Wilson Mantilla Gregory P, Chester Stephen G B, Clemens William A, Moore Jason R, Sprain Courtney J, Hovatter Brody T, Mitchell William S, Mans Wade W, Mundil Roland, Renne Paul R
Department of Biology, University of Washington, Seattle, WA 98195, USA.
Department of Paleontology, Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA.
R Soc Open Sci. 2021 Feb 24;8(2):210050. doi: 10.1098/rsos.210050.
Plesiadapiform mammals, as stem primates, are key to understanding the evolutionary and ecological origins of Pan-Primates and Euarchonta. The Purgatoriidae, as the geologically oldest and most primitive known plesiadapiforms and one of the oldest known placental groups, are also central to the evolutionary radiation of placentals and the Cretaceous-Palaeogene biotic recovery on land. Here, we report new dental fossils of from early Palaeocene (early Puercan) age deposits in northeastern Montana that represent the earliest dated occurrences of plesiadapiforms. We constrain the age of these earliest purgatoriids to magnetochron C29R and most likely to within 105-139 thousand years post-K/Pg boundary. Given the occurrence of at least two species, and a new species, at the locality, we provide the strongest support to date that purgatoriids and, by extension, Pan-Primates, Euarchonta and Placentalia probably originated by the Late Cretaceous. Within 1 million years of their arrival in northeastern Montana, plesiadapiforms outstripped archaic ungulates in numerical abundance and dominated the arboreal omnivore-frugivore niche in mammalian local faunas.
近猴形哺乳动物作为灵长类的祖先，是理解泛灵长类和真灵长大目进化及生态起源的关键。普尔加托里猴科作为已知地质年代最古老、最原始的近猴形动物，也是已知最古老的胎盘类动物群之一，对于胎盘类动物的进化辐射以及陆地白垩纪 - 古近纪生物复苏也至关重要。在此，我们报告了来自蒙大拿州东北部古新世早期（早普尔加期）沉积层的新牙齿化石，这些化石代表了最早有年代记录的近猴形动物。我们将这些最早的普尔加托里猴科动物的年代限定在磁极性亚时C29R，最有可能在白垩纪 - 古近纪灭绝事件（K/Pg）边界之后10.5万至13.9万年之间。鉴于该地点至少出现了两个物种以及一个新物种，我们提供了迄今为止最有力的证据，表明普尔加托里猴科动物，进而泛灵长类、真灵长大目和胎盘类动物可能起源于晚白垩世。在抵达蒙大拿州东北部后的100万年之内，近猴形动物在数量上超过了古老有蹄类动物，并在哺乳动物当地动物群中占据了树栖杂食 - 食果动物的生态位。
