Reigitherium

{{Short description|Extinct family of mammals}} {{Speciesbox | fossil_range = Late Cretaceous, {{fossilrange|Campanian|Maastrichtian}} | genus = Reigitherium | parent_authority = Bonaparte, 1990<ref name="Bonaparte1990">Bonaparte, J. F. (1990). New Late Cretaceous mammals from the Los-Alamitos formation, Northern Patagonia. National Geographic Research 6.1 63-83.</ref> | species = bunodontum | authority = Bonaparte, 1990 }}

'''''Reigitherium''''' was a mammal that lived during the Late Cretaceous (Late Campanian-Maastrichtian). Its fossils have been found in the Los Alamitos and the La Colonia Formations of Argentina.

==Description== The original specimen of ''Reigitherium'' was a fragmentary single molar tooth, with a lot of the surface detail damaged.<ref name="Bonaparte1990"/> It was mistakenly identified as an upper left molar, but new material - including a whole tooth row of this species - clarifies that it was a lower right tooth.<ref name="Harper2018"/>

''Reigitherium'' was a small mammal with simple premolars that increased in size along the tooth row to an enlarged fourth premolar. The molar teeth them decreased in size along the tooth row.

== Taxonomy == ''Reigitherium'' has proven difficult to classify until recently, because the original fossil material was sparse, damaged, and difficult to identify. It was initially thought to be a dryolestid mammal when described in 1990.<ref name="Bonaparte1990"/> Ten years later, Pascual et al. argued that it was a docodont based on the wear patterns they interpreted on the teeth.<ref name="Pascual2000">Pascual R., Goin F.J., Gonzalez P., Ardolino A. & Puerta P.F. (2000) A highly derived docodont from the Patagonian Late Cretaceous Geodiversitas 22 (3) [http://www.mnhn.fr/publication/geodiv/g00n3a4.pdf Documento pdf] {{webarchive|url=https://web.archive.org/web/20120414214950/http://www.mnhn.fr/publication/geodiv/g00n3a4.pdf |date=2012-04-14 }}.</ref> In 2011, Rougier ''et al.'' argued again for it being a dryolestoid, within Meridiolestida, an order of Gondwanan dryolestoids.<ref name=Cronopio>{{cite journal |author1=Guillermo W. Rougier |author2=Sebastián Apesteguía |author3=Leandro C. Gaetano |year=2011 |title=Highly specialized mammalian skulls from the Late Cretaceous of South America |journal=Nature |volume=479 |issue=7371 |pages=98–102 |doi=10.1038/nature10591 |pmid=22051679|bibcode=2011Natur.479...98R |s2cid=4380850 }} [http://www.nature.com/nature/journal/v479/n7371/extref/nature10591-s1.pdf Supplementary information]</ref> More complete fossils have now supported this analysis<ref name="Harper2018">Harper T, Parras A, Rougier GW. 2018. ''Reigitherium'' (Meridiolestida, Mesungulatoidea) an enigmatic Late Cretaceous mammal from Patagonia, Argentina: morphology, affinities, and dental evolution. ''Journal of Mammalian Evolution''.</ref>

A recent phylogenetic study finds it to be the sister taxon to ''Peligrotherium''.<ref name="Harper2018"/> Although the latter is much larger than ''Reigitherium'', they share many tooth and skull characteristics that indicate they are closely related. It was also found to be close to ''Yeutherium'', which was placed into Reigitheriidae as only the second genus in the family.<ref>{{cite journal |last1=Püschel |first1=H. P. |last2=Martinelli |first2=A. G. |last3=Soto-Acuña |first3=S. |last4=Ortiz |first4=H. |last5=Leppe |first5=M. |last6=Vargas |first6=A. O. |year=2025 |title=A subantarctic reigitheriid and the evolution of crushing teeth in these enigmatic Mesozoic mammals |journal=Proceedings of the Royal Society B: Biological Sciences |volume=292 |issue=2052 |at=20251056 |doi=10.1098/rspb.2025.1056 |pmid=40763811 |pmc=12324878 |pmc-embargo-date=August 6, 2026 }}</ref>

== References == {{Reflist}}

{{Mammalia|H.}} {{Taxonbar|from=Q3814978}} Category:Meridiolestida Category:Prehistoric mammal genera Category:Campanian life Category:Maastrichtian life Category:Late Cretaceous mammals of South America Category:Cretaceous Argentina Category:Fossils of Argentina Category:Los Alamitos Formation Category:Cañadón Asfalto Basin Category:Fossil taxa described in 1990 Category:Taxa named by José Bonaparte