Ben Creisler
Some recent non-dino papers:
Free pdf:
Pedro L. Godoy, Roger B. J. Benson, Mario Bronzati & Richard J. Butler (2019)
The multi-peak adaptive landscape of crocodylomorph body size evolution.
bioRxiv 405621;Â
Background: Little is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3-7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller (< 1.2 m). This suggests a pattern of size increase through time that could be caused by multi-lineage evolutionary trends of size increase or by selective extinction of small-bodied species. In this study, we characterise patterns of crocodylomorph body size evolution using a model fitting-approach (with cranial measurements serving as proxies). We also estimate body size disparity through time and quantitatively test hypotheses of biotic and abiotic factors as potential drivers of crocodylomorph body size evolution.Â
Results: Crocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent essentially continually decreases in disparity since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Cope's rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions.Â
Conclusions: Shifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution than do climatic factors, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors.
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A. D. Ryanskaya, D. V. Kiseleva, O. P. Shilovsky & E. S. Shagalov (2019)
XRD study of the Permian fossil bone tissue.
Powder Diffraction (advance online publication)
This paper is devoted to the X-ray diffraction study of bone fragments of Permian parareptile Deltavjatia vjatkensis obtained from the Kotelnich vertebrate fossil site, one of the richest of the Permian period, which is characterized by the excellent preservation of fossil remains because of their burial in a silty anaerobic environment similar to modern bogs. The bone is well-preserved and consists of fluorapatite, calcite, quartz, and dolomite. The refined apatite unit-cell parameters of a and b-axis (9.3526 Â 0.0001 and 9.3587 Â 0.0001) Ã and c-axis (6.8930 Â 0.0001 and 6.8968 Â 0.0001) Ã correspond to F-apatite. Crystallinity index determined as the full width at half maximum of the 002 reflection in degrees 2Î is 0.266â0.250, which is typical for Mesozoic vertebrate bones. Apatite crystallite size (length 70.3â74.9 nm, width 30.7â30.3 nm) in fossil pareiasaur bone is larger than in subfossil and recent mammal bone and is in a good agreement with the values for seismosaurus bone. Both crystallite size and aspect ratio (2.3â2.5) are independent of the fossil pareiasaur bone length.
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Li & Wenze You (2019)
Lower Cretaceous turtle tracks from Hekou Group of Northwest China.
Cretaceous Research (advance online publication)
Two small assemblages of turtle swim tracks from the Hekou Group, Gansu Province, represent the sixth and seventh reports of turtle tracks from the Cretaceous of China. One assemblage from Liujiaxia Dinosaur National Geopark, with seven tracks, is interpreted to represent a partial trackway with a few isolated tracks, and another one with six tracks from the Fangtai site is interpreted to represent turtle swim tracks, including one inferred manus pes set. At least five turtle body fossil taxa are known from the Cretaceous body fossil record in Gansu, and although no one taxon can be matched with the tracks described here based on size all can be considered as possible potential trackmakers.
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Also:
Matthew Walker & Stuart Humphries (2019)
3D Printing: Applications in evolution and ecology.
Ecology and Evolution (Early View)
In the commercial and medical sectors, 3D printing is delivering on its promise to enable a revolution. However, in the fields of Ecology and Evolution we are only on the brink of embracing the advantages that 3D printing can offer. Here we discuss examples where the process has enabled researchers to develop new techniques, work with novel species, and to enhance the impact of outreach activities. Our aim is to showcase the potential that 3D printing offers in terms of improved experimental techniques, greater flexibility, reduced costs and promoting open science, while also discussing its limitations. By taking a general overview of studies using the technique from fields across the broad range of Ecology and Evolution, we show the flexibility of 3D printing technology and aim to inspire the next generation of discoveries.