Species in this family can typically grow large to very large (over 30 cm), are relatively flat, have an inverted egg-shaped outline, opisthoparian sutures, a glabella that in early genera has parallel sides and expands forward in later representatives, and approaches or reaches the frontal border.
Species within this family commonly attain considerable sizes (over 30 cm), exhibit a flattened shape, possess an inverted egg-like silhouette, have opisthoparian sutures, a glabella that starts with parallel sides and expands forward in later forms, and can extend to or touch the frontal border.