Repenomes ( lat. Repenomamus , from repens - crawling, and mam from mammalia - mammals; literally - reptile mammal ) - the largest mammals of the Lower Cretaceous ( 125.45-122.46 million years ago) [2] , fossil remains of which were found in the Yixian Formation in Liaoning Province ( PRC ). They ate dinosaurs as well , but at the moment it’s impossible to say with certainty whether they caught live prey or were scavengers.
| † repenomas | |||||||||||||||||||||||||||||||||||||||||
 Skull Repenomamus giganticus | |||||||||||||||||||||||||||||||||||||||||
| Scientific classification | |||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||||||||||||||||||||||||||||||
| International scientific name | |||||||||||||||||||||||||||||||||||||||||
Repenomamus Li, Wang, Wang, Li, 2000 | |||||||||||||||||||||||||||||||||||||||||
| Views [1] | |||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||
| Geochronology 125.45-122.4 million years
◄ Nowadays◄ Cretaceous-Paleogene extinction◄ Triassic extinction◄ Perm mass extinction◄ Devonian extinction◄ Ordovician-Silurian extinction◄ Cambrian explosion | |||||||||||||||||||||||||||||||||||||||||
Content
Paleobiology
Apparently, the repenomes did not know how to run fast. The humerus and femur departed from the joints at a wide angle, and the limbs were relatively short in relation to the size of the body. Feet were flat.
In appearance and, probably, in behavior, the repenomes resembled a modern Tasmanian devil .
It is safe to say that the repenomes ate meat. The skeleton of Repenomamus robustus was found with fragments of the skeleton of a young psittacosurus in the stomach. This indicates that Mesozoic mammals could eat dinosaurs. Other examples of dinosaur eating (in particular, archeornitoids ) by mammals have been previously described [3] .
Size
The larger species, Repenomamus giganticus , was the largest mammal of the Cretaceous period . Perhaps some mammals of that era, for example, the giant platypus collicodon , were larger, but they are known only by small fragments, and their real size remains in question. The total length of Repenomamus giganticus was about 1 meter , and body weight - about 12-14 kg. His skull was 16 cm in length, the body length was 52 cm , and the remaining part of the tail was 36 cm . Repenomamus giganticus was larger than some species of feathered dinosaurs found in the same rock formation in China: synornitosaurus , caudipteryx and mei .
The type species of this genus, Repenomamus robustus , had a body length of less than 50 cm and weighed 4-6 kg.
These findings are considered important because they expanded the understanding of the ecological niche that mammals occupied during the domination of dinosaurs. Before the discovery of the repenomam, the only known mammals of that period were nocturnal insect eaters, in many respects resembling modern shrews. It was assumed that animal niches larger than 1 meter were filled exclusively with dinosaurs and other reptiles (turtles, crocodiles, etc.) until they died out at the turn of the Cretaceous and Tertiary periods and diversified mammals into Cenozoic.
Taxonomy
Repenomamus was first described together with the type species R. robustus in 2000 in a publication by Lee, Wang, Wang and Li ( Li, Wang, Wang, Li ) as part of the family Repenomamidae, then included in the squad (or nadotryad) trikonodontov (Triconodonta). In 2005, Hu, Meng, Wang, and Li ( Hu, Meng, Wang, Li ) described a second species, R. giganticus .
In 2004, for the first time they expressed the opinion that Repenomamidae is a junior synonym for the Gobiconodontidae family, which was refuted by a group of scientists who described the second species. In 2010, synonymy was finally established, having simultaneously withdrawn the family from the order of trikonodontov [2] . In 2015, Martin and colleagues confirmed the 2003 version that the Gobiconodontidae family is a member of the Eutriconodonta squad [4] , a valid squad formed from the related treasure trove of the invalid group of trikonodonts previously considered detachment. However, both the representatives of the detachment Eutriconodonta and the group of trikonodonts died out, leaving no modern descendants.
Cladogram
A cladogram taken from the work of Martin and colleagues in 2015 shows the evolutionary links in the detachment of Eutriconodonta [4] :
| Eutriconodonta |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
- Comments to the cladogram
- ↑ 1 2 3 4 The name of this clade is absent in the source; it has been restored to the taxons included in it.
See also
- List of genera of Mesozoic mammals
Notes
- ↑ † Repenomamus (English) information on the Fossilworks website. (Checked on October 5, 2016) .
- ↑ 1 2 Repenomamus (English) . Paleobiology Database Classic . (Checked on October 5, 2016) .
- ↑ Elzanowski, Andrzej, Wellnhofer, Peter. (1993). “Skull of Archaeornithoides from the Upper Cretaceous of Mongolia” American Journal of Science 293-AA: 235-252.
- ↑ 1 2 Martin T., Marugán-Lobón J., Vullo R., Martín-Abad H., Luo Z.-X., and Buscalioni AD (2015). A Cretaceous eutriconodont and integument evolution in early mammals. Nature 526 : 380-384. DOI : 10.1038 / nature14905 .
Literature
- J. Li, Y. Wang, Y. Wang, & C. Li. A new family of primitive mammals from the Mesoic of Western Liaoning, China (Eng.) // Chinese Science Bulletin: journal. - 2001. - Vol. 46 , no. 9 - P. 782—785 . - ISSN 1001-6538 . - DOI : 10.1007 / BF03187223 .
- Yaoming Hu, Jin Meng, Yuanqing Wang, Chuankui Li. Large Mesozoic mammals fed on young dinosaurs (eng.) // Nature . - 2005. - Vol. 433 , no. 7022 . - P. 149-152 . - DOI : 10.1038 / nature03102 . - PMID 15650737 .
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.