[dinosaur] Jeholbaatar, new multituberculate mammal from Early Cretaceous of China

Ben Creisler
[email protected]

A new paper:

Jeholbaatar kielanae gen. et sp. nov.


Haibing Wang, Jin Meng & Yuanqing Wang  (2019)
Cretaceous fossil reveals a new pattern in mammalian middle ear evolution.
Nature (advance online publication)
doi:10.1038/s41586-019-1792-0
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nature.com_articles_d41586-2D019-2D03605-2D1&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=01hjP7k34Pm2qKjuxaU2685SKcEhEz7dugmEb1nja-g&s=FqkAxiEPvW0s1FQ_U-L991YPPVAZZO6PdpiEXgquAPs&e= 


The evolution of the mammalian middle ear is thought to provide an example
of 'recapitulation'--the theory that the present embryological development
of a species reflects its evolutionary history. Accumulating data from both
developmental biology and palaeontology have suggested that the
transformation of post-dentary jaw elements into cranial ear bones occurred
several times in mammals. In addition, well-preserved fossils have revealed
transitional stages in the evolution of the mammalian middle ear. But
questions remain concerning middle-ear evolution, such as how and why the
post-dentary unit became completely detached from the dentary bone in
different clades of mammaliaforms. Here we report a definitive mammalian
middle ear preserved in an eobaatarid multituberculate mammal, with
complete post-dentary elements that are well-preserved and detached from
the dentary bones. The specimen reveals the transformation of the
surangular jaw bone from an independent element into part of the malleus of
the middle ear, and the presence of a restricted contact between the
columelliform stapes and the flat incus. We propose that the malleus–incus
joint is dichotomic in mammaliaforms, with the two bones connecting in
either an abutting or an interlocking arrangement, reflecting the
evolutionary divergence of the dentary–squamosal joint. In our phylogenetic
analysis, acquisition of the definitive mammalian middle ear in
allotherians such as this specimen was independent of that in monotremes
and therians. Our findings suggest that the co-evolution of the primary and
secondary jaw joints in allotherians was an evolutionary adaptation
allowing feeding with unique palinal (longitudinal and backwards) chewing.
Thus, the evolution of the allotherian auditory apparatus was probably
triggered by the functional requirements of the feeding apparatus.

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News:

All ears about ancient mammals

https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nature.com_articles_d41586-2D019-2D03605-2D1&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=01hjP7k34Pm2qKjuxaU2685SKcEhEz7dugmEb1nja-g&s=FqkAxiEPvW0s1FQ_U-L991YPPVAZZO6PdpiEXgquAPs&e= 

Free pdf:
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.nature.com_magazine-2Dassets_d41586-2D019-2D03605-2D1_d41586-2D019-2D03605-2D1.pdf&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=01hjP7k34Pm2qKjuxaU2685SKcEhEz7dugmEb1nja-g&s=EOIQ9B3IzUXiIxkOLcHvGKKU-uKjBzVCfoRGrWmPALk&e= 

Also:

https://urldefense.proofpoint.com/v2/url?u=https-3A__phys.org_news_2019-2D11-2Dcretaceous-2Dmammal-2Dfossil-2Devolution-2Dmiddle.html&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=01hjP7k34Pm2qKjuxaU2685SKcEhEz7dugmEb1nja-g&s=iOlHj90nzt0RxLdL9vrZEMkAD5CKe4_6FpIUH7sTLv4&e= 

https://urldefense.proofpoint.com/v2/url?u=https-3A__www.eurekalert.org_pub-5Freleases_2019-2D11_caos-2Dncm112719.php&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=01hjP7k34Pm2qKjuxaU2685SKcEhEz7dugmEb1nja-g&s=C7qJf3osN5-SU_cGlKVI74NGUbdSbbMaTma9M0IkAjw&e= 

https://urldefense.proofpoint.com/v2/url?u=https-3A__gizmodo.com_this-2Dnewly-2Ddiscovered-2Dcretaceous-2Dmammal-2Dhad-2Dreally-2Dfrea-2D1840066819&d=DwIFaQ&c=clK7kQUTWtAVEOVIgvi0NU5BOUHhpN0H8p7CSfnc_gI&r=Ry_mO4IFaUmGof_Yl9MyZgecRCKHn5g4z1CYJgFW9SI&m=01hjP7k34Pm2qKjuxaU2685SKcEhEz7dugmEb1nja-g&s=4_mzQfOocaio0O7gHEiIb4O9gdEWZEn8W94p2d62oS4&e=