Abstract. Phylogenetic inference typically assumes that the data has evolved under Stationary, Reversible and Homogeneous (SRH) conditions. Many empirical

Prof Matthew Cobb The life and times of Francis Crick, or why it sometimes matters who does science

There are many ways to become a parasite , and there are parasites with vastly different ancestries that end up joining the same path on th...

The phyla making up the major animal clade of Spiralia have been clear since the advent of molecular phylogenetics; the relationships between these spiralian phyla have not. The lack of consensus over the relationships between these important animal phyla might be a clue implying their emergence in an explosive radiation. Focusing on the five largest spiralian phyla (Annelida, Brachiopoda, Mollusca, Nemertea and Platyhelminthes) and using two phylogenomic datasets, we have applied site-bootstrapping and taxon-jackknifing to explore this example of taxonomic instability. Analyses on the 105 possible rooted trees relating them showed that interphylum branches are very short. Preference for rooting Spiralia on Platyhelminthes is a long-branch artefact. Most analyses on the 15 unrooted trees showed a preference for the same topology but the support over other solutions was non significant. We conclude that the spiralian phyla emerged in rapid succession resulting in a difficult to resolve radiation. The deep history we infer for Spiralia has wide ranging implications for our interpretation of Cambrian fossils and for the evolution of traits such as biomineralization, segmentation and larvae. Impact Statement Analyses of two independent phylogenomic datasets suggest an explosive radiation at the origin of Spiralia, with implications for understanding the group’s evolutionary history. ### Competing Interest Statement The authors have declared no competing interest.

Evolution of Nervous Systems, Third edition Four-volume set includes wholly new content, all chapters from the previous edition have been thoroughly u...

The Huayuan biota exhibits extraordinary biodiversity, illuminating the impact of the Phanerozoic mass extinction around 513 million years ago and offering critical insights into the transformation of...

For almost two decades, scientists have debated whether sponges or comb jellies are the first animal lineage. Now some are calling for a more harmonious approach.

Il nuovo progetto GRNevo, finanziato con un grant FIS-3 Advanced da 1,9 milioni di euro, studierà come si formano i neuroni durante lo sviluppo in specie animali molto distanti tra loro: dal moscerino...

It is one of the most tantalising – and entertaining – puzzles in art, stretching from the Louvre to the Loire via, well, Norfolk. And our critic thinks he has just worked it out

Bilaterian guts share conserved embryonic patterning, but how does this relates to adult gut organization? This study uses transcriptomic analyses across five species to reveal conserved transcription...