnologia, Portugal). We thank the Comunidad Autónoma de Madrid (Dirección General de Patrimonio Histórico) for its continuous funding support andresearch permissions

Machairodont adaptations and affinities of the Holarctic late Miocene homotherin Machairodus (Mammalia, Carnivora, Felidae): the case of Machairodus catocopis Cope, 1887

The craniodental anatomy of Machairodus catocopis is assessed through the study of a well-preserved specimen from the early Hemphillian site of Sebastin Place (Kansas) and through comparisons with other Miocene American and Eurasiatic machairodonts, in order to resolve its affinities and to gain a clearer understanding of the evolution of machairodontine felids in the Holarctic. In view of the similarities with the Old World species Machairodus aphanistus, the original generic assignment seems correct, and later attribution of this species to the genus Nimravides appears unjustified. Similarities with Old World Miocene homotherins are too extensive to be the result of convergent evolution, especially considering the mosaic evolution of different machairodont adaptations. Hypotheses suggesting that M. catocopis is a part of a native American lineage originating from a feline, rather than machairodontine, immigrant are unjustified on anatomical or evolutionary grounds. The succession of sabertoothed felid species in the American Miocene is best explained as the result of three immigration events. A first immigration of a felid of Pseudaelurus grade led to the evolution of primitive species such as Pseudaelurus intrepidus and Nimravides pedionomus. A second immigration of a species of Machairodus aphanistus grade around the time of the ‘Hipparion event’ would result in the evolution of M. catocopis. The late Hemphillian species ‘Machairodus’ coloradensis is clearly a member of the Old World Turolian Amphimachairodus lineage, and would be the result of a third immigration eventThis study is part of the research project CGL2008–00034 (Direccíon General de Investigacion, Ministerio de Ciencia e Innovacíon, Spain). M.J.S. is a contracted researcher within the ‘Ramon y Cajal’ program (Ministerio de Ciencia e Innovación reference RYC2007-00128), and G.S. is predoctoral FPI fellow of the project CGL2008-00034. M.J.S. belong to the research group UCM-BSCH-910607. We thank J. Galkin from the American Museum of Natural History (New York, U.S.A.) for the access to the material of Machairodus catocopis from Sebastin Place. We also thank R. Payne and R. Stucky, from the Denver Museum of Nature & Science (Denver, U.S.A.), for providing us with images of the holotype and paratype of Amphimachairodus coloradensisPeer Reviewe

Comparative anatomy of the shoulder region in the Late Miocene Amphicyonid magericyon anceps (Carnivora): Functional and paleoecological inferences

We describe and discuss several aspects of the functional anatomy of the shoulder of the Miocene amphicyonid Magericyon anceps, focusing on the scapula and proximal half of the humerus. This species, only known from the late Miocene (Vallesian, MN 10) site of Batallones-1 (Madrid, Spain), is the last amphicyonid known in the fossil record of Western Europe. Magericyon anceps combines a more hypercarnivorous dentition than previous amphicyonids (including relatively more flattened canines) with primitive features on its shoulder region: its scapulo-humeral region shows a reduced caudoventral projection of the acromion, the postscapular fossa, and the teres major process, suggesting some differentiation from the two morphotypes exhibited by other derived amphicyonids, and showing similarities with primitive, generalized, medium-sized species of this family. This unique combination of a derived dentition and a relatively generalized shoulder region points towards M. anceps being a different ecological morphotype from that showed by other amphicyonids such as the larger, bear-like amphicyonines from the European middle Miocene and the markedly cursorial North American temnocyonines and daphoenines.This study is part of the research projects CGL2008-00034, and CGL2011-25754 (Ministerio de Economía y Competitividad, Spanish Government) and PICS-CNRS 4737. MJS and JM belong to the Research Group UCM-BSCH 910607. GS was a pre-doctoral FPI fellowship of the project CGL2008-00034.Peer reviewe

Built for Strength: Functional Insights from the Thoracolumbar and Sacrocaudal Regions of the Late Miocene Amphicyonid Magericyon anceps (Carnivora, Amphicyonidae) from Batallones-1 (Madrid, Spain)

We describe and discuss the morphology and functional anatomy of the thoracolumbar and sacrocaudal regions of the vertebral column of the late Miocene amphicyonid Magericyon anceps. These regions are essential for body support, and very relevant for locomotion and prey capture, and thus their study provides interesting insights on the paleobiology and biomechanics of this top predator. Magericyon anceps, the last known amphicyonid in the fossil record of Western Europe, is recorded only from the Vallesian sites of Batallones-1 and Batallones-3 (Madrid, Spain), which have yielded hundreds of fossils of this species, constituting one of the best-known samples of an amphicyonid ever recorded. The morphology of the thoracolumbar region of M. anceps shows some interesting features, such as a characteristic anticlinal region and a powerful and remarkably rigid lumbar region. This suggests that the back of this carnivoran was built for supporting extremely strong tensions that could be generated during different activities, such as running, but these tensions would be more likely suffered when subduing prey during hunting. Also, M. anceps had a long muscular tail, which could be helpful in balancing of various body motions during these activities. In summary, all these features suggest that M. anceps was a powerful predator built for strength, supporting previous hypotheses about the adaptation of this carnivoran to fast killing of prey inhabiting relatively well-vegetated habitats.This study is part of the research project CGL2015-68333-P (MINECO/FEDER, UE). GS is member of the Research Group “Bioacústica Evolutiva y Paleoantropología” and she thanks the Postdoctoral Program from the Universidad de Alcalá (Madrid, Spain) for funding. MJS is member of the Research Groups CSIC 641538 (Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain), FOCONTUR (Fundación Conjunto Paleontológico de Teruel-Dinópolis, Teruel, Spain), and IDL-RG2 (Coast, Water and Earth surface processes) (Instituto Dom Luiz and Universidade de Lisboa, Lisbon, Portugal)

New fossils of amphicyonidae (Carnivora) from the middle miocene (mn6) site of carpetana (Madrid, Spain) Nouveaux fossiles d’amphicyonidae (Carnivora) du miocène moyen (mn6) de carpetana (Madrid, Espagne)

[EN] Herein, we present a study of an interesting sample of fossils of the giant amphicyonid Megamphi-cyon giganteus (Schinz, 1825) from the Spanish middle Miocene (MN6) site of Carpetana (Madrid city), obtained during public works for the Madrid underground in 2008. Although the dentition of this species is known from other sites, the postcranial bones are very poorly known, and the new material provides new data on the locomotor adaptations of this spectacular predator, and allows an estimation of its body mass, which would be around 600 kg. Surprisingly, despite this giant size, the morphology of both femur and tibia shows that this animal exhibited higher cursorial capacity than large extant carnivorans, such as bears, which together with a high degree of pronation/supina-tion movement of the forearm, reveals adaptations of M. giganteus to occupy the niche of active top predator in middle Miocene ecosystems.[FR] Nouveaux fossiles d’Amphicyonidae (Carnivora) du Miocène moyen (MN6) de Carpetana (Madrid, Espagne).Nous présentons ici l’étude d’un échantillon intéressant de fossiles de l’amphicyonidé géant Megam-phicyon giganteus (Schinz, 1825) du gisement espagnol du Miocène moyen (MN6) de Carpetana (Madrid), obtenus lors de travaux publics dans le métro de la ville en 2008. Bien que la dentition de cette espèce soit connue sur d’autres sites, les os postcrâniens sont très mal connus, et le nouveau matériel fournit de nouvelles données sur les adaptations locomotrices de ce spectaculaire prédateur, et permet une estimation de sa masse corporelle, qui avoisinerait 600 kg. Étonnamment, malgré cette taille gigantesque, la morphologie du fémur et du tibia montre que cet animal présentait des capacités de coureur plus élevées que les grands carnivores existants, tels que les ours, ce qui, outre un degré élevé de mouvements de pronation/supination sur l’avant-bras, révèle les adaptations de M. giganteus à occuper le créneau des principaux prédateurs actifs des écosystèmes du Miocène moyen.This study is part of the research project CGL2015-68333-P (MINECO/FEDER, UE). GS is member of the research group “Bioacústica Evolutiva y Paleoantropología”. JM is member of the research groups UCM-BSCH-910607, and CSIC-641538. MJS is member of the research groups CSIC-641538, and FOCONTUR (Fundación Conjunto Paleontológico de Teruel-Dinópolis)

Concealed weapons: A revised reconstruction of the facial anatomy and life appearance of the sabre-toothed cat Homotherium latidens (Felidae, Machairodontinae)

Homotherium is one of the sabre-toothed felid genera with a more extensive overlap in space and time with species of our own genus Homo, who must have been familiar with the animal, but now we only have its fossil remains to infer its life appearance. A revised reconstruction of the soft tissue and life appearance of Homotherium latidens is proposed here on the basis of new observations on the anatomy of extant carnivorans and a re-evaluation of the fairly preserved skull and mandible from the classical Late Pliocene site of Perrier (France). This fossil specimen provides some of the best information available about the morphology of the skull and mandible. Like other large early specimens of Homotherium, it has enormous upper canines relative to skull size and high-crowned enough to protrude beyond the lips in the living animal. On the other hand, observations of facial expressions in living big cats and dissected specimens show that, contrary to previous conclusions, the soft tissue around the mouth and the lower lip in particular can cover the upper canines of large felids, even when those are considerably high-crowned. Such observations lead us to propose a revised hypothesis about the life appearance of Homotherium and other sabre-toothed carnivorans, where the upper canines may have been covered in life when the mouth was completely closed.This study is part of the research project EVOFEL (reference PID2020-112642 GB-I00) funded by MCIN/AEI/10.13039/501100011033. M. J. Salesa is member of the Research Groups CSIC 641538 (Museo Nacional de Ciencias Naturales-CSIC, Madrid,Spain), and FOCONTUR (Fundación Conjunto Paleontológico de Teruel-Dinópolis).Peer reviewe