Non-decoupled morphological evolution of the fore- and hind limb of sabretooth predators.

Política de acceso abierto tomada de: https://v2.sherpa.ac.uk/id/publication/6894Specialized organisms are useful for exploring the combined effects of selection of functional traits and developmental constraints on patterns of phenotypic integration. Sabretooth predators are one of the most interesting examples of specialization among mammals. Their hypertrophied, sabre-shaped upper canines and their powerfully built forelimbs have been interpreted as adaptations to a highly specialized predatory behaviour. Given that the elongated and laterally compressed canines of sabretooths were more vulnerable to fracture than the shorter canines of conical-tooth cats, it has been long hypothesized that the heavily muscled forelimbs of sabretooths were used for immobilizing prey before developing a quick and precise killing bite. However, the effect of this unique adaptation on the covariation between the fore- and the hindlimb has not been explored in a quantitative fashion. In this paper, we investigate if the specialization of sabretooth predators decoupled the morphological variation of their forelimb with respect to their hindlimb or, in contrast, both limbs vary in the same fashion as in conical-tooth cats, which do not show such extreme adaptations in their forelimb. We use 3D geometric morphometrics and different morphological indices to compare the fore- and hindlimb of conical- and sabretooth predators. Our results indicate that the limb bones of sabretooth predators covary following the same trend of conical-tooth cats. Therefore, we show that the predatory specialization of sabretooth predators did not result in a decoupling of the morphological evolution of their fore- and hindlimbs. The role of developmental constraints and natural selection on this coordinate variation between the fore- and the hindlimb is discussed in the light of this new evidenc

In the pursuit of the predatory behavior of borophagines (Mammalia, Carnivora, Canidae): inferences from forelimb morphology.

Política de acceso abierto tomada de: https://v2.sherpa.ac.uk/id/publication/14270Here, we perform an ecomorphological study on the major bones (humerus, radius, and ulna) of the carnivoran forelimb using three-dimensional geometric morphometrics. More specifically, we test the association between forelimb morphology and predatory behavior. Our results suggest that the main morphological adaptions of carnivorans to different predatory behaviors relate to: (i) the capacity to perform long and efficient runs as in pounce/pursuit and pursuit predators; (ii) the ability to maneuver as in occasional predators; and (iii) the capacity to exert and resist large loads as in ambushing predators. We used borophagine canids as a case study, given the controversy on the predatory behavior of this extinct subfamily. Our results indicate that borophagines displayed a limited set of adaptions towards efficient running, including reduced joint mobility in both the elbow and the wrist, aspects in which they resemble the living canids. Furthermore, they had forelimbs as powerful as those of the extant ambushing carnivorans (i.e., most felids). This combination of traits suggests that the predatory behavior of borophagines was unique among carnivorans, as it was not fully equivalent to any of the living species

On the Relationships of Postcanine Tooth Size with Dietary Quality and Brain Volume in Primates: Implications for Hominin Evolution

Brain volume and cheek-tooth size have traditionally been considered as two traits that show opposite evolutionary trends during the evolution of Homo. As a result, differences in encephalization and molarization among hominins tend to be interpreted in paleobiological grounds, because both traits were presumably linked to the dietary quality of extinct species. Here we show that there is an essential difference between the genus Homo and the living primate species, because postcanine tooth size and brain volume are related to negative allometry in primates and show an inverse relationship in Homo. However, when size effects are removed, the negative relationship between encephalization and molarization holds only for platyrrhines and the genus Homo. In addition, there is no general trend for the relationship between postcanine tooth size and dietary quality among the living primates. If size and phylogeny effects are both removed, this relationship vanishes in many taxonomic groups. As a result, the suggestion that the presence of well-developed postcanine teeth in extinct hominins should be indicative of a poor-quality diet cannot be generalized to all extant and extinct primates.This research has been funded by the Spanish Ministry of Science and Innovation (Projects CGL2010-18124, CGL2011-30334, and HAR2008-04577) and supported by the Department of Economy, Innovation and Science, Junta de Andalucía, Spain (Project P11-HUM-7248 and Research Groups HUM-607 and RNM-146)

Presence of the Asian origin Bovini, Hemibos sp. aff. Hemibos gracilis and Bison sp., Q1 at the early Pleistocene site of Venta Micena (Orce, Spain).

https://v2.sherpa.ac.uk/id/publication/13196The assemblages of large bovids from the European Late Villafranchian are dominated by the presence of the genus Bison, a descendant of the Early-Middle Villafranchian forms of Leptobos. Chronologically, the oldest record of this genus at the gates of Europe is at Dmanisi, Georgia (1.77 Ma), where it was firstly named Dmanisibos. It is recorded until the Holocene. It is the most abundant Quaternary buffalo of the continent and is nearly the only genus recorded in most post-Olduvai Early Pleistocene sites of Europe. The revision of all bone and tooth remains of large bovids from the site of Venta Micena (w1.5 Ma) shows that two species of buffaloes are present at this Early Pleistocene locality. One is clearly a form of Bison, while the other corresponds to other different Bovini of small size that may be ascribed to the genus of Indian origin Hemibos, thus representing the first record of this genus in the Late Villafranchian of Europe. This paper presents the cranial material of both buffaloesEste estudio ha sido financiado por el Ministerio de Ciencia e Innovación de España (Subvención CGL2010-15326) y la Consejería de Cultura de la Junta de Andalucía, España

Inferring flight parameters of Mesozoic avians through multivariate analyses of forelimb elements in their living relatives

Our knowledge of the diversity, ecology, and phylogeny of Mesozoic birds has increased significantly during recent decades, yet our understanding of their flight competence remains poor. Wing loading (WL) and aspect ratio (AR) are two aerodynamically relevant parameters, as they relate to energy costs of aerial locomotion and flight maneuverability. They can be calculated in living birds (i.e., Neornithes) from body mass (BM), wingspan (B), and lift surface (S L). However, the estimates for extinct birds can be subject to biases from statistical issues, phylogeny, locomotor adaptations, and diagenetic compaction. Here we develop a sequential approach for generating reliable multivariate models that allow estimation of measurements necessary to determine WL and AR in the main clades of non-neornithine Mesozoic birds. The strength of our predictions is supported by the use of those variables that show similar scaling patterns in modern and stem taxa (i.e., non-neornithine birds) and the similarity of our predictions with measurements obtained from fossils preserving wing outlines. In addition, although our WL and AR values are based on estimates (BM, B, and S L) that have an associated error, there is no cumulative error in their calculation, and both parameters show low prediction errors. Therefore, we present the first taxonomically broad, error-calibrated estimation of these two important aerodynamic parameters in non-neornithine birds. Such estimates show that the WL and AR of the non-neornithine birds here analyzed fall within the range of variation of modern birds (i.e., Neornithes). Our results indicate that most modern flight modes (e.g., continuous flapping, flap and gliding, flap and bounding, thermal soaring) were possible for the wide range of non-neornithine avian taxa; we found no evidence for the presence of dynamic soaring among these early birds

Shape at the cross-roads: Homoplasy and history in the evolution of the carnivoran skull towards herbivory

Patterns of skull shape in Carnivora provide examples of parallel and convergent evolution for similar ecomorphological adaptations. However, although most researchers report on skull homoplasies among hypercarnivorous taxa, evolutionary trends towards herbivory remain largely unexplored. In this study, we analyse the skull of the living herbivorous carnivorans to evaluate the importance of natural selection and phylogenetic legacy in shaping the skulls of these peculiar species. We quantitatively estimated shape variability using geometric morphometrics. A principal components analysis of skull shape incorporating all families of arctoid carnivorans recognized several common adaptations towards herbivory. Ancestral state reconstructions of skull shape and the reconstructed phylogenetic history of morphospace occupation more explicitly reveal the true patterns of homoplasy among the herbivorous carnivorans. Our results indicate that both historical constraints and adaptation have interplayed in the evolution towards herbivory of the carnivoran skull, which has resulted in repeated patterns of biomechanical homoplasy

Sixty-six million years along the road of mammalian ecomorphological specialization.

Open acess (ce 31/01/24)The fossil record of the large terrestrial mammals of the NorthAmerican Cenozoic has previously been quantitatively summarizedin six sequential episodes of faunal associations—“evolutionary faunas”—that correspond well with previously proposed qualitative“Chronofaunas.”Here, we investigate the ecological spectrum ofthese faunas by classifying their major taxonomic components intodiscrete ecomorphological categories of diet, locomotion, and bodysize. To specifically address the potential influence of long-termclimatic shifts on the ecomorphological composition of these faunas,we analyze via contingency tables and detrended correspondenceanalyses the frequency distribution of ecomorph types within fau-nas. We show that each evolutionary fauna has a unique, nonran-dom association of ecomorphs, and we identify a long-term trendtoward greater ecomorphological specialization over successive fau-nas during the past 66 My. Major vegetation shifts induced by cli-matic changes appear to underlie the ecomorphological dynamics ofthese six temporal associations that summarize Cenozoic NorthAmerican mammalian evolutionary history.CGL2012-37866, GL2015-68300-P, GL2016-7857

Demythologizing Arctodus simus, the ‘short-faced’ long-legged and predaceous bear that never was

In this study, we review the previous evidence on the paleobiology of the giant, ‘short-faced’ bear Arctodus simus (Mammalia: Carnivora: Ursidae) and contribute new ecomorphological inferences on the paleobiology of this enigmatic species. Craniodental variables are used in a comparative morphometric study across the families Felidae, Hyaenidae, Canidae, and Ursidae. Principal components analyses (PCAs) do not show an ecomorphological adaptation towards bonecracking or hypercarnivory in the ‘short-faced’ bear. In contrast, PCAs and discriminant analyses restricted to the craniodental data set of ursids suggest close morphological resemblance between A. simus and the extant omnivorous bears. In addition, the scaling of snout length on neurocranial length in bears indicates that the face of A. simus was not particularly short. Body mass estimates obtained from major limb bone measurements reveal that A. simus specimens of around 1000 kilograms were more common than previously suspected. Scaling relationships in extant bears of limb lengths on the least width of the femoral shaft (the variable best correlated with body mass) indicate that A. simus was not as relatively long-legged as previously thought. For these reasons, although the isotopic signature of A. simus has been interpreted as evidencing that it consumed large amounts of flesh relative to some contemporary populations of Ursus arctos, our results do not support the previous views of A. simus as a fast-running super-predator or as a specialized scavenger. In contrast, the picture that emerges from this study is one of a colossal omnivorous bear whose diet probably varied according to resource availability

The effect of long-term atmospheric changes on the macroevolution of birds.

Política de acceso abierto tomada de: https://v2.sherpa.ac.uk/id/publication/16838Atmospheric conditions are critical for a range of biological functions—locomotion among others—and long-term changes in these conditions have been identified as causal for different macroevolutionary patterns. Here we examine the influence of variations in atmospheric O2 concentration (AOC), temperature (Tair), and air density (ρair) on the power efficiency, as it relates to locomotion, during the evolutionary history of birds. Specifically, our study centers on four key evolutionary events: (1) the body mass reduction of non-avian theropods prior to the rise of birds; (2) the emergence of flapping flight in the earliest birds; (3) the divergence of basal pygostylians; and (4) the diversification of modern birds. Our results suggest that a marked increase in AOC and ρair during the Middle Jurassic—coeval with a trend in miniaturization—improved the power efficiency of the dinosaurian predecessors of birds. Likewise, an increase in these conditions is hypothesized as having played a major role in the diversification of early pygostylians during the Early Cretaceous. However, our analyses do not identify any significant paleoatmospheric effects on either the emergence of flapping flight or the early cladogenesis of modern birds. Extinct birds flew within the range of atmospheric conditions in which modern birds fly but varying past conditions influenced their flight performance. Our study thus highlights the importance of considering paleoatmospheric conditions when reconstructing the flight efficiency of the forerunners of modern birds

The Epivillafranchian and the arrival of pigs into Europe

Suids are found in Europe before and during the Olduvai subchron, including the Fonelas P-1 (~2.0 Ma), in which the remains have been ascribed to Potamochoerus magnus, and many other localities that record the presence of Sus strozzii. However, there is no pig record in the biochronological range comprised between the post Tasso Faunal Unit, which marks the base of the Late Villafranchian (~1.8 Ma), and their arrival in Western Europe at layer TE9 from Sima del Elefante, Atapuerca, Northern Spain (~1.2 Ma), where pigs are recorded under the name of Sus sp., and at the sites of Untermassfeld, Vallonnet and layer EVT12 of Vallparadís Estació, dated 1.1-1.0 Ma (MIS31). Later, the genus Sus is recorded everywhere in Europe as a ubiquitous member of the Epivillafranchian/Galerian and posterior faunas. When pigs are in an ecosystem, they use to be abundant in the large mammal community given their opportunistic feeding behavior and high reproductive success. For this reason, suids are usually preserved in the fossil assemblages after their dispersal and colonization of a geographic region. The arrival of suids phylogenetically related to Sus gr. scrofa into Europe marks the end of the Late Villafranchian and the beginning of the Epivillafranchian, which is approximately dated at ~1.2 Ma. Given that suids are omnivorous, generalist mammals with bunodont teeth that do not tolerate very low temperatures, this suggests that their colonization of Europe can be related to a change in the ecosystems and climate. In addition, the arrival of suids postdates the earliest arrival of hominins into Western Europe, which is documented at the Orce sites of Barranco León-D and Fuente Nueva-3 (~1.5-1.2 Ma). In these sites, rich faunal assemblages, abundant lithic artifacts and one human tooth have been unearthed after more than twenty years of xcavations, but no evidence of pigs has yet been detected.Este trabajo forma parte de un proyecto autorizado y financiado por la Consejería de Educación, Cultura y Deportes de la Junta de Andalucía (contrato Exp. B090678SV18BC) y también ha sido apoyado por subvenciones del Ministerio de Economía y Competitividad de España CGL2010-15326/BTE, CGL2011-28681, CGL2011- 30334/BTE, proyecto P11-HUM- 7248 de la Junta de Andalucía, subvención HAR2010-19957/HIST, Generalitat de Catalunya GENCAT 2009 SGR 324 y 2009 SGR 754 GR