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[dinosaur] Pterosaur vertebrae pneumatic foramina (free pdf) + feather evolution




Ben Creisler
bcreisler@gmail.com

Some recent papers:


Free pdf:

Richard Buchmann and Taissa Rodrigues (2019)Â
The Evolution of Pneumatic Foramina in Pterosaur Vertebrae.Â
Anais da Academia Brasileira de CiÃncias 91, suppl.2: e20180782.ÂÂ

Free pdf:

Pterosaurs possess skeletal pneumatization, which can be assessed externally through the observation of pneumatic foramina. These foramina vary in position, shape, and number among taxa. Here we propose new characters referring to the position and number of pneumatic foramina present in cervical and dorsal vertebrae of pterosaurs. A cladistic analysis was performed after first-hand study of material in collections and using data from the literature in order to test these new characters for homology, and they were subsequently mapped in a strict consensus tree. The analysis resulted in nine equally parsimonious trees with 215 steps each. The strict consensus tree obtained does not present significant differences in relation to trees obtained in previous studies. The mapping performed identified that most pneumatic foramina evolved independently in several lineages, and only two of the eight added characters appeared once in the evolution of pterosaurs. In general, pneumatic foramina were more common in the Dsungaripteroidea, however, the flattened preservation of non-pterodactyloids and in the Archaeopterodactyloidea often precludes their visualization, and therefore the presence of vertebral pneumatization may be broaden with the discovery of new, better preserved specimens.

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Y. P. Zhao & X. Y. Fan (2019)
Feather evolution from knotted barbules to hooked and unhooked barbules and its finite element analysis.
Micron 122: 28-31


Highlights

The process of the knotted barbules forming barbules through evolutionary.
A growth model of feather plume was proposed.
Metlab 2D contour microstructure of sectioned section of knotted feather.
Three-dimensional structural models of barbules were established.
Finite element stress analysis.


Abstract

Experiments involving scanning electron microscopy of the microstructure of barbules and optical microscopy of knotted barbules were conducted: the behaviour of knotted barbules, and their evolution to form a branch of hooked barbules and unhooked barbules were analysed. A growth model for a feather plume was proposed. MATLABâ 2-d contour microstructures of sectioned knotted feathers and three-dimensional structural models of barbules were established, moreover, these were analysed using the finite element method. The response under load of different parts of the barbules was obtained. The results showed that there were stress concentrations in feather barbules. The study laid a foundation for finding the internal and external causes of the evolutionary transition of knotted barbules.