''Microchampsa'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

protosuchia Protosuchia is a group of extinct Mesozoic crocodyliforms. They were small in size (~1 meter in length) and terrestrial. In phylogenetic terms, Protosuchia is considered an informal group because it is a grade of basal crocodyliforms, not a tru ...

crocodylomorph Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. During Mesozoic and early Cenozoic times, cro ...

that existed during the

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...

Fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s have been found from stratum 6 of the Dahuangtian locality, an outcrop of the Lower Red Beds of the

Lufeng Formation The Lufeng Formation (formerly Lower Lufeng Series) is a Lower Jurassic sedimentary rock formation found in Yunnan, China. It has two units: the lower Dull Purplish Beds/Shawan Member are of Hettangian age, and Dark Red Beds/Zhangjia'ao Member ar ...

Yunnan Yunnan , () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

.Lucas, S. G. (2001). Chinese fossil vertebrates. Columbia University Press, 375 pp.

Description

Parts of the postcranial skeleton, such as the dorsal

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amp ...

s, vertebrae, ribs, and bones of the manus, are known.Young, C. C. (1951). The Lufeng saurischian fauna in China. ''Palaeontologia Sinica, New Series C'' 13:1-96. The dorsal osteoderms of the lumbar region are fused to double headed ribs. All osteoderms are rectangular and overlap each other.

History

''Microchampsa'' was named in 1951 on the basis of an incomplete skeleton consisting of cervical and anterior dorsal vertebrae as well as ribs and three rows of dorsal osteoderms. Three other specimens of crocodylomorphs described in 1965 also seemed to display three rows of osteoderms, and as a result were assigned to the genus ''Microchampsa''.Simmons, D. J. (1965). The non-therapsid reptiles of the Lufeng Basin, Yunnan, China. ''Fieldiana: Geology'' 15(1):1-93. However, later studies revealed that the specimens had only two rows of osteoderms that more closely resembled those of the genus '' Platyognathus'', and that the presence of three rows of osteoderms in the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

of ''Microchampsa'' may have been an artifact of preservation. However, this hypothesis is speculative as the holotype of ''Microchampsa'' had since been lost by the time of the studies.

Taxonomy

It was assigned to the

suborder Order ( la, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and ...

Protosuchia Protosuchia is a group of extinct Mesozoic crocodyliforms. They were small in size (~1 meter in length) and terrestrial. In phylogenetic terms, Protosuchia is considered an informal group because it is a grade of basal crocodyliforms, not a tru ...

in 1965 and the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Notochampsidae in 1992. However, later studies argued that it is a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium'' it may be impossible to determine whether a s ...

'' due to the lack of diagnostic material in the incompletely known remains.Wu, X. C. and Sues, H. D. (1995) Protosuchia (Archosauria: Crocodyliformes) from China. ''In:'' Sun, A. and Yuanqing, W. (eds.) ''Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers''. Beijing. China Ocean Press, 57-62. Thus it can only be regarded as a poorly known protosuchian.

References

External links

''Microchampsa''
in the

Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database (PBDB) originated in the NCEAS-funded Phanerozoic Marine Pale ...

Early Jurassic crocodylomorphs Terrestrial crocodylomorphs Early Jurassic reptiles of Asia Prehistoric pseudosuchian genera {{paleo-archosaur-stub