Majungasaurinae

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Majungasaurinae
Temporal range:
Ma
Majungasaurus crenatissimus mounted skeleton, Stony Brook University
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Abelisauridae
Subfamily: †Majungasaurinae
Tortosa et al., 2014
Type species
†
Majungasaurus crenatissimus
(Depéret, 1896 [originally Megalosaurus]) Lavocat
, 1955
Subgroups
Synonyms

Majungasaurini Tortosa et al., 2014 vide Delcourt, 2018

Majungasaurinae (after Majungasaurus, itself named after the city of Mahajanga in Madagascar) is a subfamily of large carnivorous theropods from the Upper Cretaceous, found in Madagascar, India, and France. It is a subgroup within the theropod family Abelisauridae, a Gondwanan clade known for their thick and often horned skulls and vestigial arms. The two subfamilies of Abelisauridae are Carnotaurinae, best known from the South American Carnotaurus, and Majungasaurinae, consisting of Madagascar’s Majungasaurus and its closest relatives. Their ancestors emerged in the Middle Jurassic, and the clade lasted until the Upper Cretaceous.

The majungasaurines were mid-sized, bipedal predators, but relatively slow moving. Their stout legs were built for striding, not running. They had tall, deep heads with powerful jaws, but small forearms without carpals in the wrists. Because of their slow gait and small arms, they likely preyed upon the larger, slower sauropods rather than the smaller, faster

ornithopods
. Their ancestors lived on a unified southern continent, Gondwana, in the Early Cretaceous, but as the land mass divided they became distinct from their South American cousins, and eventually from each other.

Anatomical identification

The abelisaurids all possess distinct, vestigial, and immobile forelimbs, with highly reduced manual

occipital condyle.[3]
These differences are important because derived abelisaurids are classed as either majungasaurines or carnotaurines based on their synapomorphies.

History of study

The first majungasaurine to be uncovered was Indosaurus, discovered in India in 1933 by Charles Alfred Matley and Friedrich von Huene, and Majungasaurus, discovered in Madagascar in 1955 by René Lavocat.[citation needed] Both species were misidentified at the time of their discoveries as they were known from only partial remains: Indosaurus was believed to be an allosaurid, and Majungasaurus was believed to be a pachycephalosaurid. It was not until 1991 that paleontologist Jose Bonaparte theorized that these and many other theropods belonged to the same family, the abelisaurids.[4]

Classification

Taxonomy[5]

Phylogeny

The clade Majungasaurinae is relatively new, proposed in March 2014 by paleontologist Thierry Tortosa and colleagues in the description of Arcovenator. It is defined as all abelisaurids more closely related to Majungasaurus than to Carnotaurus. The cladogram below shows the result of the study's phylogenetic analysis.[6]

Abelisauridae

The following cladogram is a consensus tree of the latest phylogenies from 2018.[7] Only the phylogenies for Abelisauridae is depicted here.

Abelisauridae


Paleobiology

Geographic range

The majungasaurines and their carnotaurine sister group emerged in what is now South America. From there they spread to the rest of Gondwana: modern Africa and India, and presumably Australia and Antarctica as well.[8] Fragmentary evidence of abelisaurs in southern France indicates they may have spread into Europe as well, but the relationship of these species to the rest of Majungasaurinae is not well established.[9]

Feeding habits

Like all abelisaurs, the majungasaurines were carnivorous and had bulbous teeth, short heads, and strong necks. This meant that their wide jaws were very powerful, and could crush their prey’s trachea or vertebrae once they bit down.[10] Majungasaurus is known to have preyed upon medium-sized sauropods such as Rapetosaurus, and its teeth marks have been found on the ribs of other Majungasaurus. Whether it actively hunted members of its own species or merely cannibalized their scavenged remains is unknown. This behavior has not been observed in any other majungasaurines.[11]

See also

References

  1. doi:10.1111/j.1469-7998.2009.00640.x
    .
  2. ISBN 978-0-253-35289-7
    .
  3. doi:10.1016/j.annpal.2013.10.003
    .
  4. S2CID 30068953
    .
  5. doi:10.1016/j.cretres.2015.12.018
    .
  6. ISSN 0753-3969
    .
  7. ^ https://www.researchgate.net/publication/326017886_Ceratosaur_palaeobiology_New_insights_on_evolution_and_ecology_of_the_southern_rulers
  8. PMID 15306329
    .
  9. ISBN 978-0-375-82419-7
    .
  10. ISBN 0521282373
    .
  11. S2CID 4389583
    .
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