The Devil, Hairier

As an update to my previous post, Rendering Unto Nature What is Nature’s Due, I’ve taken the opportunity to create another careful skeletal diagram for the purposes of creating silhouettes for Mike Keesey’s Phylo Pic. I’ve already rendered one for Pterorhynchus wellnhoferi, which as it turned out is the 600th image submitted! This time, however, I decided to render my Sordes pilosus Sharov, 1971 (you know, the “hairy devil”), which proved a bit more challenging.

Before, I laid out five steps for creating these silhouettes, with the first being the production of the skeletal diagram. The second step involves transforming this into a basic silhouette, which I can also submit to Phylo Pic, but I suspect it’s unrealistic “life” appearance is rather poor for the site. Instead, I had to then produce normal integument, and for this there are three types to consider:

1. The wing membranes: propatagium, cheiropatagium, and uropatagium.

2. Body “hair”, comprised of pycnofibres (otherwise known as “pterofuzz”).

3. The tail “vane,” rendered here as a modified form of squamous or perhaps modified pycnofibrous structure.

Pterosaur wing membranes appear to be covered in fine pycnofibres (Kellner et al., 2009), especially notable on the anurognathid Jeholopterus ningchengensis (Wang et al., 2002) but also known (and first!) on Sordes pilosus. This means that the wings needed a bit of hair, and this step was pretty interesting as I first tried various brushes before I realized I could just create a stamp tool and just carefully “stamp out” the “hairs” along the membranes.

The distinction between “living” and body neck thickness is, even more than the last skeletal I showed, apparent here. This was somewhat intentional, as I wanted to compare directly to the short and “seemingly” thick necks of bats, in which necks are often completely (seemingly) missing.

The final note to make on this is that the wings are not actually super narrow-chord. The wing membrane is intended to reach toward the ankle, as implied by the natural fossil preservation, while the chord shown narrow here is a result of the (probably) unnatural posture the animal is in, with the leg and wing shown in extreme extension away from one another, which would result in a narrowing of the membrane chord due to the membrane’s trailing edge being pulled closer to the limbs.

Figure from Elgin et al. (2011), in which B (4) is implied as present, but D (8) is intended.

Many groups of animals might require an additional step or two depending on what additional elements they preserve might require tweaking the general model. In birds, this would mean the rhamphotheca, and probably the keratinous talons, while in mysticete whales, an open mouth model would require baleen (modified hair! — the same would be true of horns in rhinos) to be shown separately.

Elgin, R. A., Hone, D. W. E. & Frey, E. 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica 56(1):99–111.
Kellner, A. W. A., Wang, X.-l., Tischlinger, H., Campos, D. A., Hone, D. W. E. & Meng X. 2009. The soft tissue of Jeholopterus (Pterosauria, Anurognathidae, Batrachognathinae) and the structure of the pterosaur wing membrane. Proceedings of the Royal Society, B: Biological Sciences 277: 321–329. (pre-print online version available here)
Sharov, A. G. 1971. [New flying reptiles from the Mesozoic of Kazakhstan and Kirgizia]. Трудй Палеотологыческого Института Академий Наук СССР — Transactions of the Palaeontological Institute of the Academy of Sciences, SSSR 130:104–113. (in Russian)
Wang X.-l., Zhou Z.-h., Zhang F.-c. & Xu X. 2002. A nearly completely articulated rhamphorhynchoid pterosaur with exceptionally well−preserved wing membranes and “hairs” from Inner Mongolia, northeast China. Chinese Science Bulletin 47:226–230.

This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License (the second figure is the property of the publisher of the paper it is from).

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2 Responses to The Devil, Hairier

  1. Two short comments born of curiosity. If the Sordes wing membrane trailing edge attached proximally to a fuselage fillet terminating at mid thigh (see, then you would not have to make excuses for the way it appears in your drawing. Second, I thought the traditional uropatagium (singular) of Sordes was supposed to extend from leg to leg without connecting to the tail, but your uropatagia, while an improvement in their duality, seem to extend rather far posteriorly connected to the tail, rather than following the pattern seen in all other pterosaurs, including Sordes, of merely filling in the back of the knee. Otherwise, nice job on the bipedal take-off!

    • Understand that, first, the posture of the animal predates data regarding the more efficient and likely quad-launch of Habib and Cunningham. I had also done the illustrations of pterosaurs in a dynamic bipedal posture in order to pair with my non-pterosaurian bipedal “running” animals, especially birds and dinosaurs, rather than to explicate a particular style of launching. Thus, the one has little to do with the other.

      That out of the way:
      1. Sordes pilosus, especially the holotype, the tail is askew to the uropatagium, which lends support to the implications that both the tail is not engaged in the patagium, and that the patagium doesn’t extend down the tail as much as i had shown it. The illustration was done rather without consideration of this, and meant merely to depict the “bit-wing” style of integumentary extent. This issue came up on the discussion over at my DeviantArt page on the illustration; I’ve just never corrected it, but rest assured it will be corrected.

      2. I will also be following Elgin, Hone & Frey in regards to the design of the pterosaur wing as, rather than what has been suggested in the past, in Sordes pilosus does in fact show ankle attachments of the cheiropatagium. I understand this differs strongly with your counter-arguments, but I feel the authors are persuasive on this count, at least for this taxon and possibly further.

      Elgin, R. A., Hone, D .W. E. & Frey, E. 2011. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica 56:99-111.

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