Amber centipedes and their bearing on dating chilopod divergences

Publication Type:Conference Paper
Year of Publication:2016
Authors:G. D. Edgecombe
Conference Name:The 7th International Conference on Fossil Insects, Arthropods and Amber
Date Published:26/04/2016
Publisher:Siri Scientific Press
Conference Location:National Museum of Scotland, Edinburgh
Abstract:

Like many soil arthropod groups, Chilopoda has a fossil record informed by a few Palaeozoic Konservat-Lagerstätten (notably the Rhynie/Windyfield cherts, Gilboa and Mazon Creek), and phylogenetic work on fossils has focused on these taxa for their effects on inferring and dating ordinal-level divergences. The Mesozoic and Cenozoic have been less intensely investigated. Until the past decade, published taxonomic work on Chilopoda in amber mostly consisted of mid-19th Century descriptions from Baltic amber, these being species assigned to extant genera and in need of modern revision. Up to 2009, the Mesozoic record of centipedes consisted of a few holotypes of monotypic genera preserved in lithographic limestones from Germany and Brazil. Recent descriptions of Geophilomorpha from Late Cretaceous amber from western France and Burma (Myanmar) allowed assignment to extant families. In light of recent phylogenetic schemes based on combined morphological and molecular data, Cenomanian members of Schendylidae and Geophilidae constrain the divergence times of deep branches of Geophilomorpha. An extinct species of Scolopocryptops from Mexican amber provided the majority of morphological characters coded for extant taxa in a dataset dominated by molecular characters. A new species of the extant genus Theatops Newport, 1844, is presented from Baltic amber. This genus has a disjunct distribution in temperate North America, the Mediterranean and Sichuan, China, its record in Baltic amber consistent with the extant distribution being pruned by extinction. Morphological parsimony analysis nests the Eocene species within European–North America clades. The degree of completeness of its external morphological information permits its coding into more broadly sampled analyses of scolopendromorph phylogeny that also code for multi-locus sequence data, allowing for an empirical comparison of traditional node calibration and tip-dating (“total evidence”) approaches for estimating divergence times.

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