Some recent avian papers:
Abundant well-preserved bird tracks from lacustrine Green River Formation (Eocene) deposits in Utah, are diverse and paleoecologically significant, but remain poorly known. Three of the four previously reported morphotypes (A-D) are named here for the first time with two representing new ichnotaxa. In order of increased footprint length (L) the ichnotaxa are: cf. Avipeda phoenix (L = 2.0 cm); Quadridigitus semimembranus ichnogen. et ichnosp. nov. (L = ~3.5 cm); Jindongornipes falkbuckleyi ichnosp. nov. (L ~ 8.0 cm); and previously named, web-footed Presbyornithiformipes feduccii (L = 9.5 cm). Collectively these avian ichnotaxa, associated invertebrate traces including ubiquitous nematode trails (Cochlichnus), and other rarer, small tetrapod tracks represent the "shorebird" ichnofacies or ichnocoenosis. However, the local track assemblages from the Uinta Basin do not correspond to the avian body fossil record from multiple Green River basins in the larger region. Thus, both records are essential for a cumulative picture. The Green River ichnotaxa are morphologically similar to those from lake basins in the Korean Cretaceous, and modern shorebird assemblages. As modern shorebirds are not known from Cretaceous or Eocene body fossils, the most plausible explanation is community convergence, among taxonomically disparate, but ecologically convergent trackmakers. Community convergence concepts help refine the ichnofacies paradigm.
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Extant cassowaries (Casuarius ) are unique flightless birds found in the tropics of IndoâAustralia. They have garnered substantial attention from anatomists with focus centered on the bony makeup and function of their conspicuous cranial casques, located dorsally above the orbits and neurocranium. The osteological patterning of the casque has been formally described previously; however, there are differing interpretations between authors. These variable descriptions suggest that an anatomical understanding of casque anatomy and its constituent elements may be enhanced by developmental studies aimed at further elucidating this bizarre structure. In the present study, we clarify casque osteology of the southern cassowary (C. casuarius ) by detailing casque anatomy across an extensive growth series for the first time. We used microâcomputed tomography (ÎCT) imaging to visualize embryonic development and postâhatching ontogeny through adulthood. We also sampled closely related emus (Dromaius novaehollandiae ) and ostriches (Struthio camelus ) to provide valuable comparative context. We found that southern cassowary casques are comprised of three paired (i.e., nasals, lacrimals, frontals) and two unpaired elements (i.e., mesethmoid, median casque element). Although lacrimals have rarely been considered as casque elements, the contribution to the casque structure was evident in ÎCT images. The median casque element has often been cited as a portion of the mesethmoid. However, through comparisons between immature C. casuarius and D. novaehollandiae we document the median casque element as a distinct unit from the mesethmoid.
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