Dyffransow ynter amendyansow a "Chordata"

An [[fylum]] '''Chordata''' yw onan a'n brassa fyla a [[eneval]]es, ow komprehendya a-dro dhe 65,000 a [[ehen]]now.<ref>Chapman, Arthur D. (2009) ''[http://www.environment.gov.au/biodiversity/abrs/publications/other/species-numbers/2009/pubs/nlsaw-2nd-complete.pdf Numbers of Living Species in Australia and the World]''. Drehedhys 16 Ebrel 2013.</ref> An [[mellkeynek|mellkeynogyon]] ([[pysk|puskes]], [[diwelvennek|diwelvenogyon]], [[kramvil]]es, [[edhen|ydhyn]] ha [[bronnvil]]es) yw eseli a'n Chordata. Yma dew bagasvagas a enevales heb mellow keyn, [[Tunicata]] ([[skitvil]]es hag erel) ha [[Cephalochordata]], y'n fylum ynwedh. An kynsa eseli a'n Chordata a omdhiskwedhas nans yw 550&nbsp;milyon bledhen.<ref>Hennessey, Kathryn & Victoria Wiggins (2010) ''The Natural History Book'', Dorling Kindersley, Loundres.</ref>