Majungasaurus crenatissimus

Majungasaurus crenatissimus was the dominant large theropod in the latest Cretaceous Maevarano ecosystem of northwestern Madagascar. An unusually rich sample of skulls and skeletons makes it one of the best-known abelisaurids. Its head was short, deep and broad, with a thickened nasal region, rough facial bone and a low dome-like horn on top of the skull. The neck and hind limbs were powerful, but the forelimbs were drastically reduced. Tooth marks matching Majungasaurus teeth occur on bones of both sauropods and other Majungasaurus individuals, providing direct evidence that at least some members of the species fed on conspecific carcasses.

Its fossils occur between approximately 70 and 66 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

The skull was proportionally short and deep, with fused thickened nasals, a broad rear surface for strong neck muscles and a single rounded frontal dome rather than paired brow horns. Short-crowned serrated teeth lined jaws capable of some movement between their constituent bones. The face carried heavily textured bone associated with a tough external covering. Robust neck vertebrae and ribs reinforced the head-neck system. Like other abelisaurids, Majungasaurus had extremely short forelimbs with four reduced digits, while a deep pelvis, muscular tail and stout hind limbs supported bipedal movement.

• Short, deep and broad skull with thick fused nasal bones
• Single low dome-like ornament on the frontal bones
• Coarsely textured facial bones associated with tough skin
• Short-crowned, recurved teeth with serrated edges
• Robust neck and expanded sites for neck-muscle attachment
• Extremely reduced forelimbs with four short digits
• Stout hind limbs and a deep, powerfully muscled tail

Charles Depéret named isolated teeth from the Mahajanga region Megalosaurus crenatissimus in 1896. René Lavocat erected Majungasaurus in 1955 for additional material, but a domed skull roof was later named Majungatholus atopus and interpreted as a pachycephalosaur. Mahajanga Basin Project expeditions beginning in the 1990s recovered abundant associated remains, including excellent skulls and a nearly complete skeleton. The comprehensive 2007 monograph showed that the dome belonged to the same abelisaurid and restored Majungasaurus crenatissimus as the valid name.

Naming authors: Charles Depéret.

The Maevarano Formation records seasonally dry river channels and floodplains crossed by episodes of drought and intense flooding. Majungasaurus shared this environment with the titanosaurian sauropods Rapetosaurus and Vahiny, the small theropod Masiakasaurus, giant and small crocodyliforms, turtles, snakes, mammals and the enormous frog Beelzebufo. Madagascar had already been geographically isolated, helping produce a distinctive endemic fauna.

Serrated tooth marks on sauropod bones document carcass feeding, while matching marks on Majungasaurus bones establish conspecific feeding. The evidence cannot distinguish active predation from scavenging or show how frequently cannibalism occurred. Its reinforced skull and neck may have supported a bite-and-hold feeding style, but that remains a biomechanical hypothesis. No trackway or associated group demonstrates pack hunting, and the function of the cranial dome is unknown.

• A skull dome once thought to belong to a pachycephalosaur is now recognized as part of Majungasaurus.
• It is among the anatomically best-known abelisaurids because expeditions recovered multiple skulls and associated skeletons.
• Its own tooth pattern matches feeding marks found on Majungasaurus bones.
• The tiny arms retained four highly reduced fingers even though the wrist and hand had little useful mobility.

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1. 01
   Overview of the history of discovery, taxonomy, phylogeny, and biogeography of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar

   David W. Krause, Scott D. Sampson, Matthew T. Carrano, Patrick M. O'Connor · Journal of Vertebrate Paleontology 27, Supplement 2, Memoir 8, 1–20 · 2007

   Open source
2. 02
   Craniofacial anatomy of Majungasaurus crenatissimus (Theropoda: Abelisauridae) from the Late Cretaceous of Madagascar

   Scott D. Sampson, Lawrence M. Witmer · Journal of Vertebrate Paleontology 27, Supplement 2, Memoir 8, 32–104 · 2007

   Open source
3. 03
   Cannibalism in the Madagascan dinosaur Majungatholus atopus

   Raymond R. Rogers, David W. Krause, Kristina Curry Rogers · Nature 422, 515–518 · 2003

   Open source