Atreipus acadianus was produced by a habitually quadrupedal tetrapod with a tridactyl pes and a functionally tetradactyl manus.
The only possible dinosaurian ichnites from the Red Head Member are functionally tridactyl or even didactyl tracks with an unusually elongate digit IV and an apparent trenchant claw on digit II assigned to the ichnogenus Evazoum (Lockley and Lucas 2013; Fig.
The dinosaur's footprints usually toe slightly inward (slightly negative footprint rotation), as is typical of Comanchean tridactyl footprints attributed to theropods (Farlow 1987).
Most of the footprints in the two trails are little more than vague holes in the ground, but the better-preserved tracks, such as they are, suggest a tridactyl foot (Fig.
DESCRIPTION: Small bipedal, tridactyl, right theropod pes impression preserved in convex hyporelief, 7 cm long and 4.
REMARKS: The four common functionally tridactyl dinosaurian ichnogenera are Anchisauripus, Anomoepus, Eubrontes, and Grallator.
Two parallel tridactyl trackways are preserved, indicating a direction of movement of 182[degrees].
Pittman (1992) referred tridactyl tracks from the Glen Rose to the theropod ichnotaxa Grallator (Hitchcock 1858), and noted that Irenesauripus displays character states diagnostic of Grallator.