Thursday, September 22, 2016

[Paleontology • 2016] Rativates evadens • A New Ornithomimid Theropod from the Dinosaur Park Formation of Alberta, Canada


Rativates evadens 
McFeeters, Ryan, Schröder-Adams & Cullen, 2016 

ABSTRACT
A partial ornithomimid skeleton, ROM 1790, from the lower Dinosaur Park Formation (upper Campanian) of Alberta was previously referred to Struthiomimus altus, but lacks diagnostic characters of that species. It is here described as the holotype of a new species, Rativates evadens, gen. et sp. nov., diagnosed by the form of the maxilla-jugal contact, the reduction of the mid-caudal neural spines, the convex fusion of the left and right ischial shafts, the straight-edged distal end of the third metatarsal, and possibly the relatively enlarged medial condyle of the tibia. A histological section of the femur confirms that the type specimen is not a juvenile, despite its relatively small size (approximately 50% the size of large individuals of Struthiomimus altus). Phylogenetic analysis recovers Rativates as a member of a derived ornithomimid clade that includes Ornithomimus, Struthiomimus, and the Asian taxa Anserimimus and Qiupalong. Fusion of the proximal tarsals to the tibia in some ornithomimid specimens was observed to be more complete than previously recognized, increasing the suite of features that these non-avian dinosaurs share homoplastically with birds.


Rativates evadens  
Illustration: Andrey Atuchin 

SYSTEMATIC PALEONTOLOGY

THEROPODA Marsh, 1881
ORNITHOMIMOSAURIA Barsbold, 1976

ORNITHOMIMIDAE Marsh, 1890

RATIVATES, gen. nov.

Etymology—Latin ‘ratis’ meaning raft, in reference to the ratite birds; and Latin ‘vates’ meaning seer or foreteller. The name Rativates (‘ræt-aɪ-veɪ-tiz’) alludes to the paradox of an ‘ostrich mimic’ that existed before ostriches.

Diagnosis—As for the type species, R. evadens.

RATIVATES EVADENS, sp. nov.

Etymology— Latin ‘evadere’ meaning to evade, in reference to this swift-footed dinosaur’s ability to evade predators in the Late Cretaceous, as well as recognition as a new species in the 80 years following the discovery of the holotype.

Holotype— ROM 1790, incomplete skull and postcranial skeleton.

Type Locality— Quarry no. Q028 (Currie and Koppelhus, 2005) in the lower Dinosaur Park Formation (upper Campanian) near Dinosaur Provincial Park, Alberta, Canada.

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CONCLUSIONS : 
A new ornithomimid, Rativates evadens, is described on the basis of a partial skull and skeleton collected in 1934 from the lower Dinosaur Park Formation of Alberta. Previous referrals of the type specimen ROM 1790 to Struthiomimus altus are unjustified. Rativates evadens is diagnosed by a suite of derived cranial, axial, and appendicular characters, despite regions of the skeleton (primarily the posterior skull, forelimbs, and distal caudals) critical to taxonomic and phylogenetic placement of other ornithomimids being unknown. The phylogenetic relationships of R. evadens, S. altus, and O. edmontonicus remain unresolved, but the consensus tree is consistent with the hypothesis of these species representing a single radiation of derived ornithomimids that entered Laramidia during the Campanian. Rativates evadens is among the oldest named ornithomimid species in North America and increases the diversity of approximately contemporaneous ornithomimid taxa in the lower part of the Dinosaur Park Formation. Reevaluation of previously collected material from other Upper Cretaceous formations in North America may identify additional overlooked ornithomimid species.


Bradley McFeeters, Michael J. Ryan, Claudia Schröder-Adams and Thomas M. Cullen. 2016. A New Ornithomimid Theropod from the Dinosaur Park Formation of Alberta, Canada. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1221415 

    

An international group of researchers led by Bradley McFeeters, currently a Ph.D. student at Carleton University in Ottawa, Canada, has announced the discovery of a new ostrich-mimic dinosaur, Rativates evadens, from the lower Dinosaur Park Formation near Dinosaur Provincial Park, Alberta. The new species lived about 76 million years ago during the Late Cretaceous Period. Research describing the new species is published online in the Journal of Vertebrate Paleontology.

Congratulations to Brad McPheeters & Curator Dr. Michael Ryan on co-describing a new dinosaur! Welcome, #Rativates!  ‏@CMNHVertPaleo  cmnh.org/announcements/rativates-evadens

New Ostrich-Mimic Dinosaur From Alberta Named for Its Ability to Evade Predators

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