A body fossil of a thorny-headed worm (Acanthocephala) has been dated to the Jurassic period, about 165 million years ago. It has characteristics of both Acanthocephala and tiny animals called ...

This structure closely resembles that found in Gnathifera, a group that includes Gnathostomulida, Micrognathozoa, and Syndermata (which encompasses Rotifera and Acanthocephala). To determine the ...

This important study identifies species- and sex-specific neuronal cell types and gene expression in the preoptic area (POA) to help understand the evolutionary divergence of social behaviors. The ...