The skull of Xianglong – Early Cretaceous kuehneosaur

Xianglong zhaoi (Li et al. 2007) Yixian Formation, Early Cretaceous, 15.5 cm in length was originally considered an agamid lizard with elongated transverse processes and hyperelongated ribs, like the extant Draco volans. However Xianglong has a larger suite of traits shared with Kuehneosaurus and Icarosaurus. Not a lizard, Xianglong was a kuehneosaur that survived into the Cretaceous. That clade nests outside of the Lepidosauria in nearly all cladograms including the large reptile tree.

The skull was complete, but thoroughly crushed (Fig. 1).

Figure 1. Xianglong animated GIF file. Here DGS (digital graphic segregation) is the technique used to pull bone shapes out of this apparent chaos. Many of the bones overlap others and many long bones are broken. See figure 2 for the reconstruction. The light green vomers here are gold in figure 2.

Figure 1. Xianglong animated GIF file. Here DGS (digital graphic segregation) is the technique used to pull bone shapes out of this apparent chaos. Many of the bones overlap others and many long bones are broken. See figure 2 for the reconstruction. The light green vomers here are gold in figure 2.

The animated GIF (Fig. 1)
shows skull and mandible/hyoid elements on segregated layers using digital graphic segregation (DGS). Below (Fig.2) in the second half of any DGS process, those elements are reset to reproduce the skull in dorsal, palatal and lateral views.

Figure 2. Skull elements of Xianglong reconstructed in several views. Some soft tissue is also shown (light green).

Figure 2. Skull elements of Xianglong reconstructed in several views. Some soft tissue is also shown (light green). Elements pulled from figure 1. If you find any errors here, please call them to my attention.

The reconstruction
is rather straightforward, moving elements back into their in vivo positions. Some elements seen edge-on, like the skull roof in lateral view, are either freehanded to the correct length and curved to fit, or reduced in one direction using the scaling tool of Photoshop. Note the great resemblance of this skull to that of a sister taxon, Kuehneosaurus (Fig. 4).

Figure 3. Xianglong overall. Note the detail recovered in the tracing of the skull here. These authors had the original in their hands, yet DGS was able to pull more data out using published photos.

Figure 3. Xianglong overall. Note the detail recovered in the tracing of the skull here. These authors had the original in their hands, yet DGS was able to pull more data out using published photos.

The skull of Xianglong
was originally traced with little regard to details (Fig. 3). DGS (Fig. 1) was able to pull those details out in a matter of hours from the published literature. Despite the large number of current detractors, DGS has value. This is just one of many such demonstrations.

The Triassic kuehneosaur gliders and their non-gliding precursors.

Figure 4. Click to enlarge. The Permian, Triassic and Early Cretaceous kuehneosaur gliders and their non-gliding precursors. Included are Coelurosauravus, Mecistotrachelos, Kuehneosaurus, Icarosaurus and Xianglong, all with extended dermal processes mimicking ribs. Palaegama and Saurosternon do not have these gliding/display elements.

Draco volans (Fig. 5) is an extant iguanian squamate lepidosaur with genuine elongate ribs framings its gliding membrane. Note the distinct skull shape. Also note the complete lack of elongate transverse processes on the dorsal vertebrae. Those elongate so-called transverse processes on kuehneosaurs are often, but not always the actual ribs, fused to the vertebrae (the proportion of rib to transverse process changes along each spinal column), as discussed earlier here in yet another heretical observation at odds with current paleontological conventions and paradigms.

Figure 6. Draco volans a living true rib glider. Note the distinct skull morphology, closer to that of Iguana than to Xianglong.

Figure 5.  Draco volans a living true rib glider. Note the distinct skull morphology, closer to that of Iguana than to Xianglong.

References
Li P-P, Gao K-Q, Hou L-H and Xu X. 2007. A gliding lizard from the Early Cretaceous of China. PNAS 104(13): 5507-5509. doi: 10.1073/pnas.0609552104 online pdf

wiki/Xianglong

History of reptile Interrelationship hypotheses: Meckert’s PhD thesis

There is a long history
of workers creating hypotheses of reptile interrelationships going back to the mid 18th century (Carl von Linneaus 1758). That history, up until 1995 (Laurin and Resiz 1995 and Meckert 1995), was summarized by Dirk Meckert in his PhD thesis, which otherwise  concentrated on all available specimens of Barasaurus. You can download that thesis here online and read that short but fascinating history for yourself.

Some interesting notes arise from Meckert’s short history:

  1. Some studies united pareiasaurs and turtles. Others did not.
  2. Other studies united pareiasaurs, diadectids and procolophonids (which happened here just yesterday). Meckert wrote: “The Procolophoniformes contain Procolophonia and Testudinomorpha as sister-groups. Testudines are the sister-group of Pareiasauria within the Testudinomorpha.”
  3. Mesosaurs are commonly considered of uncertain affinities. But not here.
  4. Many prior studies had the synapsids branch off first. That is incorrect as shown here.
  5. No prior studies recognized the original dichotomy of lepidosauromorphs and archosauromorphs.
  6. No prior studies recognized Gephyrostegus bohemicus as a sister to the basalmost amniote.
  7. Diadectomorpha have been nested in and out of the Amniota. They’re in here.

No studies prior to reptileevolution.com
have included as many as 571 individual species as taxa, not counting the therapsid tree (with 52 additional taxa) and pterosaur tree (with 228 additional taxa) for a total of 851 taxa.

Other studies more recent than 1995
(not included in Meckert’s history) include

  1. http://www.palaeos.org/Reptilia and http://palaeos.com/vertebrates/amniota/reptiles.html
  2. http://whozoo.org/herps/herpphylogeny.html
  3. https://en.wikipedia.org/wiki/Amniote as determined by Benton, M.J. (2004). Vertebrate Paleontology. Blackwell Publishers. xii–452.
  4. University of Maryland (John Merck)
  5. online pdf, Amniote Origins and Nonavian Reptiles
  6. YouTube video by Walter Jahn
  7. Tree of Life
  8. Hedges 2012
  9. Gauthier, Kluge and Rowe 1988 online
  10. Hill 2005
  11. Mikko’s phylogeny archive
  12. ReptileEvolution.com
  13. Let me know if I missed any. I’ll add them here.

A while back
we looked at the differences between astronomy and paleontology. As noted earlier, time is never of the essence in paleontology — and that extends to idea acceptance. So many hypotheses of reptile interrelationships are still floating around out there. A definitive and all encompassing demonstration, like the large reptile tree, will probably just float forever with the other several dozen hypotheses out there, hashed, rehashed and rehashed again without end.

This is one of the frustrations of paleontology. And many think it is largely ego driven.

On that note
In astronomy the data, be it observation or spectral analysis, is immediate and widespread. You just have to look up with the right tool in the right direction. Or study the shared data (photos, etc.) Everyone can confirm the observation.

In paleontology the data comes out piecemeal, in low resolution, or imprecise tracings, not from every angle of view. Some key parts are lost and others are hidden beneath other bones or matrix. Sometimes you have to assemble dozens or hundreds of specimens for a proper study. No one is interested in confirming observations or analyses perhaps for years if ever. They’re all too busy with their own projects. Checking the characters and scores of an analysis can take weeks, months or years (as long as it took to build originally), and to do so requires the same amount of globe-hopping to see all the specimens in all the museums. No one is going to do that. They’d rather be making their own discoveries… and adding their taxa to established trees created by hungry PhD candidates, like Dirk Meckert in 1995, done at the nadir or advent of their experience.

The paleo-mantra remains: you must see the specimen!
And even that is no guarantee.

And if you want to break a paradigm or two,
like Ostrom did in the 1960s, you might have to wait for widespread (but never universal) acceptance. Paleontologists like their paradigms. They don’t like to give them up.

References
Benton MJ 2004. Vertebrate Paleontology. Blackwell Publishers. xii–452.
Carroll RL 1988. 
Vertebrate Paleontology and Evolution, WH Freeman & Co.
Laurin M and Reisz R 1995. 
A reevaluation of early amniote phylogeny. Zoological Journal of the Linnean Society, 113: 165–223.
Linnaeus C 1758. 
Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Meckert D 1995.
 The procolophonid Barasaurus and the phylogeny of early amniotes. PhD thesis McGill University. Online Barasaurus dissertation

 

 

 

A shift in the topology of the large reptile tree

As loyal readers know…

  1. I have challenged others to find taxa that are improperly nested.
  2. So far this year no one has stepped up to the challenge. Well, they had their chance…
  3. Yesterday I discovered a mistake in the large reptile tree and made the correction (Fig. 1). The diadectomorph clade (including procolophonids) have moved closer to the bolosaurids and pareiasaurs.
Figure 1. A shift in the tree topology moves diadectids (and procolophonids) closer to pareiasaurs and away from limnoscelids. But Orobates stayed back.

Figure 1. A shift in the tree topology moves diadectids (and procolophonids) closer to pareiasaurs and away from limnoscelids. But Orobates stayed back. At the bottom of the chart, that line leads to macroleterids and nycteroleterids, then on to the lepidosauriformes and lepidosaurs.

The problem was
so much of the data for the taxa around these nodes are represented by drawings, sometimes with errors. The most difficult taxa and perhaps the least interesting of all reptiles (judging by the number of papers written about them) are also at this node: Saurorictus, Milleretta (both specimens) and the bolosaurids (sans Eudibamus, which nests with Petrolacosaurus). While a single tree was found then, and is also found now, the bootstrap scores were not strong, now or then. The present bootstrap scores could use a boost owing to the skull-only and otherwise unfortunately incomplete data in several taxa often represented only by drawings. Many taxa were rescored.

The other problem was
diadectomorphs nest pretty well with Orobates, millerettids, caseasaurs and limnoscelids. Now they nest just a little better with bolosaurs and pareiasaurs. At one point it was either way.

What sparked this change?
When I added Bashkyroleter, added data to Procolophon and Belebey, and created a new skull restoration of Sauropareion. Issues arose and I took another look at several dozen taxa.

On the plus side,
Stephanospondylus (still known from very poor data) has traditionally been considered a diadectomorph. Now it nests as a sister to that clade. Some diadectids had some widely expanded ribs, as did Stephanospondylus. Both were experimenting with a morphology that would be perfected in their now closer relatives, the turtles.

The limnoscelids and their kin, including Orobates, are all long-bodied taxa now. The diadectids plus pareiasaurs plus turtles are all shorter bodied taxa with progressively wider bodies and shorter tails.

The true procolophonids (Procolophon and kin) are now closer to the nycteroleterids and owenettids, which were traditionally associated in a large single clade. They’re still not directly related.

As noted earlier, one of the earmarks of good Science is correcting errors. I encourage the finding of errors in reptileevolutiion.com. Behind the scenes, as you already know, I make corrections and additions all the time. As mentioned earlier:

Carl Sagan (in the Demon Haunted World) wrote:
“Science has built-in error-correcting mechanisms—because science recognizes that scientists, like everybody else, are fallible, that we make mistakes, that we’re driven by the same prejudices as everybody else. There are no forbidden questions. Arguments from authority are worthless. Claims must be demonstrated. Ad hominem arguments—arguments about the personality of somebody who disagrees with you—are irrelevant; they can be sleazeballs and be right, and you can be a pillar of the community and be wrong.”

In other words,
watch out for those who hold dearly to their paradigms, whether religious or scientific. It’s okay to test those paradigms.

Paleoart Issues – SVPCA talks

Paleoartists,
M Witton, D Naish and J Conway express their unhappiness with current paleoart trends in an abstract published in the upcoming SVPCA talk titles and abstracts.

From the Witton, Naish Conway abstract:
“Palaeoartists fight a losing battle for credibility and even moderate commercial success…and we ascribe its ongoing nature to low awareness of three major issues.

Firstly, palaeoart is rife with copying and plagiarism.

Secondly, the scientific rigour associated with many palaeoartworks, even those produced in close association with consulting academics, is often low. 

Thirdly, many palaeoart patrons have unrealistic concepts of financing artwork.”

All three authors are good artists.
Unfortunately there have been times when all three have freehanded things that should have been strictly traced. Unfortunately there have been times when these guys embraced bad hypotheses (archosaur origin for pterosaurs, deep chord wing attached to the ankle, single uropatagium presence, allometry during ontogeny for pterosaurs, forelimb wing launch, etc.) which adversely affected their art. And did I mention these data deniers have blackwashed the work of other workers without providing competing candidate solutions? So they’re not the little angels they think they are. Nevertheless, they raise some interesting issues that should be discussed and perhaps adopted.

References
Witton MP, Naish D and Conway J 2015. Trends and patterns in modern palaeoartistry: a call for change. SVPCA abstracts 2015.

Pterosaur reproduction and gender identification – SVPCA talks

Two upcoming SVPCA talks worth discussing:
Kellner et al and Unwin + Deeming both discuss pterosaur reproduction, growth and gender.

Key notes from the Kellner et al. (2015) abstract: All eggs show depressions, clearly indicating their overall pliable nature. SEM analysis shows that the eggshell structure is similar to some squamates. SEM analysis of [another] eggshell did not reveal an external calcareous layer suggesting that it was either removed due to taphonomy or not present at all. Histological section of the femur lacks medullary layer, a bone tissue reported in avian dinosaurs during ovulation and egg-laying phase. Those specimens, associated with experimental taphonomic studies, show that pterosaurs had two functional oviducts and laid eggs even smaller than previously thought, indicating that they have developed a reproductive strategy more similar to basal reptiles than to birds.”

Like I’ve been saying since 2007 and before.
Pterosaurs are non-squamate lepidosaurs. Egg shell morphology is just one more clue to this.

Unwin and Deeming abstract:
“Sexual dimorphism is common in extant vertebrates and almost certainly occurred in extinct species as well, but identifying this phenomenon in fossils is difficult. Meeting two key criteria: a large sample size in which all ontogenetic stages are present; and independent evidence of gender, is rarely possible, but has now been achieved for the early Upper Jurassic pterosaur Darwinopterus modularis. This pterosaur is represented by over 20 individuals ranging from hatchlings through juveniles to mature adults (ontogenetic status determined from osteological, histological and morphometric data). One example, ‘Mrs T’, is preserved with two eggs and thus clearly a female. Approximately half the mature individuals of Darwinopterus exhibit a cranial crest and several of these individuals have a relatively narrow pelvis. The remainder lack a cranial crest and in two cases, including Mrs T, have a relatively broad pelvis. All immature individuals lack a crest, an observation that applies to other species of pterosaur in which immature individuals are known. This pattern of morphological variation shows that the cranial crest and pelvis of Darwinopterus modularis are sexually dimorphic. Datasets for other pterosaurs are less complete and/or lack independent evidence of gender, but many species including Ctenochasma gracile, Germanodactylus cristatus and Pteranodon longiceps, exhibit directly, or closely, comparable patterns of anatomical variation to Darwinopterus and are likely to have been sexually dimorphic. We conclude that the spectacular variability in the shape and size of pterosaur cranial crests was likely generated by sexual selection rather than processes such as species recognition.”

Unfortunately
other than with the presence of eggs in association, sexual dimorphism has not been determined in other pterosaurs in which a large sample size is present (Rhamphorhynchus, Pteranodon, Germanodactylus, Pterodactuylus), even without eggs in association. This is widely recognized, hence the excitement level in the abstract for Darwinopterus. Rather speciation of these taxa has been determined through phylogenetic analysis. Speciation has also been determined for the several Darwinopterus specimens. Currently published specimens don’t divide neatly in two. If that changes with the addition of 15 more, I’ll be happy to note that. Unwin and Deeming do not mention phylogenetic analysis in their abstract. If this is a clue to their methods such laziness in skipping phylogenetic analysis is becoming more and more common, especially when it suits a false paradigm. You can’t just eyeball these things. You have to put your data through analysis. Otherwise the work will always be doubted and you’ll be ‘pulling a Bennett’ (assertion of association without cladogram evidence). The purported hatchlings noted by Unwin and Deeming also need to be run through analysis. Are they examples of phylogenetic miniaturization or actual juveniles? Adding hatchlings and embryos along with tiny adults to analysis has been online for more than four years, so there is no excuse for avoiding it.

Tiny wukongopterids are welcome news, by the way. This clade is one of a few that currently lacks any tiny representatives and that lack is the current best reason why wukongopterids left no descendants in the Cretaceous.

The bone originally identified as an ischium on Mrs. T was a misidentified displaced prepubis. The actual ischia were preserved in the counter plate and they were relatively narrow.

Unwin does not support isometric growth during ontogeny, which is otherwise a well established fact in pterosaurs. So he may be accepting dissimilar morphologies as juvenile examples (pulling another Bennett). Very dangerous. As in all other pterosaurs, like Pteranodon, you have to evolve crested derived forms from non-crested basal forms. Unwin and Deeming, if you’re reading this: before you publish your paper, send me your data, if you don’t want to do the analysis yourself. I’ll send back the recovered cladogram. Don’t make the same mistakes again. However, if the juveniles are isometric copies of the adults, then congratulations and remember to give credit where credit is due.

References
Kellner  AWA et al. 2015. Comments on pterosaur reproduction based on recently found specimens from the Jurassic and Cretaceous of China. Among the most spectacular pterosaur finds done in recent years is the bone-bed from the Tugulu Group (Lower Cretaceous) discovered in the Hami area, Xinjiang Uyghur Autonomous Region of China. SVPCA 2015 abstracts.
Peters D 2007. The origin and radiation of the Pterosauria.
Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27
Unwin DM and Deeming CD 2015. New evidence for sexual dimorphism in the basal monofenestratan pterosaur Darwinopterus. SVPCA 2015 abstracts.

Moschops and Simosuchus convergence

Earlier we looked at several instances of convergence within the Reptilia. Here is another illustrated example.

Certain therapsids and crocodylomorphs became plant-eaters.
In doing so some converged on a short, squat body plan. Moschops (Broom 1911, Gregory 1926) is one such therapsid. Much smaller Simosuchus (Kraus and Kley 2010) is one such crocodylomorph (Fig.1).

Figure 1. Moschops (above) was a 2.7m long herbivorous therapsid. Simosuchus was a 75cm long herbivorous crocodylomorph.

Figure 1. Moschops (above) was a 2.7m long herbivorous therapsid. Simosuchus was a 50-75cm long herbivorous crocodylomorph with a similar body shape.

Though different in size,
both taxa evolved from longer, longer-tailed forms with longer jaws filled with sharp teeth. Tiny Simosuchus was armored. Moschops was not. Both taxa had an elevated skull, a deep, wide torso, sprawling limbs and a deep pelvis.

References
Broom R 1911. On some new South African Permian reptiles. Proceedings of the Zoological Society of London 81(4):1073-1082.
Gregory W 1926. The skeleton of Moschops capensis, a dinocephalian reptile from the Permian of South Africa. Bulletin of the American Museum of Natural History 56 (3): 179–251.
Krause DW and Kley NJ eds. 2010. Simosuchus clarki (Crocodyliformes: Notosuchia) from the Late Cretaceous of Madagascar. Journal of Vertebrate Paleontology 30, Supplement to Number 6: 236 pp.

A new Rhamphorhynchus with soft tissue: TMP 2008.41.001

A new PeerJ paper by Hone, Henderson, Therrien and Habib (2015) reports on a new complete, articulated (with a crushed and scattered torso) Rhamphorhynchus specimen, TMP 2008.41.001, the Tyrrell specimen (Fig. 1_.

Figure 1. The new Tyrrell specimen of Rhamphorhynchus.

Figure 1. The new Tyrrell specimen of Rhamphorhynchus.

One species
Hone et al report, “Here we follow Bennett (1995) in considering all Solnhofen specimens of Rhamphorhynchus to belong to a single species, R. muensteri.” This is wrong and lazy. Phylogenetic analysis (Fig. 2), which Hone et al do not attempt, divides this genus into several clades. Even the feet have distinct pedal proportions. The Tyrrell specimen nests at the base of the JME SOS 4785 (Darkwing specimen) clade and is similar in size to other clade members.

Figure 2. Cladogram of Rhamphorhynchus.

Figure 2. Cladogram of Rhamphorhynchus. See, they’re not all one species. And phylogenetic miniaturization occurred at the genesis of this genus.

Juveniles and subadults?
Hone et al. report, “The genus has previously been split into a dozen or more species but these have convincingly been shown to consist of juveniles and subadults of a single species (see Bennett, 1995 for a review).” This is also wrong. We know from several single genus bone beds that hatchlings and juveniles of all tested pterosaurs had adult proportions. We know from phylogenetic analysis that a juvenile Rhamphorhynchus was recovered in phylogenetic analysis because it scored identical to an adult but was less than half as tall.

The specimen used to be in a private collection
of the quarry owners. It was discovered in 1965 and recently sold to the Tyrrell. It is preserved in ventral view with light impressions of wing membranes and a trapezoidal tail vane.

The skull
Hone et al. report, “Some sutures in the skull can be tentatively identified but these are mostly not clear, either because they are being obliterated as a result of cranial fusion during ontogeny, or owing to crushing of elements.” Here (Fig. 3). DGS colorizes the skull bones. I did not notice any obliteration in the sutures.

Figure 3. Rhamphorhynchus Tyrrell specimen after DGS colorizing of the bones.

Figure 3. Rhamphorhynchus Tyrrell specimen after DGS colorizing of the bones.

The teeth
Hone et al. considered the tooth count (twelve uppers, ten lowers) “higher than normal” for Rhamphorhynchus (ten uppers, seven lowers), but the extras appear to be incipient teeth or tooth tips from the right side of the skull.

Sacrum
Hone et al. identify four sacrals (Fig. 5), not counting the anterior vertebrae that lie between the ilia and sends out processes to the anterior ilia.

Caudals
Hone et al. report, “The divisions between the vertebrae are difficult to distinguish along the majority of the length of the tail and parts are covered by the left pes, so a vertebral count is not possible.” I had less of an issue while applying DGS (Fig. 4). But then I had only a jpeg, not the real thing. The photo looks good. Is this a case where DGS trumps first hand observation? See figure 6 for comparison.

Figure 4. Rhamphorhynchus, Tyrrell specimen, caudals. They are distinct from one another contra Hone et al. 2015.

Figure 4. Rhamphorhynchus, Tyrrell specimen, caudals. They are distinct from one another contra Hone et al. 2015. Click to enlarge.

Dorsal ribs
Hone et al. report, “Numerous dorsal ribs and gastralia are preserved on the specimen but a count is not possible given that many elements overlap one another.” This is exactly what DGS does best (Fig. 5) because the eye get overwhelmed by the chaos and colors segregate and ultimately simplify the issue.

Figure 5. Torso of Rhamphorhynchus from Hone et al. 2015. Above as originally interpreted. Below using DGS. What Hone et al. identify as a mc (metacarpal) is the radius + ulna. Scale bar = 2 cm. One rib is actually a prepubis. An extra sacral rib is identified here. The coracoids are in light blue. The light gray areas maybe an egg. A smaller second possible egg is also in gray. The sternal complex (not just the sternum) appears to be broken into several parts. Fibula parts are identified along with a second ischium.

Figure 5. Torso of Rhamphorhynchus from Hone et al. 2015. Above as originally interpreted. Below using DGS. What Hone et al. identify as a mc (metacarpal) is the radius + ulna. Scale bar = 2 cm. One rib is actually a prepubis. It is much more robust then even the anterior ribs. A fifth acral rib is identified here. The coracoids are in light blue. The light gray areas maybe an egg. A smaller second possible egg is also in gray. The sternal complex (not just the sternum) appears to be broken into several parts. Fibula parts are identified along with a second ischium.

Sternal complex
Hone et al. refer to the sternal complex as the sternum. That’s inexact. They know it’s not just a sternum, but also includes the clavicles and interclavicle. Nesbitt (2011) assumed these latter elements were missing from pterosaurs in his analysis, so such deletions have real world consequences in cladograms.

Figure 6. Rhamphorhynchus Tyrrell specimen wing GIF movie showing vane and wing tip ungual visible in high contrast.

Figure 6. Rhamphorhynchus Tyrrell specimen right wing GIF movie showing vane and wing tip ungual visible in high contrast. Note the lack of differentiated caudal vertebrae. Click to enlarge.

Wings and their membranes
Hone et al. identify an ulna where an ulna + radius is present, as described in their text. In prior works these authors have supported the deep chord wing membrane false hypothesis, despite all evidence demonstrating otherwise. Here again is another narrow chord wing membrane with a direct connection to the elbow. That the knees are drawn up does not negate this observation, which is universal in pterosaurs.

FIgure 9. Rhamphorhynchus wing GIF movie (click to enlarge) showing radius + ulna, pteroid and standard narrow chord wing membrane.

FIgure 9. Rhamphorhynchus left wing GIF movie (click to enlarge) showing radius + ulna, pteroid and standard narrow chord wing membrane.

Wing tip
Hone et al. note that both wings terminate in a squared off tip. They were not present when this specimen was prepared 50 years ago. I agree that no wing tip ungual is readily apparent here, as opposed to the many seen on several specimens previously. If you bump up the contrast on the matrix, several ungual candidates appear (Fig. 10). The “squared-off tip” described by Hone et al. looks like any other articular surface, as in the other interphalangeal joints on the wing. This should have been noted.

Figure 10. Right wing tip of Tyrrell specimen of Rhamphorhynchus showing blunt tip and, with higher contrast, several ungual candidate impressions.

Figure 10. Right wing tip of Tyrrell specimen of Rhamphorhynchus showing blunt tip and, with higher contrast, several ungual candidate impressions.

 

Figure 11. Pelvic elements of Rhamphorhynchus, Tyrrell specimen, replaced to their in vivo positions in lateral view along with the two possible egg candidates for comparison to the pelvic opening. Seems like a good fit.

Figure 11. Pelvic elements of Rhamphorhynchus, Tyrrell specimen, replaced to their in vivo positions in lateral view along with the two possible egg candidates for comparison to the pelvic opening. Seems like a good fit. The prepubis, originally identified as a rib, has no counterparts among the ribs. It is more robust and straighter.

Pelvis
Hone et al. report, “The pelvis is partially disarticulated and some elements appear to have been lost.” The ilia are both easy to see. Hone et al. report, “The proximal part of the right pubis is articulated with the right ilium, but only the articular end is visible and the rest appears to be hidden below other elements.” I did not see that. I did see both pubes scattered in the mix (Fig. 5). They are not readily apparent. Hone et al. report, “Only one ischium (?right) can be identified.” I found both (Fig. 5) parallel to each other. Hone et al. report, “Both prepubes are preserved but are in poor condition and covered by other elements. They are in close association but are not articulated with one another and lie posterior and ventral to the sacrum.” The authors did not identify the prepubes in their tracings. In ventral view the prepubes should not be covered by other elements (which elements?). I found one prepubis, misidentified as a rib by Hone et al. and the other one where they said it was. I don’t think they realize how large the prepubes are in this species of Rhamphorhynchus, which is a ‘chubbier’ pterosaur than most others owing to its long ribs, gastralia and deep prepubes. No other ribs are robust like the prepubis. And all of the anterior ribs, those likely to be more robust, but are not in this species, are accounted for. Plus it matches the darkling prepubis (Fig. 12).

Figure 12. The darkling specimen of Rhamphorhynchus, very similar to the Tyrrell specimen, showing the depth of the gastralia and prepubis.

Figure 12. The darkling specimen of Rhamphorhynchus, very similar to the Tyrrell specimen, showing the depth of the gastralia and prepubis.

The foot
traits alone nested the Tyrrell specimen within its clade as this is the only clade with penultimate pedal phalanges longer than the others (Fig. 13). Click here to see others.

Figure 13. Pes of the Tyrrell specimen of Rhamphorhynchus.

Figure 13. Pes of the Tyrrell specimen of Rhamphorhynchus.

The wing membrane
Hone et al. report, “Each wing has a more narrow chord along most of its length than seen in some specimens of Rhamphorhynchus (e.g., BSPG 1938 I 503a, the ‘DarkWing’ specimen—Frey et al., 2003) suggesting some postmortem shrinkage of the membranes (Elgin, Hone & Frey, 2011).”

There is no shrinkage!
Hone et all are refusing to face the facts. They are making up scenarios to avoid the narrow-wing morphology (Peters 2002). This pterosaur, like all others, has a narrow chord wing membrane. Hone et al acknowledge that. And so does the dark-wing specimen, as documented earlier and shown below (Fig. 14). When the wing is outstretched, as if in flight, the membrane goes with the wing finger and it is stretched between the elbow and wing tip. Any other attachment points needlessly complicate matters. Any other scenarios are excuses and just-so stories.

Figure 1. The darkwing specimen of Rhamphorhynchus. Top: in situ. Middle: Soft tissues highlighted. Bottom: Neck and forelimb restored.

Figure 15. The darkwing specimen of Rhamphorhynchus. Top: in situ. Middle: Soft tissues highlighted. Bottom: Neck and forelimb restored with wings outstretched. This is another narrow chord wing membrane when the parts are restored to their in flight position. The arrows show how much the wing would have to stretch to attach to the ankle. But there’s no muscle and bone to stretch it. Remember, in flight the tibia stick almost straight out laterally,

Biut wait… there’s more!
Hone et al. report, “Proximal to the elbow, the right tenopatagium (Fig. 6) is rather less clearly preserved than the left actinopatagium (Fig. 5), but does appear to meet the left ankle as is considered common, or even ubiquitous, for pterosaur wing membranes (Elgin,Hone & Frey, 2011).” Yeah, right… This is really reaching. This is why these guys keep rejecting my papers and why I don’t attend pterosaur symposia. They are adamant about rejecting anything I have published on. Evidently, I have (figuratively) poisoned the well. And that’s a sorry state of affairs. They will never say, “well, I guess Peters 2002 was right about the narrow chord wing membrane. It’s right here in front of us.”

You should know
Hone et al. report, “Furthermore, at least some parts of the wings have been covered with some form of transparent preservative and brush marks (e.g., swirls) are clearly visible in places on the matrix.”

Uropatagia are preserved
But due to the extreme bending of the knees, their shape cannot be determined. Hone et al. provided an extreme closeup of fibrils in a uropatagium (their figure 7, but note the singular state here as they falsely believe, based on the Sordes error, that one membrane extended from leg to leg). They reported the element on the right is the right tibia, but the right tibia is devoid of tissue, as far as I can tell. I was unable to match the extreme closeup to any other wider view shots. There does appear to be soft tissue between the left femur and tibia (remember the specimen is on its back so left is right and right is left). Their figure 8 has a wider view and represents the left tibia. Still the fibrils are close to the tibia and they provide no evidence that these are not separate uropatagia, as in all other pterosaurs.

Gut contents
Hone et al report gut contents of an indeterminate vertebrate. “most of these are distorted and difficult to identify though their overall shape appears to be that of squat cylinders. Their exact identity cannot be determined as they are incomplete and partially covered by other elements, and much of the chest cavity has calcite crystal buildup. –– These bones may represent fish or tetrapod elements, but are not part of the pterosaur as they match none of the dissociated or missing material (ribs, gastralia, sternal ribs, pteroids, pelvic elements) but instead are a sub rectangular series and associated subcircular elements that collectively may be vertebrae (Fig. 3).” Rhamphorhynchus is typically considered a fish eater as fish have been found within certain specimens. ‘Hooklets’ [= simple spikes and hook-like shapes] are found by the thousands in the coprolites. Hone et al. report, “If the diagnosis is correct, this is the first recorded coprolite for any pterosaur.”

Odd that the torso should be so upset, but the soft coprolites untouched.

Hone et al. did not consider the possibility
of an internal immature egg. The item has an oval outline (Fig. 11). And there may be a second smaller, even more immature egg in the mix (Fig. 11). Hard to tell in all that chaos.

Ontogeny
Hone et al. are correct in stating the Tyrrell specimen is adult or nearly so. But sutures are not a reliable indicator of ontogeny. Several clades fuse early and others never fuse, patterns common to lepidosaurs, not archosaurs.

Found typos
Perhaps these can be corrected since they are online:

  1. several specimens seen to have consumed fish”
  2. The uropatagium has become displaced relative to the bones even in some exceptionally preserved specimens (e.g., Sordes PIN 2585-33). The holotype is PIN 2585-3). I find no record for #33 on the Internet.

References
Hone D, Henderson DM, Therrien F and Habib MB 2015. A specimen of Rhamphorhynchus with soft tissue preservation, stomach contents and a putative coprolite. PeerJ 3:e1191; DOI 10.7717/peerj.1191