Theropod non-locomotory limb function

[Infinity Blade]

Oh yeah, avisaurids have turned out to be Mesozoic birds of prey. I remember reading Matt Martyniuk's Mesozoic bird book where he claims the same thing, but this recent study is further support of it.

The m. tibialis cranialis tubercle in avisaurids is larger and more distomedially located on the tarsometatarsus than in any Mesozoic bird, non-avian theropod, and nearly every extant bird [12]. The presence of the large distomedially located m. tibialis cranialis tubercle in avisaurids, together with the lower aspect ratio of the tarsometatarsus, suggests a functional similarity with extant birds of prey that distinguishes them from other enantiornithines. Based on the numerous shared morphologies with strigids, avisaurid tarsometatarsi were likely adapted for strong dorsiflexion and carrying proportionally large prey items while volant (Fig 11). However, it should be noted that the largest avisaurids are estimated to be nearly twenty times larger than G. gnoma, (G. gnoma 80 g, A. archibaldi ~ 1700 g) which limits the proportional size of prey that could likely be lifted given that as an object’s surface area increases, its volume increases at a greater rate (i.e., the square-cube law). Carrying similar proportionally-sized prey as some strigids (e.g., Surnia, Glaucidium, Aegolius) may have been more plausible for smaller-bodied avisaurids like Gettyia (Zeffer and Norberg, 200). Gettyia (Fig 4D) exhibits the proportionally distal-most m. tibialis cranialis tubercle. It is also the smallest known avisaurid (~ 540 g), with a tarsometatarsal length that is less than half that of A. archibaldi (30.9 mm, A. archibaldi 73.9 mm) [16] (Fig 8A).

journals.plos.org/plosone/article?id=10.1371/journal.pone.0310686