Earliest Palaeocene purgatoriids and the initial radiation of stem primates

Abstract

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 Purgatorius 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, Purgatorius janisae 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.

The Complete Mitochondrial Genome of Dendrogale murina (Tupaiidae) and Phylogeny of Scandentia

“…The separation time of the Dendrogale genus is estimated as Late Eocene with an average of 35.8 MYA. Due to the use of a younger calibration point at the root [ 38 , 39 ] and the addition of a calibration point to the node B, the common ancestor of Tupaia , Dendrogale , and Ptilocercus genera, we observe an increase in the age of basal nodes within the genus Tupaia compared to the results of Kundu et al [ 26 ]. Our result of dating the divergence of Dendrogale and Tupaia genera is slightly older than shown in Roberts et al [ 11 ], who dated this split approximately to the Eocene–Oligocene boundary based on the analysis of mitochondrial ribosomal genes 12S , tRNA-Val, and 16S .…”

“…Three fossil calibration points were applied to constrain the analysis. The total tree height (node A) was considered a log-normal prior (with the offset = 65.79 MYA and 95 % HPD of 126-67 MYA), as was done in Vries and Beck [ 38 ], according to the fossil Purgatorius mckeeveri Wilson Mantilla et al, 2021, from the early Palaeocene [ 39 ]. The most recent common ancestor (MRCA) of Scandentia representatives (node B) was calibrated with a log-normal distribution (with the offset = 34 MYA and 95 % HPD of 65-34 MYA), based on the fossil of P. kylin from the early Oligocene [ 13 ].…”

Fossil primate research at the 81st Annual Meeting of the Society of Vertebrate Paleontology

“…This sample illuminates the poorly understood transition from the low‐diversity Puercan NALMA to the much higher‐diversity Torrejonian, approximately doubling the plesiadapiform species richness within this interval. It further documents the presence of purgatoriids in the Torrejonian and contributes to emerging knowledge of the temporal range of this oldest euarchontan family extending both before and after the Puercan 6 …”

Ecological selectivity and the evolution of mammalian substrate preference across the K–Pg boundary

“…At present, the oldest known total-clade euarchontan-the arboreal stem primate Purgatorius-appears shortly after the K-Pg boundary, ca. 65.9 MYA (Wilson Mantilla et al, 2021). Thus, direct fossil evidence bearing on whether arboreality was retained across the K-Pg boundary in euarchontans or primatomorphans is lacking.…”