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[dinosaur] Maiopatagium and Vilevolodon, new gliding mammaliaforms from Jurassic of China




Ben Creisler
bcreisler@gmail.com


New papers (the supplementary information  is free):

Also, interview audio clip


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Maiopatagium furculiferum gen. nov. & spec. nov.


Qing-Jin Meng, David M. Grossnickle, Di Liu, Yu-Guang Zhang, April I. Neander, Qiang Ji & Zhe-Xi Luo (2017)
New gliding mammaliaforms from the Jurassic.
Nature (advance online publication)
doi:10.1038/nature23476
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23476.html



Stem mammaliaforms are Mesozoic forerunners to mammals, and they offer critical evidence for the anatomical evolution and ecological diversification during the earliest mammalian history. Two new eleutherodonts from the Late Jurassic period have skin membranes and skeletal features that are adapted for gliding. Characteristics of their digits provide evidence of roosting behaviour, as in dermopterans and bats, and their feet have a calcaneal calcar to support the uropagatium as in bats. The new volant taxa are phylogenetically nested with arboreal eleutherodonts. Together, they show an evolutionary experimentation similar to the iterative evolutions of gliders within arboreal groups of marsupial and placental mammals. However, gliding eleutherodonts possess rigid interclavicle–clavicle structures, convergent to the avian furculum, and they retain shoulder girdle plesiomorphies of mammaliaforms and monotremes. Forelimb mobility required by gliding occurs at the acromion–clavicle and glenohumeral joints, is different from and convergent to the shoulder mobility at the pivotal clavicle–sternal joint in marsupial and placental gliders.


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Vilevolodon diplomylos gen. nov. & spec. nov.


Zhe-Xi Luo, Qing-Jin Meng, David M. Grossnickle, Di Liu, April I. Neander, Yu-Guang Zhang & Qiang Ji (2017)
New evidence for mammaliaform ear evolution and feeding adaptation in a Jurassic ecosystem.
Nature (advance online publication)
doi:10.1038/nature23483
http://www.nature.com/nature/journal/vaop/ncurrent/full/nature23483.html


Stem mammaliaforms are forerunners to modern mammals, and they achieved considerable ecomorphological diversity in their own right. Recent discoveries suggest that eleutherodontids, a subclade of Haramiyida, were more species-rich during the Jurassic period in Asia than previously recognized. Here we report a new Jurassic eleutherodontid mammaliaform with an unusual mosaic of highly specialized characteristics, and the results of phylogenetic analyses that support the hypothesis that haramiyidans are stem mammaliaforms. The new fossil shows fossilized skin membranes that are interpreted to be for gliding and a mandibular middle ear with a unique character combination previously unknown in mammaliaforms. Incisor replacement is prolonged until well after molars are fully erupted, a timing pattern unique to most other mammaliaforms. In situ molar occlusion and a functional analysis reveal a new mode of dental occlusion: dual mortar–pestle occlusion of opposing upper and lower molars, probably for dual crushing and grinding. This suggests that eleutherodontids are herbivorous, and probably specialized for granivory or feeding on soft plant tissues. The inferred dietary adaptation of eleutherodontid gliders represents a remarkable evolutionary convergence with herbivorous gliders in Theria. These Jurassic fossils represent volant, herbivorous stem mammaliaforms associated with pre-angiosperm plants that appear long before the later, iterative associations between angiosperm plants and volant herbivores in various therian clades.


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News:

https://phys.org/news/2017-08-winged-mammals-jurassic-period.html



http://news.nationalgeographic.com/2017/08/fossils-flying-gliding-mammals/


https://cosmosmagazine.com/palaeontology/earliest-gliding-mammals-force-rethink-of-dinosaurs-reign


http://www.sciencemag.org/news/2017/08/meet-mammals-soared-through-jurassic-skies