Phascolotherium

{{Short description|Extinct family of mammals}} {{Automatic taxobox |fossil_range = Bathonian ~{{fossil range|167|165}} |image = Stonsefield_mammal.jpg |image_caption = Fossil jaw and teeth |taxon = Phascolotherium |authority = Owen, 1838 |type_species = {{extinct}}'''''Didelphys bucklandi''''' |type_species_authority = Broderip, 1828 |subdivision_ranks = Species |subdivision = * {{Extinct}}'''''P. bucklandi''''' (Broderip, 1828) * {{Extinct}}'''''P. simpsoni''''' Butler & Sigogneau-Russell, 2016 }}

'''''Phascolotherium''''' is a genus of extinct eutriconodont mammal from the Middle Jurassic of the United Kingdom.<ref>{{Cite web|url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=207503|title=Fossilworks: Phascolotherium bucklandi}}</ref> Found in the Stonesfield Slate, it was one of the first Mesozoic mammals ever found and described, although like the other mammal jaws found at the same time, it was mistakenly thought at first to be a marsupial.<ref name="Broderip1828">Broderip W.J. 1828. Observations on the jaw of a fossil mammiferous animal found in the Stonesfield Slate. Zoological Journal of London 3, 408–412</ref>

==Discovery== ''Phascolotherium'' was one of the first mammals described from Mesozoic-aged rocks. It is only known from single lower jaws and some isolated teeth.

Buckland showed the fossil jaws of Stonesfield to the exceptional comparative anatomist, Georges Cuvier, who incorrectly identified them as marsupials, based on the similarity of the bones to modern marsupials. Blainville also attributed the fossil to his newly erected genus, Amphitherium.<ref>Kermack, KA. 1988 British Mesozoic mammal sites. Special Papers in Palaeontology, 40:85-93</ref> More than one specimen was given to Buckland, and one of these lower jaws was lost, but found again in 1827 by William Broderip,<ref name="Broderip1828"/> and thought by Charles Lyell to be evidence that mammals dated from the earliest times without having changed.<ref name="Rudwick2010">{{cite book|author=Martin J. S. Rudwick|title=Worlds Before Adam: The Reconstruction of Geohistory in the Age of Reform|url=https://books.google.com/books?id=uQNX5jhoLPsC&pg=PT269|date=5 April 2010|publisher=University of Chicago Press|isbn=978-0-226-73130-8|page=247}}</ref>

However, British comparative anatomist Richard Owen later recognized the Stonesfield fossils as being distinct from opossums and from another mammal found in the same rocks, named ''Amphitherium''. The new genus ''Phascolotherium'' was given to ''"D." bucklandi''.<ref name="Broderip1828"/><ref>Owen, R. 1838. On the jaws of the Thylacotherium prevostii (Valenciennes) from Stonesfield. Proceedings of the Geological Society of London 3, 5–9.</ref> A second species, ''P. simpsoni'' was named from specimens from the Kirtlington mammal bed and Watton Cliff, both of the Forest Marble Formation in 2016.<ref>Percy M. Butler; Denise Sigogneau-Russell (2016). "Diversity of triconodonts in the Middle Jurassic of Great Britain" (PDF). Palaeontologia Polonica. 67: 35–65. doi:10.4202/pp.2016.67_035.</ref>

== Description == The body mass of ''P. simpsoni'' has been estimated to have been between 1.46 g and 9.00 g, close to the lower size limit of endotherm body mass.<ref>{{Cite journal |last1=Huang |first1=E. J. |last2=Wilson |first2=Jacob D. |last3=Bhullar |first3=Bhart‐Anjan S. |last4=Bever |first4=Gabriel S. |date=4 March 2024 |title=High‐precision body mass predictors for small mammals: a case study in the Mesozoic |url=https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12692 |journal=Palaeontology |language=en |volume=67 |issue=2 |doi=10.1111/pala.12692 |issn=0031-0239 |access-date=25 November 2025 |via=Wiley Online Library|url-access=subscription }}</ref>

== References == {{Reflist}}

Category:Eutriconodonta Category:Bathonian life Category:Middle Jurassic mammals of Europe Category:Jurassic England Category:Fossils of England Category:Fossil taxa described in 1838 Category:Taxa named by Richard Owen Category:Prehistoric mammal genera