Assertion: petrel's bill | /r/HasProperty | upper
Facets:
Source sentences:
text: Procellariform birds have between seven and nine distinct horny plates for their bill, and in petrels one of these plates forms the hooked portion of their upper bill called the maxillary unguis.
text: Procellariform birds have between seven and nine distinct horny plates for their bill, and in petrels one of these plates forms the hooked portion of their upper bill called the maxillary unguis.