Though shallower, the nearly complete
braincase of
Arcovenator is otherwise similar in size to those of
Majungasaurus and
Carnotaurus; it was thus initially estimated as being about long, The
skull roof exhibits as a
unique diagnostic character a midline
foramen, possibly housing the
pineal gland, situated on the posterior surface of a slight dome formed by
frontal bones as moderately thick as in
Aucasaurus, thus less so than for
Rajasaurus, though more than those of
Rugops. Less characteristically, above the
orbit is a low
fossa with a small
fenestra bordered by the
lacrimal, frontal, and postorbital. The
parietal bordering the supratemporal fenestrae forms ridges medially on the latter's respective anteromedial margins which, as they approach the
parietal eminence, fuse into a
sagittal crest. The
postorbital is intermediate between the
plesiomorphic T-shaped condition of
Eoabelisaurus and the derived inverted
L-shaped one of
Carnotaurus due to the unique feature of having a sheet of bone linking its ventral and posterior processes. It has, in a similar autapomorphic fashion, a thick, rough-surfaced process dorsal to the eye socket that extends to the lacrimal, forming a bony
brow ridge, and in a less notable way, a lateral rugose tuberosity on the extremity of its ventral process. The paroccipital processes have remarkable accessory dorsal and ventral bony bars, that thus bound depressions lateral to the
foramen magnum. The
ear region closely resembles that of
Majungasaurus, though differing most substantially on a laterally directed basipterygoid process, with the shorter crista prootica and the smaller extent of a groove anterior to the
2nd and
3rd cranial nerve foramina being minor deviances from Majungasaurinae's type. The
squamosal is similar to that of the latter except for a less prominent parietal process. Generally, the external bone ornamentation is more subdued than that of
Majungasaurus. The tall teeth (3-5.5 cm) have denticles on the apical portion of the
mesial carina and along the length of the distal one, with varying density. The
caudal vertebrae of
A. escotae are remarkably similar to those of
Majungasaurus, though more dorsoventrally compressed. The centra possess amphicoelous articulations with the pertinent facets of an intermediate nature between the circular ones of
Ilokelesia and those of the elliptical shape in
Rajasaurus and have neither pneumatic recesses nor accessory
hyposphene-hypantrum articulations. The
transverse processes of the
neural arches are not as inclined as in the
Brachyrostra. The
cnemial crest of
Arcovenator's the
slender 51-cm
tibia is well developed as is characteristic of
abelisauroids. It has a proximal
lateral condyle more prominent than the
medial one, a slight anterodorsal curve on the proximal aspect of the fibular crest, a noticeable distal longitudinal ridge, and tapered
malleoli. The nearly half-meter-long
fibula possesses the typical anatomical characters of
ceratosaurs. Arcovenator's diet would include small rhabdodontids and
dromaeosaurids such as
Pyroraptor. ==Classification and systematics==