Morphological adaptation of the dentition in the order carnivora involves greater transformations in the upper dentition than in the lower dentition.

Starting from a given morphology, adaptation to different lifestyles and environments involves the modification of structures through natural selection. The dentition of carnivores is a clear example of this. To quantify the degree of divergence in the dentition of current carnivore families, the dentition has been divided into different regions (canines, premolars, carnassials and molars) and standardized for size by dividing by the total area of the dentition. Morphological divergence quantified as the distance from the centroid of the entire order or from that of each family is generally greater for the upper dentition than for the lower dentition. This suggestsdifferential selection pressures on the upper and lower dentition to adapt members of the order Carnivora to the different niches they occupy. This, which seems obvious for the machairodontine felids, is also observed in all other living families of both feliforms and caniforms.Grupo Paidi RNM 146 (Junta de Andalucía). Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Morphological disparity and integration in the vertebral column of pinnipeds (Mammalia, Carnivora).

The vertebral column has a very important role in locomotion in aquatic mammals, such as pinnipeds. However, the mode of aquatic locomotion differs between pinniped groups. Otariids generate thrust with their forelimbs (pectoral rowing) while phocids move laterally the pelvic region (pelvic oscillation). Therefore, to explore differences between these groups can provide new clues about the evolution of the land-to-sea transition in pinnipeds. In this study, we explore the disparity and morphological integration of the presacral vertebrae of a set of living and extinct pinnipeds. The results obtained show that vertebral morphological disparity is higher in phocids than in otariids. In addition, disparity through time analyses indicate that, for most vertebrae, otariids subclades tend to explore different regions of the morphospace, whereas phocid lineages overlap within similar regions. Finally, the study of integration between vertebrae in otariids reveals an absence of a modular pattern along the spine, in contrast to the modular pattern found in phocids. These results suggest that adaptation to the aquatic environment in both groups follows two completely different pathways, probably associated with their mode of aquatic locomotion. Future studies on the biomechanics of the pinniped vertebral column may confirm the association of morphology and evolutionary patterns with locomotor performance.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Investigating the land‑to‑sea transition in carnivorans from the evolution of sacrum morphology in pinnipeds

The form and function of the sacrum are of great relevance to understand the evolution of locomotion in tetrapods because it is a key piece of the vertebrate skeleton. The sacrum connects the caudal and presacral regions of the vertebral column and the hindlimbs through the pelvis. Here, we investigate sacrum shape evolution in pinnipeds (Carnivora: Pinnipedia) in relation to terrestrial mammalian carnivorans (fissipeds), and we include crown and stem taxa to quantify the morphological changes they experience in relation to the aquatic environment they inhabit. We use 3D geometric morphometric methods to explore the morphological variability and disparity of the sacrum in a set of terrestrial and aquatic carnivoran species. Our results show that the morphology of the sacrum of each pinniped family is remarkably different and that these differences may be related to the aquatic mode of locomotion (pectoral or pelvic oscillation), the use of hindlimbs to support body weight on land (otariids in contrast with phocids), and the presence or absence of a functional tail. In addition, disparity-through-time analyses indicate that the sacrum of pinnipeds is less constrained than that of fissipeds, which suggests a gravitational origin of such constraints in fissipeds. In conclusion, our results give further support to the important role played by this skeletal structure in the locomotory adaptations of mammals.Funding for open access publishing: Universidad Málaga/CBUA. This work has been funded by the Spanish Ministry of Science and Universities (Grant # PID2019-111185GB-I00) and Junta de Andalucía (Grant # P18-FR-3193). Support for laser scanning the specimen of Puijila darwini was provided by the Canadian Museum of Nature. Funding for open access charge: Universidad de Málaga / CBU

Evolución de la columna vertebral en pinnípedos actuales y extintos.

La columna vertebral desempeña un papel muy importante en la locomoción de los mamíferos acuáticos, como los pinnípedos. Sin embargo, el modo de locomoción acuática difiere entre los dos linajes principales de pinnípedos. Los otáridos generan empuje con sus extremidades anteriores (remo pectoral) mientras que los fócidos mueven lateralmente la región pélvica (oscilación pélvica). Por tanto, explorar las diferencias entre estos grupos puede aportar nuevas pistas sobre la evolución de la transición conocida como “land-to-sea” en los pinnípedos. En este estudio, exploramos la disparidad e integración morfológica de las vértebras presacrales de un conjunto de pinnípedos actuales y extintos. Los resultados obtenidos muestran que la disparidad morfológica vertebral es mayor en los fócidos que en los otáridos. Además, los análisis de disparidad a través del tiempo indican que, para la mayoría de las vértebras, los subclados de otáridos tienden a explorar diferentes regiones del morfoespacio, mientras que los linajes de fócidos se solapan en las mismas regiones. Por último, el estudio de la integración entre vértebras en otáridos revela la ausencia de un patrón modular a lo largo de la columna vertebral, en contraste con los módulos vertebrales encontrados en los fócidos. Estos resultados sugieren que la adaptación al medio acuático en ambos grupos siguió dos caminos completamente diferentes, probablemente asociadas a sus distintos modos de locomoción acuática. Futuros estudios sobre la biomecánica de la columna vertebral de los pinnípedos pueden confirmar la asociación entre morfología y estrategia locomotriz.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Evolution of axial regionalization in Aves during the Mesozoic and its impact on the survival of modern lineages to K/Pgmass extinction

Archivo que contiene el resumen y la presentación del estudio presentado en este congreso.The axial column of Neornithes (modern birds) is characterized by regional fusions in caudal vertebrae (pygostyle), lumbosacrals (synsacrum), and thoracics (notarium in several taxa) that provide a rigid and stable axis during flight. Such a configuration integrates into a body plan highly suited for wing-assisted locomotion (with feathered forelimbs, modified girdles, and crouched limbs) that evolved from running dinosaurs and stem birds over the last ~150 million years. Shifts in count numbers and fusion of vertebrae have had paramount implications on the avian diversification and flight refinement. However, how the organization of precaudal vertebrae evolved across the dinosaur–bird lineage, and how and when the highly tuned axial column of neornithines was acquired are unexplored. Here, we quantify vertebral numbers in pennaraptoran dinosaurs –including Aves—, and show how the axial configuration of birds was driven from different shifts between two primary developmental mechanisms of body-axis organization: segmentation and homeotic regionalization. We demonstrate that the configuration highly tuned for flight of modern birds was not fully acquired until the appearance of Neornithes. The acquisition of a trunk-sacrum configuration more efficient to deal with stresses derived from the flapping flight could be a key factor in the survivorship of neornithines and the extinction of non-neornithine birds during the end-Cretaceous mass extinction event.Ministerio de Ciencia, Innovación y Universidades (proyectos CGL2015-68300-P y PID2019-111185GB-I00) Junta de Andalucía (proyectos P18-FR3193 y PAIDI-DOC-00095) Natural History Museum of Los ángeles County (project ‘Aerodynamics of early birds’) Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Sobre el modo de entrampamiento de los grandes mamíferos conservados en rancho la brea: un análisis basado en el estado de meteorización de los restos óseos

Comunicación oral en el congresoLa interpretación tradicional sobre el modo en que se acumularon los restos fósiles conservados en La Brea plantea que los animales herbívoros que deambulaban por la llanura aluvial de esta región californiana durante el Pleistoceno Superior se quedarían ocasionalmente entrampados en pozas superficiales de alquitrán, cuya viscosidad sería mayor en verano. A su vez, cada uno de estos cadáveres atraería a numerosos carnívoros carroñeros, tanto terrestres como aéreos, los cuales correrían también el riesgo de verse atrapados en el alquitrán, lo que explica la abundancia de estos organismos en la tafocenosis. Con el tiempo, los niveles de alquitrán crecerían formando cuerpos cónicos gracias al depósito de sedimentos aluviales, enterrándose en ellos los restos esqueléticos. Si este escenario es correcto, los animales quedarían entrampados por la porción más distal de sus extremidades, lo que implica que los elementos esqueléticos autopodiales se enterrarían en el alquitrán inmediatamente, protegiéndolos de la meteorización subaérea. Por ello, las falanges, los metapodios y los huesos carpales/tarsales deberían ser los que mostrasen un menor grado de meteorización, mientras que, conforme a esta secuencia distoproximal de entrampamiento, los huesos zeugopodiales (radio, ulna, tibia y fíbula) deberían mostrar un grado intermedio de meteorización y los estilopodiales (húmero y fémur), que serían los más expuestos, estarían más meteorizados. Para someter a prueba esta hipótesis se analizó la meteorización de los elementos del esqueleto apendicular en las dos especies de carnívoros mejor representadas en la acumulación de La Brea conocida como Pit-91, el gran félido Smilodon fatalis y el cánido de tamaño medio Canis dirus, cuyos restos dan cuenta del 78% de la tafocenosis.Sociedad Española de Paleontología Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Déjà vu: on the use of meat resources by sabretooth cats, hominins, and hyaenas in the Early Pleistocene site of Fuente Nueva 3 (Guadix‑Baza Depression, SE Spain)

The late Early Pleistocene archaeological site of Fuente Nueva 3 (Orce, Guadix-Baza Depression, SE Spain), dated to ~1.4 Ma, provides evidence on the subsistence strategies of the first hominin population that dispersed in Western Europe. The site preserves Oldowan tool assemblages associated with abundant remains of large mammals. A small proportion of these remains show cut marks and percussion marks resulting from defleshing and bone fracturing, and a small proportion of bones also show tooth marks. Previous taphonomic studies of FN3 suggested that the hominins had secondary access to the prey leftovers abandoned by sabretooth cats and other primary predators. However, a recent analysis by Yravedra et al. (2021) of the frequency of anthropogenic marks and tooth marks has concluded that the hominins had primary access to the carcasses of a wide variety of ungulate prey, even though the frequency of evisceration marks is strikingly low. In this rebuttal, we analyse the patterns of bone preservation in FN3, which show that the exploitation of bone marrow by the hominins after hammerstone breakage was a usual activity at the site. Our study also reviews the evidence available on the lesser abilities of sabretooth cats for carcass processing compared to pantherine felids. This reinforces the hypothesis that primary predators provided the hominins the opportunity to scavenge sizeable chunks of meat and bone marrow of their prey carcasses before the arrival of hyaenas. Finally, we also provide new inferences on resource availability and competition intensity among the members of the carnivore guild in FN3, which reinforce our interpretation that a secondary access by the Oldowan hominins to the prey leftovers of sabretooth cats was an optimal foraging strategy in the Guadix-Baza Depression.Funding for open access publishing: Universidad Málaga/CBUA This work has been granted by projects CGL-2016-78577-P, CGL-2016-80975-P, and PID2019-111185GB-I00 of the Spanish Ministry of Science, Innovation and University, “Junta de Andalucía” (FEDER) project UMA18-FEDERJA-188, “Generalitat de Catalunya” grant GENCAT 2017SGR 859, and by Research Group RNM-146 from “Junta de Andalucía.” Funding for open access charge: Universidad de Málaga / CBU

Taking a look into the orbit of mammalian carnivorans

In this study, we explore the relationship between orbit anatomy and different ecological factors in carnivorous mammals from a phylogenetic perspective. We calculated the frontation (α), convergence (β), and orbitotemporal (Ω) angles of the orbit from 3D coordinates of anatomical landmarks in a wide sample of carnivores with different kinds of visual strategy (i.e. photopic, scotopic, and mesopic), habitat (i.e. open, mixed, and closed), and substrate use (i.e. arboreal, terrestrial, and aquatic). We used Bloomberg's K and Pagel's λ to assess phylogenetic signal in frontation, convergence, and orbitotemporal angles. The association of orbit orientation with skull length and ecology was explored using phylogenetic generalized least squares and phylogenetic manova, respectively. Moreover, we also computed phylomorphospaces from orbit orientation. Our results indicate that there is not a clear association between orbit orientation and the ecology of living carnivorans. We hypothesize that the evolution of the orbit in mammalian carnivores represents a new case of an ecological bottleneck specific to carnivorans. New directions for future research are discussed in light of this new evidence