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Arcovenator
''Arcovenator'' ("Arc hunter") is a genus of abelisaurid theropod dinosaur hailing from the Late Cretaceous of France. The type and only described species is ''Arcovenator escotae''.〔
==Description==
Though shallower, the nearly complete braincase of ''Arcovenator'' is otherwise similar in size to those of ''Majungasaurus'' and ''Carnotaurus'', implying an animal 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 there is above the orbit 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 dorso-ventrally 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 persuasion in ''Rajasaurus'' and have neither pneumatic recesses nor accessory hyposphene-hypantrum articulations.〔 The transverse processes of the neural arches aren't as inclined as in Brachyrostra.〔
The cnemial crest of ''Arcovenators 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.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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