Mass extinction of lizards and snakes at the Cretaceous–Paleogene boundary

Abstract

Fig. 1. The phylogenetic distribution of ABO phenotypes and genotypes. Shown is a phylogenetic tree of primate species, with a summary of phenotypic/ genotypic information given in the first column, and the genetic basis for the A versus B phenotype provided in the second column (functionally important codons at positions 266 and 268 are in uppercase letters). See Dataset S1 for the source of information about phenotypes/genotypes. Only species with available divergence times are represented here (34 of 40). The phylogenetic tree is drawn to scale, with divergence times (on the x axis) in millions of years taken from ref. 29. OWM, Old World monkeys; NWM, New World monkeys. Under a model of convergent evolution, these data suggest that A is the ancestral allele, and a turnover (e.g., a neutral substitution) occurred on the branch leading to Old World monkeys. If instead, B were ancestral, all Old World monkeys would have had to serendipitously converge from ATG to TTG to encode a leucine, whereas all New World monkeys and hominoids would have had to converge to the CTG codon.

Biogeography of worm lizards (Amphisbaenia) driven by end-Cretaceous mass extinction

“…This pattern of radiation has been proposed to characterize lizards as well [22] but our study is, to our knowledge, the first to provide both fossil and molecular evidence for post-Cretaceous radiation in a reptilian clade.…”

“…However, evidence from fossils and molecules show that many of the clades that are diverse and widespread today originated and spread only after the Chicxulub impact at 66 Ma [22,[56][57][58]. Like Amphisbaenidae, the Iguanidae, Agamidae, Varanidae, Lacertidae, Booidea and Caenophidia radiate and become widespread in the Cenozoic [22], requiring oceanic dispersal. Among the more striking examples is the Fijian iguana Brachylophus; its close relationship to New World species [7,59] implies trans-Pacific dispersal from the Americas to the South Pacific.…”

“…The Bug Creek Anthills are an earliest Palaeocene (Puercan 1) fauna with reworked Cretaceous fossils [19]. AMNH 30799 is most likely Palaeocene, given that the assemblage primarily contains Palaeocene fossils, and that intensively studied Maastrichtian squamate assemblages from western North America [20][21][22] lack amphisbaenians.…”

Making the Most of Clade Selection

“…The academic and popular paleontological literature focuses as much on extinction (and thus, indirectly, survival) as on speciation (e.g. Van Valen 1994;McKinney 1997;Raup 1991;Jablonski 2001;Longrich et al 2012;Wagner and Estabrook 2014), perhaps because it is easier to observe, and more dramatic. In contrast, the gene-centric Modern Synthesis, though touting "survival and reproduction", values the former only insofar as it serves the latter.…”

“…Many discussions of clade-level evolutionary processes, particularly in the paleontological literature, imply selection, to be sure (McKinney 1997;Finnegan et al 2012;Longrich et al 2012). But most fail to offer any sufficiently explicit MLS formulation or to distinguish between species-level and higher-level processes, paying little attention to the problem of non-reproduction of clades more inclusive than species, the problem I focus on here.…”