Pionoolithus quyuangangensis oogen. & oosp. nov.
HE Qing, ZHANG Shukang, XING Lida, JIANG Qin, AN Yanfei & YANG Sen (2019)
A New Oogenus of Dendroolithidae from the Late Cretaceous in the Quyuangang Area, Henan Province, China.Â
Acta Geologica Sinica 93(2): 477-478 (English edition)
DOIï10.1111/1755-6724.13779
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The Quyuangang dinosaur eggs from the Late Cretaceous in the Henan Province, China, can be assigned to a new oogenus and a new oospecies Pionoolithus quyuangangensis based on the spherical shape, the close arrangement in the nest, and asymmetrically branched eggshell units.
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Gerald MAYR & Thierry SMITH (2019)
New Paleocene bird fossils from the North Sea Basin in Belgium and France.
Geologica Belgica 37 (1-2)
We describe new avian remains from Paleocene localities of Belgium and France. Four bones from the early to middle Selandian of Maret (Belgium) are among the earliest Cenozoic avian remains known from Europe and include the oldest temporally well constrained European records of the Gastornithidae, as well as tentative records of the palaeognathous Lithornithidae and the Ralloidea. A more comprehensive fossil assemblage from the middle Thanetian of Templeuve (France) contains multiple bones of the Lithornithidae as well as a record of the Pelagornithidae. Specimens from the latest Thanetian of Rivecourt-Petit PÃtis (France) are tentatively assigned to the Ralloidea and Leptosomiformes (cf. Plesiocathartes). Because of the fragmentary nature of the fossils, the taxonomic identity of a number of other specimens remains uncertain. We note, however, that Paleocene avifaunas of Europe and North America appear to have had different compositions and only a few taxa, such as the palaeognathous Lithornithidae, are known from both continents. This suggests that the very similar early Eocene avifaunas of Europe and North America are the result of early Cenozoic dispersal events.
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Mark C. DeBlois & Ryosuke Motani (2019)
Flipper bone distribution reveals flexible trailing edge in underwater flying marine tetrapods.
Journal of Morphology (advance online publication)
Hydrofoilâshaped limbs (flipperâhydrofoils) have evolved independently several times in secondarily marine tetrapods and generally fall into two functional categories: (1) those that produce the majority of thrust during locomotion (propulsive flipperâhydrofoils); (2) those used primarily to steer and resist destabilizing movements such as yaw, pitch, and roll (controller flipperâhydrofoils). The morphological differences between these two types have been poorly understood. Theoretical and experimental studies on engineered hydrofoils suggest that flapping hydrofoils with a flexible trailing edge are more efficient at producing thrust whereas hydrofoils used in steering and stabilization benefit from a more rigid one. To investigate whether the trailing edge is generally more flexible in propulsive flipperâhydrofoils, we compared the bone distribution along the chord in both flipper types. The propulsive flipperâhydrofoil group consists of the forelimbs of Chelonioidea, Spheniscidae, and Otariidae. The controller flipperâhydrofoil group consists of the forelimbs of Cetacea. We quantified bone distribution from radiographs of species representing more than 50% of all extant genera for each clade. Our results show that the proportion of bone in both groups is similar along the leading edge (0â40% of the chord) but is significantly less along the trailing edge for propulsive flipperâhydrofoils (40â80% of the chord). Both flipperâhydrofoil types have little to no bony tissue along the very edge of the trailing edge (80â100% of the chord). This suggests a relatively flexible trailing edge for propulsive flipperâhydrofoils compared to controller flipperâhydrofoils in line with findings from prior studies. This study presents a morphological correlate for inferring flipperâhydrofoil function in extinct taxa and highlights the importance of a flexible trailing edge in the evolution of propulsive flipperâhydrofoils in marine tetrapods.
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