The Sericipterus mandible reconstructed – new insights using Photoshop

I love it when this happens.
I made a mistake here earlier today, and within just a few hours, I am able to correct it. So what you are about to read here has been thoroughly rewritten to reflect the latest thinking.

Earlier I misidentified what looked like a too gracile mandible (relative to the other skull parts) on the pterosaur, Sercipterus (Figs. 1-3), as a tibia and fibula. Here is the illustration in which I made the mistake (Fig. 1). And made a further mistake by calling out the original interpretation as an error.

Figure 1. From Andres et al. 2010, where they misidentify a tibia/fibula and call it a mandible with surangular.

Figure 1. Click to enlarge. From Andres et al. 2010, where they identify a mandible and surangular. I thought it odd that it would be preserve narrow edge up, and where are the teeth or their alveoli? But now i see the reason for this. Read on.

At the time I overlooked the left mandible. It’s easy to do. There’s not much that makes it look like a mandible. The back half is all that is preserved. The left mandible appears to be a little deeper, which it needs to be according to phylogenetic bracketing.

This is the key. 
Allthough the fossil had been thoroughly stirred during preservation so that nothing is where it was in the living pterosaur, there are two bones that are indeed in their original configuration: the two posterior mandibles (Fig. 2, in pink). How can this be??

Figure 2. When you use your imagination, and a little Photoshop, you can retire the front of the mandible. What we're seeing is the ventral view, so no teeth are visible. The reason why the mandibles remain in their original configuration is the front of the fused mandibles, now vanished. And that's why the right mandible is preserved narrow end up.

Figure 2. When you use your imagination, and a little Photoshop, you can restore the front of the mandible. What we’re seeing here is the ventral view, so no teeth are visible. The reason why the posterior mandibles remain in their original edge-on configuration is due to the front of the fused mandibles, now vanished. The entire mandible was originally preserved in its flattest plane. And that’s why the right mandible remains narrow end up.

Restoration of the missing parts clears up all the confusion.
When you extend the lines of the posterior mandible, the anterior portion becomes plainly visible. Now we have a mandible that is the proper length for the skull parts (actually it elongates the earlier restoration of the skull and suggests a larger antorbital fenestra than in other dorygnathids, Fig. 3). And now the narrow mandible makes sense because it is not preserved in lateral view.

Figure 3. New reconstruction of Sericipterus with restored mandible in lateral view based on the related MBR 1920 specimen, in color at right.

Figure 3. New reconstruction of Sericipterus with restored mandible in lateral view based on the related MBR 1920 specimen, in color at right.

Colleague [name deleted] was kind enough to drop a note on this (see below) that prompted a review of the situation. Later Mike wrote, “Sometimes it is better to trust people who have spent many hours with the specimen in front of them and read the descriptions.”

That’s a common notion,
but that’s not the thought you should take-away from this exercise.

Science doesn’t work on trust.
It works on testing. Having never seen a mandible preserved edge-on in the matrix, without obvious alveoli and too gracile for the skull, I sought another explanation for the questionable portion of the fossil. The tibia/fibula seemed to be a good fit.

But I was wrong. The mandible was not preserved edge-on, but flattened along its widest dimensions, like most fossils are. Then the anterior half of the fused mandible was lost leaving the posterior parts edge-on. Now it makes sense.

It would have helped if the above restoration was made prior to publication. I’m sure you can see how well it illustrates the situation here. Making mistakes is one way to shed new light on a problem. I never would have arrived at this solution and explanation had I merely trusted the original authors.

When something doesn’t make sense, keep working on it until it does makes sense.

It’s a process. And I’m always glad to accept any help that is offered. Getting it right is the ultimate goal.

References
Andres B, Clark JM and Xing X 2010. A new rhamphorhynchid pterosaur from the Upper Jurassic of Xinjiang, China, and the phylogenetic relationships of basal pterosaurs, Journal of Vertebrate Paleontology 30: (1) 163-187.

4 thoughts on “The Sericipterus mandible reconstructed – new insights using Photoshop

    • I understand this fossil better now after going through the exercise of making a mistake then reexamining the data, finding a reason for the mistake and explaining the process in the above blog. Thank you, Mike.

  1. “Science doesn’t work on trust. It works on testing.”

    No, this is a very bad understanding of science, and you are confusing trust with faith, they are
    different things. Any question concerning the credibility of a researcher involves matters of trust, for all I know, Sericipterus might not exist at all, but I trust that the authors do have a real specimen on their hands, and I have to start out that way if I have not seen it in person. Do not divorce the scientific inquiry from the scientific researcher. The reliability of the observer is just as important as the observation. Both go hand-in-hand, and without some level of trust in a researcher’s credibility and work, no scientific claims could be made at all.

    Even if you say you are wrong, you trust your current results enough to evaluate the former ones. You certainly seem to trust your results enough to post about them. Furthermore, scientists must trust prior researchers, lest they keep on releating the same experiments for eternity. If no scientist trusted any other scientist’s work, people to this day would be dropping cannonballs from tall buildings to figure out how gravity operates, but would make little progress in theoretical physics. Forget about Einstein, he’s getting too far ahead of himself! How can Gallileo and Newton be trusted? After all, it never is a matter of trust. It’s a matter of testing, and surely we must test Gallileo and Newton, and test, and test again. Sure, trust can be misguided, but if some level of trust were not present in science, it would not progress. (There’s an added dimension of trust involved when using scientific data to predict future events, but I’ll leave that out of the scope for now)

    I trust that scientists are operating in a way such they are credible and their results are not fabricated or stolen, and that their conclusions make sense in light of the data at hand and do not introduce any extraordinary claims. This still leaves room for a scientist to be proven wrong, but notice that the one thing I am not not trusting a scientist to do is to be feeding me an absolute truth, science does not deal with truth (a matter of yes-or-no absolutism), it deals with hypotheses (which are always shifting about in probability from highly likely to highly unlikely, with no absolutes). I trust a scientist to have arrived at a hypothesis through appropriate means. Usually, when a scientist betrays that trust it becomes quite well known and there is little that can be done to recover.

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