Machaeridians are Palaeozoic animals that are dorsally armoured with serialized, imbricating shell plates that cover or enclose the body. Prior to the discovery of an articulated plumulitid machaeridi
Eggs and embryos are rare in fossil record; however, when preserved, they can offer crucial insights into the evolutionary developmental biology of extinct animals. Here we report new exceptionally pr
Tracing the evolution of the siboglinid group, peculiar group of marine gutless annelids, requires the detailed study of the fragmentarily explored central nervous system of vestimentiferans and other
