First Ornithomimid (Theropoda, Ornithomimosauria) from the Upper Cretaceous Djadokhta Formation of Tögrögiin Shiree, Mongolia

Abstract

The Upper Cretaceous Djadokhta Formation has been intensively surveyed for its fossil vertebrate fauna for nearly a century. Amongst other theropods, dromaeosaurids and parvicursorines are common in the formation, but ornithomimosaurs are extremely rare. A new ornithomimosaur material was discovered from the Djadokhta Formation, represented by eolian deposits, of the Tögrögiin Shiree locality, Mongolia. This is only the third ornithomimosaur specimen reported from this formation, and includes the astragalus, the calcaneum, the third distal tarsal, and a complete pes. The new material is clearly belonged to Ornithomimidae by its arctometatarsalian foot condition and has the following unique characters; unevenly developed pair of concavities of the third distal tarsal, curved contacts between the proximal ends of second and fourth metatarsals, the elongate fourth digit, and a laterally inclined medial condyle on phalanx IV-1. These diagnostic characters of the Djadokhtan ornithomimosaur indicate that this is a new taxon. Our phylogenetic analysis supports three clades within derived ornithomimosaurs, and the new taxon is placed a member of the derived ornithomimosaurs. The present specimen is the first ornithomimid record from eolian Tögrögiin Shiree locality, and is indicative of their capability to adapt to arid environments.

Differential locomotor and predatory strategies of Gondwanan and derived Laurasian dromaeosaurids (Dinosauria, Theropoda, Paraves): Inferences from morphometric and comparative anatomical studies

“…Most of the measurements were obtained from published datasets (e.g. Holtz, 1994;Karhu and Rautian, 1996;Xu, 2002;Mayr et al 2007;Zhou et al 2010;Turner et al 2011;Lü and Brusatte, 2015;Tsogtbaatar et al 2017). Other values were measured directly on materials deposited in different collections (Appendix S1).…”

“…1). These were based on previously published phylogenies of several theropod clades (Spicer and Dunipace, 2004;Livezey and Zusi, 2007;Hackett et al 2008;Bunce et al 2009;Wink et al 2009;Makovicky et al 2010;Xu et al 2011;Carrano et al 2012;Turner et al 2012;Kimball et al 2013;Wu et al 2015;McFeeters et al 2016;Apesteguía et al 2016a;Lü et al 2017;Tsogtbaatar et al 2017;Xu and Qin, 2017;Xu et al , 2018Gianechini et al 2018;Hartman et al 2019).…”

“…;Vickers-Rich et al 2002;Makovicky et al 2004;Fowler et al 2011;Xu et al 2011;Currie et al 2016;Funston et al 2016;McFeeters et al 2016;Tsogtbaatar et al 2017). …”

The locomotor and predatory habits of unenlagiines (Theropoda, Paraves): inferences based on morphometric studies and comparisons with Laurasian dromaeosaurids

“…Further, in these birds the foot is symmetrical since digit III is the more developed and the main weight bearer, with non-ginglymoid interphalangeal articular surfaces, whereas digits II and IV have a similar length to each other, are shorten than digit III and have more ginglymoid interphalangeal articular facets, indicating that they were under higher torsional efforts [9,[72][73]. Similar features are observed especially in Mesozoic theropod taxa considered with greater cursorial capabilities, much of them possessing long tibiae and metatarsi and an arctometatarsalian condition, such as ornithomimids, alvarezsaurids, caenagnathids, and Avimimus (e.g., [9,13,33,38,55,[74][75][76][77][78][79][80][81][82][83].…”

“…For instance, basal taxa included in the analysis, such as basal tetanurans and the basal coelurosaur Gorgosaurus are almost indifferently located on similar values of PPC1, although they are separated along PPC2 and PPC3 (Figs 5 and 6). The ornithomimids also are significantly separated mainly along PPC2, although the scarce sample of this group of theropods and recent phylogenetic analyses[55], which show them in a polytomy on the cladogram, difficult to shed light to how phylogeny and the distribution along the mosphospace are related.…”