''Rahiolisaurus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of abelisaurid theropod

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

which existed in

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

period. It was described in

2010 File:2010 Events Collage New.png, From top left, clockwise: The 2010 Chile earthquake was one of the strongest recorded in history; The Eruption of Eyjafjallajökull in Iceland disrupts air travel in Europe; A scene from the opening ceremony of ...

, based on fossils recovered from the Lameta Formation in the Indian state of

Gujarat Gujarat (, ) is a state along the western coast of India. Its coastline of about is the longest in the country, most of which lies on the Kathiawar peninsula. Gujarat is the fifth-largest Indian state by area, covering some ; and the ninth ...

. These fossils include elements from at least seven different individuals and are believed to have been from the

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...

stage, sometime between and 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 In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

''Rahiolisaurus gujaratensis''.

Discovery and naming

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''. Individual bones of the newly discovered abelisaurid was given separate catalogue numbers. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

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 Indian Statistical Institute (ISI) is a higher education and research institute which is recognized as an Institute of National Importance by the 1959 act of the Indian parliament. It grew out of the Statistical Laboratory set up by Prasanta C ...

, Kolkata. ''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

" in Latin.

Description

''Rahiolisaurus'' was initially described as a large-sized abelisaurid and around long and weighing , but the allometry-based estimate for the right femur specimen (ISIR 557) suggests a shorter body length of . It shares many similarities with another Indian abelisaurid, '' Rajasaurus'', but includes differences such as an overall more gracile and slender-limbed form.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. . . 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. Abelisaurids likely had a bite force similar to '' Allosaurus'' at around .

Classification

In 2014, the subfamily

Majungasaurinae 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 thero ...

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. The following cladogram was recovered by Tortosa (2014):

Palaeoecology

''Rahiolisaurus'' has been found in the Lameta Formation, a rock unit

radiometrically dated Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...

to the

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

of the latest Cretaceous representing an

arid A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ar ...

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 The Deccan Traps is a large igneous province of west-central India (17–24°N, 73–74°E). It is one of the largest volcanic features on Earth, taking the form of a large shield volcano. It consists of numerous layers of solidified flood ...

. ''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; though eggs belonging to large theropods have been found, it is unknown if they belong to ''Rahiolisaurus''. Sauropod

coprolite A coprolite (also known as a coprolith) is fossilized feces. Coprolites are classified as trace fossils as opposed to body fossils, as they give evidence for the animal's behaviour (in this case, diet) rather than morphology. The name is de ...

remains indicate they lived in a forested landscape, consuming plants such as '' Podocarpus'', ''

Araucaria ''Araucaria'' (; original pronunciation: .ɾawˈka. ɾja is a genus of evergreen Conifer, coniferous trees in the family Araucariaceae. There are 20 extant taxon, extant species in New Caledonia (where 14 species are endemism, ende ...

'', and

Cheirolepidiaceae Cheirolepidiaceae is an extinct family of conifers. They first appeared in the Triassic, and were widespread during most of the Mesozoic era. They are united by the possession of a distinctive pollen type assigned to the form genus '' Classopolli ...

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

cycads Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or ...

;

palm tree The Arecaceae is a family of perennial flowering plants in the monocot order Arecales. Their growth form can be climbers, shrubs, tree-like and stemless plants, all commonly known as palms. Those having a tree-like form are called palm trees ...

s; early

grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

; and

Caryophyllaceae Caryophyllaceae, commonly called the pink family or carnation family, is a family of flowering plants. It is included in the dicotyledon order Caryophyllales in the APG III system, alongside 33 other families, including Amaranthaceae, Cactacea ...

Sapindaceae The Sapindaceae are a family of flowering plants in the order Sapindales known as the soapberry family. It contains 138 genera and 1858 accepted species. Examples include horse chestnut, maples, ackee and lychee. The Sapindaceae occur in tempera ...

, and Acanthaceae flowering plants. Several dinosaurs have been described from the Lameta Formation, such as the

noasaurid Noasauridae is an extinct family of theropod dinosaurs belonging to the group Ceratosauria. They were closely related to the short-armed abelisaurids, although most noasaurids had much more traditional body types generally similar to other ther ...

Laevisuchus ''Laevisuchus'' (, "light crocodile") is a genus of theropod dinosaur from the Late Cretaceous. Its remains were discovered by Charles Alfred Matley near Jabalpur in Maastrichtian deposits in the Lameta Formation in India, and were named and des ...

''; abelisaurids '' Indosaurus'', ''

Indosuchus ''Indosuchus'' () is a genus of abelisaurid dinosaur from the Late Cretaceous Period (70 to 66 million years ago – the Maastrichtian), a theropod related to '' Abelisaurus''. Like most theropods, ''Indosuchus'' was a bipedal carnivore. It was ...

'', '' Lametasaurus'', and '' Rajasaurus''; and the

titanosaur Titanosaurs (or titanosaurians; members of the group Titanosauria) were a diverse group of sauropod dinosaurs, including genera from all seven continents. The titanosaurs were the last surviving group of long-necked sauropods, with taxa still th ...

ian sauropods ''

Jainosaurus ''Jainosaurus'' is a genus of titanosaurian sauropod dinosaur of India and wider Asia, which lived in the Maastrichtian (approximately 68 mya (unit), million years ago). No accurate estimate of the length, height, or weight has yet been mad ...

'', ''

Titanosaurus ''Titanosaurus'' (; ) is a dubious genus of sauropod dinosaurs, first described by Richard Lydekker in 1877.R. Lydekker. (1877). Notices of new and other Vertebrata from Indian Tertiary and Secondary rocks. ''Records of the Geological Survey of I ...

'', and ''

Isisaurus ''Isisaurus'' (named after the Indian Statistical Institute) is a genus of titanosaurian dinosaur from the Late Cretaceous Lameta Formation of India. The genus contains a single species, ''Isisaurus colberti''. Discovery and Naming The type spe ...

''. The diversity of abelisauroid and titanosaurian dinosaurs in Cretaceous India indicates they shared close affinities to the dinosaur life of the other

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...

n continents, which had similar inhabitants. Dinosaurs in India probably went extinct due to volcanic activity around 350,000 years before the

Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end of ...

. They likely avoided areas with volcanic

fissure vent A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive eruption, explosive activity. The vent is often a few metres wide an ...

s and

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

References

{{Taxonbar, from=Q134070 Majungasaurines Dinosaurs of India and Madagascar Late Cretaceous dinosaurs Fossil taxa described in 2010 Taxa named by Fernando Novas Taxa named by Sankar Chatterjee

Discovery and naming

Description

Classification

Palaeoecology

See also

References