Manuel J. Salesa

Functional anatomy of the forelimb in Promegantereon ogygia (Felidae, Machairodontinae, Smilodontini) from the Late Miocene of Spain and the origins of the sabre-toothed felid model

We examine the functional anatomy of the forelimb in the primitive sabre‐toothed cat Promegantereon ogygia in comparison with that of the extant pantherins, other felids and canids. The study reveals that this early machairodontine had already developed strong forelimbs and a short and robust thumb, a combination that probably allowed P. ogygia to exert relatively greater forces than extant pantherins. These features can be clearly related to the evolution of the sabre‐toothed cat hunting method, in which the rapid killing of prey was achieved with a precise canine shear‐bite to the throat. In this early sabre‐toothed cat from the Late Miocene, the strong forelimbs and thumb were adapted to achieve the rapid immobilization of prey, thus decreasing the risk of injury and minimizing energy expenditure. We suggest that these were the major evolutionary pressures that led to the appearance of the sabre‐toothed cat model from the primitive forms of the Middle Miocene, rather than the hunting of very large prey, although these adaptations reached their highest development in the more advanced sabre‐toothed cats of the Plio‐Pleistocene, such as Smilodon and Homotherium. Although having very different body proportions, these later animals developed such extremely powerful forelimbs that they were probably able to capture relatively larger prey than extant pantherins.

Implications of the functional anatomy of the hand and forearm of Ailurus fulgens (Carnivora, Ailuridae) for the evolution of the ‘false-thumb’ in pandas

Both the giant panda (Ailuropoda melanoleuca) and the red panda (Ailurus fulgens) possess a ‘false‐thumb’, actually an enlarged radial sesamoid bone, which contributes to the gripping action of the hand. These species are not closely related, however, as one is an ursid and the other an ailurid, so the fact that they share this adaptation implies a remarkable convergence. We studied the functional anatomy of this structure in the red panda, comparing it with existing descriptions of the grasping mechanism in both pandas. Previous interpretations of the radial sesamoid in Ailurus as a rod‐like structure without direct articulation to the wrist bones are inaccurate. There are various important differences between the red panda and the giant panda. In the former, the lesser development of the radial sesamoid, its connection with the flexor retinaculum, the presence of an insertion of the muscle abductor pollicis longus in the first metacarpal, which enhances its supinatory action, and the presence of a muscle flexor brevis digitorum manus point to thin‐branch climbing features serving as an exaptation to the more recent role of the red panda hand in the manipulation of bamboo.

Systematics and phylogeny of the small felines (Carnivora, Felidae) from the Late Miocene of Europe: a new species of Felinae from the Vallesian of Batallones (MN 10, Madrid, Spain)

The Spanish fossil localities of Batallones-1 and Batallones-3 are two Vallesian (Late Miocene) natural traps known for their high concentration of carnivoran mammals. These include amphicyonids, ailurids, mustelids, ursids, hyaenids, machairodont felids, and two species of small-bodied felines, one the size of an European wildcat, Felis sylvestris, and the other the size of a caracal, Caracal caracal. Although these felines are much less abundant at the sites than their larger relatives, the sabre-toothed felids, the available samples from Batallones-1 and Batallones-3 are rich; they include postcranial elements, skulls and mandibles of the smaller species, while the larger feline species is solely known from postcranial elements recorded at Batallones-1. The small feline from Batallones-1 and Batallones-3, although showing similarities with the Turolian felines, is more related to the Middle Miocene genus Styriofelis Kretzoi, 1929, and thus we propose for it the new species name Styriofelis vallesiensis. On the other hand, the new generic name Pristifelis is proposed for the species Felis attica, which shows important differences with extant Felis.

The evolution of the bone-cracking model in carnivorans: cranial functional morphology of the Plio-Pleistocene cursorial hyaenid Chasmaporthetes lunensis (Mammalia: Carnivora)

Abstract Fossil species of the family Hyaenidae represent a wide range of ecomorphological diversity not observed in living representatives of this carnivoran group. Among them, the cursorial meat-and-bone specialists are of particular interest not only because they were the most cursorial of the hyaenids, but also because they were the only members of this family to spread into the New World. Here we conduct a functional morphological analysis of the cranium of the cursorial meat-and-bone specialist Chasmaporthetes lunensis by using finite element modeling to compare it with the living Crocuta crocuta, a well-known bone-cracking carnivoran. As found with previous finite element studies on hyaenid crania, the cranium of C. lunensis is not differentially adapted for stress dissipation between the bone-cracking and meat-shearing teeth. A smaller occlusal surface on the more slender P3 cusp of C. lunensis allowed this species to use less bite force to crack a comparably-sized bone relative to C. crocuta, but higher muscle masses in the latter probably allow it to process larger food items. We use two indices, the stress slope and the bone-cracking index, to show that C. lunensis has a well-adapted cranium for stress dissipation given its size, but the main stresses placed on its cranium might have been more from subduing prey and less from cracking bones. Throughout the Cenozoic, other carnivores besides hyaenids convergently evolved similar morphologies, including domed frontal regions, suggesting an adaptive value for a repetitive mosaic of features. Our analyses add support to the hypothesis that bone-cracking adaptations are a complex model that has evolved convergently several times across different carnivoran families, and these predictable morphologies may evolve along a common gradient of functionality that is likely to be under strong adaptive control.

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.

El cambio de ideas acerca de la evolución y morfología functional de los félidos Machairodontinos

Sabre-toothed felids, the machairodontines, have attracted much attention among palaeontologists for many decades, not only because of their spectacular morphology but also because they are a striking example of convergent evolution that is most probably linked to strong selective pressures. In this paper we provide a summary of the changing interpretations of their functional anatomy and evolution, from early hypotheses proposing a stabbing mode of attack and a pleiotropic control of the complex of machairodont morphologies, to the current views favouring the canine shear-bite model and a mosaic evolution of anatomical features.

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.

Evolution of the Family Ailuridae: Origins and Old-World Fossil Record

Publisher Summary This chapter presents the early evolution of the Ailurids, its Old-World fossil record, and the implications of the paleontological evidence for the position of the ailurids among other carnivoran families. The red panda family is unusual because its only extant representative is a derived form, far removed from the groups morphotypical condition. The extreme adaptations of the red panda skull and dentition for a vegetarian diet imply that the study of the fossil record is essential if scientific community wants to gain an understanding of the original biology and ecology of the ailurids. Fossil ailurids have remained frustratingly rare and fragmentary findings for many decades, but recent years have seen a dramatic improvement of their record. This has been especially the case with the recent finds of dramatically complete remains of the simocyonine Simocyon batalleri from Batallones-1 in Madrid, Spain, and of the ailurine Pristinailurus bristoli from Gray Fossil Site in Tennessee, USA. Taking into account the information provided by these and other recent findings, it is now possible to gain a more complete picture than ever before of the true place of ailurids within the Carnivora, and of the evolutionary processes that led to the remarkable convergences between the only living ailurid and the unrelated giant panda.

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.