Having never delved deeply into the past of a geographic place, Rockman consulted with various ecology specialists to pinpoint where to collect soil, sand, and random detritus. Carl Mehling, for instance, who works at the American Museum of Natural History, which Rockman haunted as child, took the artist on a driving tour of significant sites around the boroughs. Rockman depicted a hadrosaur and an ankylosaur with soil gathered at Clay Pit Ponds State Park Preserve in Staten Island, where fossils from the time of these dinosaurs had been uncovered, and an American mastodon with material sampled from Tighe Triangle in upper Manhattan, where a tusk from the Pleistocene-era mammal was dug up in the late 19th century. He waded into the East River underneath the Queensboro Bridge at low tide to collect sand and pebbles, with which he created the barnacle-like texture in his drawing of a manatee once spotted swimming upriver. He dodged oncoming traffic on Bruckner Boulevard in the Bronx to scoop up dirt infused with garbage, with which he rendered the tree fern and horsetail plants.