How is the maxillary bone split in the Bolyerine Snakes described in T.H Frazzetta's "From Hopeful Monsters to Bolyerine Snakes?"

In T. H. Frazzetta, "From Hopeful Monsters to Bolyerine Snakes?" He describes boid snakes on the island of Mauritius as being unique among snakes in that they had a split jaw, connected by a joint. This was said to be an example of how continuous evolution could not be true for all cases, as what is the point of 1/2 of jaw, according to Stephen J Gould.

I dont seem to understand the pictures illustrated in the aritcle though, and how the maxillary bone is split and where it is connected to a joint. I could not find a legible picture of a Bolyerine Snake described like this, if anyone could help with understanding it with a picture that would be appreciated.

I would provide the pictures, but I am not sure if that counts as plagiarism.


Published by: The University of Chicago Press for The American Society of Naturalists, Available from: http://www.jstor.org/stable/2459073

  • $\begingroup$ What figure(s) are you having trouble with in the paper? $\endgroup$
    – kmm
    Apr 5 '15 at 14:17
  • $\begingroup$ @kmm I cant find the figures pertaining to the Bolyerine Snakes that label the "split" in the maxillary bone. $\endgroup$
    – Ro Siv
    Apr 5 '15 at 19:11

If you look at Fig. 2 in the paper, the bottom jaw has the split maxillary bone. Do you see how it says "MX" with two lines, instead of "MX" with 1 line on the top skull from Fig. 2? Each of those lines go to part of the split maxilla, with the joint being where it is pinched off (between teeth 5 and 6 on the drawing). There is also a CT image of the skull somewhere online that I've run across a few times (actually saw your question while looking for that image now).

I would also amend your statement a little in that it is not "as what is the point of 1/2 of jaw", it is that you can't have 1/2 of the joint(or split bone) existing. Either the maxilla is 1 piece or it is 2, but you cannot gradually go from 1 bone to 2 (similarly, either the cartilage of the joint exists or it doesn't. There can be a gradual change in how much cartilage there is, but if it's there or not is a binary question).

I hope that helps, off to look for the CT scan!

  • 1
    $\begingroup$ Nice answer - welcome to Biology.SE! The second part of your answer might be better as a comment on the question, which only asks about the interpretation of the figure. $\endgroup$
    – arboviral
    Jun 2 '16 at 15:00

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