STL Science Center

STL Science Center

07 February 2012

Changing the Face of Nigersaurus

©Sereno et al. 2007
The original inference made here, and made by the originally discovering community of paleontologists was that the teeth of Nigersaurus were well suited to stripping trees in moments. However, and I had read this at the time but decided to present that old inference as the obvious bit to notice with a sauropod and the dental battery of Nigersaurus, the paper by Sereno et al in 2007 stated that the neck of Nigersaurus was not meant to soar like a crane boom scouring the trees and shearing needles and leaves from Cretaceous branches, but was aimed downward, held in a neutral position, and meant to clip grasses in a wide arc determined by the neck's side to side motion before the dinosaur had to move on to a new patch of grasses. It has been found, in studies such as that conducted by Michael Taylor, Matthew Wedel, and Darren Naish, that the necks of certain animals can be guessed at by looking at living species. Their study came to the summation that Sereno et al's 2007 figure (left) was a possible feeding position for Nigersaurus, but not its normal resting position.

To that end it is stated that the neck did not normally rest in that position during locomotion and that the head and neck of the sauropod may be revisited in the living equestrian genera as they too are animals which feed off the ground and have downward sloping skulls, but that they hold their necks high at rest, not neutral or downward sloping. John Whitlock, in an independent paper looking at the indications snout shape make on diet, agreed with the 2007 paper of Sereno in that grasses were the most likely diet due to both microwear on the teeth and the shape of the snout as it indicated downward feeding habits. That this agrees does not prove the Taylor study invalid, it in fact makes the likelihood of the analogy to horse neck posture even more accurate as it confirms that an animal could have the head, teeth, and angle of attack to eat at ground level but still possess qualities which cause it to carry its head high while walking. One last paper, by Sereno and Wilson- 2005, looks at the teeth and dental battery of Nigersaurus as well in comparison with and as part of sauropod dental evolution. This paper is six years older than Whitlock's and came out prior to the 2007 paper (obviously), but agrees with points in both and sets up the case for grass eating habits.

All of this scholarly debate on head position and tooth wear and downward angles of heads can seem perplexing and tedious, but what evolves from all of these papers, if we take the parts they agree on, or maybe even their strongest points only and mesh them together carefully, is that Nigersaurus was most likely a sauropod of modest size which walked with its head held high and alert with its brow facing slightly downward and ate, as Sereno says, in the fashion of a "Mesozoic cow."

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