[D] Majungasaurus crenatissimus [T]
Cretaceous Late Campanian
Saurischia Theropoda Abelisauridae
Gres de Maevarano, Berivotro Formation, Majunga, Madagascar
Majungasaurus (Lavocat, 1955) > Majungasaurus crenatissimus (Deperet, 1896) >> Megalosaurus crenatissimus (Deperet, 1896)
Majungasaurus > Majungatholus atopus (Sues & Taquet, 1979)
Partial mandible, 2 teeth, a caudal and 2 sacral centra, and a claw.
Named for an incomplete dentary. Although Lavocat did not propose a specific name for this specimen, he did assign Megalosaurus crenatissimus (Deperet, 1896) to Majungasaurus, and this has been accepted as the type species.
The mandible, although incomplete, is distinctly concave dorsally, has triangular interdental plates, and a longitudinal medial shelf. Lavocat associated this mandible with Deperet\\\'s material because of the similarity of the teeth.
No elements with diagnostic carnosaurian features are known for Megalosaurus crenatissimus. However among other theropods only Carnotaurus sastrei has a similarly curved mandible. Sampson et. al. Majungatholus (presumed Madagascan pachycephalosaur) proved Majungatholus atopus is the same as Majungasaurus, so it is actually a bone-headed abelisaur.
Two abelisaurs are already known to have thickened cranial elements - Carnotaurus sastrei and Indosaurus matleyi. In Carnotaurus sastrei the frontal elements were developed as pointy horns; in Indosaurus, the bulging frontals may represent the bases of horn cores.
O\\\'Connor and Claessens , (2005) reported on the basis of a comparative analysis of region-specific pneumaticity with extant birds, evidence for cervical and abdominal air-sac systems in non-avian theropods, along with thoracic skeletal prerequisites of an avian-style aspiration pump.The authors demonstrated by examination of an exceptional new specimen of Majungatholus atopus, (Majungasaurus), documenting these features in a taxon only distantly related to birds. Taken together, these specializations imply the existence of the basic avian pulmonary Bauplan in basal neotheropods, indicating that flow-through ventilation of the lung is not restricted to birds but is probably a general theropod characteristic.\\\"