ABSTRACT
The Jurassic-Cretaceous pygopid ‘key-hole’ brachiopods, possessing a central perforation of the shell, were able to live in poorly oxygenated environments probably because of effective use of nutrients and wide dispersal of young individuals. Their shells appear to have been oriented on the substrate by a well-developed pedicle muscle. Although specifically adapted to deep-sea conditions, the pygopids might also have been opportunists able to live in shallow slope settings in competition with other benthos.
