Pappochelys: Can taxon deletion force a relationship with turtles?

Earlier we looked at a new diapsid, Pappochelys (Schoch and Sues 2015, Fig. 1), touted as a basalmost turtle nesting along with Odontochelys.

Unfortunately
Pappochelys nested in the large reptile tree with basalmost placodonts, like Palatodonta and Majiashanosaurus. That nests it far from turtles and their kin.

Today
we’ll see if we can get Pappochelys to nest with turtles by taxon deletion (step-by-step removal of all putative sister taxa).

Figure 6. Pappochelys compared to placodont sister taxa and compared to the Schock and Sues reconstruction, which appears to have several scale bar errors and underestimated the number of dorsal vertebrae. Click to enlarge. So few ribs and vertebrae are known for Pappochelys that their order, size and number could vary from that shown here. Note the ribs of Paraplacodus are also expanded. The number of dorsal vertebrae is unknown and probably more than nine based on sister taxa.

Figure 1. Pappochelys compared to placodont sister taxa and compared to the Schock and Sues reconstruction, which appears to have several scale bar errors and underestimated the number of dorsal vertebrae. Click to enlarge. So few ribs and vertebrae are known for Pappochelys that their order, size and number could vary from that shown here. Note the ribs of Paraplacodus are also expanded. The number of dorsal vertebrae is unknown and probably more than nine based on sister taxa.

 

If we remove
200+ of the closest known sisters to Pappochelys, extending those deletions to half of the large reptile tree, where do you think Pappochelys will nest?

With turtles?
No.

For some reason,
perhaps due to its diapsid temporal region, the basal placodont, Pappochelys nests with long-necked tritosaur, Tanystropheus, when 200+ of its otherwise closest known sisters are deleted. That’s a classic ‘by default’ nesting.

Take away all of the tritosaurs
and Pappochelys nests at the base of the Sphenodontia/lepidosauria.

Take away all of the lepidosauria
and Pappochelys nests at the base of the lepidosauriformes, taxa with a diapsid temporal morphology, but not related to convergent diapsids related to Petrolacosaurus and kin.

Take away all of the lepidosauriformes
and Pappochelys nests with Barasaurus and other owenettids.

Take away all of the owenettids 
and Pappochelys finally nests between two turtles, Proganochelys and Odontochelys.

So Pappochelys resists nesting with turtles, given several grand opportunities to do so. It is morphologically that different. Pappochelys would rather nest with a long list of other taxa than nest with turtles.

References
Schoch RR and Sues H-D 2015. A Middle Triassic stem-turtle and the evolution of the turtle body plan. Nature (advance online publication) > doi:10.1038/nature14472 online

 

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More tiny birds and tiny pterosaurs

Earlier we took a peek at a few tiny birds and pterosaurs. Here (Fig. 1) are several more.

Traditional paleontologists
insist that these tiny pterosaurs were babies of larger forms that looked different, (Bennett 1991, 1992, 1994, 1995, 1996, 2001, 2006, 2007, 2012, 2014) ignoring or not aware of the fact that we know pterosaur embryos and juveniles were virtually identical to their adult counterparts (Fig. 2). Bennett (2006) matched two tiny short-snouted pterosaurs (JME SoS 4593 and SoS 4006 (formerly  PTHE No. 1957 52) to Germanodactylus, but they don’t nest together in the large pterosaur tree.

Figure 1. Tiny pterosaurs and tiny birds to scale showing that tiny pterosaurs were generally about the size of the tiny Early Cretaceous bird.

Figure 1. Tiny pterosaurs and tiny birds to scale showing that tiny pterosaurs were generally about the size of the tiny Early Cretaceous bird. I have, for over a decade, promoted the fact that these tiny pterosaurs were adults, the size of modern hummingbirds and wrens.

One of the most disappointing aspects of modern paleontology
is the refusal of modern pterosaur workers to include in their analyses the small and tiny pterosaurs. They were all the size of living hummingbirds and wrens. Many were similar in size to extinct Early Cretaceous birds (Fig. 1). Those workers don’t want to add these taxa to their lists on the false supposition that the tiny pterosaurs are babies of, so far unknown adults. Note Bennett’s long body of work (see below) indicated otherwise, but never with phylogenetic analysis.

Phylogenetic analysis (Peters 2007) reveals these tiny pterosaurs are adults or can be scored as adults. They are surrounded by adults and they often form transitional taxa in the evolutionary process of phylogenetic miniaturization between larger long-tailed pterosaurs and larger short-tailed pterosaurs.

Figure 1. Click to enlarge. There are several specimens of Zhejiangopterus. The two pictured in figure 2 are the two smallest above at left. Also shown is a hypothetical hatchling, 1/8 the size of the largest specimen.

Figure 2. Click to enlarge. There are several specimens of Zhejiangopterus. The two pictured in figure 2 are the two smallest above at left. Also shown is a hypothetical hatchling, 1/8 the size of the largest specimen. This is evidence that juveniles were virtually identical to adults, except in size.

More importantly,
earlier we discussed several examples of juvenile pterosaurs morphologically matching adults here, here and here. So young pterosaurs have been shown to match their adult counterparts. They don’t transform like young mammals and dinosaurs do. They were ready to fly upon hatching IF they were the minimum size to avoid desiccation, as discussed earlier here.

The most interesting aspect
to the whole tiny pterosaur story is how small their smallest hatchlings would be. We looked at that earlier here.

References
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodon and Systematics of the Pterodactyloidea. [Volumes I & II]. Ph.D. thesis, University of Kansas, University Microfilms International/ProQuest.
Bennett SC 1992. 
Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.
Bennett SC 1994. 
Taxonomy and systematics of the Late Cretaceous pterosaur Pteranodon (Pterosauria, Pterodactyloidea). Occassional Papers of the Natural History Museum University of Kansas 169: 1–70.
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen limestone of Germany: year classes of a single large species. Journal of Paleontology 69, 569–580.
Bennett SC 1996. 
Year-classes of pterosaurs from the Solnhofen limestones of Germany: taxonomic and systematic implications. Journal of Vertebrate Paleontology 16:432–444.
Bennett SC 2001.
 
The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part I. General description of osteology. Palaeontographica, Abteilung A, 260: 1–112. Part II. Functional morphology. Palaeontographica, Abteilung A, 260: 113–153
Bennett SC 2006. Juvenile specimens of the pterosaur Germanodactylus cristatus, with a revision of the genus. Journal of Vertebrate Paleontology 26(4): 872–878.
Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.
Bennett  SC (2012) [2013] 
New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus. Paläontologische Zeitschrift (advance online publication) doi: 10.1007/s12542-012-0159-8
http://link.springer.com/article/10.1007/s12542-012-0159-8
Bennett SC 2014. A new specimen of the pterosaur Scaphognathus crassirostris, with comments on constraint of cervical vertebrae number in pterosaurs. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen, 271(3): 327-348.
Peters D 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27

 

Bird origins: trees encourage phylogenetic miniaturization

Figure 1. The evolution of birds as a consequence of miniaturization. Artist: Davide-Bonnadonna

Figure 1. The evolution of birds as a consequence of miniaturization. Artist: Davide-Bonnadonna. Unfortunately this horizontal image, while correct, ignores the influence of tree clinging.

Earlier a paper (Lee et al. 2014) demonstrated the well understood concept of phylogenetic miniaturization in birds (Fig. 1). We’ve seen this pattern often in the origin of major clades. Perhaps overlooked in birds, the behavior of tree clinging is key to their reduction in overall size, the increase in forelimb length and the evolution of flight feathers.

During this time some pre-bird dinosaurs became arboreal quadrupeds 
while remaining terrestrial bipeds. Smaller lighter taxa with longer forelimbs find it easier to climb trees. The smallest taxa can perch bipedally on slender branches (Fig. 2), eliminating the need to use the forelimbs for clinging. As a consequence, forelimbs can be modified for flight.

Figure 2. Bird origins should be shown in a vertical format as big tree clingers evolved through phylogenetic miniaturization through Aurornis to become perching taxa, like Archaeopteryx.  Black images are to scale. Gray images are enlarged to show detail.

Figure 2. Bird origins should be shown in a vertical format as big tree clingers evolved through phylogenetic miniaturization through Aurornis to become perching taxa, like Archaeopteryx. Black images are to scale. Gray images are enlarged to show detail.

Archaeopteryx was not the smallest of basal birds.
As early birds continued to evolve, becoming ever more bird-like, taxa continued to shrink in size (Fig. 3). Some were as small as hummingbirds and the smallest adult pterosaurs.

Figure 3. The Eichstätt specimen of Archaeopteryx together with a selection of more derived birds, all smaller.

Figure 3. The Eichstätt specimen of Archaeopteryx together with a selection of more derived birds, all smaller.

The act of tree clinging
builds up those all important pectoral muscles over several hundred generations and finds a likely analogous behavior (based on a similar morphology) in the arboreal non-flying fenestrasaur ancestors of pterosaurs, like Longisquama (Fig. 4).

Figure 1. Longisquama on a tree trunk.

Figure 4. Longisquama on a tree trunk.

The perching ability of birds
finds a convergent ability in basal pterosaurs, with the exception that pterosaurs use pedal digit 5 rather than pedal digit 1 to serve as a universal wrench. (Fig. 5, Peters 2000, 2002, 2010). Even so, most pterosaurs (ctenochasmatids and nyctosaurs not included) continued to retain large, tree-clinging fore limb claws.

Figure 1. The pterosaur Dorygnathus perching on a branch. Above the pes of Dorygnathus demonstrating the use of pedal digit 5 as a universal wrench (left), extending while the other four toes flexed around a branch of any diameter and (right) flexing with the other four toes. As in birds, perching requires bipedal balancing because the medially directed fingers have nothing to grasp.

Figure 5. The pterosaur Dorygnathus perching on a branch. Above the pes of Dorygnathus demonstrating the use of pedal digit 5 as a universal wrench (left), extending while the other four toes flexed around a branch of any diameter and (right) flexing with the other four toes. As in birds, perching requires bipedal balancing because the medially directed fingers have nothing to grasp. Note that most pterosaurs do not lose their tree grappling fingers, but quadrupedal beach combing forms, like ctenochasmatids, generally do.

References
Lee MSY, Cau A, Naish D and Dyke GJ 2014. Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds.
Peters, D. 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods. Ichnos, 7: 11-41
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Peters D 2010. In defence of parallel interphalangeal lines. Historical Biology iFirst article, 2010, 1–6 DOI: 10.1080/08912961003663500

Finger 5 in Triassic pterosaurs

Earlier
we looked at examples of manual digit 5 in pterosaurs here, here and here. Traditional paleontologists don’t recognize it. In fenestrasaur pterosaur precursors, like Cosesaurus, Sharovipteryx and Longisquama, manual digit 5 is small, but easier to see because it is relatively larger. You can see the evolution of the pterosaur hand here.

In pterosaurs manual digit 5 is extremely tiny and hard to find (Fig. 1). It can be lost during taphonomy. Fossilization tends to scatter the elements over metacarpal 4, which is often cracked and covered with sinewy soft tissue, factors that make identification all the more difficult. More to the point, based on the current paradigm, no one looks for it during preparation. These are NOT the best examples.

Figure 1. While difficult to discern at this scale, here is where I think the elements of manual digit 5 reside on these four Triassic pterosaurs.

Figure 1. These are not the best examples. While difficult to discern at this scale, here is where I think the elements of manual digit 5 reside on these four Triassic pterosaurs. Images from Dalla Vecchia and Cau 2014. Metacarpal 5 is located, as in other tetrapods, lateral to metacarpal 4, but in pterosaurs metacarpal 4 is axially rotated 90 degrees and metacarpal 5 ends up dorsal to metacarpal 4.

Complete loss of a body part is rare.
Often enough, as in basal whales and snakes, a vestige, like manual digit 5 in pterosaurs, remains. Granted it’s not easy to see. On the other hand, we’re not looking for it. Start with the proximodorsal surface of metacarpal 4. While there look for c5, mc5 and digit 5 composed of three elements including the ungual.

While we’re here looking at the metacarpus,
note that metacarpal 1 is connected only to metacarpal 2 and metacarpal 2 is connected only to metacarpal 3 and metacarpal 3 is connected only to metacarpal 4 — as in all tetrapods. There is no draw bridge-like rotation of mc1-3 to attach dorsal-to-dorsal to metacarpal 4, as promoted by pterosaurs workers who think fingers 1-3 were palmar side anteriorly during flight. That large space dorsal of metacarpals 1-3 is where all the finger extensors remain free to operate, with the wing finger tendon largest by far.

References
Dalla Vecchia FM and Cau Andrea 1014. Re-examination of the purported pterosaur wing metacarpals from the Upper Triassic of England. Historical Biology. To link to this article: http://dx.doi.org/10.1080/08912963.2014.933826

A second egg found in Darwinopterus

Earlier we wondered if a second egg was present in the Darwinopterus specimen with an expelled egg. Now word arrives that indeed there is indeed a second egg present in the counterplate IVPP V18403 of the specimen ZMNH M8802, but it is not the one that appeared to be present (Fig. 1) in the plate. All three are shown below.

Figure 1. Animated GIF of female gravid Darwinopterus. One immature egg was expelled. The other two are inside. The eggs enlarge as they develop. Click to enlarge. 

Figure 1. Animated GIF of female gravid Darwinopterus. One immature egg was expelled. The other two are inside. The eggs enlarge as they develop. Click to enlarge. Images from Wang et al. 2015.

Note that two recognized egg shapes
are about the same size. An immature and poorly ossified embryo matching the proportions of the mother was traced inside the expelled egg here. The internal eggs did not preserve embryonic remains and all are crushed flat and without eggshell.

From the abstract
“The counterpart of a previously described non-pterodactyloid pterosaur with an egg revealed the presence of a second egg inside the body cavity of this gravid female. It clearly shows that pterosaurs had two functional oviducts and demonstrates that the reduction of one oviduct was not a prerequisite for developing powered flight, at least in this group. Compositional analysis of one egg suggests the lack of a hard external layer of calcium carbonate. Histological sections of one femur lack medullary bone and further demonstrate that this pterosaur reached reproductive maturity before skeletal maturity. This study shows that pterosaurs laid eggs even smaller than previously thought and had a reproductive strategy more similar to basal reptiles than to birds. Whether pterosaurs were highly precocial or needed parental care is still open to debate.”

Despite the mother’s size
there are also no lines of arrested growth (LAGs), Wang et al. report, “In these volant reptiles endosteal resorption is regarded as very extensive (Prondvai et al. 2012) and only the most recent chapter of a pterosaur’s life might be captured by the bones.”

Wang et al. also report, “The two eggs were the same length, but not the same width. Despite the different mass estimation of both eggs, with the one inside the body cavity being about 15.4% lighter than the other, all observable features suggest that they were at a similar developmental stage. This corroborates the idea that this pterosaur had two productive oviducts, which is the most common condition within extant reptiles.”

Wang et al. report, “Furthermore, the eggs of this gravid female were small and probably did not constitute a significant impediment for this animal to fly.” Actually they were similar in size to those of other known pterosaur parent/egg pairs in which the hatchling would have been 12% or one-eighth the size of the adult with adult proportions — just large enough to squeeze through the pelvic opening with that pliable, extremely thin, squamate-like shell.

Eggshell?
In order to test if the eggs of IVPP V18403 had calcium carbonate in the external layer, a fragment of the eggshell was submitted to Energy Dispersive Spectroscopy (EDS) done under SEM (Fig. 4). The analysis revealed no substantial traces of calcium carbonate nor showed any significant composition difference between the matrix and the eggshell. That may be so because eggshell is applied last, just prior to parturition (birth/egg laying). The expelled egg was immature, an abortion. Wang et al. report, “This indicates that the calcium carbonate from the eggshell was either removed during the fossilization process, was resorbed during embryogenesis (Grellet-Tinner et al. 2014), or that none was present at all. Another alternative is that these eggs were not in the calcifying developmental stage when the animal died.”

Hanging, for no apparent reason,
on the hypothesis of a pterosaur/dinosaur relationship, Wang et al. report in the mother there was no evidence of medullary bone and that a medullary layer must therefore be an evolutionary novelty in the dinosaur-bird lineage (probably true!). However, in the large reptile tree pterosaurs nest with lepidosauromorphs, not dinosaurs. So no medullary layer is to be expected and eggshells are expected to be very thin and parchment-like because pterosaurs, like many living lizards, retain the embryo within the mother until just prior to egg hatching.

Wang et al. also reported
(as noted above) “Histological sections of one femur lack medullary bone and further demonstrate that this pterosaur reached reproductive maturity before skeletal maturity.” Not necessarily, unless you expect medullary bone and its absence means lack of skeletal maturity to you. That’s jumping to the wrong conclusion based on ignoring the most complete cladograms available. There is another more logical answer that agrees better with the data (see above).

References
Lü J, Unwin DM, Deeming DC, Jin X, Liu Y and Ji Q 2011a. An egg-adult association, gender, and reproduction in pterosaurs. Science, 331(6015): 321-324. doi:10.1126/science.1197323
Wang X et al. 2015.
Eggshell and Histology Provide Insight on the Life History of a Pterosaur with Two Functional Ovaries. Anais da Academia Brasileira de Ciências (Annals of the Brazilian Academy of Sciences)
Printed version ISSN 0001-3765 / Online version ISSN 1678-2690. http://www.scielo.br/aabc
http://dx.doi.org/10.1590/0001-3765201520150364

Austriadraco – a new name for BSp 1994 I51

Yesterday we looked at Bergamodactylus wildi, the basalmost pterosaur, newly named by Kellner (1995). In that same paper Kellner also named Austridraco dallavecchiai (BSp 1994 I51) a small Triassic pterosaur known from scattered bits and pieces. Among those pieces is a mandible (Fig. 1) with an apparent mandibular fenestra. Earlier Nesbitt and Hone (2010) attempted to show that pterosaurs were archosauriforms based on this autapomorphy (not found in other pterosaurs). Both of the above papers considered the mandible preserved in lateral view, contra the original interpretation by Wellnhofer (2001) of a medial view.

Figure 1. Austriadraco, BSp 1994 I51, a Triassic pterosaur mandible. Is it exposed in medial view or lateral view? Below the line is Eudimorphodon, which preserves mandibles in lateral and medial view. Which one is more similar to Austriadraco? You decide. Click to enlarge. Also note the tiny mandibular fenestra in the lateral view of Eudimorphodon not replicated on the medial view and apparently caused by a shift in the covering bone. Arrow points to apparent broken strip of bone that would otherwise have made the long light blue bone continuous.

Figure 1. Austriadraco, BSp 1994 I51, a Triassic pterosaur mandible. Is it exposed in medial view or lateral view? Below the line is Eudimorphodon, which preserves mandibles in lateral and medial view. Which one is more similar to Austriadraco? You decide. Click to enlarge. Also note the tiny mandibular fenestra in the lateral view of Eudimorphodon not replicated on the medial view and apparently caused by a shift in the covering bone. Arrow points to apparent broken strip of bone that would otherwise have made the long light blue bone continuous.

Austriadraco had a hole preserved in the mandible.
The question is, was that extra bone (in light blue, just anterior to the glenoid) not found in other pterosaurs, the displaced lid for the mandibular fenestra? Or was there yet another unexposed bone that shifted position, as shown in Dimorphodon, that would have acted like a lid for that hole? In any case, the reality of that fenestra in situ is not in doubt. What is in doubt is the reality of that fenestra in vivo.

Still wondering
if the mandible of Austriadraco is exposed in medial or lateral view? Here are some questions you might ask a researcher, one who has actually seen the fossil.

  1. Does the coronoid have a substantial exposure below the rim of the mandible?
  2. Is there a concave pocket for insertion of the jaw muscles in the surangular?
  3. Does the articular have a broad or narrow presence?
  4. Do you see the dentary foramina (fo) that Kellner reported?
  5. Does the articular have a deep or shallow glenoid (pocket) for reception of the quadrate?
  6. Does the dentary have a long low shelf below a long concavity?
  7. Does the splenial have a large exposure?*
  8. Does the angular extend posteriorly medial to the articular?
  9. Is the exposed surface of the articular generally convex or concave?

All four above named paleontologists
have seen the specimen first hand, but it was three to one against a medial exposure. Which side are you on? (and don’t forget, you’re using DGS to make your decision).

* I don’t think Wild illustrated this one correctly based on the data in the photograph (Fig. 1).

Figure 2. Austriadraco reconstructed from available parts.

Figure 2. Austriadraco reconstructed from available parts.

On a side note:
Lateral and occipital view photographs of BPI 2871, the Triassic basal choristodere, were added to that blogpost here.

References
Dalla Vecchia FM 2009. Anatomy and systematics of the pterosaur Carniadactylus (gen. n.) rosenfeldi (Dalla Vecchia, 1995). Rivista Italiana de Paleontologia e Stratigrafia 115 (2): 159-188.
Kellner AWA 2015. Comments on Triassic pterosaurs with discussion about ontogeny and description of new taxa. Anais da Academia Brasileira de Ciências (2015) 87(2): (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690.
Nesbitt SJ and Hone DWE 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225-233.
Wellnhofer P 2001. A Late Triassic pterosaur from the northern calcareous Alps. In: Sabatier P., Ed. 2003. Two Hundred Years of Pterosaurs. Toulouse, Laboratoire de Géologie sédimentaire et Paléolontologie, Université Strata Série 1-11: 99–100.

 

Bergamodactylus wildi- a new name for the basalmost pterosaur, MPUM 6009

Finding higher resolution data
is always a delight. Here DGS and a reconstruction perhaps reveal more accurate data on a skull of a basal pterosaur than direct observation (Fig. 1). You decide.

Figure 1. Begamodactylus skull using DGS to segregate and reconstruct the elements. Lower images from Kellner 2015.

Figure 1. Begamodactylus skull using DGS to segregate and reconstruct the elements. Lower images from Kellner 2015. Note the difference in the tracing of the jugal and the reconstruction of the jugal by Kellner 2015. Some odd things are happening on close examination. Kellner actually traced both jugals there and the quadratojugal is actually the postorbital process of the jugal. The squamosal process of the postorbital is broken so the divergence has been reduced. The teeth are also different. The occiput was not traced originally. A hyoid is in the braincase, overlooked by Kellner.

Kellner (2015)
commented on several Triassic European pterosaurs. Among them, MPUM 6009 was originally described as a juvenile Eudimorphodon by Wild (1978) and later congeneric with the basal anurognathid, Carniadactylus by Dalla Vecchia (2009). Peters (2007) nested this specimen as the basalmost pterosaur, though this reference was not listed. Kellner (2015) reported “no indication that MPUM 6009 is a juvenile.” confirming the assessment here.

Bergamodactylus wildi
is the new name for MPUM 6009 a Late Triassic (Norian) basal pterosaur from Bergamo, Italy. Unfortunately the tracing of the specimen is very vague (Fig. 1). Both jugals are drawn as one and many bones are not identified. This is remedied by DGS, which not only identifies left and right bones, but enables an accurate reconstruction with all parts fitting as in other articulated pterosaurs. Note the twin anterior dentary extensions. Are those teeth? A keratin extension has been hypothesized for other basal pterosaurs. Part of the maxilla ascending process is broken and flipped but repaired above. The posterior process of the left postorbital is broken like a wishbone. Here (Fig. 1) it is repaired to resemble the right postorbital. The occiput is identified along with several hyoids that were overlooked earlier. Does the coronoid have a tall triangular process? Perhaps, but that could also be an ectopterygoid. We’ll have to see about that.

Figure 2. Updated reconstruction of Bergamodactylus to scale with an outgroup, Cosesaurus.

Figure 2. Updated reconstruction of Bergamodactylus to scale with an outgroup, Cosesaurus. Compared to the cranium and declined quadrates, the face appears to be downturned. This only makes sense in a bipedal configuration, as shown.

References
Dalla Vecchia FM 2009. Anatomy and systematics of the pterosaur Carniadactylus (gen. n.) rosenfeldi (Dalla Vecchia, 1995). Rivista Italiana de Paleontologia e Stratigrafia 115 (2): 159-188.
Kellner AWA 2015. Comments on Triassic pterosaurs with discussion about ontogeny and description of new taxa. Anais da Academia Brasileira de Ciências (2015) 87(2): (Annals of the Brazilian Academy of Sciences) Printed version ISSN 0001-3765 / Online version ISSN 1678-2690.
Nesbitt SJ and Hone DWE 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225-233.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Wild R 1978. Die Flugsaurier (Reptilia, Pterosauria) aus der Oberen Trias von Cene bei Bergamo, Italien. Bolletino della Societa Paleontologica Italiana 17(2): 176–256.

wiki/Eudimorphodon