The Collaborative International Dictionary of English v.0.48:

Clamatores \Clam`a*to"res\, n. pl. [L. clamator, pl. clamatores,
   a bawler.] (Zool.)
   A division of passerine birds in which the vocal muscles are
   but little developed, so that they lack the power of singing.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Clamatores
    n 1: used in some classification systems; a suborder or
         superfamily nearly coextensive with suborder Tyranni;
         Passeriformes having relatively simple vocal organs and
         little power of song; clamatorial birds [syn: Clamatores,
         suborder Clamatores]