Douzhanopterus: Not the pterosaur they think it is + overlooked wing membranes.

A new paper by Wang et al. 2017
describes a ‘transitional’ pterosaur (Figs. 1,4) that was purported to link long-tail basal pterosaurs to short-tail derived pterosaurs (Fig. 2).

Unforunately this pterosaur does not do that.
No one single pterosaur can do that (see below, Fig. 3). But the new pterosaur is a new genus with a set of unique traits that nests at the base of the Pterodactylus clade, the Pterodactylidae, not the base of the so-called ‘Pterodactyloidea.’

Figure 1. Douzhanopterus at top in situ compared to scale with related pterosaurs, including Jianchangopterus, Ningchengopterus and the Painten pterosaur, all at the base of the Pterodactylidae.

Figure 1. Douzhanopterus (Wang et al. 2017) at top in situ compared to scale with related pterosaurs, including Jianchangopterus, Ningchengopterus and the Painten pterosaur, all nesting at the base of the Pterodactylidae.

Douzhanopterus zhengi (Wang et al. 2017; STM 19–35A & B; Late Jurassic, Fig. 1) originally nested (Fig. 2) between the Wukongopterids (Wukongopterus, Darwinopterus, Kunpengopterus.) and the Painten pterosaur (Fig. 1) and the rest of the purported clade Pterodactyloidea, beginning with Pterodactylus antiquus. Unfortunately, this is an antiquated matrix based on Wang et al. 2009 modified from Andres et al. 2014 with additional taxa. Unfortunately it includes far too few additional taxa and it produces an illogical cladogram in which clade members recovered by the large pterosaur tree (LPT) become separated from one another.

Figure 2. Basal portion of a cladogram provided by Liu et al. but colorized here to show the division of clades recovered in the LPT.

Figure 2. Basal portion of a cladogram provided by Wang et al. but colorized here to show the division of clades recovered in the LPT. Note that dorygnathids are basal to all derived cyan taxa and Scaphognathids are basal to all derived amber taxa.

As readers of this blogpost know
there was not one origin to the ‘Pterodactyloidea” clade, there were four origins to the pterodactyloid grade: two out of two Dorygnathus specimens and two out of small Scaphognathus descendants (subset of the LPT, Fig. 3). Once again, taxon exclusion is the problem in Wang et al. 2017. Too few taxa were included and many key taxa were ignored.

Should we get excited about the length of the tail
or the retention of an elongate pedal digit 5? No. These are common traits widely known in sister taxa and too often overlooked by pterosaur workers.

I understand the difficulties here.
Wang et al. saw no skull (but see below!) and the rest of the small skeleton is rather plesiomorphic, except for those long shins (tibiae). Even so, plugging in traits to the LPT reveals that Douzhanopterus is indeed a unique genus.

Figure 3. Subset of the LPT focusing on Pterodactylus with Douzhanopterus at its base.

Figure 3. Subset of the LPT focusing on Pterodactylus with Douzhanopterus at its base. Many of these taxa were not included in the Wang et al. 2017 study, but not the proximity of the Painten pterosaur, similar to the Wang et al study.

Here Douzhanopterus nests
in the LPT as a larger sister to Jianchangopterus (Lü and Bo 2011; Middle Jurassic; Fig. 1) at the base of the Pterodactylidae. These are just those few taxa closest to the holotype Pterodactylus and includes the Painten pterosaur, as in the Wang et al. study. Here that pterosaur was likewise demoted from the base of the Pterodactyloidea to the base of the Pterodactylidae.

Figure 4. Douzhanopterus in situ, original drawing and color tracing showing the overlooked soft tissue membranes and skull. Click to enlarge.

Figure 4. Douzhanopterus in situ, original drawing and color tracing showing the overlooked soft tissue membranes and skull. Click to enlarge.

Wang et al. overlooked
the skull and soft tissue membranes (Fig. 4) that are readily seen in the published in situ photo image. Click here to enlarge the image. These shapes confirm earlier findings (Peters 2002) in which the wing membranes had a narrow chord + fuselage fillet and were stretched between the elbow and wingtip, not the knee or ankle and wingtip. The uropatagia were also had narrow chords and were separated from one another, not connected to the tail or to each other, contra traditional interpretations.

DGS
This is what Digital Graphic Segregation is good for. I have not seen the specimen firsthand yet I have been able to recover subtle data overlooked by firsthand observation. The headline for this specimen should have been about the wing membranes, not the erroneous phylogenetic placement.

References:
Andres B, Clark J and Xu X 2014. The earliest pterodactyloid and the origin of the group. Curr. Biol. 24, 1011–1016.
Lü J and Bo X 2011. A New Rhamphorhynchid Pterosaur (Pterosauria) from the Middle Jurassic Tiaojishan Formation of Western Liaoning, China. Acta Geologica Sinica 85(5): 977–983.
Peters D 2002.  A New Model for the Evolution of the Pterosaur Wing – with a twist.  Historical Biology 15: 277–301.
Wang X.Kellner AWA, Jiang S and  Meng X 2009. An unusual long-tailed pterosaur with elongated neck from western Liaoning of China. An. Acad. Bras. Cienc. 81, 793–812.
Wang et al. 2017. New evidence from China for the nature of the pterosaur evolutionary transition. Nature Scientific Reports 7, 42763; doi: 10.1038/srep42763

wiki/Jianchangopterus
wiki/Ningchengopterus
wiki/Douzhanopterus (not yet posted)

Bat wing ‘pose’ in pterosaurs? – SVP abstracts 2016

Manafzadeh and Padian 2016
attempt to provide insights into pterosaur abilities by comparing certain skeletal elements with those of a chicken, then a bat.

From the Manafzadeh and Padian 2016 abstract (abridged)
“Hip mobility is determined in part by the osteological morphology of the acetabulum and femoral head. However, the joint capsule and its ligaments constrain motion to a smaller range than what seems possible from dry bones alone. Paleontologists have tried to reconstruct the locomotion of extinct ornithodirans (1) (bird-line archosaurs) without accounting for ligamentous constraints in the hips of their extant avian relatives. We dissected the hip joint capsules of 30 free-range farmed specimens of the domestic chicken (Gallus galls) (2). For each specimen, maximum hip ranges of motion in the sagittal, frontal, and transverse planes were first determined from manipulation of carcasses. These values were then compared to ranges of motion obtained from manipulating the femora and pelvic bones alone. In the light of archosaur soft tissue homologies, these data suggest that many inferences drawn from dry bones alone have overestimated ranges of hip motion and have proposed stances and gaits for ornithodirans that would have been made implausible or impossible by soft tissues. Specifically, our findings suggest that ligamentous constraints would have prevented batlike incorporation of the pterosaur hindlimb into a uropatagium. (3) These data suggest that the “4-wing gliding” model of basal maniraptoran flight (e.g., Microraptor) would have been difficult or impossible if it required bringing the hindlimbs into a strictly horizontal plane.” (4)

Notes

  1. Everyone should know by now, pterosaurs are not stem birds. This has been known for 16 years (Peters 2000). They are stem squamates in the LRT. This has been known for 5 years, since the origin of ReptileEvolution.com and for 11 years if you read abstracts from Flugsaurier meetings (Peters 2007).
  2. Thus, using a chicken (Gallus) is inappropriate. Among living taxa, the use of the squamate Chlamydosaurus would have been phylogenetically much closer to pteros. Even then, a stretch.
  3. The bat-wing pterosaur argument has never been supported by evidence. And the uropatagium myth has also never found any evidence. It is founded on one misinterpreted specimen. Funny that the uropatagium is not found in chickens and makes its one and only appearance in the abstract here at the conclusion. Did pterosaurs have a bat-like wing [deep chord]? Or did they adopt a bat-like pose [upside down]? The abstract headline needs to clarify which is correct.
  4. The inability of theropods to abduct the femur into the parasagittal plane was shown in a Nova PBS special. Details and links here.
  5. If you want to see the range of poses in pterosaurs, click here to start. The angle of the femoral head to the shaft varies widely within the Pterosauria, from dino-like in Dimorphodon, to more splayed in higher taxa like Pteranodon (Fig. 1), Anhanguera and Quetzalcoatlus.
  6. Working with reinflated pterosaur bone replicas (Fig. 1) shows the femoral head, though able to rotate on its axis and wobble about its axis, need not move much in order to supply all necessary movement to the hind limb in flight or walking. The same holds true working with uncrushed bones. Reconstructions are SO important and so typically ignored.
Standing Pteranodon

Figure 1. Standing Pteranodon Remember, the wing membranes fold up to near invisibility in all known fossils that preserve a folded wing as the membrane is stretched between wingtip and elbow with a small fuselage fillet to mid thigh from the elbow.

References
Manafzadeh AR and Padian K 2016. Could pterosaurs adopt a batlike wing pose? Implications of a functional analysis of the avian hip ligaments for the evolution of ornithodiran stance and gait. Abstract from the 2016 meeting of the Society of Vertebrate Paleontology.
Peters D 2000. A redescription of four prolacertiform genera and implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106: 293-336.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

Pterosaur pubis retroversion – SVP abstract 2016

RA Frigot 2016 
produced an abstract that appears to have no basis in reality. After reading the notes below, please send any examples of any pterosaur with a retroverted pubis, as noted in her abstract headline. I find no such examples in my fairly large collection of reconstructions.

From the Frigot 2016 abstract
“It has been demonstrated that the pelvis in archosaurs (1) repeatedly shows convergence towards acquisition of an anteriorly projecting ilium and a retroverted pubis. Pterosaurs have independently evolved these features, with the anterior iliac process universal across the taxon and the retroverted pubis occurring in several taxa (2). The latter cannot be appreciated as readily in pterosaurs as in other archosaurs due to the fused nature of the ischium and pubis (3). Geometric and linear morphometrics were used to quantify the shape and angle of the anterior margin of the pubis or puboischiadic plate. The angle and the PCA score were applied as end taxa to a reduced phylogenetic tree and nodes were reconstructed using least-squares parsimony. Retroversion is defined here as the anterior margin of the pubis subtending an angle of greater than 90° to the long axis of the spinal column (4).

“By examining the pubis, it can be seen that it becomes retroverted not once at the base of the Pterodactyloidea, as is consistent with existing hypotheses on gait, but in several different lineages independently. Due to the constraints of flight, it is unlikely that this retroversion accommodated a more massive gut, as is the consensus in Ornithischia and Therizinosauroidea. Retroversion has been associated with increased femoral retraction in Maniraptora, and a similar function of the retroverted pubis in pterosaurs is hypothesized here (5).”

“As the pubis becomes retroverted, the surface area caudad to the femur increases and surface area craniad to the acetabulum is reduced. Accordingly, moment arms of femoral protractors originating from the puboischiadic plate are reduced, and in some cases come to function as additional adductors. By contrast, the adductors are brought immediately ventral to the acetabulum, giving them greater mechanical advantage. This shape change is likely enabled by the expansion of the hip protractors onto the anteriorly expanded ilium. In terms of gait, a strongly retroverted pubis is unlikely to correspond to a vertical clinging style of arboreality, as the caudally rotated retractors are at an extreme mechanical disadvantage. This suggests either a terrestrial mode of locomotion, or a horizontal substrate arboreality (6). In addition, strong femoral retractors and adductors played a crucial role in developing and maintaining tension in the wing membrane (7), and in maintaining its planform and preventing collapse of the wing.”

Notes

  1. Pterosaurs have never been shown to be archosaurs without massive taxon exclusion. On the positive side, pterosaurs have been shown to be fenestrasaur tritosaur lepidosaurs in the large reptile tree which tests a wide gamut of taxa, including archosaurs.
  2. I have never seen a pterosaur with a retroverted pubis, but all have an anteriorly projecting ilium, starting earlier than stem facultative biped pterosaur taxa like Cosesaurus.
  3. Not all pterosaurs fuse the pubis and ischium. Many don’t.
  4. I just looked at several dozen reconstructions at ReptileEvolution.com and none of the pterosaurs has a pubis that extends more than 90º to the spinal column.
  5. Not sure we can talk about a special function here when there is no retroverted pubis in any pterosaur.
  6. Funny, no discussion of the prepubis here, which serves as an anteroventral (not posterovental) extension of the pubis and an anchor for femoral muscles on both vertical and horizontal surfaces. And it is present in all pterosaurs and non-pterosaur fenestrasaurs.
  7. Evidence says no. The pterosaur wing is stretched between the wingtip and elbow with a shallow fuselage fillet extending to mid thigh in all pterosaurs that preserve the wing membrane. There is still no evidence for a wingtip-to-tibia-or-ankle deep chord wing membrane in any pterosaur. If you have such evidence, please send it.

What am I not getting here?
This abstract doesn’t make sense. How did it pass peer review?

prepubes, prepubis

Figure 1. The pelvis and prepubis of several tritosaurs, fenestrasaurs and pterosaurs

References
Frigot RA 2016. Retroversion of the pubis in pterosauria and its significance in reconstructing gait. Abstract from the 2016 meeting of the Society of Vertebrate Paleontology.

The carpus (wrist) of Pterodactylus scolopaciceps

Earlier we looked at the pectoral girdle of Pterodactylus scolopaciceps  BSP 1937 I 18 (Broili 1938, P. kochi n21 of Wellnhofer 1970, 1991).. And even earlier we looked at that elusive (they say it doesn’t exist!) manual digit 5. Today, some more thoughts on that wonderful wrist… (Fig. 1).

Figure 1. The wrist of Pterodactylus scolopaciceps BSP 1937 I 18 (Broili 1938, P. kochi n21 of Wellnhofer 1970, 1991). Manual digit 5 is a vestige, but it is there.

Figure 1. The wrist of Pterodactylus scolopaciceps BSP 1937 I 18 (Broili 1938, P. kochi n21 of Wellnhofer 1970, 1991). Manual digit 5 is a vestige, but it is there.

Manual digit 5
is here. So is metacarpal 5 and distal carpal 5

Figure 1. The wrist of Pterodactylus scolopaciceps BSP 1937 I 18 (Broili 1938, P. kochi n21 of Wellnhofer 1970, 1991). Manual digit 5 is a vestige, but it is there.

Figure 2. The wrist of Pterodactylus scolopaciceps BSP 1937 I 18 (Broili 1938, P. kochi n21 of Wellnhofer 1970, 1991). Manual digit 5 is a vestige, but it is there.

Metacarpals 1-3
are not pasted onto the anterior (during flight) face of the big metacarpal 4 as tradition dictates. Here mc1-3 are in their natural positions for tetrapods, palmar side down. Only metacarpal 4 is axially rotated so the wing finger folds (flexes) and extends in the place of the hand like bird and bat wings do. That means only metacarpal 3 attaches to metacarpal 4, mc2 lies between 1 and 3 and 1 hangs out in front.

Fingers 1-3
are dislocated and axially rotated anteriorly. In life they palms of the fingers would have been ventral, just like metacarpals 1-3 — not flexing anteriorly as they do here after crushing. Note the fingers are all disarticulated at the knuckle, which was a very loose joint, enabling 90 degrees of extension dorsally (in flight) or laterally (while quadrupedal for walking. Moreover, digit 3 was able to flex in the plane of the wing, like the wing. That produces manus impressions in which digit 3 is oriented posteriorly. That’s very weird for most tetrapods, but common in pterosaurs, as it indicates the quadrupedal configuration was achieved secondarily from an initial bipedal configuration.

Of added interest here….
Note the sawtooth posterior edges of the forelimb, hand and finger four where the wing membrane was attached, fed and enervated. Note also the large extensor tendon distal to the preaxial carpal. It is rarely preserved.

The preaxial carpal and pteroid
as you might remember, are former centralia having migrated to the outside (Peters 2009). We looked at analogous migrations here.

Radius and ulna
as in birds and bats, there is no pronation or supination in the pterosaur wrist and forearm. The elements are too close together to permit this. And that’s a good thing to keep the wing in the best orientation for flight. Bats and birds don’t twist their forearms either.

As you already know, every body part that disappears
goes out with a vestige.

References
Broili F 1938. Beobachtungen an Pterodactylus. Sitz-Bayerischen Akademie der Wissenschaten, zu München, Mathematischen-naturalischenAbteilung: 139–154.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

wiki/Pterodactylus

Nesting the Zittel wing of Rhamphorhynchus in the large pterosaur cladogram

Traditionally
the well-preserved Zittel wing (Fig. 1; Zittel 1882) had been assigned to Rhamphorhynchus gemmingi, of which n74 (TM 6922/6923) is the holotype.

Figure 1. The Zittel wing of Rhamphorhynchus is traced here. It nests not with R. gemmingi specimens, but with R. muensteri specimens.

Figure 1. The Zittel wing of Rhamphorhynchus is traced here. It nests not with R. gemmingi specimens, but with R. muensteri specimens. Click to enlarge. Both manual digit 5 and ungual 4.5 are present here along with wonderful shallow chord wing membrane tissue and propatagium.

I wondered if
the wing specimen had enough character traits to nest it in the large pterosaur cladogram. There it nests between the famous ‘dark wing’ specimen (JME Sos 4784, also famous for soft tissue preservation) and the MTM V 2998.33.1 specimen (Fig. 2), both assigned to R. muensteri. The Zittel wing is a little larger than both.

Figure 2. The Zittel wing specimen B St 188 II 8 nests between the 'dark wing' JME specimen and the MTM specimen, both in the Rhamphorhynchus muensteri clade.

Figure 2. The Zittel wing specimen B St 188 II 8 nests between the ‘dark wing’ JME Sos 4784 specimen and the MTM V 2998.33.1 specimen, both in the Rhamphorhynchus muensteri clade. This is a portion of a larger image.

You might recall
that Elgin, Hone and Frey (2010) dismissed the Zittel wing because it did not fit into their deep chord paradigm, but suffered from ‘shrinkage’. That is bogus thinking. More on pterosaur wings here and here. All known pterosaur specimens preserving wing membranes do so following the Zittel wing pattern. That’s a fact that other workers attempt to dismiss. 

References
Elgin RA, Hone DWE and Frey E 2010. The extent of the pterosaur flight membrane. Acta Palaeontologica Polonica in press. doi: 10.4202/app.2009.0145
Goldfuss A 1831. Beiträge zur Kenntnis vershiedener Reptilien der Vorwelt. Nova Acta Academiae Leopoldinae Carolinae, Breslau and Bonn, 15: 61-128
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Tischlinger H and Frey E 2002. Ein Rhamphorhynchus (Pterosauria, Reptilia) mit ungewöhnlicher Flughauterhaltung aus dem Solnhofener Plattenkalk. Archaeopteryx, 20, 1-20.
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33. Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.
Zittel KA 1882. Über Flugsaurier aus dem lithographischen Schiefer Bayerns. Palaeontographica 29: 7-80.

wiki/Rhamphorhynchus

Manual digit 5 on Bellubrunnus (= basal Rhamphorhynchus)

In several phylogenetic predecessors of pterosaurs
such as Cosesauru, Sharovipteryx and Longisquama. manual digit 5 is small but clearly present (Fig. 1). Traditional workers report that manual digit 5 is absent in pterosaurs.

pterosaur wings

Figure 1. Click to enlarge. The origin of the pterosaur wing and whatever became of manual digit 5?

In pterosaurs
I have shown here, here and here several examples of a vestigial manual digit 5 on the axially rotated metacarpal 4. Unfortunately, other workers do not yet recognize these hard to see bones. Heck, they don’t recognize these taxa as pterosaur sister taxa, so we know the similar frustration John Ostrom and John Huxley felt when workers did not accept their bird/dinosaur hypothesis reviewed here.

Bellubrunnus-digit5

Figure 2. Click to enlarge. The carpus and manus of Bellubrunnus identifying element including a vestige of manual digit 5. Yes, it’s tiny, but all vestiges are. Look closely, fellow workers, and you will find it for yourself. U = ulna. Ul = ulnare. R = radius. Ra = radiale. Pt = pteroid. PC = preaxial carpal. Numbers = unfused distal carpals and manual digits.

Hone et al. 2012
provided exquisite UV closeups of the tiny specimen, but did not identify vestigial manual digit 5. I do so here (Fig. 2). It’s clear, but tiny, as most vestiges are.

The carpal elements
are unfused because this adult specimen is the result of phylogenetic miniaturization. It’s ancestors among the genus Campylognathoides, were much larger individuals, as shown here. Essentially Bellubrunnus is a precocious adult, sexually mature in an otherwise immature, reduced size body. This can confuse those who work in bone histology and workers who don’t understand lepidosaur fusion patterns. Phylogenetic analysis, as shown here, solves these problems.

References
Hone DWE, Tischlinger H, Frey E and Röper M. 2012. A New Non-Pterodactyloid Pterosaur from the Late Jurassic of Southern Germany. PLoS ONE 7(7): e39312. doi:10.1371/journal.pone.0039312

 

 

Longisquama wings

Everyone agrees
that the anterior half of Longisquama is known because it is plainly visible. Everyone agrees that a pair of forelimbs is visible. Sharov (1970) illustrated fingers, but was stymied from completing that task because the two hands are preserved one on top of the other with the fingers intermingled. You can see that chaotic preservation here.

DGS
(digital graphic segregation) is a useful method to segregate one Longisquama hand from another and fingers from one another. Once that is done, phalangeal lengths can be matched for validity and accuracy. Ultimately a reconstruction can be produced (Fig. 1). It is readily apparent that the in situ chaos as preserved is difficult to trace, but not impossible. Anyone can do it with enough resolution and patience.

Figure 1. Longisquama left and right manus traced using DGS then reconstructed (below). This is a very large hand for a fenestrasaur and manual digit 4 is oversized, as in pterosaurs.

Figure 1. Longisquama left and right manus traced using DGS then reconstructed (below). This is a very large hand for a fenestrasaur and manual digit 4 is oversized, as in pterosaurs. Yes, membranes are preserved trailing the manus, just as plumes and other membranes are preserved elsewhere.

The importance of overcoming a chaotic preservation
to retrieve an orderly reconstruction is well illustrated by this example (Fig. 1). The fact that corresponding phalanges on both hands are equal in length self-validates the tracing. Here the phalanges are numbered and their images were copied and pasted to produce the reconstruction. Also note the shapes of the scapula and coracoid, perfect for flapping. There’s a nice sternal complex in there too. Only fenestrasaurs, including pterosaurs, have those.

The size of the manus,
relative to the humerus and antebrachium, the proportions of the phalanges, the presence of a trailing membrane and of preaxial carpals (including a pteroid) all indicate a close relationship to pterosaurs and other fenestrasaurs. No other tetrapods share these traits.

Figure 2. Click to animate. Longisquama flapping and wagging its tail.

Figure 2. Click to animate. Longisquama flapping and wagging its tail.

Scientists have been looking
for a non-flying reptile with large hands that could be a pterosaur ancestor. This is it (fig. 2), only the fingers are a little curled up and relative to the torso the entire forelimb is short, as in the sister to Longisquama, Sharovipteryx.

References
Peters D 2000.
 A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. Historical Biology 15: 277-301.
Sharov AG 1970. A peculiar reptile from the lower Triassic of Fergana. Paleontologiceskij Zurnal (1): 127–130.