Department of Anthropology, University of Toronto Scarborough, 1265 Military Trail, Toronto, Ontario, Canada M1C 1A4.
Department of Anthropology and Geography, Colorado State University, Fort Collins, CO 80523-1701, USA.
Biol Lett. 2021 Feb;17(2):20200824. doi: 10.1098/rsbl.2020.0824. Epub 2021 Feb 10.
The early Eocene of the southern Bighorn Basin, Wyoming, is notable for its nearly continuous record of mammalian fossils. Microsyopinae (?Primates) is one of several lineages that shows evidence of evolutionary change associated with an interval referred to as Biohorizon A. is replaced by a larger species, , during the biohorizon interval in what is likely an immigration/emigration or immigration/local extinction event. The latter is then superseded by after the end of the Biohorizon A interval. Although this pattern has been understood for some time, denser sampling has led to the identification of a specimen intermediate in morphology between and , located stratigraphically as the latter is appearing. Because specimens of have been recovered approximately 60 m above the appearance of , it is clear that did not suffer pseudoextinction. Instead, evidence suggests that branched off from a population of , but the latter species persisted. This represents possible evidence of cladogenesis, which has rarely been directly documented in the fossil record. The improved understanding of both evolutionary transitions with better sampling highlights the problem of interpreting gaps in the fossil record as punctuations.
怀俄明州南部大角盆地的早始新世以其近乎连续的哺乳动物化石记录而闻名。微猴亚科（？灵长目）是几个表现出与被称为生物层 A 的间隔相关的进化变化证据的谱系之一。在生物层间隔期间，较大的物种 取代了 ，这可能是移民/灭绝或移民/局部灭绝事件。后者在生物层 A 间隔结束后被 取代。尽管这种模式已经存在了一段时间，但更密集的采样导致在形态上位于 与 之间的中间标本的鉴定，其位于后者出现的地层中。由于 的标本大约在 的出现之上 60 米处被回收，因此很明显 并没有遭受假灭绝。相反，证据表明 从 种群中分支出来，但后者物种仍然存在。这代表了可能的分支发生的证据，这在化石记录中很少有直接记录。随着采样的改进，对进化转变的更好理解强调了将化石记录中的空白解释为间断的问题。
