Tuesday, July 18, 2017

[Paleontology • 2017] Albertavenator curriei • A New Species of Troodontid Theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada

Albertavenator curriei 
Evans, Cullen, Larson & Rego, 2017


Troodontid material from the Maastrichtian of North America is extremely rare, beyond isolated teeth from microvertebrate sites. Here we describe troodontid frontals from the early Maastrichtian Horseshoe Canyon Formation (Horsethief Member). The most complete specimen, TMP 1993.105.0001, is notably foreshortened and robust when compared with numerous specimens referred to Troodon from the Dinosaur Park Formation, and exhibits several characteristics that distinguish it from other Late Cretaceous troodontids. Morphometric analyses reinforce shape differences between TMP 1993.105.0001 and other North American troodontids, and show that proportional differences are independent of size. We therefore erect a new taxonAlbertavenator curriei gen. et sp. nov., which is diagnosed by the following autapomorphies: (1) primary supraciliary foramen is truncated anteriorly by the lacrimal contact; (2) superficial (ectocranial) surface of the frontal proportionally shorter than all known troodontids, with a length to width ratio under 1.3; and (3) frontoparietal contact in which an enlarged lappet of the frontal extends medially to extensively overlap the lateral region of the anteromedial process of the parietal. Interestingly, tooth and jaw morphology from the single relatively complete dentary recovered from the Horseshoe Canyon cannot be distinguished from dentaries and teeth from the Dinosaur Park Formation. If the dentary and teeth from the Horsethief Member of the Horseshoe Canyon Formation prove to belong to A. curriei, extensive overlap in tooth morphology between the Dinosaur Park and Horseshoe Canyon formations reinforces the notion that tooth morphotypes do not exhibit strong correspondence to species alpha diversity, and may encompass multiple closely related taxa.

Life recreation of Albertavenator curriei.
 Illustrated by Oliver Demuth 

Comparison of 3D frontal models in dorsal, lateral, ventral, medial, anterior, and posterior, respectively, of Albertavenator curriei (top) and Troodon inequalis.

Abbreviations: fc – frontal midline contact, lc – lacrimal contact with frontal, lcb – lacrimal buttress, lsc – laterosphenoid contact with frontal, nc – nasal contact with frontal, or – orbital rim, pc – parietal contact with frontal, pl – parietal lappet, poc – postorbital contact with frontal, scf – supraciliary foramen. Scale bar – 1 cm. 

David C. Evans, Thomas M. Cullen, Derek W. Larson and Adam Rego. 2017. A New Species of Troodontid Theropod (Dinosauria: Maniraptora) from the Horseshoe Canyon Formation (Maastrichtian) of Alberta, Canada.
 Canadian Journal of Earth Sciences. DOI: 10.1139/cjes-2017-0034

Albertavenator curriei: New Species of Bird-Like Dinosaur Identified in Canada || 
Scientists name new species of dinosaur after Canadian icon http://phy.so/419501502 via @physorg_com

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