Bemalambda
Bemalambda | |
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Skeleton of B. nanhsiungensis, National Natural History Museum of China | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | †Pantodonta |
Family: | †Bemalambdidae |
Genus: | †Bemalambda Chow et al., 1973 |
Type species | |
Bemalambda nanhsiungensis Chow et al., 1973 |
Bemalambda (meaning "stepped lambda") is a genus of extinct mammal, belonging to the pantodonts. It lived in the lower-middle Paleocene (about 63–58 million years ago) and the fossil remains have been found in China.
Description
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/28/Bemalambda_pachyoesteus%2CDB24.jpg/220px-Bemalambda_pachyoesteus%2CDB24.jpg)
It was a medium-size animal, and could reach the size of a large dog. The body was strong, the tail was short and the legs were strong and muscular. The skull was short and low, with a broad muzzle, swollen zygomatic processes, and a very small skull. The temporal fossae were deep, the sagittal crest prominent, and the coronoid process on the mandible was very high; these characteristics indicate a more developed temporal musculature (useful for chewing) than that of the subsequent pantodonts.
Like all pantodonts, Bemalambda had upper premolars with V-shaped ectolofi; the upper molars, however, had a transverse structure, almost zalambdodonte, with closely paired paracone and metaconus, and did not possess the dilambdodont W-shaped structure like the typical pantodonts. The stylar platform of the teeth from the third premolar to the third molar was very broad, and the ``ectoflexus (an additional external indentation of the molars) was deeply incised.
Classification
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/25/Skeleton_of_Bemalambda_pachyoesteus.jpg/220px-Skeleton_of_Bemalambda_pachyoesteus.jpg)
The genus Bemalambda was established in 1973 on the basis of some fossils found in the area of Nanxiong in the Lofochai formation (Guangdong, China), dating back to the lower/middle Paleocene. The study by Chow and colleagues established various species: Bemalambda crassa, Bemalambda nanhsiungensis (the type species), Bemalambda pachyoesteus, distinguished on the basis of some dental characteristics. Subsequently, in Jiangxi, fossils of a slightly more recent species (Middle Paleocene) were found, B. dingae.
Bemalambda is a rather atypical representative of the pantodonts, a group of archaic mammals with the characteristic ambdodon teeth. In particular, Bemalambda and other related forms such as Hypsilolambda would seem to be part of a radiation of primitive pantodonts of relatively modest size, developed in the Asian Paleocene, the Bemalambdidae . Probably close to this group were other small animals, such as Harpyodus and Alcidedorbignya.
Paleoecology
The representatives of the Bemalambda genus were animals with a strong and robust build, with a herbivorous or perhaps omnivorous diet. The strong legs, in particular the humerus, indicate a propensity for digging.
Bibliography
- M. M. Chow, Y.-P. Chang, B.-Y. Wang and S.-Y. Ting. 1973. New mammalian genera and species from the Paleocene of Nanhsiung, N. Kwangtung. Vertebrata PalAsiatica 11(1):31–35
- Zhou, M., Y. Zhang, B. Wang, and S. Ding. 1977. Mammalian fauna from the Paleocene of Nanxiong Basin, Guangdong. Palaeontologia Sinica, new series C 20:1–100.
- C. de Muizon and L. G. Marshall. 1992. Alcidedorbignya inopinata (Mammalia: Pantodonta) from the Early Paleocene of Bolivia: Phylogenetic and Paleobiogeographic Implications. Journal of Paleontology 66(3):499–520
- Q. Li. 2005. New material of Bemalambda from Chijiang Basin in Jiangxi, China. Vertebrata PalAsiatica 43(4):325–329
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