Flugsaurier 2018: Pterosaur crest and pelvis news – you heard it here first

Flugsaurier 2018 part 6
Since the purpose of the symposium is increase understanding of pterosaurs, I hope this small contribution helps.

Cheng, Jiang, Wang and Kellner 2018
concluded: “The size of pelvic channel and the presence and absence of premaxillary crest may not be used for distinguishing the gender of wukongopterid pterosaurs.”

That’s confirmation
of an earlier finding first discussed here. and basically throughout the seven-year course of this blogpost. Click here for Pteranodon crest phylogenetic variation. Here for Darwinopterus.

References
Cheng X, Jiang S-X, Wang X-L and Kellner AWA 2018. The wukongopterid cranial crests and pelves: sexual dimorphism or not? Flugsaurier 2018: the 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 33–34.

 

Guesswork parades as science: the ‘Dawndraco’ debate continues

Kellner 2017 rebutted Martin-Silverstone et al. 2017
who rebutted Kellner 2010 in their taxonomic assessment of a Pteranodon specimen UALVP 24238. Is it congeneric with FHSM VP 339 (GeoternbergiiaP. sternbergi)? Or is the UALVP specimen a distinct genus? Or something else…?

Figure 1. Pteranoodn (Dawndraco) UALVP 24238 in situ, with Martin-Silverstone tracing applied, with mandible moved and missing parts colorized. The putative rostral tip looks more like displaced manus elements.

Figure 1. Pteranoodn (Dawndraco) UALVP 24238 in situ, with Martin-Silverstone tracing applied, with mandible moved and missing parts colorized. The putative rostral tip looks more like displaced manus elements.

Both parties wondered about
gender differences based on pelvis shape. (Both had no clue that the one ‘female’ pelvis they pin their hopes on actually belongs to a giant Nyctosaurus).

Both parties wondered about
maturity at the age of death and used bone fusion as an ontogenetic marker. (Both have no clue that fusion patterns are phylogenetic in pterosaurs because pterosaurs are lepidosaurs and fusion patterns don’t match those of archosaurs, according to Maisano 2002a, b and confirmed by phylogenetic analysis).

Martin-Silverstone et al. dismiss
several observed variations due to postmortem distortion, evidently a favorite excuse of many paleontologists when they have run out of answers that fit their paradigm. (No distortion is found in UALVP 24238).

Name calling, too…
Kellner felt he had to defend being labeled as a ‘splitter’.

Kellner adds one more thought:
“As I have stressed before (Kellner 2010), morphology is crucial for establishing or synonymizing species.” (Very unfortunately both authors do not understand what pterosaurs are: they are fenestrasaur tritosaur lepidosaurs, because they had not performed a phylogenetic analysis in arriving at their conclusions. Only when that happens, THEN establishing and synonymizing species can happen as a result. You just have to read the tree to see who is, or is not, related to who.

Lately everyone in pterosaurs seems to be avoiding
this thing called, “phylogenetic analysis” which, in the large pterosaur tree (LPT, 232 taxa) successfully split and lumped every tested pterosaur specimen, including over a dozen Pteranodon specimens (Fig. 2). It turns out UALVP 24283 (fig. 2, specimen ‘Z’) is not a sister to FHSM VP 339 (Fig. 2, specimen ‘Y’), but both have a common ancestor close to specimen ‘W’ USNM 12167 (Fig. 2, undescribed). Do not accept pterosaur topologies that test only genera and avoid the tiny Solnhofen pterosaurs. You won’t get the big picture and you won’t speak with authority. You’ll floundering in guesswork.

Figure 2. The Tanking-Davis specimen compared to other forms. Specimen w and specimen z appear to be the closest to the Tanking-David specimen. Specimen 'w' = Pteranodon sternbergi? USNM 12167 (undescribed). Specimen 'z' = Pteranodon longiceps? Dawndraco? UALVP 24238. Click to enlarge.

Figure 2.  Click to enlarge. Every reasonably complete Pteranodon skull to scale and in phylogenetic order.

In phylogenetic analysis a big crest
is a derived trait, and yet some small crests and small skulls are derived from big crest ancestors. Only analysis reveals this.

There are no gender differences here.
No two skulls (Fig. 2) are identical except for their crests. And every Pteranodon pelvis is different. The variety here is due to phylogeny, not gender or ontogeny.

Ontogeny is only demonstrated
by the smallest Pteranodon specimens (next to specimen ‘Q’).

Why so much variety in Pteranodon?
Well, there is so much variety in every putative genus in pterosaurs. Add to that, Pteranodon lived for several million years along the long Niobrara Sea that crossed North America from Canada to the Gulf of Mexico… and who knows wherever else. That provides many latitudes for this genus to inhabit and niches to evolve to.

Pterosaur workers,
stop being so lazy! Use specimens for taxa, not a single representative from each genus. That will solve so many taxon exclusion problems, as I can tell you from experience. When you do, let me know what you get. You can safely ignore all previously published topologies that exclude so many taxa. That they are all different teaches us that those all teach us nothing.

If you want my opinion:
Keep all Pteranodon specimens (shown above in Fig. 2) within the genus Pteranodon. Divide them into species. Each one should get it’s own species. Currently ‘Dawndraco‘ nests between several other specimens referred to Pteranodon. That’s how you know ‘Dawndraco‘ really is Pteranodon.

And while you’re at it:
Keep all Rhamphorhynchus specimens (Fig. 3) within the genus Rhamphorhynchus. Divide them into species. Do the same with all Pterodactylus, Dorygnathus, Scaphognathus, etc. genera. Employ more specimens/taxa. Exclude them at your scientific peril.

Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O'Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O’Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

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 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.
Kellner AWA 2010. Comments on the Pteranodontidae (Pterosauria, Pterodactyloidea)
with the description of two new species. Anais da Academia Brasileira de Ciências 82(4): 1063-1084.
Kellner A 2017.  Rebuttal of Martin-Silverstone et al. 2017, ‘Reassessment of Dawndraco kanzai Kellner 2010 and reassignment of the type specimen to Pteranodon sternbergi Harksen, 1966’Vertebrate Anatomy Morphology Palaeontology 3:81–89.
Maisano JA 2002a. The potential utility of postnatal skeletal developmental patterns in squamate phylogenetics. Journal of Vertebrate Paleontology 22:82A.
Maisano JA 2002b. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.
Martin-Silverstone E, Glaser JRN, Acorn JH, Mohr S and Currie PJ 2017. Reassesment of Dawndraco kanzai Kellner, 2010 and reassignment of the type specimen to Pteranodon sternbergi Harksen, 1966.  Vertebrate Anatomy Morphology Palaeontology 3:47-59.
Marsh OC 1876a. Notice of a new sub-order of Pterosauria. American Journal of Science, Series 3, 11:507-509.
Miller HW 1971. A skull of Pteranodon (Longicepia) longiceps Marsh associated with wing and body parts. Kansas Academy of Science, Transactions 74(10):20-33.

http://www.reptileevolution.com/pteranodon-skulls.htm

Parietal crests on lepidosaurs

Yesterday’s post on several iguanids, one of them crested, inspired this post on parietal crests found on lepidosaurs. I wondered how many other reptiles had vertical parietal crests? (This separates ceratopsians and other with horizontal expansions of the parietal.) And how many other lepidosaurs? And how many other squamates?

Figure 1. The parietal crest of various lepidosaurs are compared here. Upper left: Corytophanes. Upper right: Basiliscus. Lower: Nytosaurus (KJ@) and Pteranodon (Jenkins specimen).

Figure 1. The parietal crest of various lepidosaurs are compared here. Upper left: Corytophanes. Upper right: Basiliscus. Lower: Nytosaurus (KJ@) and Pteranodon (Jenkins specimen).

Among squamates
crests are few. Trioceros (Fig. 2) has a vertical parietal crest. Other squamates related to Basiliscus and Corytophanes have similar crests.

Several pterosaur lepidosaurs had vertical crests.
Many were independently created. Others further extended the smaller crests of more primitive ancestors. So far as the data will take us, crests are only phylogenetic in size and shape. We have evidence for maturity level in crest shape and size, after all, it would be very difficult to tuck a long or large parietal crest into an eggshell.

On a side matter,
what sort of elongated egg shape might contain the extremely elongated rostrum of Moganopterus (Fig. 2)?? I’m willing to suspect that this pterosaur, perhaps uniquely, elongated the rostrum during ontogeny. But then Pterodaustro did not do so, so who knows?

The pterosaur Hamipterus might give us a tentative clue as to gender identity in nasal crests, but it’s not a certainty at present.

Figure 2. Parietal crests on other lepidosaurs, including several often unrelated pterosaurs.

Figure 2. Parietal crests on other lepidosaurs, including several often unrelated pterosaurs. The crest of Cosesaurus is soft, unossified and no close relatives have an ossified crest. Not to scale. 

Parietal crests on archosauromorphs
are not impossible to find, but they are rare. You can find parietal crests on certain plesiosaurs, like Pistosaurus, Trinacromerum (Fig. 3) and Brachauchenius. They would have been hidden by jaw muscles in life.

Figure 3. The plesiosaur Trinacromerum has a parietal crest, but it was laterally packed with jaw muscles.

Figure 3. The plesiosaur Trinacromerum has a parietal crest, but it was laterally packed with jaw muscles.

Likewise
on certain ichthyosaurs like Shonisaurus, Cymbospondylus and PhalarodonContectopalatus (Fig. 4). As in the plesiosaurs (above) these crests served as anchors for powerful jaw muscles.

Figure 4. Phalarodon and Contectopalatus are ichthyosaurs with a parietal crest, likewise laterally hidden in vivo with large jaw muscles.

Figure 4. Phalarodon and Contectopalatus are ichthyosaurs with a parietal crest, likewise laterally hidden in vivo with large jaw muscles.

 

The crests on hadrosaurs and certain theropods, including cassowaries, are enlarged nasals. I never thought this would add even a mote of evidence to the pterosaurs are lepidosaurs argument, but it does add one little mote, just as the longest cervicals are found in tanystropheids and azhdarchids. Coincidence? Or a genetic wild card?

Figure 1. Macrochelys (Macroclemys) skull colorized. Most workers label the bone above the curled quadrate as a squamosal, but here it is considered a supratemporal, which has horns in basal turtles.

Figure 5. Macrochelys (Macroclemys) skull colorized. Most workers label the bone above the curled quadrate as a squamosal, but here it is considered a supratemporal, which has horns in basal turtles. This skull shows a minimum of occiput invagination.

Some turtles develop a crest
that is largely created by embayment of the occipital plate of the skull and the narrow portion is chiefly formed by the supra occipital (Fig. 5).

Parietal crest development
in lepidosaurs appears to be largely for species identification and/or secondary sexual selection. In pterosaurs, since they travel at airspeeds in which streamlining and aerodynamics play a large part, crest size and shape must follow those restrictions and head turning would tend to yaw the pterosaur, but not the basilisk.

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.

Adding the Denver Pteranodon: The origin of the long crest

Updated September 20 with reception of jpegs of the specimen.

Earlier we looked at the wide variety of Pteranodon crests (Fig. 1). Placed in a phylogenetic analysis the skulls show a gradual evolution from smaller crestless species close to Germanodactylus all the way up giant crested species with a wide variety of crest shapes, followed by a reduction in size preceding extinction (lower right corner of figure 1). Contra tradition, this analysis demonstrates no gender identify and no juvenile identity based on size and crest size — other than a Pteranodon juvenile, nicknamed Ptweety (pictured behind the Q specimen, YPM 2594, which it most closely resembles.

Previously not included on this chart was the Denver specimen, DMNH 1732 (Fig. 1), which sports a complete, but short crest of the long-crest variety, and is otherwise every bit as large as other giant Pteranodon species. Details on this rarely imaged skull have arrived.

 

Figure 2. The DMNH specimen is in color, nesting between the short crest KS specimen and the long crest AMNH specimen.

Figure 2. The DMNH specimen is in color, nesting between the short crest KS specimen and the long crest AMNH specimen.

This chart shows the gradual evolution regardless of gender.
The Denver specimen might be a short-crested female, but remember, you can’t evolve a long or tall crest without first going through a small or short crest phase. That’s why we’ll have to wait for other clues* before we start assigning gender and age to various specimens of Pteranodon. The skulls all fit into a very neat completely resolved phylogenetic series here, with no two pairing off as male and female… yet.

*As we learned earlier, Bennett’s 1992 purported female Pteranodon pelvis,  KUVP 993, is morphologically just a big Nyctosaurus.

References
Bennett SC 1992. Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.

Obvious sexual dimorphism in pterosaurs?

. From Tetrapod Zoology with this caption, "Cover of TREE featuring Knell et al. (2012). Image (featuring male and female Pteranodon with obvious sexual dimorphism) by Mark Witton." While this might be true, rigorous phylogenetic testing says otherwise. These are distinct species.

Figure 1. From Tetrapod Zoology with this caption, “Cover of TREE featuring Knell et al. (2012). Image (featuring male and female Pteranodon with obvious sexual dimorphism) by Mark Witton.” Naish’s statement has been shown to be false. Attention to detail and rigorous phylogenetic testing provides other results (Fig. 2) in which these two inaccurately portrayed Pteranodon specimens actually represent distinct species. In general, smaller skulls with smaller crests are phylogenetically closer to the ancestral germanodactylids with smaller skulls and smaller crests. Not only does that make sense, it can be demonstrated phylogenetically (Fig. 2). See the juvenile? Cute, but inaccurate. (see below).

An April post at Darren Naish’s Tetrapod Zoology was headlined, “Dinosaurs and their ‘exaggerated structures’: species recognition aids, or sexual display devices?” (refs below).

Naish wrote, “Our latest paper is devoted to a discussion of the species recognition hypothesis and, specifically, why we think it’s problematic and should be discarded. We’ve noted that dinosaur workers have increasingly taken to mentioning species recognition whenever they discuss exaggerated structures (see list of citations in Hone & Naish 2013), so now is a good time to try and set the record straight.”

Pteranodon skulls

Figure 2. Click to enlarge. A family tree of Pteranodon and Nyctosaurus derived from Germanodactylus. Note the size increase is gradual. So is the crest size increase. Of all these many specimens, can you tell which are male and which are female? I can’t. There are no two skulls, sans crests, that are identical in morphology. You can’t divide this set of illustrations into two genders, and yet, according to Naish you should be able to. Attention to detail indicates there’s also much more to skull morphology than crest shape.

Is it possible to ascertain that small crested specimens are females?
Or are small crested specimens just in the lineage of large crested specimens? Contra Naish, species recognition helps us identify various dinosaurs with all their crests, horns and feathers. The same is true of pterosaurs and you can test this with phylogenetic analysis (Fig. 2). If this was gender identification in Pteranodon, there should be just two forms relatively close to one another for each of the above skulls. But no two here are even that much alike. Instead they form a series of gradually evolving shapes, which defines them as distinct individuals and species. Interestingly, there is a derived size decrease in specimens R, S, T and Z4.

Juvenile Pteranodon
The image in figure 1 also shows a juvenile Pteranodon with an appropriately short crest and short beak. Well, we have a juvenile Pteranodon (Fig. 2) and it doesn’t have any indication of a short beak, but retains the proportions of an adult, and a specific adult at that, YPM 2594, which is likewise known from a posterior skull without a complete rostrum.

Pteranodon is the Cretaceous equivalent of Darwin’s finches.
Rapid diversification in Pteranodon originated as individual variation that was enhanced over the generations by natural selection. Pteranodon was not just one or two species, but dozens, as is plainly evident when you look at dozens all once (Fig. 2). That’s the value of accurate reconstruction, something most pterosaur workers avoid like the flu.

Getting back to sexual dimorphism
Naish wrote, “And we absolutely reject Padian & Horner’s (2013) argument that sexual dimorphism is essential for the recognition of sexual selection: there’s unambiguous evidence from the living world that sexual selection is at play even when dimorphism is absent (Hone et al. 2012, Knell et al. 2012, 2013).”

To Naish’s point, there is always sexual dimorphism, whether presented in skeletal differences, beards, breasts, genitals, feathers or pheromones. Sometimes it’s more obvious. Sometimes less. In pterosaurs no one has ever been able to document male vs female differences in the skeleton, even when there’s an egg between the legs of an obvious female, a subject we looked at earlier. Males, as best as we can ascertain were outwardly identical. Crests appeared on various darwinopterids during speciation, as we looked at earlier. Some have even been named new genera by various workers.

Unfortunately, at least in pterosaurs,
there’s no evidence for gender identification that can stand up under the scrutiny of phylogenetic analysis. We don’t see only two kinds of Pterodactylus. We see several (with not one tested specimen identical to another). We don’t see only two kinds of Rhamphorhynchus. We see dozens. Lack of reconstructions and lack phylogenetic analysis leads paleontologists like Darren Naish into supposition and assumption. What’s “obvious” to him is only obvious because he hasn’t tested it to see if it is indeed true. Testing, not supposition, is what makes good Science.

And by the way,
Naish and those who are in his camp are among those who think (without testing) that tiny pterosaurs are juveniles of larger taxa. Bennett (2006) made this supposition, but his study did not stand up to phylogenetic analysis.  Tiny Solnhofen pterosaurs of all sizes and shapes nest at the bases of several major clades and are the transitional taxa from one clade to another as each phylogenetic series gradually decreases then increases in size.

Darren Naish and Modular Evolution
Naish wrote,  “So it’s almost as if the head and neck were evolving at different rates from the rest of the body: in other words, Darwinopterus looks like a classic case of ‘mosaic evolution’ or modularity (hence the species name). This much-discussed evolutionary phenomenon has been considered controversial, in part due to a lack of good examples: Darwinopterus looks like one of the best yet discovered, and this isn’t lost on Lü et al. (2009).”

A lack of good examples indeed! This hypothesis applies only to Darwinopterus in order to cover up a lack of good phylogenetic analysis, which you can see here.

Of course, there’s no such thing as “modular evolution,” made famous during the Darwinopterus bungle, but Naish embraced this fairy tale without criticism. If true we’d see it on other taxa and in other clades, but we don’t It was invented for Darwinopterus. If modular evolution were true we’d have less confidence in our reconstructions of partial skeletons because heads would be evolving leaving the legs far behind, as imagined for Darwinopterus. In reality the palate evolves along with the toes and everything else. In reality Darwinopterus is a dead end taxa leaving no known descendants, but it did convergently evolve a large skull and smaller naris. Phylogenetic analysis settles that issue.

That being said…
There’s much more in Naish’s blog that is good Science and worth considering. If interested, follow this link. He’s just got an Achilles heel when it comes to pterosaurs.

So, there’s more to Pteranodon that just size and crests.
We know of a variety of post-crania as well, some robust and some gracile with various humerus shapes (Fig. 3). Only a few Pteranodon specimens are known from associated skulls and post-crania. So, which post-crania go with which crania? We can only guesstimate now and earlier some effort was made toward this goal. Small ones might have been young or might have been primitive (more likely the latter, since juveniles, like Ptweety or so rare and the small ones are not virtually identical to any large ones (isometric growth).

Post-crania Pteranodon

Figure 3. Click to enlarge. Various Pteranodon specimens known from post-crania. Note the yellow box includes one of the largest specimens, but it has an unfused extensor tendon process, which may mean it is a very large Nyctosaurus with fingers.

If Naish is right
and there is “obvious” sexual dimorphisim in Pteranodon, let him (or someone!) present three or four pairs of males and females, then subject them to phylogenetic analysis. The gender pairs should match with their mates if true.

And finally, we need to talk about the “female” pelvis in Pteranodon.
It’s morphologically closer to Nyctosaurus as reported here. And, yes, it’s a big pelvis, but we have further evidence of Pteranodon-sized Nyctosaurus, because the former fused the extensor tendon process and the latter did not, as reported here , and we know of a very larger unfused extensor tendon process on what others have identified as a Pteranodon based on its size.

No matter what crap they throw*,
I’m not going to let Naish and Witton disfigure and fantasize pterosaurs when good solid evidence is available to counter their traditional and mistaken hypotheses. Credit will also be given when appropriate.

* By “crap,” I mean blackwashing statements that contain no pertinent specifics or evidence. You’ll know them when you see them.

References
Bennett SC 2006. Juvenile specimens of the pterosaur Germanodactylus cristatus, with a review of the genus. Journal of Vertebrate Paleontology 26:872–878.SMNS
Bennett SC 1992. Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.
Knell R, Naish D, Tompkins JL and Hone DW E 2012. Sexual selection in prehistoric animals: detection and implications. Trends in Ecology and Evolution28, 38-47.
Naish D and Cuthill IC 2012. Does mutual sexual selection explain the evolution of head crests in pterosaurs and dinosaurs? Lethaia 45, 139-156.
Naish D, Tomkins JL and Hone DWE 2013. Is sexual selection defined by dimorphism alone? A reply to Padian and Horner. Trends in Ecology and Evolution. http://dx.doi.org/10.1016/j.tree.2013.02.007