Some recent non-dino stuff:
Free pdf:
An organismâs ability to disperse influences many fundamental processes, from speciation and geographical range expansion to community assembly. However, the patterns and underlying drivers of variation in dispersal across species remain unclear, partly because standardised estimates of dispersal ability are rarely available. Here we present a global dataset of avian hand-wing index (HWI), an estimate of wing shape widely adopted as a proxy for dispersal ability in birds. We show that HWI is correlated with geography and ecology across 10,338 (>99%) species, increasing at higher latitudes and with migration, and decreasing with territoriality. After controlling for these effects, the strongest predictor of HWI is temperature variability (seasonality), with secondary effects of diet and habitat type. Finally, we also show that HWI is a strong predictor of geographical range size. Our analyses reveal a prominent latitudinal gradient in HWI shaped by a combination of environmental and behavioural factors, and also provide a global index of avian dispersal ability for use in community ecology, macroecology, and macroevolution.
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News:
Analysis of bird species reveals how wings adapted to their environment and behavior
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Free pdf:
Wallace's Line demarcates the transition between the differentiated regional faunas of Asia and Australia. However, while patterns of biotic differentiation across these two continental landmasses and the intervening island groups (Wallacea) have been extensively studied, patterns of long-term dispersal and diversification across this region are less well understood. Frogmouths (Aves: Podargidae) are a relictual family of large nocturnal birds represented by three extant genera occurring, respectively, in Asia, 'Sahul' (Australia and New Guinea) and the Solomon Islands, thus spanning Wallace's Line. We used new mitochondrial genomes from each of the extant frogmouth genera to estimate the timeline of frogmouth evolution and dispersal across Wallace's Line. Our results suggest that the three genera diverged and dispersed during the mid-Cenozoic between approximately 30 and 40 Mya. These divergences are among the oldest inferred for any trans-Wallacean vertebrate lineage. In addition, our results reveal that the monotypic Solomons frogmouth (Rigidipenna inexpectata) is one of the most phylogenetically divergent endemic bird lineages in the southwest Pacific. We suggest that the contemporary distribution of exceptionally deep divergences among extant frogmouth lineages may be explained by colonization of, and subsequent long-term persistence on, island arcs in the southwest Pacific during the Oligocene. These island arcs may have provided a pathway for biotic dispersal out of both Asia and Australia that preceded the formation of extensive emergent landmasses in Wallacea by at least 10 million years.
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Also, from last year but not yet mentioned on the DML:
Free pdf:
The Santa Cruz Formation constitutes one of the most representative units of the Early-Middle Miocene of South America for its abundant and rich fossil record of vertebrates. The diversity of extinct birds is known so far by at least 17 species grouped in 15 genera and at least 10 families. Most of the avian taxa described from these levels come from localities of the Santa Cruz Province placed next to or along the Atlantic coast. New specimens recovered from the RÃo Santa Cruz valley, with accurate geographic and stratigraphic provenances, are presented in this contribution. They include rheids, tinamids, and phorusrhacids.
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Free pdf:
Scott A. Hocknull, Richard Lewis, Lee J. Arnold, Tim Pietsch, Renaud Joannes-Boyau, Gilbert J. Price, Patrick Moss, Rachel Wood, Anthony Dosseto, Julien Louys, Jon Olley & Rochelle A. Lawrence (2020)
Extinction of eastern Sahul megafauna coincides with sustained environmental deterioration.
Nature Communications 11, Article number: 2250
doi:
https://doi.org/10.1038/s41467-020-15785-whttps://www.nature.com/articles/s41467-020-15785-wExplanations for the Upper Pleistocene extinction of megafauna from Sahul (Australia and New Guinea) remain unresolved. Extinction hypotheses have advanced climate or human-driven scenarios, in spite of over three quarters of Sahul lacking reliable biogeographic or chronologic data. Here we present new megafauna from north-eastern Australia that suffered extinction sometime after 40,100 (Â1700) years ago. Megafauna fossils preserved alongside leaves, seeds, pollen and insects, indicate a sclerophyllous forest with heathy understorey that was home to aquatic and terrestrial carnivorous reptiles and megaherbivores, including the worldâs largest kangaroo. Megafauna species diversity is greater compared to southern sites of similar age, which is contrary to expectations if extinctions followed proposed migration routes for people across Sahul. Our results do not support rapid or synchronous human-mediated continental-wide extinction, or the proposed timing of peak extinction events. Instead, megafauna extinctions coincide with regionally staggered spatio-temporal deterioration in hydroclimate coupled with sustained environmental change.
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News and blogs:
Humans coexisted with three-ton marsupials and car-sized lizards in ancient Australia
https://sciencex.com/news/2020-05-humans-coexisted-three-ton-marsupials-car-sized.html===
WHAT ARE MEGAFAUNA?
A CRIME SCENE OF THE PAST â INVESTIGATING TROPICAL ICE AGE MEGAFAUNA
DISCOVERING THE WORLDâS LARGEST KANGAROO-
PART 1: IN THE FIELD
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Free pdf:
The Ordovician saw major diversification in marine life abruptly terminated by the Late Ordovician mass extinction (LOME). Around 85% of species were eliminated in two pulses 1 m.y. apart. The first pulse, in the basal Hirnantian, has been linked to cooling and Gondwanan glaciation. The second pulse, later in the Hirnantian, is attributed to warming and anoxia. Previously reported mercury (Hg) spikes in Nevada (USA), South China, and Poland implicate an unknown large igneous province (LIP) in the crisis, but the timing of Hg loading has led to different interpretations of the LIP-extinction scenario in which volcanism causes cooling, warming, or both. We report close correspondence between Hg, Mo, and U anomalies, declines in enrichment factors of productivity proxies, and the two LOME pulses at the Ordovician-Silurian boundary stratotype (Dobâs Linn, Scotland). These support an extinction scenario in which volcanogenic greenhouse gases caused warming around the Katian-Hirnantian boundary that led to expansion of a preexisting deepwater oxygen minimum zone, productivity collapse, and the first LOME pulse. Renewed volcanism in the Hirnantian stimulated further warming and anoxia and the second LOME pulse. Rather than being the odd-one-out of the "Big Five" extinctions with origins in cooling, the LOME is similar to the others in being caused by volcanism, warming, and anoxia.