''Macelognathus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of

sphenosuchia Sphenosuchia is a suborder of basal crocodylomorphs that first appeared in the Triassic and occurred into the Middle Jurassic. Most were small, gracile animals with an erect limb posture. They are now thought to be ancestral to crocodyliforms, a ...

n 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 Mya. The J ...

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

Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to the sou ...

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

The

type species In 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 species that contains the biological type specimen( ...

, ''Macelognathus vagans'', was described by

Othniel Charles Marsh Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among ...

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, siltstone, ...

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 ("

n"). 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 com ...

, due to the similarities to

caenagnathid Caenagnathidae is a family of bird-like maniraptoran theropod dinosaurs from the Cretaceous of North America and Asia. They are a member of the Oviraptorosauria, and close relatives of the Oviraptoridae. Like other oviraptorosaurs, caenagnathids ...

dinosaurs, with which it was not closely related. It was between long. It is possibly a junior synonym of ''

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

''.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