Mistralazhdarcho: a new pterosaur, but not an azhdarchid

Vullo et al. 2018 bring us a new small ‘azhdarchid’
known from a few 3D bones. In the large pterosaur tree (LPT, 236 taxa) Mistralazhdarcho nests with tiny Nemicolopterus and mid-sized Shenzhoupterus (Fig. 1). Mistralazhdarcho is more than twice as tall as Shenzhoupterus with similar gracile cervicals, a longer radius and shorter metacarpus. Distinct from Shenzhoupterus, the mandible is gracile, more like that of Nemicolopterus.

Figure 1. Mistralazhdarcho compared to reconstructions of Shenzhoupterus and Nemicolopterus.

Figure 1. Mistralazhdarcho compared to reconstructions of Shenzhoupterus and Nemicolopterus. A longer antebrachium is found in Mistalazdarcho.

A downturned dentary
is a trait found in this clade of pterosaurs, and to a lesser extent in sister sinopterids.

The small prominence at the ‘bend’ of the mandible
in Mistralazhdarcho is a curious trait not visible in Shenzhoupterus due to closed jaws in situ. Nemicolopterus might preserve that trait, but a humerus is under the mandible exactly at that point, making it difficult to determine in photos.

A warped deltopectoral crest,
like the one found in Mistalazdarcho (Fig. 1), is not found in azhdarchids. And look at the size range in this clade!

Having reconstructions for direct comparisons,
and a large cladogram that is regularly adding new taxa are tools the LPT and www.ReptileEvolution.com offer freely online to paleontologists worldwide. Best to test here rather than trust your hunch elsewhere.

References
Vullo R, Garcia G, Godefroit P, Cincotta A, and Valentin X 2018. Mistralazhdarcho maggii, gen. et sp. nov., a new azhdarchid pterosaur from the Upper Cretaceous of southeastern France. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2018.1502670.

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Fish nibbles on Pteranodon metacarpal

Figure 1. Fish teeth compared to grazed Pteranodon metacarpal

Figure 1. Fish teeth compared to grazed Pteranodon metacarpal

Ehret and Harrell 2018
bring us news from Alabama of two distinct sets of tooth marks on a Pteranodon (Fig. 2) metacarpal (Fig. 1). They report:

“The Pteranodon specimen exhibits serrated teeth marks on the surface of the bone and a second set of larger, unserrated teeth marks unlike those of any contemporary shark species. These feeding traces compare favorably with the tooth spacing and morphology of Squalicorax kaupi, and a small to moderate-sized saurodontid fish, such as Saurodon or Saurocephalus, respectively. In both instances, feeding traces appear to be scavenging events due to the lack of any healing or bone remodeling. The specimen represents a pterosaur that either fell into marine waters or was washed out from nearshore areas and then scavenged by both a chondrichthyan and osteichthyan.”

“Many fossils from late Cretaceous Alabama appear to have been nibbled by sharks, including sea turtles and dinosaurs, which are often ‘covered in predation marks,’ says Ehret.”

NatGeo publicized the find by talking to some pterosaur experts, “Pterosaurs actually had a lot of meat on their skeletons,” says Michael Habib, a pterosaur expert at the University of Southern California who was not involved with the latest find. “They were not the skinny animals often depicted in films and art. The flight muscles in particular would have made a great meal.”

Pterosaur metacarpals,
like all metacarpals, actually are sinewy and have little to no associated muscle.

Habib adds,
“Pteranodon also inhabited this coastal environment during the late Cretaceous, making a living snatching smaller fish from the shark-filled waters. Pterosaurs could float, but being less buoyant than birds, they probably didn’t sit on the surface for long. Some species, including Pteranodon, did likely plunge into the water for prey. “They could then quickly take back off from the surface. But these diving pterosaurs might have been vulnerable to sharks just after they entered the water,” he says.

M. Witton concluded,
“It’s nice to know what species were interacting in this way.”

Ehret corrected the pterosaur experts,
“It’s also possible that the animal died near the shore and was scavenged when it washed out to sea.”

Figure 3. Triebold Pteranodon in floating configuration. Center of balance marked by cross-hairs.

Figure 2 Triebold Pteranodon in floating configuration. Center of balance marked by cross-hairs.

Contra Habib’s statement
Pteranodon was at least as buoyant as a pelican. It has been widely known for over a century that pterosaur bones are thinner than bird bones and Pteranodon metacarpals, in particular, were hollow like pontoons (Fig. 2).

Ultimately
the bite marks represent curiosity, not predation, a point understood by Ehret and Harrell.

References
Ehret DJ and Harrell TL Jr. 2018. Feeding traces of a Pteranodon (Reptilia: Pterosauria) bone from the late Cretaceous (Campanian) Mooreville Chalk in Alabama, USA. Palaios 33(9):414–418.

www.natgeo.com/

Big pterosaurs: big or little wing tips

Earlier and below (Fig. 2) we looked at large and giant pterosaur wings comparing them to the largest flying birds, including one of the largest extant flying birds, the stork, Ciconia, and the extinct sheerwater, Pelagornis, the largest bird that ever flew.

FIgure 2. A basal pteranodotid, the most complete Pteranodon, the largest Pteranodon skull matched to the largest Pteranodon post-crania compared to the stork Ciconia and the most complete and the largest Quetzalcoatlus

FIgure 1. A basal pteranodotid, the most complete Pteranodon, the largest Pteranodon skull matched to the largest Pteranodon post-crania compared to the stork Ciconia and the most complete and the largest Quetzalcoatlus. Note the much reduced distal phalanges in the complete and giant Quetzalcoatlus, distinct from the Pteranodon species.

Today
we’ll look at how the largest Pteranodon (Figs. 1, 4) compares to much larger pterosaurs, like Quetzalcoatlus northropi (Figs. 1, 2) that have vestigial wingtips similar to those of the  much smaller flightless pre-azhdarchid, SOS 2428 (Fig. 3).

Note the tiny three distal phalanges
on the wing of the largest Quetzalcoatlus, distinct from the more typical elongate and robust distal phalangeal proportions on volant pterosaurs of all sizes. Much smaller definitely flightless pterosaurs, like SOS 2428, shrink those distal phalanges, too. That’s the pattern when pterosaurs lose the ability to fly.

Figure 2. Q. northropi and Q. sp. compared to Ciconia, the stork, and Pelagornis, the extinct gannet, to scale. That long neck and large skull of Quetzalcoatlus would appear to make it top heavy relative to the volant stork, despite the longer wingspan. Pteranodon and other flying pterosaurs do not have such a large skull at the end of such a long neck (Fig. 1). The longer wings of pelagornis show what is typical for a giant volant tetrapod, and Q. sp. comes up short in comparison.

Figure 2. A previously published GIF animation. Q. northropi and Q. sp. compared to Ciconia, the stork, and Pelagornis, the extinct gannet, to scale. That long neck and large skull of Quetzalcoatlus would appear to make it top heavy relative to the volant stork, despite the longer wingspan. Pteranodon and other flying pterosaurs do not have such a large skull at the end of such a long neck (Fig. 1). The longer wings of pelagornis show what is typical for a giant volant tetrapod, and Q. sp. comes up short in comparison.Today we’ll compare the wingspan of the largest Quetzalcoatlus to the largest and more typical Pteranodon species (Fig. 2).

Unfortunately
pterosaur workers refuse to consider taxa known to be flightless, like SOS 2428 (Peters 2018). It’s easy to see why they would be flightless (Fig. 3). Scaled to similar snout/vent lengths with a fully volant pterosaur like n42 (BSPG 1911 I 31) the wing length and chord are both much smaller in the flightless form.

Lateral, ventral and dorsal views of SoS 2428

Figure 3. Lateral, ventral and dorsal views of the flightless SoS 2428 (Peters 2018) alongside No. 42, a volant sister taxon.

Comparing the largest ornithocheirid,
SMNK PAL 1136, to the largest Pteranodon (chimaera of largest skull with largest post-crania in Fig. 4) shows that large flyers have elongate distal phalanges, distinct from body and wing proportions documented in the largest azhdarchids, like Quetzalcoatlus.

Figure 5. Largest Pteranodon to scale with largest ornithocheirid, SMNS PAL 1136.

Figure 4. Largest Pteranodon to scale with largest ornithocheirid, SMNS PAL 1136. Note the long distant wing phalanges on both of these giant flyers. This is what pterosaurs evolve to if they want to continue flying. And this is how big they can get and still fly. Giant azhdarchids exceed all the parameters without having elongate wings. Note: the one on the left has a longer wingspan whir the one on the right has a more massive torso and skull together with more massive proximal wing bones and pectoral girdle. On both the free fingers are tiny, parallel oriented laterally and slightly tucked beneath the big knuckle of the wing finger. The pteroid points directly at the deltopectoral crest. 

As the largest Pteranodon and largest ornithocheirid (SMNS PAL 1136)
(Fig. 4) demonstrate, as flying pterosaurs get larger, they retain elongate distal wing phalanges. And big, robust phalanges they are.

By contrast in azhdarchids and pre-azhdarchids
there is a large size bump after n42 (BSPG 1911 I 31) the fourth wing phalanx either disappears (see Microtuban and Jidapterus) or shrinks to a vestige. Then there’s Zhejiangopterus (Fig. 5), with a big pelvis, gracile forelimbs and a giant skull on a very long neck. Just that neck alone creates such a long lever arm that the pterosaur is incapable of maintaining a center of balance over or near the shoulder joints.

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 5. 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.

As mentioned earlier, becoming flightless permitted, nay, freed azhdarchid pterosaurs to attain great size. They no longer had to maintain proportions that were flightworthy. Instead they used their shortened strut-like forelimbs to maintain a stable platform in deeper waters. And when they had to move in a hurry, their wings could still provide a tremendous amount of flurry and thrust (Fig. 6) for a speedy getaway.

Quetzalcoatlus running like a lizard prior to takeoff.

Figure 6. Quetzalcoatlus running without taking off, using all four limbs for thrust. That long lever arm extending to the snout tip in front of the center of gravity is not balanced in back of what would be the center of lift over the wings

For the nitpickers out there…
some specimens of Nyctosaurus (UNSM 93000, Fig. 7) also have but three wing phalanges, but they are all robust. The distal one is likely the fourth one because it remains curved. Phalanges 2 and 3 appear to have merged, or one of those was lost. Compare that specimen to a more primitive Nyctosaurus FHSM VP 2148 with four robust wing phalanges.

Figure 5. Cast of the UNSM 93000 specimen of Nyctosaurus. Missing parts are modeled here.

Figure 5. Cast of the UNSM 93000 specimen of Nyctosaurus. Missing parts are modeled here.

References
Peters D 2018. First flightless pterosaur (not peer-reviewed). PDF online.

 

Aurorazhdarcho: a new phylogenetic wastebasket for pterosaurs

While researching
the tiny new/old Aurorazhdarcho (Fig. 2) described during Flugsaurier 2018, I gazed upon the Wikipedia page for Auroazhdarcho and was less than delighted to see how many unrelated specimens the webpage authors attributed to that genus (Fig. 1).

Figure 1. Aurorazhdarcho specimens in the LRT according to Wikipedia.

Figure 1. Aurorazhdarcho specimens in the LRT according to Wikipedia.

These generic determinations
were not done as a result of phylogenetic analysis, as in the large pterosaur tree (LPT). Rather, ‘someone’ eyeballed these specimens and made it so. That’s not good science. And it was not validated by phylogenetic analysis.

  1. ‘Pester Exemplar’ – originally Pterodactylus micronyx (Meyer 1856) ELTE V 256 (Osi, Prondvai and Géczy 2010) is a basal member of the Cycnorhamphidae.
  2. CM 11426 – originally Pterodactylus micronyx (Meyer 1856) is a tiny basal member of the Azhdarcho clade.
  3. TM 13104 – is a tiny scaphognathid basal to the Cycnorhamphus/Ornithocheirus clade.
  4. Pterodactylus? pulchellus BM NHM 42735 — is a tiny scaphognathid basal to the Cycnorhamphus/Ornithocheirus clade.
  5. Auroazhdarcho primordius – (Frey et al. 2011) NMB Sh 110 is the holotype specimen, related to Eopteranodon, Eoazhdarcho a clade that begins with Germanodactylus and ends with Pteranodon.
  6. Aurorazhdarcho micronyx – (Habib and Pittman 2018) MB.R.3531 nests with Eopteranodon, Eoazhdarcho and Auroazhdarcho, but is much smaller.

Remember
juvenile pterosaurs are identical to adults. So small pterosaurs with a distinct morphology are not juveniles of larger adults. Small pterosaurs with a distinct morphology need to be tested in phylogenetic analysis to determine where they nest. They typically nest at the base of major and minor clades. Shrinking in size creates new types of pterosaurs.

Frey et al. 2011 rejected the use of cladistic analysis,
but chose to compare Aurorazhdarcho to Ctenochasma, but then considered Aurorazhdarcho an azhdarchoid, itself an invalid diphyletic clade. According to Wikipedia, “Bennett (2013) considered this species to be a ctenochasmatid.” In the LPT, none of the specimens are ctenochasmatids. Prior workers did not recognize the process of phylogenetic miniaturization (Peters 2007), but decided on their own that small pterosaurs were juveniles (Bennett 2013, Frey et al. 2011).

Figure 1. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx to scale.

Figure 2. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx to scale.

If things were different,
and others had produced a phylogenetic analysis of virtually all known pterosaurs and several specimens of each genus and I had, by eyeball, determined that small pterosaurs were juveniles of distinctly different larger adults, then everyone would be justified in refuting that conclusion. As it is, workers are suppressing the results of inclusive phylogenetic analysis and supporting the eyeballing of specimens. Yes, the rules are different if you have a PhD.

References
Bennett SC 2013. New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus. Paläontologische Zeitschrift. 87(2): 269–289.
Frey E, Meyer CA and Tischlinger H 2011. The oldest azhdarchoid pterosaur from the Late Jurassic Solnhofen Limestone (Early Tithonian) of Southern Germany. Swiss Journal of Geosciences 104 (Supplement 1): 35–55. doi:10.1007/s00015-011-0073-1.
Habib M and Pittman M 2018. An “old” specimen of Aurorazhdarcho micronyx with exceptional preservation and implications for the mechanical function of webbed
feet in pterosaurs. Flugsaurier 2018: The 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 41–43.
Lü J-C and Ji Q 2005. New azhdarchid pterosaur from the Early Cretaceous of western Liaoning. Acta Geologica Sinica 79 (3): 301–307.
Lü J-C and Ji Q 2006. Preliminary results of a phylogenetic analysis of the pterosaurs from western Liaoning and surrounding area. Journal of the Paleontological Society of Korea 22 (1): 239–261.
Peters D 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27

wiki/Aurorazhdarcho

Restoring the tip of the Pteranodon rostrum in UALVP 24238

Another short one today.
Everyone in pterosaur land has wondered what shape and length the missing tip of the rostrum took on in the UALVP 24238 specimen of Pteranodon (improperly called ‘Dawndraco‘, Fig. 1). That’s because, unlike most other specimens, the upper and lower margins don’t converge to form a triangle in lateral view, but remain essentially parallel for most of their length.

Figure 1. The missing tip of the UALVP 24238 skull can be restored like the similar Tanking-David specimen skull tip. The dorsal rim is straight. The ventral rim is convex.

Figure 1. The missing tip of the UALVP 24238 skull can be restored like the similar Tanking-Davis specimen skull tip. The dorsal rim is straight. The ventral rim is convex.

The privately held
Tanking-Davis specimen of Pteranodon is the most similar to the UALVP 24238 rostrum. Yes, it converges, but at a very shallower angle. Anteriorly the ventral margin curves up to meet the very straight dorsal margin. The same can be imagined/restored for the missing UALVP 24238 rostrum, and the result appears to be reasonable.

Figure 2. The UALVP 24238 specimen of Pteranodon is largely complete and here the tip of the rostrum is restored like that of a related specimen.

Figure 2. The UALVP 24238 specimen of Pteranodon is largely complete and here the tip of the rostrum is restored like that of a related specimen.

As in most pterosaur genera,
no two specimens are identical. See the panoply of known relatively complete Pteranodon skulls to scale and in phylogenetic order here.

Flugsaurier 2018: Los Angeles County Museum

Flugsaurier
is a meeting of those interested in pterosaurs that happens in another part of the world every few years. I went to the first few. Saw a lot of specimens. Met a lot of colleagues. Produced a few abstracts and gave some presentations.

Over the next few days
there’s a Flugsaurier meeting taking place in Los Angeles. Many well-known and not-so-well known speakers are giving presentations this year. I will not be among them. Why?

So far as I know,
all of the conveners and many of the presenters continue to ignore a paper I wrote 18 years ago on the origin of pterosaurs from fenestrasaurs, not archosaurs. Other papers followed on wing shape, trackmaker identification and other topics, all supporting that phylogenetic hypothesis of relationships. Evidently workers would prefer to hope that pterosaurs arose from archosaurs close to dinosaurs. This is not where the data takes anyone interested in the topic who is not a party to taxon exclusion.

In addition, several of the conveners

  1. subscribe to the invalid quad-launch hypothesis
  2. the bat-wing reconstruction of the brachiopatagium.
  3. they believe that pedal digit 5 framed a uropatagium.
  4. They refuse to add tiny Solnhofen pterosaurs to their cladograms.
  5. They refuse to add several specimens of each purported genus to cladograms—and because of this they don’t recognize the four origins of the pterodactyloid-grade (not clade).
  6. They still don’t recognize that pterosaurs grew isometrically.
  7. They still don’t accept that pterosaur mothers retained their egg/embryo within the body until just before hatching (a lepidosaur trait).
  8. They still don’t accept that pterosaur bone fusion patterns follow lepidosaur, rather than archosaur patterns.
  9. They accept the idea that giant eyeballs filled the anterior skulls of anurognathids, not realizing that the supposed ‘scleral ring’ on edge of the flathead anurognathid is actually the mandible and tiny teeth.
  10. They reject any notion that all basal and some derived pterosaurs were bipedal, despite the footprint and morphological evidence proving bipedal locomotion.
  11. They all hold out hope that the largest azhdarchids could fly.
  12. I was going to say that all workers believe that crest size and hip shape identify gender, when the evidence indicates these are both phylogenetic markers, but then I found an abstract in 2018 that casts doubt on the gender/crest/pelvis hypothesis. So there’s hope.

That’s a fairly long list of ‘basics’
that most pterosaur workers ‘believe in’ despite the fact that there is no evidence for these false paradigms — but plenty of evidence for the lepidosaur origin of pterosaurs, from which most of the above hypotheses follow.

I am not attending Flugsaurier 2018
because the convening pterosaur workers deny and suppress the data listed above. Plus, I can more actively and thoroughly test assertions made during the conference from ‘my perch’ here in mid-America.

Good luck to those attending. 
Test all assertions and hypotheses, no matter their source.

Flugsaurier 2018: ‘Young istiodactylid’ nests with tall pterodactylids in the LPT

Flugsaurier 2018 opens today, August 10,
and the abstract booklet is out. So it’s time to take a look at some of the news coming out of that Los Angeles pterosaur symposium. Since the purpose of the symposium is increase understanding of pterosaurs, I hope this small contribution helps.

Figure 1. The Erlianhaote specimen attributed by Hone and Xu 2018 to istiodactylidae nests in the LPT with the large derived pterodactylids.

Figure 1. The Erlianhaote specimen attributed by Hone and Xu 2018 to the clade Istiodactylidae (within Ornithocheiridae) nests in the LPT with the large derived pterodactylids. Note the un-warped deltopectoral crest and lack of a deep cristospine, along with the long legs and short wings.

Hone and Xu at Flugsaurier 2018
describe, “An unusual and nearly complete young istiodactylid from the Yixian Formation, China (Fig. 1). The specimen shows the characteristic istiodactylid cranial features of tooth shape and enlarged nasoantorbital fenestra. However, it has proportionally large hindlimbs and wing proportions that are similar to those of azhdarchids. This has led to suggestion that the specimen may be a composite and that only the cranial material is istiodactylid. Preparation work around some key parts revealed no inconsistencies in the matrix or evidence of glue. The specimen is held in the Erlianhaote Dinosaur Museum, Erlianhote, China.”

Figure 2. The Erlianhaote specimen nests with these pterodactylids in the LPT, not with Istiodactylus (Fig. 3).

Figure 2. The Erlianhaote specimen nests with these pterodactylids in the LPT, not with Istiodactylus (Fig. 3). Note the antorbital fenestra becomes longer with larger size in this clade. The teeth are similar to those in istiodactylids.

Reconstructed as is
(Fig. 2) and added to the large pterosaur tree (LPT, 233 taxa, not yet updated due to no museum number nor genus name) the young ‘istiodactylid’ nests as a large derived pterodactylid. 13 steps separate this taxon from the Istiodactylus clade.

Ornithocheirids,
like Istiodactylus (Figs. 3, 4) and the SMNL PAL 1136 specimen (Fig. 5), share a very large wing finger, a short metacarpus, a warped deltopectoral crest, small free fingers and deeply keeled sternal complex not found in the Erlianhote specimen.

Figure 3. Istiodactylus has a shorter neck, longer wing finger and deep cristospine, among other traits not found in the new Erlianhaote specimen.

Figure 3. Istiodactylus has a shorter neck, longer wing finger and deep cristospine, among other traits not found in the new Erlianhaote specimen.

Figure 4. Istiodactylus sinensis is an istiodactylid from China sharing few traits with the new Erlianhaote specimen. Note the warped deltopectoral crest not warped in the new specimen.

Figure 4. Istiodactylus sinensis is an istiodactylid from China sharing few traits with the new Erlianhaote specimen. Note the warped deltopectoral crest not warped in the new specimen. Manual 4.1 is shorter than in other well-known istiodactylids.

The largest ornithocheirid

Figure 5. The unnamed largest ornithocheirid, SMNK PAL 1136, nests with Istiodactylus.

Figure 6. The Erlianhaote pterodactylid reconstructed in several views.

Figure 6. The Erlianhaote pterodactylid reconstructed in several views. The imagined (gray) areas of the skull here were imagined as an istiodactylid, but the better restoration is shown in figure 2.

It’s better not to eyeball certain specimens.
Sometimes you have to run them through a phylogenetic analysis to find out what they are. That’s what the LPT is for. It minimizes taxon exclusion and handles convergence.

Pterosaurs are still lepidosaurs.
So they follow lepidosaur fusion patterns, which follow phylogeny. Hone and Xu made the mistake of imagining pterosaurs might have archosaur fusion patterns that follow ontogeny.

Why am I not at Flugsaurier 2018?
In addition to about a dozen reasons that I can list later, or your can guess now, I can be more helpful and timely here.

References
Andres B and Ji Q 2006. A new species of Istiodactylus (Pterosauria, Pterodactyloidea) from the Lower Cretaceous of Liaoning, China. Journal of Vertebrate Paleontology, 26: 70-78.
Bowerbank JS 1846. On a new species of pterodactyl found in the Upper Chalk of Kent P. giganteus). Quarterly Journal of the Geological Society 2: 7–9.
Bowerbank JS 1851. On the pterodactyles of the Chalk Formation. Proceedings of the Zoological Society, London, pp. 14–20 and Annals of the Magazine of Natural History (2) 10: 372–378.
Bowerbank JS 1852. On the pterodactyles of the Chalk Formation. Reports from the British Association for the Advancement of Science (1851): 55.
Hone DWE and Xu 2018. An unusual and nearly complete young istiodactylid from the Yixian Formation, China. Flugsaurier 2018: the 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 53–56.
Hooley RW 1913. On the skeleton of Ornithodesmus latidens. An ornithosaur from the Wealden shales of Atherfield (Isle of Wight)”, Quarterly Journal of the Geological Society, 69: 372-421
Howse SCB, Milner AR and Martill DM 2001. Pterosaurs. Pp. 324-335 in: Martill, D. M. and Naish, D., eds. Dinosaurs of the Isle of Wight, The Palaeontological Association
Wang X, Rodrigues T, Jiang S, Cheng X and Kellner AWA 2014. An Early Cretaceous pterosaur with an unusual mandibular crest from China and a potential novel feeding strategy. Scientific Reports 4 : 6329, pp. 1-9. | DOI: 10.1038/srep06329
Witton MP 2012. New Insights into the Skull of Istiodactylus latidens (Ornithocheiroidea, Pterodactyloidea). PLoS ONE 7(3): e33170. doi:10.1371/journal.pone.0033170

wiki/Istiodactylus