Better data for the manus of Eryops

Just found this reference
Dr. David Dilkes (2015) provides photo data (Fig. 1) on the carpus and manus of Eryops the giant temnospondyl. Earlier the best data I had was a decades old (Romer era) reconstruction and based on that manus and those of its sister taxa. With that data it appeared that the four digits preserved were 2–5, not 1–4 as traditionally considered. Dilkes likewise follows tradition in listing the fingers as 1–4.

Figure 1. Forelimb of Eryops from Dilkes 2005. Here freehand drawings of the manus cannot compete with a taking a tracing of the photo and restoring the digits and carpal elements to their in vivo positions. Note the subtle differences that happen in the freehand drawing by Dilkes and the Romer era illustrator.

Figure 1. Forelimb of Eryops from Dilkes 2005. Here freehand drawings of the manus cannot compete with  a tracing of the photo and restoring the digits and carpal elements to their in vivo positions (middle). Note the subtle differences that happen in the freehand drawing by Dilkes (above) and the Romer era illustrator (below).

The present data further cements
the hypothesis that the fingers of Eryops are 2–5, not 1–4.

And further cements
the hypothesis that freehand drawing is not as accurate as tracing a photo of the bones.

Today’s post also demonstrates
that better data, no matter where it comes from or makes your hypothesis go, must be incorporated. And finally…

Today’s post also demonstrates
that good Science can take place with second-hand data.

References
Dilkes D 2015. Carpus and tarsus of Temnospondyli. Vertebrate Anatomy Morphology Palaentology 1(1):51-87.

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4 thoughts on “Better data for the manus of Eryops

  1. Why should the digits be either 1-2-3-4 or 2-3-4-5? This debate makes sense in the context of bird origins, as bird forelimbs form 5 digit condensations and then reduce one, whereas in amphibians only four manual digits ever form. There’s no real reason to think that there’s a 1-to-1 relationship between amphibian digits and ancestral tetrapod digits at all.

    • Oops, sorry. You’re actually citing the 2015 paper and consistently calling it “2005”. We should both look more closely next time. :-)

      I completely fail to see how your drawing, or anything here, argues for or against any particular digit identities, though. Please explain.

  2. Please check out the updated numbered illustration for Acanthostega. Best I can do at this point based on the number of phalanges and their proportions and the hypothesis that the digits will be continuous, whether 1-4 or 2-5.

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