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Taphophoyx hodgei gen. & sp. nov.
David W. Steadman & Oona M. Takano (2019)
A new genus and species of heron (Aves: Ardeidae) from the late Miocene of Florida.Â
Bulletin of the Florida Museum of Natural History 55(9):174â186.
From the recently discovered Montbrook locality, Levy County, Florida (late Miocene; late Hemphillian land mammal age), a complete coracoid and nearly complete scapula represent a large heron that we name Taphophoyx hodgei new genus and species. While the phylogenetic affinities of T. hodgei are not well resolved, the tiger-herons Tigrisoma spp. or boat-billed heron Cochlearius cochlearius (both Neotropical) may be the closest living relative(s) of Taphophoyx, based in large part on several shared characters of the facies articularis clavicularis and facies articularis humeralis. Nevertheless, the coracoid of Taphophoyx has a uniquely prominent facies articularis humeralis and a uniquely sterno-ventral surface of corpus coracoidei. All 21 taxa of birds recorded thus far from Montbrook (mostly aquatic forms such as swans, ducks, geese, grebes, cormorants, ibises, sandpipers, etc.) probably represent extinct species, although is the only one assigned to an extinct genus.
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Alejandro Serrano-MartÃnez, Fabien Knoll, IvÃn NarvÃez & Francisco Ortega (2019)
Brain and pneumatic cavities of the braincase of the basal alligatoroid Diplocynodon tormis (Eocene, Spain).
Journal of Vertebrate Paleontology Article: e1572612Â
A well-preserved braincase of the basal alligatoroid Diplocynodon tormis was found in the middle Eocene site of 'Teso de la Flecha,' Salamanca, Spain. The specimen was scanned using computed tomography (CT), and its inner cavities were digitally rendered in three dimensions. Most bones of the left side are missing, so the reconstruction was based mainly on the right half of the braincase. The endocast of the brain cavity, nerves, part of the inner ear, and blood vessel canals was reconstructed, as well as a complex network of air-filled cavities around the hindbrain formed by the median pharyngeal sinus and pharyngotympanic sinus systems. Inner cavities of the skull are considered to be conservative structures. The comparison of this specimen with several extant crocodilians (Alligatoroidea, Crocodyloidea, and Gavialoidea) allows us to identify a neuroanatomical evolutionary pattern that matches current phylogenetic hypotheses. All internal cavities of the braincase of Diplocynodon are similar to those of other studied eusuchians, with some noteworthy differences in shape and size, particularly regarding the cerebrum and the paratympanic sinus system. Diplocynodon tormis shows a combination of alligatoroid synapomorphies and crocodylian symplesiomorphies in its internal cavities, consistent with its phylogenetic placement as a basal alligatoroid.
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Grzegorz Sadlok (2019)Â
Brasilichnium-like tracks from the Lower Triassic of the Holy Cross Mountains, Poland.
Neues Jahrbuch fÃr Geologie und PalÃontologie - Abhandlungen 292(1): 103-112 (10)
This paper describes an assemblage of minute tracks preserved on a slab of sandstone from the Lower Triassic Tumlin Sandstone (Holy Cross Mountains, Poland). The slab surface of 766.9 cm2 is covered with numerous tracks differing in size and preservation (n = 1087). Calculated track density is ~1.4 track/cm2. The size of individual tracks ranges from 0.19 to 94.8 mm2. Smaller tracks are preserved as indistinct depressions. Locally, they display a linear arrangement and may represent invertebrate trackways or vertebrate undertracks (inconclusive). Larger tracks show more details and most probably were produced by vertebrates. Locally, sets of manual and pedal imprints are observed, the pedal ones are larger. The well-preserved pedal imprints comprise a broad "heel" area and four relatively short digital imprints. Trackways are difficult to discern due to a high number of tracks. Digital techniques of visualization are used as an aid in track pattern recognition. Small synapsids were the likely trackmakers. The tracks resemble Brasilichnium ichnogenus in terms of track morphology, pes-manus size difference, pes pace angulation and environmental settings. However, the Tumlin Sandstone tracks are Early Triassic, whereas Brasilichnium is Late TriassicEarly Jurassic and Early Cretaceous in age. Predecessors of Brasilichnium tracemakers could have produced the described tracks.
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Madeleine Beekman, Michael Thompson & Marko Jusup (2019)
Thermodynamic constraints and the evolution of parental provisioning in vertebrates.Â
Behavioral Ecology, arz025Â (advance online publication)
Why is postnatal parental provisioning so rare in ectothermic vertebrates while prolonged parental care is almost ubiquitous in endotherms? We argue that the scarcity of postnatal parental care is a result of ectothermy itself. While almost all endothermic young require prolonged postnatal care due to thermal constraints, ectothermic physiology does not pose the same constraint. Most ectothermic young are thus independent from birth. Ectothermic mothers are better off investing in future reproductive events than to continue investing into independent young, because the cost of feeding young does not outweigh the benefits. Ectothermy further releases the constraint on offspring size resulting in offspring of ectothermic vertebrates often being much smaller than their parents. When parents and offspring differ greatly in size, both tend to specialize on different diets, making the feeding of young by much larger individuals not impossible, but less likely. Additionally, when the size difference between parents and offspring is significant, both are likely to live in different habitats. Such spatial segregation is also less conducive to the evolution of parental care. In those species where parents and offspring are not spatially separated and parental care does occur, it is mainly restricted to the guarding of eggs or juveniles; parents of very few species provide their offspring with food. We conclude that parental care beyond the guarding of eggs or young is much less likely to evolve in ectothermic vertebrates compared with endothermic vertebrates, unless there are exceptional circumstances that strongly select for parents to provide for their offspring.
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Yanhong Pan, Franz T. FÃrsich, Patrick Chellouche & Liang Hu (2019)Â
Taphonomy of fish concentrations from the Upper Jurassic Solnhofen Plattenkalk of Southern Germany.
Neues Jahrbuch fÃr Geologie und PalÃontologie - Abhandlungen 292(1): 73-92
The density of vertebrate fossils on bedding planes is generally very low in the Upper Jurassic plattenkalks forming the Solnhofen fossil LagerstÃtte. There are, however, a few bedding planes where large concentrations of the small fish Leptolepides sprattiformis (Blainville, 1818) occur. The aim of this paper is to analyse and interpret these fish concentrations from a taphonomic point of view. For this purpose, the taphonomic features of L. sprattiformis concentrations on three large slabs were semi-quantitatively analysed. The concentrations of individuals on bedding planes are explained as recording local mass mortality events caused by tropical storms that, for short intervals, disrupted the pycnocline which separated hypersaline, oxygen-poor to anoxic bottom waters from normal marine surface waters in the Plattenkalk basins. Mass mortality is supported by tetany features such as gaping jaws, hyperextended branchiostegal rays, and splayed fins, which occur in the majority of the specimens. The generally excellent preservation of the fish resulted from lack of postmortem floatation, rapid burial and/or overgrowth by microbial films, and quick re-establishment of the pycnocline with inhospitable conditions on the basin floor. The post-mortem concave-arching of the backbones and various displacements of the vertebral column were most likely caused by varying decay resistance of soft tissues and the pressure of decay gases in the body cavities, respectively. The taphonomic analysis of fish concentrations can provide very detailed palaeoenvironmental information and serves as an independent line of evidence for palaeoenvironmental reconstructions that complements geochemical and sedimentary data.
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Benjamin J. Burger, Margarita Vargas Estrada & Mae Sexaue rGustin (2019)
What caused Earth's largest mass extinction event? New evidence from the Permian-Triassic boundary in northeastern Utah.Â
Global and Planetary Change 177: 81-100
Highlights
Coal ignited by volcanic activity caused Earth's largest mass extinction
Global warming upwelled deep ocean methane hydrate resulting in an anoxic ocean
Active swimming animals were best adapted to the new environmental conditions
Knowledge of the event will aid researchers forecasting changes facing Earth today
Abstract
The discovery of a Permian-Triassic boundary section in northeastern Utah provided an opportunity to study the chemistry and geology associated with this event that led to one of the greatest mass extinctions on the planet. From 83% to 97% of the species living on the planet went extinct during this relatively short interval of geological time that defines the major geological boundary between the Paleozoic and Mesozoic Eras. The cause and resulting sequence of events that led to this extinction have puzzled geologists for years. The new stratigraphic section in Utah provided a framework for reconstruction of the chemistry that was in the ocean during the mass extinction. Geochemical analysis of the section demonstrates, moving across the boundary from the Paleozoic to the Mesozoic, a significant drop in carbonate and total organic carbon, and a delayed occurrence of pyrite. Carbon isotope ratios (Î13C) show a negative excursion in carbonate with ratios dropping from 2.59â to â3.63â. Elevated mercury is present at the boundary with a 4-fold increase from background levels. The boundary layer also has elevated zinc, lead, strontium, and nickel, but not at high enough levels to indicate a volcanic ash source. There is no evidence in concentrations of siderophile and chalcophile elements for an extraterrestrial impact. The stratigraphic section in Utah supports the theory of a massive release of carbon dioxide, resulting in the acidification of the oceans. High levels of mercury, as well as elevated levels of zinc and lead, implicate a coal source triggered by the contemporary Siberian Traps sill complex. The delay of enriched sulfur and barium content in the stratigraphic record indicates an anoxic ocean and upwelling of methane hydrates from depth. Further study of this stratigraphic section will aid our understanding of the global impact these catastrophic events had on life.