Past Participial Phrase
"Headed by a senior" is a past participial phrase. A participial phrase contains a participle (verb) and modifiers. It is used as an adjective to describe a noun or pronoun. The participle is "Headed". "Headed" is written in the past tense with an /ed/ at the end.
A present participial phrase is similar to a past participial phrase except for the verb is written in the present tense. If Headed had been Heading it would've been in present tense. A prepositional phrase begins with a preposition, not a verb. An appositive renames a noun with another noun.
