The northernmost record of Metatheria, Unnuakomys hutchisoni gen. et sp. nov., is described from the Pediomys Point locality in Upper Cretaceous (lower Maastrichtian) strata of the Prince Creek Formation cropping out along the Colville River on the North Slope of Alaska, USA (70°N). Based on over 60 specimens (including tooth-bearing dentaries and a maxillary fragment), the new taxon is unusual in having two well-developed stylar cusps in the C position flanking the deepest part of the ectoflexus. To examine the relationship between U. hutchisoni and other metatherians, U. hutchisoni was scored into the taxon character matrix of other studies. Our results corroborate prior studies that suggest the new Alaskan pediomyid. However, in contrast to other studies, we do not recover a sister-group relationship between U. hutchisoni and Pediomys elegans. Rather, our study suggests that U. hutchisoni is more closely allied with Aquilan species Iqualadelphis lactea and ?Aquiladelphis laurae. Teeth of U. hutchisoni greatly outnumber those recovered from other mammals at Pediomys Point, like Late Cretaceous localities in the Western Interior where metatherians are among the most abundant mammalian fossils. However, what differs between Late Cretaceous mid-latitude localities and the assemblage from the North Slope of Alaska is metatherian richness. Whereas other studies have reported up to a dozen species of metatherians from Late Cretaceous mid-latitude North American assemblages, to date all the metatherian teeth collected from Pediomys Point appear to belong to just U. hutchisoni. A sampling bias may play a role in this pattern. This can be tested through additional collection from the Prince Creek Formation. However, the abundance of U. hutchisoni at Pediomys Point implies that this tiny metatherian thrived in an environment well above the Arctic Circle whose climatic extremes may have acted as a biogeographical filter to other metatherians. As the first mammal to be described from the Prince Creek Formation, U. hutchisoni provides support for the existence of a northern high-latitude early Maastrichtian faunal province identified by others on the basis of its distinctive dinosaurian fauna – the Paaŋaqtat Province.

http://zoobank.org/urn:lsid:zoobank.org:pub:0EF38E01-2FF4-4698-A3AD-97CF2EE6847A

Metatheria的最北端的记录是Unnuakomys hutchisoni gen。等。nov。，是从Prince Creek地层的上白垩统（下Maastrichtian）地层的Pediomys Point地点描述的，沿美国阿拉斯加北坡（70°N）的Colville河流出。基于60多个标本（包括带齿的牙齿和上颌骨碎片），新分类单元在C位置有两个发育良好的硬毛尖，这是其在外屈肌最深侧翼的两侧。为了检查之间的关系U. hutchisoni等metatherians，U. hutchisoni被打入其他研究的分类群特征矩阵。我们的研究结果证实了以前的研究表明新的阿拉斯加小蜘蛛。但是，与其他研究相比，我们没有恢复荷氏梭菌和线虫Pediomys elegans之间的姐妹群关系。更确切地说，我们的研究表明，荷氏乳杆菌与Aquilan物种Iqualadelphis lactea和？天鹰座劳拉。荷氏乳杆菌的牙齿大大超过了从Pediomys Point的其他哺乳动物那里回收的生物数量，例如西部内陆的晚白垩纪地区，其中陨石是最丰富的哺乳动物化石之一。但是，晚白垩世中纬度地区与阿拉斯加北坡地区的集合之间的区别在于，其气象分布丰富。尽管其他研究报道了来自北白垩纪中纬度北美洲组合的多达十二种陨石，但迄今为止，从Pediomys Point收集的所有陨石牙齿似乎仅属于U. hutchisoni。采样偏差可能在此模式中起作用。可以通过从Prince Creek地层的额外采集来测试。但是，荷氏梭菌的数量很多Pediomys Point的研究人员表示，这个微小的Meatherian在远高于北极圈的环境中蓬勃发展，其极端气候可能已成为其他Meatherians的生物地理过滤器。作为第一个从Prince Creek构造中描述的哺乳动物，Hutchisoni支持北部高纬度的早期马斯特里赫特动物区系的存在，该省被其他人根据其独特的恐龙区系Paaqatat省确定。

http://zoobank.org/urn:lsid:zoobank.org:pub:0EF38E01-2FF4-4698-A3AD-97CF2EE6847A