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New evidence for mammaliaform ear evolution and feeding adaptation in a Jurassic ecosystem.
Nature. 2017 08 17; 548(7667):326-329.Nat

Abstract

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.

Authors+Show Affiliations

Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois 60637, USA. Committee on Evolutionary Biology, The University of Chicago, Chicago, Illinois 60637, USA.Beijing Museum of Natural History, Beijing 100050, China.Committee on Evolutionary Biology, The University of Chicago, Chicago, Illinois 60637, USA.Beijing Museum of Natural History, Beijing 100050, China.Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois 60637, USA.Beijing Museum of Natural History, Beijing 100050, China.Hebei GEO University, Shijiazhuang 050031, Hebei Province, China.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

28792934

Citation

Luo, Zhe-Xi, et al. "New Evidence for Mammaliaform Ear Evolution and Feeding Adaptation in a Jurassic Ecosystem." Nature, vol. 548, no. 7667, 2017, pp. 326-329.
Luo ZX, Meng QJ, Grossnickle DM, et al. New evidence for mammaliaform ear evolution and feeding adaptation in a Jurassic ecosystem. Nature. 2017;548(7667):326-329.
Luo, Z. X., Meng, Q. J., Grossnickle, D. M., Liu, D., Neander, A. I., Zhang, Y. G., & Ji, Q. (2017). New evidence for mammaliaform ear evolution and feeding adaptation in a Jurassic ecosystem. Nature, 548(7667), 326-329. https://doi.org/10.1038/nature23483
Luo ZX, et al. New Evidence for Mammaliaform Ear Evolution and Feeding Adaptation in a Jurassic Ecosystem. Nature. 2017 08 17;548(7667):326-329. PubMed PMID: 28792934.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - New evidence for mammaliaform ear evolution and feeding adaptation in a Jurassic ecosystem. AU - Luo,Zhe-Xi, AU - Meng,Qing-Jin, AU - Grossnickle,David M, AU - Liu,Di, AU - Neander,April I, AU - Zhang,Yu-Guang, AU - Ji,Qiang, Y1 - 2017/08/09/ PY - 2016/10/23/received PY - 2017/07/14/accepted PY - 2017/8/10/pubmed PY - 2018/1/23/medline PY - 2017/8/10/entrez SP - 326 EP - 329 JF - Nature JO - Nature VL - 548 IS - 7667 N2 - 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. SN - 1476-4687 UR - https://www.unboundmedicine.com/medline/citation/28792934/New_evidence_for_mammaliaform_ear_evolution_and_feeding_adaptation_in_a_Jurassic_ecosystem_ L2 - https://doi.org/10.1038/nature23483 DB - PRIME DP - Unbound Medicine ER -