The condition or characteristic of having the palatal bone structure typical of aegithognathous birds.
From aegithognathae (a bird group) with the suffix -ism (condition or system). This is a highly specialized ornithological term from 19th-century scientific classification.
This word is basically extinct in modern ornithology—it's a fossil of old bird classification systems. Scientists realized that birds with similar skull patterns weren't actually closely related, so they abandoned this way of sorting birds.
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