Fossiomanus
 | This article relies largely or entirely on a single source. (April 2021) |
| Fossiomanus Temporal range:
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|---|---|
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | Therapsida |
| Clade: | Cynodontia |
| Family: | †Tritylodontidae |
| Genus: | †Fossiomanus Mao et al., 2021 |
| Species: | †F. sinensis
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| Binomial name | |
| †Fossiomanus sinensis Mao et al., 2021
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Fossiomanus is an extinct genus of tritylodontid mammaliamorphs from the Early Cretaceous of China. It includes one species, F. sinensis, which is known from a single nearly complete skeleton from the Aptian Jiufotang Formation. Features of its limbs and vertebrae indicate that Fossiomanus was adapted towards a fossorial lifestyle.[1]
Fossiomanus lived roughly 120 million years ago, making it potentially the geologically youngest known tritylodontid, which would also make it the last known non-mammalian synapsid.
Discovery and naming
[edit]Fossiomanus sinensis was named in 2021 by Fangyuan Mao, Chi Zhang, Cunyu Liu, and Jin Meng, on the basis of the holotype specimen, JZMP-2107500093, a nearly complete skeleton with a damaged skull from the Jiufotang Formation of Liaoning. The genus name is derived from Latin fossio "digging" and manus "hand" and the species name means "from China".[1]
Description
[edit]Fossiomanus was 316 millimetres (12.4 in) long, excluding the 65 millimetres (2.6 in)-long tail, with a generally stocky build. Its pointed snout and short tail gave it an overall fusiform body plan. It had an elongate torso, with 26 thoracic vertebrae and 5 lumbar vertebrae. The front foot was broad and robust, with large claws.[1]
Paleobiology
[edit]Tritylodontids such as Fossiomanus were herbivores. Fossiomanus was a fossorial taxon, with its powerful forelimbs being used for digging. The long, stocky, fusiform body plan is characteristic of many burrowing mammals.[1]
Evolution
[edit]Fossiomanus belongs to Tritylodontidae, a clade of cynodonts that were the last surviving lineage of non-mammalian synapsids. Tritylodontids were widely distributed during the Early Jurassic, but had become restricted to Asia by the Late Jurassic.[2] Fossiomanus is probably the geologically youngest known tritylodontid;[1] its holotype specimen was found just below a tuff layer that has been determined to be 118.9±0.8 million years old.[3] It appears to be slightly more recent than Montirictus,[1] another late-surviving tritylodontid, which was found in strata constrained to be between 121.2±1.1 and 130.7±0.8 million years old.[4] Another late-surviving tritylodontid is Xenocretosuchus, found in the Ilek Formation of Siberia, the age of which is poorly constrained but estimated to be Barremian–Aptian.[5]
Earlier tritylodontids, such as Kayentatherium, did not have the elongate body plan that characterized Fossiomanus. The evolution of an elongate body in Fossiomanus may have been the result of a change in the GDF11 or OCT4 genes, which regulate the development of the transition from the trunk to the tail. With a total of 38 presacral vertebrae, Fossiomanus may have been at the upper limit of the number of presacral vertebrae possible in mammaliamorphs; no known terrestrial mammal exceeds this number, although hyraxes equal it.[1]
References
[edit]- ^ a b c d e f g Mao, F.; Zhang, C.; Liu, C.; Meng, J. (2021). "Fossoriality and evolutionary development in two Cretaceous mammaliamorphs". Nature. 592 (7855): 577–582. doi:10.1038/s41586-021-03433-2. PMID 33828300. S2CID 233183060.
- ^ Liu, Lu; Zhou, Chang-Fu; Wang, Jia-Shu; Xue, Jin-Zhuang (2022-07-06). "A new tritylodontid from the Middle Jurassic Shaximiao Formation of western Hubei, China". Historical Biology: 1–10. doi:10.1080/08912963.2022.2094262. eISSN 1029-2381. ISSN 0891-2963.
- ^ Yu, Zhiqiang; Wang, Min; Li, Youjuan; Deng, Chenglong; He, Huaiyu (2021). "New geochronological constraints for the Lower Cretaceous Jiufotang Formation in Jianchang Basin, NE China, and their implications for the late Jehol Biota". Palaeogeography, Palaeoclimatology, Palaeoecology. 583: 110657. doi:10.1016/j.palaeo.2021.110657. ISSN 0031-0182.
- ^ Matsuoka, Hiroshige; Kusuhashi, Nao; Corfe, Ian J. (2016-07-03). "A new Early Cretaceous tritylodontid (Synapsida, Cynodontia, Mammaliamorpha) from the Kuwajima Formation (Tetori Group) of central Japan". Journal of Vertebrate Paleontology. 36 (4): –1112289. doi:10.1080/02724634.2016.1112289. eISSN 1937-2809. ISSN 0272-4634.
- ^ Averianov, Alexander; Ivantsov, Stepan; Skutschas, Pavel; Faingertz, Alexey; Leshchinskiy, Sergey (2018). "A new sauropod dinosaur from the Lower Cretaceous Ilek Formation, Western Siberia, Russia". Geobios. 51 (1): 1–14. doi:10.1016/j.geobios.2017.12.004. ISSN 0016-6995.
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