Arcovenator ("Arc hunter") is an extinct genus of abelisaurid theropod dinosaurs hailing from the Late Cretaceous of France.[1] The type and only described species is Arcovenator escotae.[1]
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 5–6 m (16–20 ft) long,[1] but it was estimated in 2016 as being 4.8 m (16 ft) in length.[2] 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.[1] Less characteristically, above the orbit is a low fossa with a small fenestra bordered by the lacrimal, frontal, and postorbital.[1] 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.[1] 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.[1] 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.[1] The paroccipital processes have remarkable accessory dorsal and ventral bony bars, that thus bound depressions lateral to the foramen magnum.[1] 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.[1] The squamosal is similar to that of the latter except for a less prominent parietal process.[1] Generally, the external bone ornamentation is more subdued than that of Majungasaurus.[1] 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.[1]
The caudal vertebrae of A. escotae are remarkably similar to those of Majungasaurus, though more dorsoventrally compressed.[1] 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.[1] The transverse processes of the neural arches are not as inclined as in the Brachyrostra.[1]
The cnemial crest of Arcovenator's the slender 51-cm tibia is well developed as is characteristic of abelisauroids.[1] 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.[1] The nearly half-meter-long fibula possesses the typical anatomical characters of ceratosaurs.[1]
Arcovenator is a theropod genus nested within the clade Abelisauridae,[1] which in Linnaean taxonomy has the rank of family.[3] This taxonomical group has as close relatives noasaurids within the Abelisauroidea.[1][4] The latter in turn along with Limusaurus and Ceratosaurus nests within Ceratosauria.[1][5]
Distinguishing characters of abelisaurids are their short, tall skulls with extensively sculptured external surfaces, the drastically reduced fore limbs, and the stout hind limbs.[6]