@article {959, title = {Arthropod Origins: Integrating Paleontological and Molecular Evidence}, journal = {Annual Review of Ecology, Evolution, and Systematics}, volume = {51}, year = {2020}, month = {31/07/2020}, pages = {1-25}, abstract = {

Phylogenomics underpins a stable and mostly well-resolved hypothesis for the interrelationships of extant arthropods. Exceptionally preserved fossils are integrated into this framework by coding their morphological characters, as exemplified by total-evidence dating approaches that treat fossils as dated tips in analyses numerically dominated by molecular data. Cambrian fossils inform on the sequence of character acquisition in the arthropod stem group and in the stems of its main extant clades. The arthropod head problem incorporates unique appendage combinations and remains of the nervous system in fossils into a scheme mostly based on neuroanatomy and Hox expression domains for extant forms. Molecular estimates of arthropod origins in the Cryogenian or Ediacaran predate a coherent picture from the arthropod fossil record, which commences as trace fossils in the earliest Cambrian. Probabilistic morphological clock analysis of trilobites, which exemplify the earliest arthropod body fossils, supports a Cambrian origin, without the need to posit an unfossilized Ediacaran history.

}, keywords = {Cambrian, fossils, molecular dating, phylogenomics}, issn = {1543-592X}, doi = {10.1146/annurev-ecolsys-011720-124437}, url = {https://www.annualreviews.org/doi/10.1146/annurev-ecolsys-011720-124437}, author = {Edgecombe, Gregory D.} } @article {300, title = {Aquatic stem group myriapods close a gap between molecular divergence dates and the terrestrial fossil record}, journal = {Proceedings of the National Academy of Sciences}, volume = {117}, year = {2020}, month = {06/04/2020}, pages = {8966 - 8972}, abstract = {

Identifying marine or freshwater fossils that belong to the stem groups of the major terrestrial arthropod radiations is a longstanding challenge. Molecular dating and fossils of their pancrustacean sister group predict that myriapods originated in the Cambrian, much earlier than their oldest known fossils, but uncertainty about stem group Myriapoda confounds efforts to resolve the timing of the group\’s terrestrialization. Among a small set of candidates for membership in the stem group of Myriapoda, the Cambrian to Triassic euthycarcinoids have repeatedly been singled out. The only known Devonian euthycarcinoid, Heterocrania rhyniensis from the Rhynie and Windyfield cherts hot spring complex in Scotland, reveals details of head structures that constrain the evolutionary position of euthycarcinoids. The head capsule houses an anterior cuticular tentorium, a feature uniquely shared by myriapods and hexapods. Confocal microscopy recovers myriapod-like characters of the preoral chamber, such as a prominent hypopharynx supported by tentorial bars and superlinguae between the mandibles and hypopharynx, reinforcing an alliance between euthycarcinoids and myriapods recovered in recent phylogenetic analysis. The Cambrian occurrence of the earliest euthycarcinoids supplies the oldest compelling evidence for an aquatic stem group for either Myriapoda or Hexapoda, previously a lacuna in the body fossil record of these otherwise terrestrial lineages until the Silurian and Devonian, respectively. The trace fossil record of euthycarcinoids in the Cambrian and Ordovician reveals amphibious locomotion in tidal environments and fills a gap between molecular estimates for myriapod origins in the Cambrian and a post-Ordovician crown group fossil record.

}, keywords = {Arthropoda, euthycarcinoid, molecular dating, Myriapoda, Terrestrialization}, issn = {0027-8424}, doi = {10.1073/pnas.1920733117}, url = {http://www.pnas.org/lookup/doi/10.1073/pnas.1920733117}, author = {Edgecombe, Gregory D. and Strullu-Derrien, Christine and G{\'o}ral, Tomasz and Hetherington, Alexander J. and Thompson, Christine and Koch, Markus} } @article {64, title = {Evaluating Topological Conflict in Centipede Phylogeny Using Transcriptomic Data Sets}, journal = {Molecular Biology and Evolution}, volume = {31}, year = {2014}, month = {2014}, pages = {1500 - 1513}, abstract = {

Relationships between the five extant orders of centipedes have been considered solved based on morphology. Phylogenies based on samples of up to a few dozen genes have largely been congruent with the morphological tree apart from an alternative placement of one order, the relictual Craterostigmomorpha, consisting of two species in Tasmania and New Zealand. To address this incongruence, novel transcriptomic data were generated to sample all five orders of centipedes and also used as a test case for studying gene-tree incongruence. Maximum likelihood and Bayesian mixture model analyses of a data set composed of 1,934 orthologs with 45\% missing data, as well as the 389 orthologs in the least saturated, stationary quartile, retrieve strong support for a sister-group relationship between Craterostigmomorpha and all other pleurostigmophoran centipedes, of which the latter group is newly named Amalpighiata. The Amalpighiata hypothesis, which shows little gene-tree incongruence and is robust to the influence of among-taxon compositional heterogeneity, implies convergent evolution in several morphological and behavioral characters traditionally used in centipede phylogenetics, such as maternal brood care, but accords with patterns of first appearances in the fossil record.

}, keywords = {Chilopoda, Illumina, incongruence, molecular dating, Myriapoda, next-generation sequencing, phylogenomics}, isbn = {0737-4038}, doi = {https://doi.org/10.1093/molbev/msu108}, author = {Fern{\'a}ndez, Rosa and Laumer, Christopher E. and Vahtera, Varpu and Libro, Silvia and Kaluziak, Stefan and Sharma, Prashant P. and P{\'e}rez-Porro, Alicia R. and Edgecombe, Gregory D. and Giribet, Gonzalo} }