Gema Siliceo

Promegantereon ogygia (Felidae, Machairodontinae, Smilodontini) from the Vallesian (Late Miocene, MN 10) of Spain: Morphological and Functional Differences in Two Noncontemporary Populations

ABSTRACT We compare two populations of the primitive saber-toothed felid Promegantereon ogygia from the late Miocene (Vallesian, MN 10) of Spain. These populations come from two fossil sites, Batallones-1 and Batallones-3, located very close to each other, within the Cerro de los Batallones complex. The sites show differences in age and in their faunal assemblages, with Batallones-1 being older than Batallones-3. We find that the population from this latter site shows slightly derived characters in both dentition and postcranial elements, which clearly indicate evolution within the Promegantereon lineage, but are not strong enough to support a separation at the species level.

Machairodus aphanistus (Felidae, Machairodontinae, Homotherini) from the late Miocene (Vallesian, MN 10) site of Batallones-3 (Torrejón de Velasco, Madrid, Spain)

ABSTRACT In the present work we conduct a comparative study of the cranial and dental samples of the early machairodontine Machairodus aphanistus from the Vallesian (MN 10) sites of Batallones-1 and Batallones-3 (Torrejón de Velasco, Madrid, Spain). These sites, which have yielded the most abundant and complete samples of this felid, show interesting differences in faunal composition and age, thus providing a unique opportunity for both qualitative and quantitative comparisons between two populations of the same species. The study reveals differences in a number of cranial features, and statistically significant differences in teeth size and proportions. Although probably not enough to support a separation at the species level, these observations fit well with the morphological evolution of the lineage leading towards more derived forms such as the Turolian Amphimachairodus giganteus.

A rich community of Felidae (Mammalia, Carnivora) from the late Miocene (Turolian, MN 13) site of Las Casiones (Villalba Baja, Teruel, Spain)

ABSTRACT Several new fossil remains of Felidae from the late Miocene (Turolian age, MN 13, local zone M2) locality of Las Casiones (near the village of Villalge Baja, Teruel, Spain) are studied in the present paper. This felid community includes the machairodontines Amphimachairodus giganteus, Paramachaerodus orientalis, and Metailurus major, and the felines Pristifelis attica and a small, undetermined species, previously unknown in the late Miocene. With this high diversity of felids, the environment of Las Casiones was probably relatively vegetated, with shrubs and trees that allowed smaller felid species to avoid dangerous encounters with the larger ones.

Anatomía comparada de los senos frontales en el félido dientes de sable primitivo Promegantereon ogygia (Felidae, Machairodontinae) y felinos actuales de tamaño similar

In the present work, the frontal sinuses of the sabre-toothed felid Promegantereon ogygia are analysed, in comparison to those of the extant felines Acinonyx jubatus, Puma conocolor and Panthera pardus, of similar body weight. The study was carried out using 3D virtual models obtained from CT Scan images, a non-destructive technique that has revealed as a powerful tool for accessing to all kind of intracranial information. Our study shows that the frontal sinuses of P. ogygia were more similar to those of P. concolor, both in the presence of several struts reinforcing the dorsal part, and in the development of a remarkable caudal expansion. This caudal expansion would act as a thermal insulator of the brain, and would indicate a more open environment than previously supposed for this species, whereas the struts would be related to biomechanical stresses produced during the “canine shear-bite”, the killing method of the machairodontines.

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.

First Evidence of Pathology in the Forelimb of the Late Miocene Saber-Toothed Felid Promegantereon ogygia (Machairodontinae, Smilodontini)

We examined the first evidence of pathology in the forelimb of the primitive saber‐toothed felid Promegantereon ogygia, observed in a radius from the late Miocene (Vallesian, MN 10) site of La Roma 2 (Teruel, Spain). This fossil is the first evidence of a member of the Machairodontinae in this locality, and the first fossil of this species found in the Miocene basin of Teruel. The radius shows an exostosis shaped as a rough and wide bony crest probably caused by the lesion and posterior ossification of part of the tendon of the muscle abductor pollicis longus, an important extensor and abductor of the thumb. The lesion was probably due to a tearing or to high levels of exertion experienced by this muscle over a relatively long time, a general type of lesion also observed in other vertebrate fossils. With saber‐toothed felids using their thumbs to immobilize prey during the hunt, the studied lesion probably affected in a significant manner the predatory abilities of the animal, causing at least a decrease in its hunting success rate. Anat Rec, 297:1090–1095, 2014.

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

ABSTRACT 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 event.