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A New Abelisaurid from Argentina

A brand new species of dinosaur has been described from fossils present in Neuquén Province (Argentina). Named Elemgasem nubilus it’s the first unambiguous abelisaurid identified from the Coniacian faunal stage of the Late Cretaceous.

Elemgasem life reconstruction
A life reconstruction of the newly described abelisaurid Elemgasem nubilus depicted with different Late Cretaceous prehistoric fauna related to the Portezuelo Formation of Patagonia. Image credit score: Abel Germán Montes.

A area workforce of CONICET researchers have excavated the fragmentary stays of a brand new species of carnivorous dinosaur from Higher Cretaceous exposures close to to the town of Plaza Huincul, within the province of Neuquén in Patagonia (Argentina). The fossils come from the Portezuelo Formation and characterize a person animal round 4 metres in size and standing roughly two metres tall. Bone histology revealed that this abelisaurid was round eight years previous when it died. The histological evaluation means that Elemgasem most likely wouldn’t have grown a lot larger, making this predator a lot smaller than associated abelisaurids corresponding to Carnotaurus and Ekrixinatosaurus.

Thought to be a sub-adult, the scientists who embrace co-author Rodolfo Coria (Universidad Nacional de Río Negro, Argentina), writing within the journal of The Palaeontological Affiliation conclude that this dinosaur had already reached sexual maturity.

Palaeontologist Rodolfo Coria excavates dinosaur fossils
Co-author of the scientific paper Rodolfo Coria (Universidad Nacional de Río Negro) excavating fossils in Neuquén Province. Image credit score: CONICET.

Documenting the Evolution of the Abelisauridae

The Abelisauridae are a various group of medium-to-large-sized predatory dinosaurs predominately related to the landmass of Gondwana. Quite a few genera have been described primarily based on fossils discovered within the Southern Hemisphere and they’re identified from virtually all elements of Gondwana in all of the faunal levels related to the Late Cretaceous, apart from the Coniacian (90 to 86 mya roughly).

This era in Earth’s historical past is marked by a turnover in terrestrial and marine fauna attributable to world local weather change resulting in worldwide extinctions.

Explaining the importance of those fossils, co-author Rodolfo Coria said:

“The identification of a brand new species is at all times a scientifically related occasion, particularly if the species belongs to an emblematic household of carnivorous dinosaurs such because the abelisaurs. Elemgasem represents a key piece within the puzzle of the evolution of this group, which started to be put along with the primary findings of José Bonaparte, crucial Argentinean vertebrate palaeontologist of the twentieth century – within the Nineteen Eighties”

Though the fossil materials is fragmentary, a brand new genus has been erected primarily based on a number of autapomorphies together with notable rugosity on the lateral floor of the fibula and the form of the tail bones that are completely different from every other abelisaurid described to this point.

Views of the distal portion of the right femur of Elemgasem.
Views of the distal portion of the fossilised proper femur of Elemgasem nubilus with an accompanying line drawing that exhibits the place of the bone. Image credit score: Mattia A. Baiano.

The First Abelisaurid from the Portezuelo Formation

Elemgasem is the primary abelisaurid described from fossils from the Portezuelo Formation and it was a part of a various dinosaur-dominated terrestrial fauna with a number of several types of theropod current together with dromaeosaurids, alvarezsaurids and megaraptorids.

Phylogenetic evaluation signifies the E. nubilus may very well be tentatively assigned to the Brachyrostra tribe throughout the Carnotaurinae subfamily, though the restricted quantity of fossilised materials prevented the researchers from making a extra optimistic taxonomic evaluation.

The genus identify is derived from the identify of a god within the regional Tehuelche tradition and the trivial identify is from the Latin for “cloudy days”, a reference to the unusual, foggy circumstances that the dig workforce encountered while they labored within the area.

Elemgasem skeletal reconstruction.
Skeletal reconstruction of Elemgasem nubilus with identified fossil components proven in purple. Image credit score: Abel Germán Montes.

Dr Coria added:

“We already knew of abelisaurian kinds in older horizons [such as the Cenomanian] or extra trendy ones [such as the Campanian], so it was predictable that there can be some in intermediate occasions. What we didn’t count on was to discover a comparatively small abelisaur like Elemgasem, whose dimension is clearly smaller than the remainder of the species within the group, corresponding to Carnotaurus, Aucasaurus or Skorpiovenator.”

It’s the first abelisaurid from the Turonian–Coniacian interval and it will increase the range of this theropod household at a time of marked turnover within the tetrapod fauna of South America.

Every thing Dinosaur acknowledges the help of a media launch from CONICET within the compilation of this text.

The scientific paper: “Elemgasem nubilus: a brand new brachyrostran abelisaurid (Theropoda, Ceratosauria) from the Portezuelo Formation (Higher Cretaceous) of Patagonia, Argentina” by Mattia A. Baiano, Diego Pol, Flavio Bellardini, Guillermo J. Windholz, Ignacio A. Cerda, Alberto C. Garrido and Rodolfo A. Coria revealed in Papers in Palaeontology.

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