Neo and paleo virtual ornithology

La visualización y análisis de los fósiles asistido por computadoras ha revolucionado el estudio de los organismos extintos. Técnicas novedosas permiten caracterizar los restos en tres dimensiones y acceder a detalles sin precedentes. Esto ha permitido a los paleontólogos ganar importantes conocimientos sobre la anatomía, el desarrollo, la función y hasta la conservación. Las reconstrucciones digitales se pueden utilizar en análisis funcionales y en la puesta a prueba rigurosa de hipótesis sobre la paleobiología de los organismos extintos. Estos enfoques están transformando nuestra comprensión de la vida en el pasado y también de los organismos vivientes en general. El empleo de técnicas no invasivas permite la captura de grandes cantidades de datos útiles sin dañar los especímenes que se están estudiando. Debido a que los datos digitales se pueden compartir de forma instantánea y global, equipos de científicos pueden trabajar en para­lelo, acelerando el ritmo de las investigaciones. En este trabajo se ejemplifican casos en los cuales a partir de modelos virtuales se pueden abordar problemas morfológicos en aves.Visualization and analysis of fossils assisted by computers have revolutionized the study of extinct organisms. Innovative techniques allow to characterize the remains in three dimensions with unprecedented detail, allowing paleontologists to gain important knowledge about anatomy, development, function and even conservation. Digital reconstructions can be used in functional analysis and rigorous testing of hypotheses on the paleobiology of extinct organisms. These approaches are transforming our understanding about life in the past and also of living organisms in general. The use of non-invasive techniques enables capturing large amounts of data without damaging the specimens under study. As digital data can be shared instantly and globally, teams of scientists can work in parallel, accelerating research time. In this paper, cases in which virtual models were used to assess morphological problems are shown

Flexibility along the Neck of the Neogene Terror Bird Andalgalornis steulleti (Aves Phorusrhacidae)

BACKGROUND: Andalgalornis steulleti from the upper Miocene-lower Pliocene (≈6 million years ago) of Argentina is a medium-sized patagornithine phorusrhacid. It was a member of the predominantly South American radiation of 'terror birds' (Phorusrhacidae) that were apex predators throughout much of the Cenozoic. A previous biomechanical study suggests that the skull would be prepared to make sudden movements in the sagittal plane to subdue prey. METHODOLOGY/PRINCIPAL FINDINGS: We analyze the flexion patterns of the neck of Andalgalornis based on the neck vertebrae morphology and biometrics. The transitional cervical vertebrae 5th and 9th clearly separate regions 1-2 and 2-3 respectively. Bifurcate neural spines are developed in the cervical vertebrae 7th to 12th suggesting the presence of a very intricate ligamentary system and of a very well developed epaxial musculature. The presence of the lig. elasticum interespinale is inferred. High neural spines of R3 suggest that this region concentrates the major stresses during downstrokes. CONCLUSIONS/SIGNIFICANCE: The musculoskeletal system of Andalgalornis seems to be prepared (1) to support a particularly big head during normal stance, and (2) to help the neck (and the head) rising after the maximum ventroflexion during a strike. The study herein is the first interpretation of the potential performance of the neck of Andalgalornis in its entirety and we considered this an important starting point to understand and reconstruct the flexion pattern of other phorusrhacids from which the neck is unknown

Mechanical Analysis of Feeding Behavior in the Extinct “Terror Bird” Andalgalornis steulleti (Gruiformes: Phorusrhacidae)

The South American phorusrhacid bird radiation comprised at least 18 species of small to gigantic terrestrial predators for which there are no close modern analogs. Here we perform functional analyses of the skull of the medium-sized (∼40 kg) patagornithine phorusrhacid Andalgalornis steulleti (upper Miocene–lower Pliocene, Andalgalá Formation, Catamarca, Argentina) to assess its mechanical performance in a comparative context. Based on computed tomographic (CT) scanning and morphological analysis, the skull of Andalgalornis steulleti is interpreted as showing features reflecting loss of intracranial immobility. Discrete anatomical attributes permitting such cranial kinesis are widespread phorusrhacids outgroups, but this is the first clear evidence of loss of cranial kinesis in a gruiform bird and may be among the best documented cases among all birds. This apomorphic loss is interpreted as an adaptation for enhanced craniofacial rigidity, particularly with regard to sagittal loading. We apply a Finite Element approach to a three-dimensional (3D) model of the skull. Based on regression analysis we estimate the bite force of Andalgalornis at the bill tip to be 133 N. Relative to results obtained from Finite Element Analysis of one of its closest living relatives (seriema) and a large predatory bird (eagle), the phorusrhacid's skull shows relatively high stress under lateral loadings, but low stress where force is applied dorsoventrally (sagittally) and in “pullback” simulations. Given the relative weakness of the skull mediolaterally, it seems unlikely that Andalgalornis engaged in potentially risky behaviors that involved subduing large, struggling prey with its beak. We suggest that it either consumed smaller prey that could be killed and consumed more safely (e.g., swallowed whole) or that it used multiple well-targeted sagittal strikes with the beak in a repetitive attack-and-retreat strategy

Tempo and Pattern of Avian Brain Size Evolution

Relative brain sizes in birds can rival those of primates, but large-scale patterns and drivers of avian brain evolution remain elusive. Here, we explore the evolution of the fundamental brain-body scaling relationship across the origin and evolution of birds. Using a comprehensive dataset sampling> 2,000 modern birds, fossil birds, and theropod dinosaurs, we infer patterns of brain-body co-variation in deep time. Our study confirms that no significant increase in relative brain size accompanied the trend toward miniaturization or evolution of flight during the theropod-bird transition. Critically, however, theropods and basal birds show weaker integration between brain size and body size, allowing for rapid changes in the brain-body relationship that set the stage for dramatic shifts in early crown birds. We infer that major shifts occurred rapidly in the aftermath of the Cretaceous-Paleogene mass extinction within Neoaves, in which multiple clades achieved higher relative brain sizes because of a reduction in body size. Parrots and corvids achieved the largest brains observed in birds via markedly different patterns. Parrots primarily reduced their body size, whereas corvids increased body and brain size simultaneously (with rates of brain size evolution outpacing rates of body size evolution). Collectively, these patterns suggest that an early adaptive radiation in brain size laid the foundation for subsequent selection and stabilization

The Network Ontogeny of the Parrot: Altriciality, Dynamic Skeletal Assemblages, and the Avian Body Plan

We analyze the connectivity patterns and fusion events among bones leading to the adult skeletal organization during the development of the superaltricial monk parakeet (Myiopsitta monachus, Psittaciformes), providing insights about the functional and evolutionary significance in the avian structural design. By using whole mount specimens stained for cartilage and bone, we apply anatomical network analysis (AnNA) to study the ontogenetic trajectory of the entire skeleton from embryonic stage 34 to adult. As bones condense, connect, and fuse to each other, we follow skeletal assemblages forming networks that change dynamically as the monk parakeet grows. Our results show that the pelvic girdle connects with the vertebral column prior to the pectoral girdle and that the pelvic girdle and hindlimbs connection begins and ends before that of the pectoral girdle and the forelimbs. We hypothesize that connections of the girdles and limbs could be linked to the altriciality of the species due to requirements for active movement in the use of the hindlimbs inside the nest, but not the need to use forelimbs to fly until much later. Further, as bones of the skull and pelvis fuse during development they form the largest and more connected assemblages, acting as attractors to connect to other bones, showing congruence between the connectivity pattern at each ontogenetic stage and the characteristic avian body plan.Facultad de Ciencias Veterinaria

"THE PRESENT STATE OF KNOWLEDGE OF THE CENOZOIC BIRDS OF ARGENTINA" BY TONNI 1980: FOUR DECADES AFTER

“The present state of knowledge of the Cenozoic birds of Argentina” published in Contributions in Sciences in 1980, written by the argentine paleontologist Eduardo Pedro Tonni, became a must-read for those interested in the record of fossil birds. In that work, all the records known up to that time are compiled and some comments are made. Since then, there have been crucial advances in unraveling the diversity of Cenozoic birds in Argentina. Based on that work, here is a detailed updated and annotated list of all known avian records in Argentina that includes representatives of Palaeognathae (Tinamiformes and Rheiformes), Galloanseres (Anseriformes) and Neoaves (Sphenisciformes, Suliformes, Charadriiformes, Phoenicopteriformes, “Ciconiiformes”, “Gruiformes”, Pelecaniformes, Coraciimorphae, Cathartiformes, Accipitriformes, Falconiformes, Cariamiformes and Passeriformes). Besides, a substantial contribution is that here are photographs of the holotypes of all the new species that were nominated after Tonni's work and a table that compiles the main bibliographic information referring to the systematic history of each taxon

A new species of the Pleistocene furnariid <i>Pseudoseisuropsis</i> (Aves, Passeriformes)

<p><i>Pseudoseisuropsis wintu</i> sp. nov. is described from cranial material that had formerly been designated as a paratype of the extinct <i>Pseudoseisuropsis nehuen</i>. Thorough comparisons were made between the cranial specimens ascribed to <i>Pseudoseisuropsis</i> and many extant furnariid species. This new species is lower Pleistocene in age and increases the known diversity of <i>Pseudoseisuropsis</i> to three species. Cladistic analyses were performed using 43 cranial characters and a backbone constraint based on a well-supported phylogeny from a recent molecular analysis. In the most parsimonious tree, <i>Pseudoseisuropsis</i> was retrieved as a sister group of woodcreepers (Dendrocolaptinae) with low support. However, slightly suboptimal hypotheses, which could not be completely ruled out, suggest that this genus may be more closely related to other clades of Furnariidae. Hence, we agree with previous authors in regarding <i>Pseudoseisuropsis</i> as Furnariidae Incertae sedis. In addition, two fragmentary fossils ascribed to <i>Pseudoseisuropsis</i> were included in taxonomic comparisons: <i>P. cuelloi</i>, in order to assess the possibility that <i>P. wintu</i> sp. nov. belongs to that species, and another paratype of <i>P. nehuen</i>, to reassess its taxonomic identity.</p> <p>http://zoobank.org/urn:lsid:zoobank.org:pub:D26FF563-B9DB-48BD-BA9F-8C54CD13F03E</p> <p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">www.tandfonline.com/UJVP</a></p> <p>Citation for this article: Stefanini, M. I., R. O. Gómez, and C. P. Tambussi. 2016. A new species of the Pleistocene furnariid <i>Pseudoseisuropsis</i> (Aves, Passeriformes). Journal of Vertebrate Paleontology. DOI: 10.1080–02724634.2016.1100630.</p