Impacts of the Cretaceous Terrestrial Revolution and KPg Extinction on Mammal Diversification

Abstract

Previous analyses of relations, divergence times, and diversification patterns among extant mammalian families have relied on supertree methods and local molecular clocks. We constructed a molecular supermatrix for mammalian families and analyzed these data with likelihood-based methods and relaxed molecular clocks. Phylogenetic analyses resulted in a robust phylogeny with better resolution than phylogenies from supertree methods. Relaxed clock analyses support the long-fuse model of diversification and highlight the importance of including multiple fossil calibrations that are spread across the tree. Molecular time trees and diversification analyses suggest important roles for the Cretaceous Terrestrial Revolution and Cretaceous-Paleogene (KPg) mass extinction in opening up ecospace that promoted interordinal and intraordinal diversification, respectively. By contrast, diversification analyses provide no support for the hypothesis concerning the delayed rise of present-day mammals during the Eocene Period.

Nuclear organisation of some immunohistochemically identifiable neural systems in five species of insectivore —Crocidura cyanea, Crocidura olivieri, Sylvisorex ollula, Paraechinus aethiopicus and Atelerix frontalis

“…These variations in the number and complement of nuclei in the systems examined support the possibility that the microchiropterans may have a close phylogenetic affinity to the Soricidae and other insectivores, rather than the artiodactyls and perissodactyls as commonly depicted (e.g. Meredith et al, 2011).…”

“…Thus, there is substantial preliminary evidence linking the microchiropterans with the Soricidae, providing a potential phylogenetic niche for the microchiropterans in the diphyletic scenario of chiropteran evolution. While clearly a great deal more work is required to substantiate this proposed phylogenetic assignation, the microchiropteran-Soricidae link appears to make more sense that the microchiropteran-ungulate sister grouping reported in recent studies of mammalian phylogeny (Meredith et al, 2011).…”

“…Many of the earlier phylogenies, based on morphology, assumed monophyly in the Insectivora, whereas molecular-based analyses conclude that this mammalian order is paraphyletic (Symonds, 2005). The paraphyletic insectivore grouping is now generally thought to belong to the Laurasiatheria super order, which is proposed to include, in addition to the insectivores, the Artiodactyls, Perissodactyls, Carnivores and the Chiropterans (Arnason et al, 2002;Asher et al, 2009;Lee and Camens, 2009;Meredith et al, 2011).…”

Updating the evolutionary history of Carnivora (Mammalia): a new species-level supertree complete with divergence time estimates

“…[1] but are identical with those in the recent family-level supermatrix study of Meredith et al . [32]. These include the polyphyly of the traditional Mustelidae into Mephitidae and Mustelidae sensu stricto ; the polyphyly of traditional Viverridae into Eupleridae (in part), Nandinia, Prionodon and Viverridae sensu stricto ; and the paraphyly of traditional Herpestidae with inclusion of former viverrid-assigned members of Eupleridae ( Cryptoprocta and Fossa ).…”

Five palaeobiological laws needed to understand the evolution of the living biota

“…Today, there are slightly fewer than 5,500 described living mammal species. If we assume the group dates back to ~66 Myr ago 15 , and that they diversified logistically to a carrying capacity of 5,500 (recognizing that the trajectories of individual subclades are typically not logistic), then there have been a staggering ~157,000 mammal species since the extinction of the dinosaurs (see Methods). If instead one assumes the rates of origination and extinction were equal and stochastically constant (that is, not diversity dependent), and that it took about a species duration (~2 Myr) to first reach 5,500 species after the endCretaceous mass extinction (see 'Caveat'), then the estimated total number of mammal species generated in the past 64 Myr is almost the same, 156,860 species (see Methods).…”