Diverse bilaterian clades emerged apparently within a few million years during the early
Cambrian, and various environmental, developmental, and ecological causes have been …

Approximately one-third of all mammalian genes are essential for life. Phenotypes resulting
from knockouts of these genes in mice have provided tremendous insight into gene function …

Flies are one of four superradiations of insects (along with beetles, wasps, and moths) that
account for the majority of animal life on Earth. Diptera includes species known for their …

The freshwater cnidarian Hydra was first described in 1702 1 and has been the object of
study for 300 years. Experimental studies of Hydra between 1736 and 1744 culminated in the …

microRNAs (miRNAs) are approximately 22‐nucleotide noncoding RNA regulatory genes that
are key players in cellular differentiation and homeostasis. They might also play important …

Insight into the origin and early evolution of the animal phyla requires an understanding of
how animal groups are related to one another. Thus, we set out to explore animal phylogeny …

Although microRNAs (miRNAs) are among the most intensively studied molecules of the past
20 years, determining what is and what is not a miRNA has not been straightforward. Here, …

Xenoturbellida and Acoelomorpha are marine worms with contentious ancestry. Both were
originally associated with the flatworms (Platyhelminthes), but molecular data have revised …

Accurately dating when the first bilaterally symmetrical animals arose is crucial to our
understanding of early animal evolution. The earliest unequivocally bilaterian fossils are ≈555 …

An argument is proposed to explain the origin of large metazoans, based on the regulatory
processes that underlie the morphogenetic organization of pattern in modern animals. …