Bird neurocranial and body mass evolution across the end-Cretaceous mass extinction: The avian brain shape left other dinosaurs behind

Birds today are the most diverse clade of terrestrial vertebrates, and understanding why extant birds (Aves) alone among dinosaurs survived the Cretaceous-Paleogene mass extinction is crucial to reconstructing the history of life. Hypotheses proposed to explain this pattern demand identification of traits unique to Aves. However, this identification is complicated by a lack of data from non-avian birds. Here, we interrogate survivorship hypotheses using data from a new, nearly complete skull of Late Cretaceous (~70 million years) bird Ichthyornis and reassess shifts in bird body size across the Cretaceous-Paleogene boundary. Ichthyornis exhibited a wulst and segmented palate, previously proposed to have arisen within extant birds. The origin of Aves is marked by larger, reshaped brains indicating selection for relatively large telencephala and eyes but not by uniquely small body size. Sensory system differences, potentially linked to these shifts, may help explain avian survivorship relative to other dinosaurs.

New mammalian and avian records from the late Eocene La Meseta and Submeseta formations of Seymour Island, Antarctica

The middle-late Eocene of Antarctica was characterized by dramatic change as the continent became isolated from the other southern landmasses and the Antarctic Circumpolar Current formed. These events were crucial to the formation of the permanent Antarctic ice cap, affecting both regional and global climate change. Our best insight into how life in the high latitudes responded to this climatic shift is provided by the fossil record from Seymour Island, near the eastern coast of the Antarctic Peninsula. While extensive collections have been made from the La Meseta and Submeseta formations of this island, few avian taxa other than penguins have been described and mammalian postcranial remains have been scarce. Here, we report new fossils from Seymour Island collected by the Antarctic Peninsula Paleontology Project. These include a mammalian metapodial referred to Xenarthra and avian material including a partial tarsometatarsus referred to Gruiformes (cranes, rails, and allies). Penguin fossils (Sphenisciformes) continue to be most abundant in new collections from these deposits. We report several penguin remains including a large spear-like mandible preserving the symphysis, a nearly complete tarsometatarsus with similarities to the large penguin clade Palaeeudyptes but possibly representing a new species, and two small partial tarsometatarsi belonging to the genus Delphinornis. These findings expand our view of Eocene vertebrate faunas on Antarctica. Specifically, the new remains referred to Gruiformes and Xenarthra provide support for previously proposed, but contentious, earliest occurrence records of these clades on the continent.

An avian femur from the Late Cretaceous of Vega Island, Antarctic Peninsula: removing the record of cursorial landbirds from the Mesozoic of Antarctica

In 2006, a partial avian femur (South Dakota School of Mines and Technology (SDSM) 78247) from the Upper Cretaceous (Maastrichtian) Sandwich Bluff Member of the López de Bertodano Formation of Sandwich Bluff on Vega Island of the northern Antarctic Peninsula was briefly reported as that of a cariamiform—a clade that includes extant and volant South American species and many extinct flightless and cursorial species. Although other authors have since rejected this taxonomic assignment, SDSM 78247 had never been the subject of a detailed description, hindering a definitive assessment of its affinities. Here we provide the first comprehensive description, illustration, and comparative study of this specimen. Comparison of characters that may be assessed in this femur with those of avian taxa scored in published character matrices refutes the inclusion of SDSM 78247 within Cariamiformes, instead supporting its assignment to a new, as-yet unnamed large-bodied species within the genus Vegavis, and therefore its referral to a clade of semiaquatic anseriforms. Important character states diagnostic of Vegavis + Polarornis include strong craniocaudal bowing of the femoral shaft, the presence of a distinct fossa just proximal to the fibular trochlea, and the broad and flat shape of the patellar sulcus. Referral to Vegavis is based on the presence of a distinctive proximocaudal fossa and distolateral scar. This genus was previously known only from Vegavis iaai, a smaller-bodied taxon from the same locality and stratigraphic unit. Our reassignment of SDSM 78247 to Vegavis sp. removes the record of cariamiform landbirds from the Antarctic Cretaceous.

Estimating Flight Style of Early Eocene Stem Palaeognath Bird Calciavis grandei (Lithornithidae)

Lithornithids are volant stem palaeognaths from the Paleocene-Eocene. Except for these taxa and the extant neotropical tinamous, all other known extinct and extant palaeognaths are flightless. Investigation of properties of the lithornithid wing and its implications for inference of flight style informs understood locomotor diversity within Palaeognathae and may have implications for estimation of ancestral traits in the clade. Qualitative comparisons with their closest extant volant relatives, the burst-flying tinamous, previously revealed skeletal differences suggesting lithornithids were capable of sustained flight, but quantitative work on wing morphology have been lacking. Until comparatively recently, specimens of lithornithids preserving wing feather remains have been limited. Here, we reconstruct the wing of an exceptionally preserved specimen of the Early Eocene lithornithid Calciavis grandei and estimate body mass, wing surface area, and wing span. We then estimate flight parameters and compare our estimates with representatives from across Aves in a statistical framework. We predict that flight in C. grandei was likely marked by continuous flapping, and that lithornithids were capable of sustained flight and migratory behavior. Our results are consistent with previous hypotheses that the ancestor of extant Palaeognathae may also have been capable of sustained flight. Anat Rec, 303:1035-1042, 2020. © 2019 Wiley Periodicals, Inc.

Nocturnal giants: evolution of the sensory ecology in elephant birds and other palaeognaths inferred from digital brain reconstructions

The recently extinct Malagasy elephant birds (Palaeognathae, Aepyornithiformes) included the largest birds that ever lived. Elephant bird neuroanatomy is understudied but can shed light on the lifestyle of these enigmatic birds. Palaeoneurological studies can provide clues to the ecologies and behaviours of extinct birds because avian brain shape is correlated with neurological function. We digitally reconstruct endocasts of two elephant bird species, Aepyornis maximus and A. hildebrandti, and compare them with representatives of all major extant and recently extinct palaeognath lineages. Among palaeognaths, we find large olfactory bulbs in taxa generally occupying forested environments where visual cues used in foraging are likely to be limited. We detected variation in olfactory bulb size among elephant bird species, possibly indicating interspecific variation in habitat. Elephant birds exhibited extremely reduced optic lobes, a condition also observed in the nocturnal kiwi. Kiwi, the sister taxon of elephant birds, have effectively replaced their visual systems with hyperdeveloped olfactory, somatosensory and auditory systems useful for foraging. We interpret these results as evidence for nocturnality among elephant birds. Vision was likely deemphasized in the ancestor of elephant birds and kiwi. These results show a previously unreported trend towards decreased visual capacity apparently exclusive to flightless, nocturnal taxa endemic to predator-depauperate islands.

Best practices for digitally constructing endocranial casts: examples from birds and their dinosaurian relatives

The rapidly expanding interest in, and availability of, digital tomography data to visualize casts of the vertebrate endocranial cavity housing the brain (endocasts) presents new opportunities and challenges to the field of comparative neuroanatomy. The opportunities are many, ranging from the relatively rapid acquisition of data to the unprecedented ability to integrate critically important fossil taxa. The challenges consist of navigating the logistical barriers that often separate a researcher from high-quality data and minimizing the amount of non-biological variation expressed in endocasts - variation that may confound meaningful and synthetic results. Our purpose here is to outline preferred approaches for acquiring digital tomographic data, converting those data to an endocast, and making those endocasts as meaningful as possible when considered in a comparative context. This review is intended to benefit those just getting started in the field but also serves to initiate further discussion between active endocast researchers regarding the best practices for advancing the discipline. Congruent with the theme of this volume, we draw our examples from birds and the highly encephalized non-avian dinosaurs that comprise closely related outgroups along their phylogenetic stem lineage.

Potential for bias and low precision in molecular divergence time estimation of the Canopy of Life: an example from aquatic bird families

Uncertainty in divergence time estimation is frequently studied from many angles but rarely from the perspective of phylogenetic node age. If appropriate molecular models and fossil priors are used, a multi-locus, partitioned analysis is expected to equally minimize error in accuracy and precision across all nodes of a given phylogeny. In contrast, if available models fail to completely account for rate heterogeneity, substitution saturation and incompleteness of the fossil record, uncertainty in divergence time estimation may increase with node age. While many studies have stressed this concern with regard to deep nodes in the Tree of Life, the inference that molecular divergence time estimation of shallow nodes is less sensitive to erroneous model choice has not been tested explicitly in a Bayesian framework. Because of available divergence time estimation methods that permit fossil priors across any phylogenetic node and the present increase in efficient, cheap collection of species-level genomic data, insight is needed into the performance of divergence time estimation of shallow (<10 MY) nodes. Here, we performed multiple sensitivity analyses in a multi-locus data set of aquatic birds with six fossil constraints. Comparison across divergence time analyses that varied taxon and locus sampling, number and position of fossil constraint and shape of prior distribution showed various insights. Deviation from node ages obtained from a reference analysis was generally highest for the shallowest nodes but determined more by temporal placement than number of fossil constraints. Calibration with only the shallowest nodes significantly underestimated the aquatic bird fossil record, indicating the presence of saturation. Although joint calibration with all six priors yielded ages most consistent with the fossil record, ages of shallow nodes were overestimated. This bias was found in both mtDNA and nDNA regions. Thus, divergence time estimation of shallow nodes may suffer from bias and low precision, even when appropriate fossil priors and best available substitution models are chosen. Much care must be taken to address the possible ramifications of substitution saturation across the entire Tree of Life.

In vitro development to blastocysts of early porcine embryos produced in vivo or in vitro

The objective of this study was to compare the development of porcine embryos from the 2- and 4-cell stages to the blastocyst stage after in vivo or in vitro fertilization and in vivo or in vitro culture. Early-stage embryos were collected either from superovulated gilts 36 h after the second mating or after in vitro fertilization (IVF) of in vivo-matured oocytes, both followed by in vitro culture to the blastocyst stage. Blastocysts collected from superovulated donors served as controls. In the first experiment, a total of 821 2- and 4-cell embryos derived from in vivo-fertilized oocytes was cultured either in medium NCSU 23, modified Whittens' medium or modified KRB for 5 d. Significantly (P < 0.05 and P < 0.001) more embryos overcame the 4-cell block and developed to the blastocyst stage in medium NCSU 23 than in the 2 other culture media. Hatching was only observed in medium NCSU 23. In the second experiment, embryos derived from in vivo-matured oocytes fertilized in vitro were cultured in medium NCSU 23. Of 1869 mature oocytes 781 (41.8%) cleaved within 48 h after in vitro fertilization. A total of 715 embryos was cultured to the morula and blastocyst stages, and 410 (57.3%) overcame the developmental block stage, with 358 embryos (50.1%) developing to the morula and blastocyst stages. None of the embryos hatched, and the number of nuclei was significantly (P < 0.05) lower compared with that of in vivo-fertilized embryos (18.9 +/- 9.8 vs 31.2 +/- 5.8). In the third experiment, 156 blastocysts derived from in vitro fertilization and 276 blastocysts derived from in vivo fertilization and in vitro culture were transferred into synchronized recipients, while 164 blastocysts were transferred immediately after collection into 6 recipients, resulting in a pregnancy rate of 83.3%, with 35 piglets (on average 7.0) born. From the in vitro-cultured embryos, 58.3% (7/12) of the recipients remained pregnant at Day 35 after transfer, but only 33.3% maintained pregnancy to term, and 14 piglets (on average 3.5) were born. In contrast, the transfer of embryos derived from in vitro-fertilized oocytes did not result in pregnancies. It is concluded that 1) NCSU 23 is superior to modified Whittens' medium and modified KRB and 2) blastocysts derived from in vitro fertilization have reduced viability as indicated by the lower number of nuclei and failure to induce pregnancy upon transfer into recipients.

Tribulations and achievements: the early history of Olympism in Argentina

By the end of the nineteenth century, modern sport had enchanted the people of Argentina. At that time the nation enjoyed a remarkable degree of economic prosperity and embarked on increasing political democratization. These circumstances, along with the fact that the nation was represented from the beginning, in 1894, on the International Olympic Committee seemed to favour Argentina as the spearhead of the diffusion of Olympism throughout South America. However, the country only enjoyed its first official Olympic participation in the Paris Games of 1924 - a few months after the establishment of the Argentine Olympic Committee. This essay explores the reception and diffusion of Olympism in Argentina. It reveals a process of gradual adoption including conflicting views on the relationship between the state and sport, several attempts at institutionalization, international misunderstandings and the role of politics and class.

Inhibition of the ecto-ATPdiphosphohydrolase of Schistosoma mansoni by thapsigargin

ATPdiphosphohydrolases (ATPDases) are ubiquitous enzymes capable of hydrolyzing nucleoside di- and triphosphates. Although a number of possible physiological roles have been proposed for ATPDases, detailed studies on structure-function relationships have generally been hampered by the lack of specific inhibitors of these enzymes. We have previously characterized a Ca2+-activated ATPDase on the external surface of the tegument of Schistosoma mansoni, the etiologic agent of human schistosomiasis. In the present work, we have examined the effects of thapsigargin, a sesquiterpene lactone known as a high affinity inhibitor of sarco-endoplasmic reticulum calcium transport (SERCA) ATPase, on ATPDase activity. Whereas other lactones tested had little or no inhibitory action, thapsigargin inhibited ATP hydrolysis by the ATPDase (K(i) approximately 20 microM). Interestingly, hydrolysis of ADP was not inhibited by thapsigargin. The lack of inhibition of ATPase activity by orthovanadate, a specific inhibitor of P-type ATPases, and the inhibition of the Mg2+-stimulated ATP hydrolysis by thapsigargin ruled out the possibility that the observed inhibition of the ATPDase by thapsigargin could be due to the presence of contaminating SERCA ATPases in our preparation. Kinetic analysis indicated that a single active site in the ATPDase is responsible for hydrolysis of both ATP and ADP. Thapsigargin caused changes in both Vmax and Km for ATP, indicating a mixed type of inhibition. Inhibition by thapsigargin was little or not affected by changes in free Ca2+ or Mg2+ concentrations. These results suggest that interaction of thapsigargin with the S. mansoni ATPDase prevents binding of ATP or its hydrolysis at the active site, while ADP can still undergo catalysis.

Divalent cation dependence and inhibition of Schistosoma mansoni ATP diphosphohydrolase by fluorosulfonylbenzoyl adenosine

Hydrolysis of ATP or ADP catalyzed by the ATP diphosphohydrolase of Schistosoma mansoni tegument was measured in the presence of different cations. ATP diphosphohydrolase was stimulated by micromolar concentrations of either Ca2+ or Mg2+, Ca2+ producing threefold higher maximal activities than Mg2+. Kinetic studies indicated that Ca2+ and Mg2+ compete for the same binding site on the enzyme. The effect of covalent labeling of ATP diphosphohydrolase with the ATP analog fluorosulfonylbenzoyl adenosine (FSO2BzAdo) was studied. Schistosome tegument was passed through with Sephadex G-50 filtration centrifugation columns to remove endogenous nucleotides, and this was followed by labeling with FSO2BzAdo. Incubation of ATP diphosphohydrolase with 1 mM FSO2BzAdo for 1 h inhibited ATPase or ADPase activities by 60% and 50%, respectively. Addition of ATP together with FSO2BzAdo provided greater than 90% protection against FSO2BzAdo inactivation, indicating that FSO2BzAdo binds to an ATP-binding site on the ATP diphosphohydrolase. Furthermore, addition of FSO2BzAdo to a medium containing intact worms caused 30% and 50% inhibition of ATPase and ADPase activities, respectively, indicating that the ATP-binding site of diphosphohydrolase is accessible to FSO2BzAdo from the external surface of S. mansoni worms.

Erythrocytes contain cytoplasmic glycoproteins. O-linked GlcNAc on Band 4.1

Previously we reported that the novel protein-saccharide linkage, O-linked N-acetylglucosamine (GlcNAc), is found in abundance on proteins associated with the cytoplasmic and nucleoplasmic faces of the nuclear pore complex. Here we demonstrate that O-GlcNAc moieties are also added to human erythrocyte cytoplasmic proteins. Intact or permeabilized erythrocytes, as well as subcellular fractions, were labeled with bovine milk galactosyltransferase and UDP-[3H] galactose. The proportion of the incorporated label found on O-GlcNAc was determined by a variety of chemical and enzymatic techniques. The bulk of the O-GlcNAc residues are found in the cytoplasm of erythrocytes, the majority of which are on an as yet unidentified 65-kDa protein. In addition, we have determined that Band 4.1, a protein which serves as a bridge joining the cytoskeleton to the inner surface of the plasma membrane in erythrocytes, also contains O-GlcNAc moieties. One of the sites of O-GlcNAc addition has been localized to the last 117 amino acids of the carboxy terminus of Band 4.1.

Topography and polypeptide distribution of terminal N-acetylglucosamine residues on the surfaces of intact lymphocytes. Evidence for O-linked GlcNAc

Bovine milk galactosyltransferase has been used, in conjunction with UDP-[3H]galactose, as an impermeant probe for accessible GlcNAc residues on the surfaces of lymphocytes. Galactosylation of living thymic lymphocytes is dependent upon cell number, enzyme concentration, UDP-galactose concentration, and Mn2+ concentration. Kinetics of labeling are biphasic, leveling off at approximately 30 min. The data strongly indicate vectorial surface labeling and covalent attachment of galactose. Thymocytes, T-lymphocytes, and B-lymphocytes have approximately 10(6), 3 X 10(6), and 5 X 10(6) galactosylatable sites on their cell surfaces, respectively. Numerous proteins are exogalactosylated that differ quantitatively among the major functional subsets of lymphocytes. Negligible radioactivity is found in lipid. In thymocytes, 49% of the exogalactosylated oligosaccharides are alkali labile, whereas 80 and 90% of that derived from T-lymphocytes and B-lymphocytes can be beta-eliminated, respectively. Sensitivity of the intact proteins or tryptic peptides to the peptide: N-glycosidase also confirms the relative amounts of cell surface, N-linked and O-linked oligosaccharides which are exogalactosylated. Composition, size, and high performance liquid chromatography on two types of high resolution columns establish that the bulk of the exogalactosylated, beta-eliminated oligosaccharides are Gal beta 1-4GlcNAcitol. These data suggest the presence of O-glycosidically linked GlcNAc monosaccharide on many lymphocyte cell-surface proteins. However, additional experiments indicate that the majority of these moieties appear to be cryptic or inside the cell. Thus, these studies not only describe dramatic differences in the amounts and distribution of terminal GlcNAc residues on phenotypically different lymphocyte populations, but they also describe the presence of a novel protein-saccharide linkage, which is present on numerous lymphocyte proteins.