Paraxenisaurus normalensis, a large deinocheirid ornithomimosaur from the Cerro del Pueblo Formation (Upper Cretaceous), Coahuila, Mexico

Large-bodied ornithomimosaurs inhabited Appalachia during the Late Cretaceous of North America

“…Previous studies on the dissociated ornithomimosaur specimens have demonstrated that manual and/or pedal elements of ornithomimosaurs are important source of taxonomically informative anatomical information and can be diagnostic for Ornithomimosauria [30,65,126]. This is supported by several studies describing ornithomimosaurians on the basis of solely manual or pedal elements, for example A. tugrikinensis , A. planinychus , A. fridayi , P. normalensis , and T. packardensis [14,62,92,116,131]. Despite this, the likelihood of more than one co-occurring taxon in the Eutaw assemblage, coupled with a lack of association between elements, and the presence of pathologies, prevents us from confidently assigning the Eutaw specimens to finer taxonomic levels, such as a species, in this time.…”

“…Ornithomimosaurs repeatedly evolved gigantic body size during their evolutionary history [14,70,114–116] (Fig 9), although evidence for directional mass evolution, as opposed to stochastic processes, is lacking [117]. Early-diverging ornithomimosaurs from the Early Cretaceous (pre-Albian), such as Nqwebasaurus thwazi [93] from Africa, Hexing qingyi [103], Shenzhousaurus orientalis [104], and Kinnareemimus khonkaenensis [105] from Asia, Pelecanimimus polyodon [106] from Europe, and Nedcolbertia justinhofmanni [107] from North America) were universally small bodied (>12 kg [102; table S1]).…”

“…Ornithomimosaurs repeatedly evolved gigantic body size during their evolutionary history [14,70,[114][115][116] ( Fig 9), although evidence for directional mass evolution, as opposed to stochastic processes, is lacking [117]. Early-diverging ornithomimosaurs from the Early Cretaceous (pre-Albian), such as Nqwebasaurus thwazi [93] from Africa, Hexing qingyi [103],…”

“…packardensis [14,62,92,116,131]. Despite this, the likelihood of more than one co-occurring taxon in the Eutaw assemblage, coupled with a lack of association between elements, and the presence of pathologies, prevents us from confidently assigning the Eutaw specimens to finer taxonomic levels, such as a species, in this time.…”

A caenagnathid oviraptorosaur metatarsal from the Mesaverde Formation (Campanian), Wyoming

“…seen in dromaeosaurids, which is formed by a prominent groove separating medial and lateral hemicondyles (e.g., Fowler et al 2011;Hattori 2016). Derived ornithomimids, which dominated Campanian-Maastrichtian ornithomimosaur faunas in western North America (e.g., Hattori 2016), lacked a hallux with only a few possible exceptions (Longrich 2008;Serrano-Brañas et al 2020). All known first metatarsals in basal ornithomimosaurs (e.g., Beishanlong, Garudimimus) have a mediolaterally constricted shaft, and a pronounced concavity at the distal end formed by a sulcus separating the two distal hemicondyles, which nonetheless is less well-developed than in the ginglymoid condyles of dromaeosaurids.…”