Terror birds on the run: a mechanical model to estimate its maximum running speed

Abstract

'Terror bird' is a common name for the family Phorusrhacidae. These large terrestrial birds were probably the dominant carnivores on the South American continent from the Middle Palaeocene to the PliocenePleistocene limit. Here we use a mechanical model based on tibiotarsal strength to estimate maximum running speeds of three species of terror birds: Mesembriornis milneedwardsi, Patagornis marshi and a specimen of Phorusrhacinae gen. The model is proved on three living large terrestrial bird species. On the basis of the tibiotarsal strength we propose that Mesembriornis could have used its legs to break long bones and access their marrow.

Hind limb morphometry of terror birds (Aves, Cariamiformes, Phorusrhacidae): functional implications for substrate preferences and locomotor lifestyle

“…However, phorusrhacid terrestriality may include different non-exclusive styles such as jumping or hopping, walking, running or even wading. Although it has been established that the hind limb length defines the cursorial ability of phorusrhacids (e.g., Tambussi & Noriega 1996;Alvarenga & Hö fling 2003;Blanco & Jones 2005), the fact that a very long tarsometatarsus is shared by cursorial, walking and wading birds means that we must question the sole use of hind limb metrics to reflect phorusrhacid's cursoriality.…”

“…However, this assumption has long been based solely on the premise that phorusrhacid hind limb bones are long, which is a feature that is present in several extant birds that do not run, but walk or hop. Although previous studies on the biomechanics of the hind limbs (e.g., Tambussi 1997;Blanco & Jones 2005) and muscle reconstruction (Degrange 2012) pointed out that phorusrhacids were terrestrial birds with running abilities, a more extensive approach is needed. Gatesy & Dial (1996) developed the concept of locomotor modules to explain the origin and evolution of flight and the diversification of locomotor styles in modern birds.…”

“…KEY WORDS: ecomorphology, functional morphology, hind limbs, palaeobiology, phorusrhacids Terror birds (Aves, Phorusrhacidae) comprise the most outstanding group of South American Cenozoic avifauna, and have been considered as apex predators in Cenozoic ecosystems (Ameghino 1895;Andrews 1899;Alvarenga & Hö fling 2003;Blanco & Jones 2005;Bertelli et al 2007;Degrange et al 2010;Degrange 2012;Tambussi et al 2012). Their terrestrial habits have been well established based on the reduction of their forelimbs (Alvarenga & Hö fling 2003;Degrange 2012), although it is possible that minor species were able to fly in a clumsy manner (Degrange 2012).…”

The sweet spot of a biological hammer: the centre of percussion of glyptodont (Mammalia: Xenarthra) tail clubs

“…large impulses) while crushing or fighting; mantis shrimp (Patek & Caldwell 2005), snapping shrimp (Beal 1983), several bird species (Snyder & Snyder 1969;Butler & Kirbyson 1979) and humans (Walker 1975;Wilk et al 1983) are the most studied examples. Similar crushing mechanisms have been suggested for some fossil vertebrates, such as some carnivorous flightless birds of the Phorusrhacidae family (Blanco & Jones 2005) and early hominids (Blumenschine 1995;Selvaggio 1994 and references therein), perhaps useful for breaking long bones in order to access bone marrow. In some sports such as tennis, baseball and golf, the mechanical properties of the corresponding tools have been studied (Brody 1979(Brody , 1981(Brody , 1986(Brody , 1987Hatze 1994;Cross 1998aCross ,b, 2004Carello et al 1999).…”

Evolution of Locomotor Trends in Extinct Terrestrial Giants Affected by Body Mass

“…Following Schmidt-Neielsen (1984), it has been widely recognized that body mass is often a major locomotory factor scaling muscle force output establishing limits for body ability in animals (Alexander, 1985b;Hutchinson & Garcia, 2002;Biewener, 2005, Hutchinson et al, 2005Marden, 2005), through their maximal speed (Garland, 1983;Jones & Lindstedt, 1993;Sellers & Manning, 2007) and maximal size (Hokkanen, 1986a;Biewener, 1989;Kokshenev, 2007). Reconstructing body mass and locomotion in extinct animals (Alexander, 1989(Alexander, , 1991(Alexander, , 1998(Alexander, , 2006Fariña & Blanco, 1996;Fariña et al, 1997;Carrano, 1998;2001;Carrano & Biewener, 1999;Farlow et al, 2000;Wilson & Carrano, 1999;Hutchinson & Gatesy, 2006, Sellers & Manning, 2007, the biomechanical modeling also includes their locomotor habits (e.g., Fariña, 1995;Paul & Christiansen, 2000;Christiansen & Paul 2001;Blanco & Jones, 2005;Fariña et al, 2005). The evolutionary history of dinosaurs and mammals provide evidence for convergent similarities of skeletal design (e.g., near parasagittal limb postures and hinge-like joints), locomotor kinematics (Alexander, 1991(Alexander, , 1998Farlow et al, 2000;Carrano, 1998Carrano, , 19992001;…”