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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Which of the following is not present at bih?
assistant
The correct answer is  The mastoid process is absent or rudimentary in neonatal skull. It forms postnatally as sternocleidomastoid develops and pulls on the bone Web search