Rahiolisaurus

Last updated

Rahiolisaurus
Temporal range:
Late Cretaceous, 70–66  Ma
O
S
D
C
P
T
J
K
Pg
N
Rahiolisaurus restoration.png
Life restoration of Rahiolisaurus gujaratensis
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: Abelisauridae
Subfamily: Majungasaurinae
Genus: Rahiolisaurus
Novas et al., 2010
Species:
R. gujaratensis
Binomial name
Rahiolisaurus gujaratensis
Novas et al., 2010

Rahiolisaurus is a genus of abelisaurid theropod dinosaur which existed in India during the Late Cretaceous period. It was described in 2010, based on fossils recovered from the Lameta Formation in the Indian state of Gujarat. These fossils include elements from at least seven different individuals and are believed to have been from the Maastrichtian stage, sometime between 70 and 66 million years ago, making it one of the last non-avian dinosaurs known in the fossil record. Despite representing a variety of different growth stages, all recovered fossils from the locality indicate a single species, the type species Rahiolisaurus gujaratensis.

Contents

Discovery and naming

The landscape of the Indian state of Gujarat, in which the remains of Rahiolisaurus were found Kakda Kho 02.jpg
The landscape of the Indian state of Gujarat, in which the remains of Rahiolisaurus were found

During two expeditions, one in 1995 and the other in 1997, numerous remains of abelisaurids were recovered from a single quarry 50 square metres in area. The collected remains included cervical, dorsal, sacral, and caudal vertebrae, portions of pectoral and pelvic girdles, and several hind limb bones. Because of the unearthing of seven differently sized right tibiae, it was suggested that the assemblage was formed by at least seven individuals of different ontogenetic stages. Within the collection were several duplicate bones, such as the ilia, pubes, femora and tibiae, that exhibited similar morphological features of typical abelisauroid traits. However, despite these remains being of different size gradation and representing growth series, hardly any taxonomic variation was discovered. It was interpreted by Novas et al. that the entire theropod collection from this quarry may be referred to the single species Rahiolisaurus. [1]

Individual bones of the newly discovered abelisaurid was given separate catalogue numbers. The holotype of Rahiolisaurus is represented by a partial association of pelvic elements and a femur that were found in the field. It consists of a right ilium (ISIR 550), a right pubis (ISIR 554), and a right femur (ISIR 557). In addition, an axis (ISIR 658) was found in articulation with cervicals 3 (ISIR 659) and 4 (ISIR 660) and are attributed to the species. These bones are currently housed at the collection of the Geology Museum, Indian Statistical Institute, Kolkata. [1]

Rahiolisaurus was named after the village of Rahioli, located near the fossil site where the dinosaurs remains were discovered. The specific name, gujaratensis, means "from Gujarat" in Latin. [1]

Description

Size of Rahiolisaurus gujaratensis compared to a human Rahiolisaurus size.jpg
Size of Rahiolisaurus gujaratensis compared to a human

Rahiolisaurus was initially described as a large-sized abelisaurid and around 8 metres (26 ft) long and weighing 2 metric tons (2.2 short tons), [1] [2] but the allometry-based estimate for different specimens suggest a shorter body length of 6.22–6.75 metres (20.4–22.1 ft). [3] It shares many similarities with another Indian abelisaurid, Rajasaurus , but includes differences such as an overall more gracile and slender-limbed form. [1] Abelisaurids typically had four fingers, short arms, and, to compensate, a heavily constructed head which was the primary tool for hunting; however, the skull was short, they probably had modest jaw musculature, and the teeth were short. [2] Abelisaurids likely had a bite force similar to Allosaurus at around 3,500 newtons (790 lbf). [4]

Classification

In 2014, the subfamily Majungasaurinae was erected by palaeontologist Thierry Tortosa to separate the newly discovered European Arcovenator , Majungasaurus , Indosaurus , Rahiolisaurus, and Rajasaurus from South American abelisaurids based on physical characteristics such as elongated antorbital fenestrae in front of the eye sockets, and a sagittal crest that widens into a triangular surface towards the front of the head. Despite large oceanic barriers, it has been suggested that a migration of abelisaurids took place in the Late Cretaceous between Africa, Europe, Madagascar, and India which ultimately isolated South American abelisaurids; it is possible that migration occurred between Europe and India across Africa given its proximity to both, and the volcanic Dras-Kohistan island arc may have allowed island hopping and an indirect path to Asia, though these are still questionable explanations. [5] [6]

The following cladogram was recovered by Tortosa (2014): [5]

Ceratosauria

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

Abelisauridae

Palaeoecology

India was an island in the Late Cretaceous LateCretaceousMap.jpg
India was an island in the Late Cretaceous

Rahiolisaurus has been found in the Lameta Formation, a rock unit radiometrically dated to the Maastrichtian age of the latest Cretaceous representing an arid or semi-arid landscape with a river flowing through it–probably providing shrub cover near the water–which formed between episodes of volcanism in the Deccan Traps. [8] [9] Rahiolisaurus likely inhabited what is now the Narmada River Valley. The formation is known for being a sauropod nesting site, yielding several dinosaur eggs, and sauropod herds likely chose sandy soil for nesting; [10] though eggs belonging to large theropods have been found, it is unknown if they belong to Rahiolisaurus. [11] Sauropod coprolite remains indicate they lived in a forested landscape, consuming plants such as Podocarpus , Araucaria , and Cheirolepidiaceae conifers; cycads; palm trees; early grass; and Caryophyllaceae, Sapindaceae, and Acanthaceae flowering plants. [12]

Several dinosaurs have been described from the Lameta Formation, such as the noasaurid Laevisuchus ; abelisaurids Indosaurus , Indosuchus , Lametasaurus , and Rajasaurus ; and the titanosaurian sauropods Jainosaurus , Titanosaurus , and Isisaurus . The diversity of abelisauroid and titanosaurian dinosaurs in Cretaceous India indicates they shared close affinities to the dinosaur life of the other Gondwanan continents, which had similar inhabitants. [13] Dinosaurs in India probably went extinct due to volcanic activity around 350,000 years before the Cretaceous–Paleogene boundary. They likely avoided areas with volcanic fissure vents and lava flows. [14]

See also

Related Research Articles

<i>Rajasaurus</i> Abelisaurid dinosaur genus from Late Cretaceous India

Rajasaurus is a genus of carnivorous abelisaurid theropod dinosaur from the Late Cretaceous of India, containing one species: Rajasaurus narmadensis. The bones were excavated from the Lameta Formation in the Gujarat state of Western India, probably inhabiting what is now the Narmada River Valley. It was formally described by palaeontologist Jeffrey A. Wilson and colleagues in 2003 based on a partial skeleton comprising the braincase, spine, hip bone, legs, and tail–a first for an Indian theropod. The dinosaur likely measured 6.6 metres (22 ft), and had a single horn on the forehead which was probably used for display and head-butting. Like other abelisaurids, Rajasaurus was probably an ambush predator.

<i>Indosuchus</i> Abelisaurid theropod dinosaur genus from the Late Cretaceous Period

Indosuchus is a genus of abelisaurid dinosaur from the Late Cretaceous Period, a theropod related to Abelisaurus. Like most theropods, Indosuchus was a bipedal carnivore. It was about 7 metres long, weighed about 1.2 tonnes, and had a crested skull, flattened on the top.

<span class="mw-page-title-main">Abelisauridae</span> Extinct family of dinosaurs

Abelisauridae is a family of ceratosaurian theropod dinosaurs. Abelisaurids thrived during the Cretaceous period, on the ancient southern supercontinent of Gondwana, and today their fossil remains are found on the modern continents of Africa and South America, as well as on the Indian subcontinent and the island of Madagascar. Isolated teeth were found in the Late Jurassic of Portugal, and the Late Cretaceous genera Tarascosaurus and Arcovenator have been described in France. Abelisaurids first appear in the fossil record of the early middle Jurassic period, and at least three genera survived until the end of the Mesozoic era 66 million years ago.

<i>Aucasaurus</i> Extinct genus of dinosaurs

Aucasaurus is a genus of medium-sized abelisaurid theropod dinosaur from Argentina that lived during the Late Cretaceous of the Anacleto Formation. It was smaller than the related Carnotaurus, although more derived in some ways, such as its extremely reduced arms and almost total lack of fingers. The type skeleton is complete to the thirteenth caudal vertebra, and so is relatively well understood, and is the most complete abelisaurid yet described. However, the skull is damaged, causing some paleontologists to speculate that it was involved in a fight prior to death.

<span class="mw-page-title-main">Abelisauroidea</span> Extinct clade of dinosaurs

Abelisauroidea is a diverse superfamily of ceratosaurian dinosaurs, typically regarded as a Cretaceous group, though the earliest abelisaurid remains are known from the Middle Jurassic of Argentina and possibly Madagascar. Possible Abelisauridae remains were also discovered in Late Jurassic Tendaguru Beds in Tanzania.

<i>Ilokelesia</i> Extinct genus of reptiles

Ilokelesia is an extinct genus of abelisaurid theropod, preserved in the layers of the earliest Late Cretaceous of the Huincul Formation, Neuquén Group, located near Plaza Huincul, Neuquén Province, Argentina. The specimen, consisting of very fragmentary elements of the skull and the axial and appendicular skeleton, was described by Rodolfo Coria and Leonardo Salgado in late 1998.

<i>Quilmesaurus</i> Extinct genus of dinosaurs

Quilmesaurus is a genus of carnivorous abelisaurid theropod dinosaur from the Patagonian Upper Cretaceous of Argentina. It was a member of Abelisauridae, closely related to genera such as Carnotaurus. The only known remains of this genus are leg bones which share certain similarities to a variety of abelisaurids. However, these bones lack unique features, which may render Quilmesaurus a nomen vanum.

<i>Indosaurus</i> Extinct genus of dinosaurs

Indosaurus is a genus of carnivorous theropod dinosaur that lived in what is now India, about 69 to 66 million years ago during the Maastrichtian division of the Late Cretaceous.

<i>Compsosuchus</i> Extinct genus of dinosaurs

Compsosuchus is a dubious genus of abelisauroid dinosaur from the Late Cretaceous Lameta Formation of India.

<i>Isisaurus</i> Extinct genus of dinosaurs

Isisaurus is a genus of titanosaurian dinosaur from the Late Cretaceous Lameta Formation of India and Pab Formation of Pakistan. The genus contains a single species, Isisaurus colberti.

<i>Majungasaurus</i> Abelisaurid theropod dinosaur from the Late Cretaceous period

Majungasaurus is a genus of abelisaurid theropod dinosaur that lived in Madagascar from 70 to 66 million years ago, at the end of the Cretaceous Period, making it one of the last-known non-avian dinosaurs that went extinct during the Cretaceous–Paleogene extinction event. The genus contains a single species, Majungasaurus crenatissimus. This dinosaur is also called Majungatholus, a name which is considered a junior synonym of Majungasaurus.

<i>Ekrixinatosaurus</i> Extinct genus of dinosaur

Ekrixinatosaurus is a genus of abelisaurid theropod which lived approximately 100 to 97 million years ago during the Late Cretaceous period. Its fossils have been found in Argentina. Only one species is currently recognized, Ekrixinatosaurus novasi, from which the specific name honors of Dr. Fernando Novas for his contributions to the study of abelisaurid theropods, while the genus name refers to the dynamiting of the holotype specimen. It was a large abelisaur, measuring between 6.5 and 8 m in length and weighing 800 kg (1,800 lb).

<i>Laevisuchus</i> Extinct genus of dinosaurs

Laevisuchus is a genus of theropod dinosaur from the Late Cretaceous. Its remains were discovered by Charles Alfred Matley near Jabalpur in Maastrichtian "Carnosaur Bed" deposits in the Lameta Formation in Madhya Pradesh, central India, and were named and described by paleontologists Friedrich von Huene and Matley in 1933.

<i>Lametasaurus</i> Extinct genus of reptiles

Lametasaurus named for the Lameta Formation, Jabalpur, India, is the generic name given to a possibly chimeric dinosaur species. The type species is L. indicus.

<span class="mw-page-title-main">Lameta Formation</span> Geologic formation in India

The Lameta Formation, also known as the Infratrappean Beds, is a sedimentary geological formation found in Madhya Pradesh, Gujarat, Maharashtra, Telangana, and Andhra Pradesh, India, associated with the Deccan Traps. It is of the Maastrichtian age, and is notable for its dinosaur fossils

<i>Austrocheirus</i> Genus of reptiles (fossil)

Austrocheirus is an extinct genus of theropod dinosaur that lived during the Late Cretaceous period. It was named and described by Martin Ezcurra, Federico Agnolin and Fernando Novas in 2010. It contains the type species Austrocheirus isasii. The generic name means "southern hand". The specific epithet honours discoverer and preparator Marcelo Pablo Isasi.

<i>Arcovenator</i> Extinct genus of dinosaurs

Arcovenator is an extinct genus of abelisaurid theropod dinosaurs hailing from the Late Cretaceous of France. The type and only described species is Arcovenator escotae.

<span class="mw-page-title-main">Majungasaurinae</span> Extinct subfamily of reptiles

Majungasaurinae 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.

<span class="mw-page-title-main">Timeline of ceratosaur research</span>

This timeline of ceratosaur research is a chronological listing of events in the history of paleontology focused on the ceratosaurs, a group of relatively primitive, often horned, predatory theropod dinosaurs that became the apex predators of the southern hemisphere during the Late Cretaceous. The nature and taxonomic composition of the Ceratosauria has been controversial since the group was first distinguished in the late 19th century. In 1884 Othniel Charles Marsh described the new genus and species Ceratosaurus nasicornis from the Late Jurassic Morrison Formation of the western United States. He felt that it belonged in a new family that he called the Ceratosauridae. He created the new taxon Ceratosauria to include both the Ceratosauridae and the ostrich-like ornithomimids. The idea of the Ceratosauria was soon contested, however. Later that same decade both Lydekker and Marsh's hated rival Edward Drinker Cope argued that the taxon was invalid.

Tralkasaurus is a genus of abelisaurid dinosaur from the Huincul Formation from Río Negro Province in Argentina. The type and only species is Tralkasaurus cuyi, named in 2020 by Mauricio Cerroni and colleagues based on an incomplete skeleton. A medium-sized abelisaurid, Tralkasaurus exhibits a conflicting blend of characteristics found among the early-diverging abelisauroids with others that characterize the highly specialized clade Brachyrostra, and thus its position within the clade is poorly-resolved.

References

  1. 1 2 3 4 5 Novas, Fernando E., Chatterjee, Sankar, Rudra, Dhiraj K., Datta, P.M. (2010). "Rahiolisaurus gujaratensis, n. gen. n. sp., A New Abelisaurid Theropod from the Late Cretaceous of India" in: Saswati Bandyopadhyay (ed.): New Aspects of Mesozoic Biodiversity. Springer Berlin / Heidelberg. pp. 45–62. doi : 10.1007/978-3-642-10311-7. ISBN   978-3-642-10310-0.
  2. 1 2 Paul, G. S. (2010). The Princeton Field Guide to Dinosaurs. Princeton University Press. pp.  84–86. ISBN   978-0-691-13720-9.
  3. Grillo, O. N.; Delcourt, R. (2016). "Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king". Cretaceous Research. 69: 71–89. doi:10.1016/j.cretres.2016.09.001.
  4. Delcourt, R. (2018). "Ceratosaur Palaeobiology: New Insights on Evolution and Ecology of the Southern Rulers". Scientific Reports. 8 (9730): 9730. doi:10.1038/s41598-018-28154-x. PMC   6021374 . PMID   29950661.
  5. 1 2 Tortosa, T.; Buffetaut, E.; Vialle, N.; Dutour, Y.; Turini, E.; Cheylan, G. (2014). "A new abelisaurid dinosaur from the Late Cretaceous of southern France: Palaeobiogeographical implications". Annales de Paléontologie. 100: 63–86. doi:10.1016/j.annpal.2013.10.003.
  6. Kapur, V. V.; Khosla, A. (2016). "Late Cretaceous terrestrial biota from India with special reference to vertebrates and their implications for biogeographic connections". Cretaceous Period: Biotic Diversity and Biogeography. 71: 161–172.
  7. https://www.researchgate.net/publication/326017886_Ceratosaur_palaeobiology_New_insights_on_evolution_and_ecology_of_the_southern_rulers
  8. Brookfield, M. E.; Sanhi, A. (1987). "Palaeoenvironments of the Lameta beds (late Cretaceous) at Jabalpur, Madhya Pradesh, India: Soils and biotas of a semi-arid alluvial plain". Cretaceous Research. 8 (1): 1–14. doi:10.1016/0195-6671(87)90008-5.
  9. Mohabey, D. M. (1996). "Depositional environment of Lameta Formation (late Cretaceous) of Nand-Dongargaon inland basin, Maharashtra: the fossil and lithological evidences". Memoirs of the Geological Survey of India. 37: 1–36.
  10. Tandon, S. K.; Sood, A.; Andrews, J. E.; Dennis, P. F. (1995). "Palaeoenvironments of the dinosaur-bearing Lameta Beds (Maastrichtian), Narmada Valley, Central India" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology. 117 (3–4): 153–184. doi:10.1016/0031-0182(94)00128-U.
  11. Lovgren, S. (13 August 2003). "New Dinosaur Species Found in India". National Geographic News. Archived from the original on December 11, 2003. Retrieved 8 April 2009.
  12. Sonkusare, H.; Samant, B.; Mohabey, D. M. (2017). "Microflora from Sauropod Coprolites and Associated Sedimentsof Late Cretaceous (Maastrichtian) Lameta Formation of Nand-Dongargaon Basin, Maharashtra". Geological Society of India. 89 (4): 391–397. doi:10.1007/s12594-017-0620-0. S2CID   135418472.
  13. Weishampel, D. B.; Barrett, P. M.; Coria, R.; Le Loeuff, J.; Xijin, Z.; Xing, X.; Sahni, A.; Gomani, E. M. P.; Noto, C. R. (2004). "Dinosaur Distribution". In Weishampel, D. B.; Dodson, P.; Osmólska, H. (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. p.  595. ISBN   978-0-520-24209-8.
  14. Mohabey, D. M.; Samant, B. (2013). "Deccan continental flood basalt eruption terminated Indian dinosaurs before the Cretaceous–Paleogene boundary". Geological Society of India Special Publication (1): 260–267.