sentences:  In 1877, at age 10, he purchased two 16th century daggers from the collection of Henry Cogniat and started his personal collection.In 1881, he entered the College of the City of New York at only 14 years of age and graduated in 1886; He enrolled in zoology and palaeontology at Columbia University, and received his Ph.D in 1890.Dean became an assistant for Professor John Strong Newberry who studied Devonian armored fishes.