[2] Collected in the summer of 1977 at the newly discovered Clark locality northwest of Casper Wyoming, the specimens assigned to H. clarki were described in a brief article[2] and two master's theses at Wayne State University, Detroit.

The type locality of H. clarki occurs within a succession of red beds and carbonates above the Crow Mountain Formation which in turn overlies the Alcova Limestone within the Chugwater Group.

The age of the type locality is not precisely known, but since it is lithostratigraphically equivalent to the lower Popo Agie Formation, though possibly chronostratigraphically older, it is probably Carnian or late Ladinian.

It is unknown whether this taxon was an obligate quadruped or faculative biped and the only limb elements represented are a fragmentary humerus, an ulna, a tibia, calcanea, possible metapodials, and some phalanges that may be referable.

Zawiskie et al. (2011) diagnosed Heptasuchus based on two autapomorphies, anatomical features that differentiate it from all other known archosaurs: the presence of large, posteriorly directed flanges on the parabasisphenoid and a distinct, orbit-overhanging postfrontal.

[10] A phylogenetic analysis of archosaurs presented in an abstract found sister taxon relationship between Heptasuchus and Batrachotomus within Loricata, with a strong support of at least six shared discrete character states.

Similar aggregations of predators include the famous Allosaurus concentration at the Cleveland-Lloyd dinosaur quarry in the Morrison Formation of Utah and the asphalt pits at Rancho LaBrea from the Pleistocene of Los Angeles.