Phylogenetic trees of present-day species allow investigation of the rate of evolution that led to the present-day diversity. A recent analysis of the mammalian phylogeny challenged the view of explosive mammalian evolution after the Cretaceous-Tertiary (K/T) boundary (65 Mya). However, due to lack of appropriate methods, the diversification (speciation minus extinction) rates in the more recent past of mammalian evolution could not be determined. In this paper, I provide a method that reveals that the tempo of mammalian evolution did not change until ∼33 Mya. This constant period was followed by a peak of diversification rates between 33 and 30 Mya. Thereafter, diversification rates remained high and constant until 8.55 Mya. Diversification rates declined significantly at 8.55 and 3.35 Mya. Investigation of mammalian subgroups (marsupials, placentals, and the six largest placental subgroups) reveals that the diversification rate peak at 33-30 Mya is mainly driven by rodents, cetartiodactyla, and marsupials. The recent diversification rate decrease is significant for all analyzed subgroups but eulipotyphla, cetartiodactyla, and primates. My likelihood approach is not limited to mammalian evolution. It provides a robust framework to infer diversification rate changes and mass extinction events in phylogenies, reconstructed from, e. g., present-day species or virus data. In particular, the method is very robust toward noise and uncertainty in the phylogeny and can account for incomplete taxon sampling.macroevolution | maximum-likelihood inference | speciation rates I t has been a long-standing question whether the rise of presentday mammals began following the mass extinction event at the K/T boundary (1, 2). The hypothesis of a significant rise in mammals following the K/T boundary was challenged when the mammalian phylogeny, including 4,510 present-day species, became available (3). This phylogeny is ∼83% complete at the species level (4). It allowed detection of diversification rate (speciation rate minus extinction rate) shifts throughout the evolutionary past of almost all present-day mammals. No shift was detected at the K/T boundary; however, a peak in diversification rates at ∼93 Mya was detected (3).Estimating the time and amount of diversification rate changes is a key toward understanding evolutionary patterns (5, 6). For example, reliable diversification rate estimates can have the power to decide if species richness is typically due to intrinsic causes (the ancestor evolved a new feature) or extrinsic causes (the environment changed) or a complex combination of both. Already in 1996, Sanderson and Donoghue (ref. 5, p. 1) wrote "Few issues in evolutionary biology have received as much attention over the years [ . . . ] as those involving evolutionary rate." However, until now there has been no general framework available to estimate diversification rates and their changes through time.Detecting diversification rate changes is typically done by detecting changes in the slope of the lineages-through-time...