Ekrixinatosaurus

Ekrixinatosaurus
Artistic live representation of Ekrixinatosaurus novasi
Temporal occurrence
Upper Cretaceous ( Cenomanium )
100.5 to 93.9 million years
Locations
Argentina ( Candeleros formation )
Systematics
Lizard dinosaur (Saurischia) Theropoda Ceratosauria Abelisauridae Brachyrostra Ekrixinatosaurus
Scientific name
Ekrixinatosaurus
Calvo , Rubilar-Roger & Moreno , 2004
Art
Ekrixinatosaurus novasi

Ekrixinatosaurus is a genus of theropod dinosaur from the Abelisauridae group . It is known from a single, fragmentary skeleton that was found in the Argentine province of Neuquén and is dated to the Upper Cretaceous ( Cenomanium ). It was a very large, two-legged carnivore , which, like the closely related genera Skorpiovenator and Carnotaurus, is characterized by a short and high skull. Ekrixinatosaurus wasscientifically described in 2004 by researchers around Jorge Calvo with the only species E. novasi .

The skeleton was accidentally uncovered during the blasting for the construction of a gas pipeline . The name Ekrixinatosaurus ( Greek ekrixi - "explosion", nato - "born", saurus - "lizard"), which means something like "lizard born by an explosion", refers to this fact. The second part of the species name, novasi , honors Fernando Novas , a paleontologist who has made a special contribution to researching the Abelisaurids.

features

Calvo and colleagues (2004) estimate the length of the only known skeleton to be 7 to 8 m. A more recent study by Juárez Valieri and colleagues (2011), which focused on the body proportions of this genus, estimated the body length to be 10 to 11 meters, making Ekrixinatosaurus one of the largest or even the largest known representatives of the Abelisauridae. Ekrixinatosaurus was characterized by a tall and short skull. It was an overall relatively massive and compactly built Abelisaurid; the shinbone (tibia) and the thighbone (femur) in particular were relatively short and robust.

Systematics

The preliminary cladistic analysis by Calvo and colleagues (2004) combines Ekrixinatosaurus , Majungasaurus , Carnotaurus and Aucasaurus into an unnamed group - Ilokelesia is the sister taxon of this group. Researchers working with Juan Canale (2008) combine Ekrixinatosaurus , Aucasaurus , Carnotaurus , Ilokelesia and Scorpiovenator in the new group Brachyrostra ; Representatives of this group are characterized by relatively short skulls. These researchers see Ekrixinatosaurus as a sister genus of Scorpiovenator .

Cladogram , simplified from Canale and colleagues, 2008:
Abelisauridae  Rugops     Abelisaurus  Carnotaurinae  Majungasaurus  Brachyrostra  Carnotaurus     Aucasaurus     Ilokelesia     Scorpiovenator     Ekrixinatosaurus
Systematic position of Ekrixinatosaurus .

Paleoecology

The skeleton comes from the Candeleros Formation , which is dated to the Cenomanium , the oldest stage of the Upper Cretaceous. The Abelisauridae showed a rapidly increasing biodiversity from the following Turonium , which is possibly related to the assumed extinction of the Carcharodontosauridae at this time - another group of very large theropods. According to one hypothesis, particularly large representatives of the Abelisauridae could only develop after the disappearance of the Carcharodontosauridae. Ekrixinatosaurus seems to refute this hypothesis, since this genus shared its habitat with the very large Carcharodontosauriden Giganotosaurus . Rubén and colleagues (2011) speculate that the two major thermopods may occupy different ecological niches ; so one of these carnivores could have been an active predator while the other was possibly a specialized scavenger. The physique of Ekrixinatosaurus would suggest a slow, sturdy animal that would have been able to hold its own against other carnivores on carcasses.

Find

The only known skeleton ( holotype , MUCPv294) consists of a few skull bones (upper jaw, basicranium, dentals and teeth), a few vertebrae and hemal arches (cervical, dorsal, sacral and caudal vertebrae), ribs, pelvic bones (iliac bone, pubic bone, an ischial bone fragment) and leg bones (thigh bone, shin bone, astragalus, calcaneum, a fibula fragment, metatarsal, toe bone and a claw). Arms, most of the cervical vertebrae and the skull are missing.

The skeleton was found in a well-preserved but disarticulated state (the bones were no longer in their original anatomical position). The site is located about 34 km northwest of Añelo .

Individual evidence

1. ^ Matthew T. Carrano, Scott D. Sampson: The Phylogeny of Ceratosauria (Dinosauria: Theropoda). In: Journal of Systematic Palaeontology. Vol. 6, No. 2, 2008, ISSN  1477-2019 , pp. 183-236, here p. 202, doi : 10.1017 / S1477201907002246 .
2. ↑ ^{a b c d} Jorge O. Calvo , David Rubilar-Rogers, Karen Moreno: A new Abelisauridae (Dinosauria: Theropoda) from northwest Patagonia. In: Ameghiniana. Vol. 41, No. 4, 2004, ISSN  0002-7014 , pp. 555-563, digitized version (PDF; 939.68 kB) ( Memento of the original from March 9, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. . 
3. ^ ^{A b} Rubén D. Juárez Valieri, Juan D. Porfiri, Jorge O. Calvo: New Information on Ekrixinatosaurus novasi Calvo et al 2004, a giant and massively-constructed Abelisauroid from the "Middle Cretaceous" of Patagonia. In: Jorge Calvo, Juan Porfiri, Bernardo González Riga, Domenica Dos Santos (eds.): Paleontología y Dinosaurios desde América Latina. (= Series Documentos y Testimonios. Aportes. No. 24). EDIUNC, Mendoza 2011, ISBN 978-950-39-0265-3 , pp. 161–169, digitized version (PDF; 643.51 kB) ( Memento of the original from March 16, 2012 in the Internet Archive ) Info: The archive link was automatically used and not yet tested. Please check the original and archive link according to the instructions and then remove this notice. . 
4. ^ ^{A b} Juan I. Canale, Carlos A. Scanferla, Federico L. Agnolin, Fernando E. Novas : New carnivorous dinosaur from the Late Cretaceous of NW Patagonia and the evolution of abelisaurid theropods. In: The natural sciences . Vol. 96, No. 3, 2009, pp. 409-414, doi : 10.1007 / s00114-008-0487-4 .
5. ^ Rodolfo A. Coria , Philip J. Currie , Ariana Paulina Carabajal: A new abelisauroid theropod from northwestern Patagonia. In: Canadian Journal of Earth Sciences. Vol. 43, No. 9, 2006, ISSN  0008-4077 , pp. 1283-1289, doi : 10.1139 / E06-025 .