The lower portion of the formation was laid down in fluvial channel environments and consists primarily of fine- to medium-grained, crossbedded sandstones.

The upper portion, which was deposited in overbank and floodplain environments, consists primarily of massive to laminated, organic-rich mudstones with abundant root traces, and thin beds of bentonite.

This group of species is replaced higher in the formation by a different ornithischian fauna characterized by the presence of Lambeosaurus and Styracosaurus.

[6] The appearance of several new, rare species of ornithischian at the very top of the formation may indicate that a third distinct fauna had replaced the second during the transition into younger, non-Dinosaur Park sediments, at the same time an inland sea transgresses onto land, but there are fewer remains here.

However, the authors were unable to determine what specific factors shaped nesting ground choice in the formation's hadrosaurs.

They suggested that behavior, diet, soil condition, and competition between dinosaur species all potentially influenced where hadrosaurs nested.

Darren Tanke has observed that an experienced collector could actually discover multiple juvenile hadrosaur specimens in a single day.

The most common remains of young hadrosaurs in the Dinosaur Park Formation are dentaries, bones from limbs and feet, as well as vertebral centra.

[35] Foraminacephale F. brevis Also present in the Oldman Formation Frontoparetal dome, various other skull fragments including juvenile and subadult material Once thought to be a species of Stegoceras

[40] Sphaerotholus S. lyonsi[41] Upper, 76.10 ± 0.5 Ma[41] Right squamosal[41] Stegoceras S. validum Specimens including frontoparietal dome.

In the Dinosaur Park Formation, small theropods are rare due to the tendency of their thin-walled bones to be broken or poorly preserved.