This image shows the bones that were studied by Degrange et al. (2019) in white and the remainder of the reconstructed skeleton (Paul 2002) in grey. As we mentioned very briefly yesterday, the skull is massive. We can appreciate that by taking into account the scale bar from the paper, shown at the bottom, which equals 1 m. However, one part of Phorusrhacos we have not discussed really are the enormous legs that this animal possessed. The femur (and therefore thigh) is shorter than the leg (tibiotarsus) and the bone (tarsometatarsus) that is made up of bones that we possess in our ankle and the superior (upper) portion of the foot. This leg and foot are immense, like the skull, and have led many to consider the hypothesis that in addition to being able to run down prey and strike with their beaks, Phorusrhacos (and related birds) were able to stomp and kick their prey to death in a similar manner to the way that cassowary or secretary birds can kick attackers or prey (in the case of the secretary bird). The secretary bird (on a casual stroll in this video) looks a lot like what we might picture a theropod dinosaur looking like, as it skulks around the savannah. Add in the last portion of that video, where the bird kicks and stomps some lizards into submission, and then extrapolate that to a bird that is nearly 100 kg and 2.4 m (7.9 ft) tall. Then picture the animal it is trampling being a small mammal that looks something like a weasel. Those are actually pretty scary, and awe inspiring, legs on a flightless bird.

 

Literature Cited:
Degrange, F. J., Eddy, D., Puerta, P. Clarke, J. (2019). New skull remains of Phorusrhacos longissimus (Aves, Cariamiformes) from the Miocene of Argentina: implications for the morphology of Phorusrhacidae. Journal of Paleontology. 93 (6): 1221-1233. DOI: https://doi.org/10.1017/jpa.2019.53