''Amphitherium'' is an extinct genus of stem cladotherian mammal that lived during the Middle

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 ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...

. It was one of the first

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Creta ...

mammals ever described. A recent phylogenetic study found it to be the sister taxon of ''

Palaeoxonodon ''Palaeoxonodon'' is an extinct genus of Cladotherian mammal from the Middle Jurassic of England and Scotland. Discovery The first fossils of ''Palaeoxonodon ooliticus'' were found in the Kirtlington cement quarry, Oxfordshire, England. This si ...

''. It is found in the

Forest Marble Formation The Forest Marble is a geological formation in England. Part of the Great Oolite Group, it dates to the late Bathonian stage of the Middle Jurassic.Weishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weish ...

and the

Taynton Limestone Formation The Taynton LimestoneWeishampel, David B; et al. (2004). "Dinosaur distribution (Middle Jurassic, Europe)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 5 ...

Etymology

''Amphitherium'' comes from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''amphi'' meaning 'on both sides', and ''therion'' meaning 'wild beast'. This was in reference to de Blainville's incorrect belief that the original fossil jaw of this animal was not a mammal, but something in between mammals and reptiles.

History

The first jaws of mammals from the

- including ''Amphitherium'' - were found in the

Stonesfield Slate Stonesfield is a village and civil parish about north of Witney in Oxfordshire, and about 10 miles (17 km) north-west of Oxford. The village is on the crest of an escarpment. The parish extends mostly north and north-east of the village, ...

, part of the

near

Stonesfield Stonesfield is a village and civil parish about north of Witney in Oxfordshire, and about 10 miles (17 km) north-west of Oxford. The village is on the crest of an escarpment. The parish extends mostly north and north-east of the village, ...

in England.Rudwick, M.J.S. 2008
Worlds Before Adam
/ref> These were bought by a student of the British paleontologist

William Buckland William Buckland DD, FRS (12 March 1784 – 14 August 1856) was an English theologian who became Dean of Westminster. He was also a geologist and palaeontologist. Buckland wrote the first full account of a fossil dinosaur, which he named ' ...

. Although he thought the jaws were mammalian, the anatomist

Georges Cuvier Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French naturalist and zoologist, sometimes referred to as the "founding father of paleontology". Cuvier was a major figure in na ...

misidentified them as being from a

marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a ...

mammal, ''

Didelphis ''Didelphis'' is a genus of New World marsupials. The six species in the genus ''Didelphis'', commonly known as Large American opossums, are members of the ''opossum'' order, Didelphimorphia. The genus ''Didelphis'' is composed of cat-sized om ...

''. Later they were identified as being a new genus, and named ''Amphitherium''. It was first mentioned in the scientific literature alongside ''

Megalosaurus ''Megalosaurus'' (meaning "great lizard", from Greek , ', meaning 'big', 'tall' or 'great' and , ', meaning 'lizard') is an extinct genus of large carnivorous theropod dinosaurs of the Middle Jurassic period (Bathonian stage, 166 million years ...

'', by William Buckland. It came from the

of Oxfordshire, England, and Buckland described it in 1824 as "''not less extraordinary''" than the dinosaur,http://trn.lyellcollection.org/content/s2-1/2/390.full.pdf but it was the larger fossil reptile that captured public imagination. Additional remains were recovered in the late 20th century from the Kirtlington Quarry and Watton Cliff, both part of the

Other early mammal discoveries included '' Amphilestes'', '' Phascolotherium'', and the mammal relative, ''

Stereognathus ''Stereognathus'' is an extinct genus of tritylodontid cynodonts from the Middle Jurassic of the United Kingdom. There is a single named species: ''S. ooliticus'', named after the Great Oolite deposits of England. A second species, ''S. hebridic ...

''.

References

Amphitheriida Bathonian genera Middle Jurassic mammals of Europe Jurassic England Fossils of England Fossil taxa described in 1838 Prehistoric mammal genera {{jurassic-mammal-stub