''Macelognathus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of sphenosuchian crocodylomorph from the Late

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

. Originally it was believed be a turtle and later a dinosaur. It lived in what is now

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

, in

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

.Moodie, R.L. 1908. The relationship of the turtles and plesiosaurs. Kansas University Scientific Bulletin, 4: 319–327. Macelognathus vagans

The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

, ''Macelognathus vagans'', was described by

Othniel Charles Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of paleontology. A prolific fossil collector, Marsh was one of the preeminent paleontologists of the nineteenth century. Among his legacies are the discovery or ...

in 1884 as a turtle based on a partial jaw from the Late Jurassic

Morrison Formation The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltston ...

at Como Bluff, Wyoming. After being referred to the Dinosauria by Moodie in 1908, it was later reclassified by Ostrom in 1971 as a crocodilian relative.Ostrom, J.H. (1971). "On the systematic position of ''Macelognathus vagans''". ''Postilla'' 153:1-10. Based on new material from the Morrison Formation at Fruita, Colorado, in 2005 Göhlich ''et al.'' identified it as a basal crocodylomorph (" sphenosuchian"). It is considered an example of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

, due to the similarities to caenagnathid dinosaurs, with which it was not closely related. It was between long. It is possibly a

junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

of ''

Hallopus victor ''Hallopus'' was a prehistoric reptile, named in 1877 as a species of ''Nanosaurus'' and classified as a genus by Othniel Charles Marsh, O. C. Marsh in 1881 from the Late Jurassic Morrison Formation. Today though the animal is thought to be a pse ...

''.Göhlich, U., L.M. Chiappe, J.M. Clark, and H.-D. Sues (2005) The systematic position of the Late Jurassic alleged dinosaur ''Macelognathus'' (Crocodylomorpha: Sphenosuchia). ''Canadian Journal of Earth Sciences'' 42: 307–321.

References

{{Taxonbar, from=Q6723239 Late Jurassic crocodylomorphs Terrestrial crocodylomorphs Morrison fauna Late Jurassic crocodylomorphs of North America Fossil taxa described in 1884 Taxa named by Othniel Charles Marsh Prehistoric pseudosuchian genera