A 3-month-old male infant is brought to the pediatrician by his parents due to feeding difficulties and characteristic facial features. Upon examination, the infant displays downward-slanting palpebral fissures, colobomas of the lower eyelids, malar hypoplasia, and a prominent nose with a flat nasal bridge. Additionally, the infant has a small mandible (micrognathia) with a high-arched palate. These features are consistent with Treacher Collins syndrome (TCS). 

Which of the following embryological processes is most directly implicated in the pathogenesis of this syndrome?