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Docofossor and Agilidocodon, new Jurassic docodont mammaliaforms from China

Ben Creisler

New in Science magazine:


Zhe-Xi Luo, Qing-Jin Meng, Qiang Ji, Di Liu, Yu-Guang Zhang, and April
I. Neander (2015)
Evolutionary development in basal mammaliaforms as revealed by a docodontan.
Science  347(6223): 760-764
DOI: 10.1126/science.1260880
Free supplementary information:

A new Late Jurassic docodontan shows specializations for a
subterranean lifestyle. It is similar to extant subterranean golden
moles in having reduced digit segments as compared to the ancestral
phalangeal pattern of mammaliaforms and extant mammals. The reduction
of digit segments can occur in mammals by fusion of the proximal and
intermediate phalangeal precursors, a developmental process for which
a gene and signaling network have been characterized in mouse and
human. Docodontans show a positional shift of thoracolumbar ribs, a
developmental variation that is controlled by Hox9 and Myf5 genes in
extant mammals. We argue that these morphogenetic mechanisms of modern
mammals were operating before the rise of modern mammals, driving the
morphological disparity in the earliest mammaliaform diversification.



Qing-Jin Meng, Qiang Ji, Yu-Guang Zhang, Di Liu, David M. Grossnickle,
and Zhe-Xi Luo (2015)
An arboreal docodont from the Jurassic and mammaliaform ecological
Science 347(6223): 764-768
DOI: 10.1126/science.1260880

A new docodontan mammaliaform from the Middle Jurassic of China has
skeletal features for climbing and dental characters indicative of an
omnivorous diet that included plant sap. This fossil expands the range
of known locomotor adaptations in docodontans to include climbing, in
addition to digging and swimming. It further shows that some
docodontans had a diet with a substantial herbivorous component,
distinctive from the faunivorous diets previously reported in other
members of this clade. This reveals a greater ecological diversity in
an early mammaliaform clade at a more fundamental taxonomic level not
only between major clades as previously thought.


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