Presence (+) and absence (-) of pneumatic characters found on the caudal vertebrae from specimens of the 11 taxa studied. The penguin with the pneumatised vertebrae is Pygoscelis papua (NHMUK unregist
Michael J. Bok, María Capa, Dan-Eric Nilsson, Here, There and Everywhere: The Radiolar Eyes of Fan Worms (Annelida, Sabellidae), Integrative and Comparative Biology, Volume 56, Issue 5, November 2016,