Repenomamus
| Repenomamus |
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|---|---|
| File:Repenomamus giganticus skull.JPG | |
| Fossil skull of R. giganticus | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Class: | Mammalia |
| Order: | †Gobiconodonta |
| Family: | †Gobiconodontidae |
| Genus: | †Repenomamus Li et al., 2000 |
| Type species | |
| <templatestyles src="Noitalic/styles.css"/>†Repenomamus robustus Li et al., 2001[1]
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| Species | |
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<templatestyles src="Noitalic/styles.css"/>†Repenomamus robustus Li et al., 2000 |
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Repenomamus is a gobiconodontid[2] mammal genus containing two species, Repenomamus robustus and Repenomamus giganticus. Both species are known from fossils found in China that date to the early Cretaceous period, about 125-123.2 million years ago. R. robustus is one of several Mesozoic mammals[6] for which there is good evidence that it fed on small vertebrates, including young dinosaurs, though it is not possible to determine if it actively hunted live dinosaurs or scavenged dead ones. R. giganticus is among the largest mammals known from the Mesozoic era.
Contents
Classification and discovery
The fossils were recovered from the lagerstätte of the Yixian Formation in the Liaoning province of China, which is renowned for its extraordinarily well-preserved fossils of feathered dinosaurs. They have been specifically dated to 125-123.2 million years ago, during the Early Cretaceous period.
Repenomamus is a genus of triconodonts, a group of early mammals with no modern relatives. R. robustus was described by Li, Wang, Wang and Li in 2000, and R. giganticus was described by Hu, Meng, Wang and Li in 2005. The two known species are the sole members of the family Repenomamidae, which was also described in the same paper in 2000. It is sometimes alternatively listed as a member of the family Gobiconodontidae; although this assignment is controversial, a close relationship to this family is well-founded.
Description
Individuals of the known species in Repenomamus are the largest known Mesozoic mammals represented by reasonably complete fossils, adults of R. robustus were the size of a Virginia opossum with an estimated mass of Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). while the known adult of R. giganticus was about 50% larger with a total length of around Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value). and an estimated mass of Lua error in Module:Convert at line 1851: attempt to index local 'en_value' (a nil value).. These finds extend considerably the known body size range of Mesozoic mammals. In fact, Repenomamus was larger than several small sympatric dromaeosaurid dinosaurs like Graciliraptor.[7] Features of its shoulder and legs bones indicate a sprawling posture as in most of small to medium sized living therian mammals, with plantigrade feet. Unlike therian mammals, Repenomamus had proportionally longer bodies with shorter limbs.
Paleobiology
Features of the teeth and jaw suggest that Repenomamus were carnivorous and a specimen of R. robustus discovered with the fragmentary skeleton of a juvenile Psittacosaurus preserved in its stomach represents the first direct evidence that at least some Mesozoic mammals were carnivorous and fed on small vertebrates, including young dinosaurs.[7]
Like most other non-therian mammals, Repenomamus had an epipubic bone, meaning that it gave birth to or laid eggs that hatched into undeveloped young like modern marsupials and monotremes.[7]
See also
References
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Gregory P. Wilson* and Jeremy A. Riedel, New Specimen Reveals Delta Theroidan Affinities of the North American Late Cretaceous Mammal Nanocuris, Journal of Vertebrate Paleontology 30(3):872-884. 2010 doi: http://dx.doi.org/10.1080/02724631003762948
- ↑ CHRISTIAN DE MUIZON and BRIGITTE LANGE-BADRÉ, Carnivorous dental adaptations in tribosphenic mammals and phylogenetic reconstruction, Article first published online: 29 MAR 2007 DOI: 10.1111/j.1502-3931.1997.tb00481
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ Other eutriconodonts and deltageroidean metatherians adaptations towards specialised carnivory[3][4][5]
- ↑ 7.0 7.1 7.2 Lua error in package.lua at line 80: module 'strict' not found.
External links
- "Prehistoric badger had dinosaurs for breakfast". Michael Hopkin. Nature.com. January 12, 2005.
- "Fierce mammal ate dinos for lunch". BBC News. January 12, 2005.
