Open Paleo

Indosuchus

Huene & Matley, 1933 IN-do-SOOK-us Disputed

From India (where it was found) and Greek suchos (crocodile); meaning 'Indian crocodile'

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Indosuchus is a genus of abelisaurid dinosaur from the Late Cretaceous Period (Maastrichtian, 70 to 66 million years ago) of what is now India. Like most theropods, Indosuchus was a bipedal carnivore. It was about 7 meters (23 ft) long, weighed about 1.2 tonnes (1.3 short tons), and had a crested skull, flattened on the top.

Under dispute

Novas and colleagues (2010) consider Indosuchus raptorius a nomen dubium, its holotype offering no clear autapomorphies, while Dalman and Gishlick (2011), studying the material in full, treat it as valid and recover it within Carnotaurinae; Carrano and Sampson (2008) allow that the Lameta abelisaurids may be only one or two taxa, though they find Indosuchus the most distinct. Its abelisaurid affinity is not in question. Much of the material once referred to it has been reassigned: Novas and colleagues (2010) made the Rahioli skeleton the basis of Rahiolisaurus, and Dalman and Gishlick (2011) refer the AMNH specimens to an indeterminate basal abelisaurid.

Diagnosis

  1. Narrow, sharp parietal crest formed by sudden wedge-shaped contraction of parietals posteriorly
  2. Skull roof between orbits flat and smooth dorsally, not concave or transversely crested
  3. No horn-like tuberosities on postfrontals
  4. Divided olfactory canal: sphenethmoid forms two separate oval openings (14 mm high) separated by vertical mesethmoid lamella
  5. Orbitosphenoid visible in depth of supratemporal opening, with horn-like lateral processes lying below posterior borders of frontals

Species

Indosuchus raptorius Huene & Matley, 1933 Disputed

Type species

From Latin 'raptorius' meaning 'raptorial', in reference to the predatory nature of the animal.

Lectotype
GSI K27/685 , Geological Survey of India (lost)
Material
Partial braincase
Notes
Huene and Matley (1933) founded the species on three skull fragments (GSI K20/350, K27/690 and K27/685) without designating a type. Chatterjee (1978) found K27/685 to be the only one still extant in the GSI collection and designated it the lectotype; K20/350 and K27/690 are paralectotypes. Novas and colleagues (2004) report all three as lost or misplaced in the GSI collection.
Horizon
Carnosaur Bed Bed, Lameta Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
Bara Simla, Jabalpur, Madhya Pradesh, India

References

  1. Huene, F. V.; Matley, C. A. (1933). The Cretaceous Saurischia and Ornithischia of the Central Provinces of India. Palaeontologica Indica (New Series), Memoirs of the Geological Survey of India 21(1): 1-74. huene1933a
  2. Chatterjee, S. (1978). Indosuchus and Indosaurus, Cretaceous carnosaurs from India. Journal of Paleontology 52(3): 570-580. chatterjee1978a
  3. Novas, F. E.; Agnolín, F. L.; Bandyopadhyay, S. (2004). Cretaceous theropods from India: A review of specimens described by Huene and Matley (1933). Revista del Museo Argentino de Ciencias Naturales 6(1): 67-103. doi:10.22179/REVMACN.6.74 novas2004b
  4. Novas, F. E.; Chatterjee, S.; Rudra, D. K.; Datta, P. M. (2010). Rahiolisaurus gujaratensis, n. gen. n. sp., A New Abelisaurid Theropod from the Late Cretaceous of India. Lecture Notes in Earth Sciences 45-62. Springer Berlin Heidelberg. doi:10.1007/978-3-642-10311-7_3

    Considers Indosuchus raptorius a nomen dubium, with Lametasaurus indicus and Indosaurus matleyi, and refers the Rahioli material to the new genus Rahiolisaurus.

    novas2010b
  5. Carrano, M. T.; Sampson, S. D. (2008). The Phylogeny of Ceratosauria (Dinosauria: Theropoda). Journal of Systematic Palaeontology 6(2): 183-236. doi:10.1017/S1477201907002246

    Confirms the abelisaurid affinity, allows that the Lameta abelisaurids may be only one or two taxa, and finds the Indosuchus type the most distinct of them.

    carrano2008a
  6. Dalman, S. G.; Gishlick, A. D. (2011). Theropod material from Lameta, India, in the collection of the American Museum of Natural History and its bearing on the diagnosis and phylogenetic and taxonomic status of Indosuchus raptorius. Society of Vertebrate Paleontology, 71st Annual Meeting, Program and Abstracts. Society of Vertebrate Paleontology, Las Vegas.

    Treats Indosuchus raptorius as valid, recovers it within Carnotaurinae and not with Indosaurus, and separates the AMNH material as a basal abelisaurid.

    dalman2011a