STL Science Center

STL Science Center

22 December 2015

Use It To Crunch Seeds

Evidence has mounted that Gastornis was not a carnivore a great deal since it was originally covered in this blog. Back in 2012 when we originally discussed the diet of the giant bird and share all kinds of illustrations and clips from the Walking With series, meat was the only thing considered to be on the menu for Gastornis. Since that time biomechanical studies from earlier have been countered by evidence from chemical analyses that show that the diets of these birds were most likely highlighted by vegetable matter. When we look at the beak both possibilities obviously make sense. The Witmer and Rose biomechanical study asserted that the beak was strong enough to break bones and certainly to kill small animals like Eohippus. They are not incorrect and the implications that they made regarding diet are logical, especially for a bird that appears to be extremely convergent with South American terror birds. However, that power could have also been used to break open tough seeds and their meat inside. The large beak appears to have been mostly flattened in the oral cavity (the roof of the oral cavity or the ventral shelf of the premaxilla and maxilla), which is good for crushing, but not entirely ideal for breaking seeds open in the most efficient manner. What could be more efficient for this purpose may be considered coincidental or may have been lost in fossilization. The anatomical character that we are considering here could be a ridge or sharp edge to the beak that was keratinized for added strength. Assuming that this was not lost and may not have existed (I have not seen the fossils first hand and cannot therefore assert to its existence or loss) another option to make the breaking open of seeds more efficient, is occlusion of the upper beak that we have discussed many times with the lower beak or mandible (dentary, splenial, angular, and surangular). This occlusion can be seen, but is minimal between the beak and mandibles. It can be assumed from these bones that the keratin ramphotheca covering the beak would not have occluded differently, but we cannot say that they did not have sharp edges capable of shearing seeds. Given all of the papers and anatomical evidence, it seems that we could consider Gastornis more of a terror to seeds, than other animals.

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