1999/03/01 by John Alroy · 3 citations
Earth and Planetary Sciences · Environmental Science · #Evolution and Paleontology Studies #Animal Ecology and Behavior Studies #Paleontology and Evolutionary Biology #Cretaceous #Cenozoic #Paleontology #Extinction event #Extinction (optical mineralogy) #Mesozoic #Fossil Record #Evolution of mammals #Range (aeronautics) #Biology #Mammal #Biological dispersal #Structural basin
paper · pdf · doi:10.1080/106351599260472
openalex publication_date 1999/03/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Paleontologists long have argued that the most important evolutionary radiation of mammals occurred during the early Cenozoic, if not that all eutherians originated from a single common post-Cretaceous ancestor. Nonetheless, several recent molecular analyses claim to show that because several interordinal splits occurred during the Cretaceous, a major therian radiation was then underway. This claim conflicts with statistical evidence from the well-sampled latest Cretaceous and Cenozoic North American fossil record. Paleofaunal data confirm that there were fewer mammalian species during the latest Cretaceous than during any interval of the Cenozoic, and that a massive diversification took place during the early Paleocene, immediately after a mass extinction. Measurement data show that Cretaceous mammals were on average small and occupied a narrow range of body sizes; after the Cretaceous-Tertiary mass extinction, there was a rapid and permanent shift in the mean. The fact that there was an early Cenozoic mammalian radiation is entirely compatible with the existence of a few Cretaceous splits among modern mammal lineages.