Assertion: tropic bird | /r/IsA | part of the order
Facets:
value: traditionally
type: OTHER
Source sentences:
text: Though tropic birds are traditionally classified as part of the order Pelecaniformes on the basis of morphological and behavioral characteristics, molecular genetic analyses suggest that they are related only distantly to other pelecaniform birds and should be placed in their own order, Phaethontiformes.