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BackgroundDomestication, including selective breeding, can lead to morphological changes of biomechanical relevance. In birds, limb proportions and sternum characteristics are of great importance and have been studied in the past for their relation with flight, terrestrial locomotion and animal welfare. In this work we studied the effects of domestication and breed formation in limb proportions and sternum characteristics in chicken (Gallus gallus), mallard ducks (Anas plathyrhynchos) and Muscovy ducks (Cairina moschata).MethodsFirst, we quantified the proportional length of three long bones of the forelimb (humerus, radius, and carpometacarpus) and the hind limb (femur, tibiotarsus, and tarsometatarsus) in domestic chickens, mallard ducks, and Muscovy ducks and their wild counterparts. For this, we took linear measurements of these bones and compared their proportions in the wildvs.the domestic group in each species. In chicken, these comparisons could also be conducted among different breeds. We then evaluated the proportional differences in the context of static and ontogenetic allometry. Further, we compared discrete sternum characteristics in red jungle fowl and chicken breeds. In total, we examined limb bones of 287 specimens and keel bones of 63 specimens.ResultsWe found a lack of significant change in the proportions of limb bones of chicken and Muscovy duck due to domestication, but significant differences in the case of mallard ducks. Variation of evolvability, allometric scaling, and heterochrony may serve to describe some of the patterns of change we report. Flight capacity loss in mallard ducks resulting from domestication may have a relation with the difference in limb proportions. The lack of variation in proportions that could distinguish domestic from wild forms of chicken and Muscovy ducks may reflect no selection for flight capacity during the domestication process in these groups. In chicken, some of the differences identified in the traits discussed are breed-dependent. The study of the sternum revealed that the condition of crooked keel was not unique to domestic chicken, that some sternal characteristics were more frequent in certain chicken breeds than in others, and that overall there were no keel characteristics that are unique for certain chicken breeds. Despite some similar morphological changes identified across species, this study highlights the lack of universal patterns in domestication and breed formation.

A new left premaxillary bone is revealed by non-invasive imaging of the fossil basal ornithischian Laquintasaura venezuelae, from the Jurassic of Venezuela, South America, We report and describe the new left premaxillary bone of the basal ornithischian Laquintasaura venezuelae coming from a bonebed of the La Quinta Formation in the Andes of Venezuela. Previous dating of the bonebed based on U-Pb zircon analysis suggested an earliest Jurassic (Hettangian) maximum age. To our knowledge, for the first-time high-resolution computer tomography scanning was applied to rocks of this site to search for fossils, leading to the discovery reported here and the promise of this method to cope with unprepared blocks from the same site. We created a three-dimensional model of the fossil and show that the left premaxilla of L. venezuelae presents the unusual characteristic of a seven dental grooves count. This number is known only in other two basal thyreophorans such as Huayangosaurus taibaii and Gargoyleosaurus parkpini. This is consistent to the general trend reported for ornithischian evolution to lose premaxillary teeth, which suggests that Laquintasaura represents the plesiomorphic state of the character, with a high tooth count. Only with new anatomical data on Laquintasaura can we generate robust hypothesis of its evolutionary relationships, which address some of the earliest history of dinosaurs and their occurrence in the otherwise poorly documented equatorial areas of the globe.

We describe a trackway (LH-Mg-10-16) occurring in laminated carbonated limestones of the Las Hoyas locality, Serranía de Cuenca, Spain. It is unmistakably a large theropod dinosaur trackway encompassing two unusual aspects, namely, wide-steps, and a set of equally deformed left footprints (with a dislocated digit). The layer also preserves other vertebrate trails (fish Undichna) and different impressions in the sediment. To address these complex settings, we devised a multidisciplinary approach, including the ichnological and taphonomical descriptions, characterisation of the rock lithofacies using thin-sections, 3D structured-light digitalisation with a high precision of 200–400 μm, and a geometric morphometric comparison with a large sample of bipedal dinosaur trackways. Sedimentary analyses showed that the trackway was produced in a humid, benthonic microbial mat, the consistency and plasticity of which enabled the preservation of the details of the movement of the animal. The results of the geometric analysis indicate that the “wide-steps” of the trackway is not unusual compared to other trackways, providing evidence that it was made by a single individual with an estimated hip height approximately 2 m. Analogous pathologies in extant archosaurs that yield the combination of wide steps and deformed digits in the same trackway were considered. All results mutually support the hypothesis that a large theropod dinosaur, with a pathological foot, generated the trackway as it crossed an area of shallow water while slowly walking towards the main water source, thus stepping steadily over the benthonic mat over which multiple fish were swimming.