Tuesday, March 6, 2012

[Paleontology • 1999] Jeholodens jenkinsi • A Chinese triconodont mammal and mosaic evolution of the mammalian skeleton


Illustration: Mark A. Klingler

This artistic reconstruction shows Jeholodens jenkinsi, a triconodont mammal that lived about 120 to 140 million years ago during the Mesozoic. The animal has three cusps on its teeth and fed on insects and aquatic arthropods. It lived near a shallow fresh water lake and co-existed with a very rich fauna of fish, amphibians, feathered dinosaurs, birds, and lizards, plus very abundant plants and insects.

Its sprawling hind legs and pelvis had a reptilian posture, yet its forearms and shoulders were more flexible. The animal is a ground-living mammal, suggesting that mammals probably originated from ground (instead of tree) habitat.

The reconstruction shows how the animal would look in life, in contrast to the fossil skeleton of the same specimen preserved in the sedimentary rock.

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Class Mammalia 
Infraclass Triconodonta (McKenna and Bell 1997) 
Order Eutriconodonta (Kermack et al. 1973) 
Family Incertae sedis 
Jeholodens jenkinsi gen. et sp. nov.

Etymology. Jehol: an ancient geographic name for the western part of the Liaoning Province, China; the namesake of the Jehol fauna in the Yixian Formation that yielded the holotype; odens (Latin): tooth; jenkinsi (Latin): in honour of F. A. Jenkins Jr for his pioneer studies of the evolutionary morphology of the mammalian postcranial skeleton.

Holotype. GMV 2139 a, b, a nearly complete skeleton consisting of a partial skull and all of the postcranial skeleton preserved as two counterparts (Fig. 1a; a reconstruction of the specimen is shown in Fig. 1b).

FIGURE 1. Jeholodens jenkinsi (National Geological Museum of China, holotype GMV 2139a).
a, Dorsal view of the dorsoventrally compressed skeleton. b, Reconstruction of J.jenkinsi as a ground-dwelling animal that had a plantigrade gait, sprawling hindlimbs and a mobile pectoral girdle with relatively wide range of excursion of the scapula but a sprawling elbow.







Ji, Q.; Luo, Z. and Ji, S. 1999. A Chinese triconodont mammal and mosaic evolution of the mammalian skeleton. Nature 398 (6725): 326–330. doi:10.1038/18665

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