Growth pattern of a new large Romualdo pterosaur

Bantim et al. 2020 document
a new “pteranodontoid pterosaur with anhanguerid affinities (MPSC R 1935) from the Romualdo Formation (Lower Cretaceous, Aptian-Albian), is described here and provides one of the few cases where the ontogenetic stage is established by comparison of skeletal fusion and detailed osteohistological analyses.”

Figure 1. Excellent wing finger carpophalangeal joint from the Bantim et al. 2020 paper. Note the unfused sesamoid (extensor tendon process), a phylogenetic trait of lepidosaurs, not an ontogenetic trait of archosaurs, as phylogenetic analysis documents.

Continuing from the abstract
“The specimen … consists of a left forelimb, comprising an incomplete humerus, metacarpal IV, pteroid and digits I, II, III, IV, including unguals. This specimen has an estimated maximized wingspan of 7.6 meters, and despite its large dimensions, is considered as an ontogenetically immature individual. Where observable, all bone elements are unfused, such as the extensor tendon process of the first phalanx and the carpal series. The absence of some microstructures such as bone resorption cavities, endosteal lamellae, an external fundamental system (EFS), and growth marks support this interpretation. Potentially, this individual could have reached a gigantic wingspan, contributing to the hypothesis that such large flying reptiles might have been abundant during Aptian-Albian of what is now the northeastern portion of Brazil.”

Figure 2. Anhanguera.

By comparison,
coeval Anhanguera has a 4.6m (15 ft) wingspan. The largest complete ornithocheirid, SMNK PAL 1136 has a 6.6m wingspan.

Bone elements fuse and lack fusion
in phylogenetic patterns (rather than ontogenetic patterns) in the clade Pterosauria, as documented earlier here in 2012. That is why you can’t keep pretending pterosaurs are archosaurs and not expect problems like this to accumulate. Your professors are taking your time and money and giving you invalidated information.

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

It is a continuing black mark on the paleo community
that pterosaurs continue to be considered archosaurs by paid professionals when phylogenetic analysis (and Peters 2007 and the LRT) nests pterosaurs with lepidosaurs. That is why pterosaurs have lepidosaur phylogenetic fusion patterns (Maison 2002, 2002) distinct from archosaur ontogenetic fusion patterns. Just add taxa colleagues. The pterosaur puzzle piece does not fit into the archosaur slot… everyone admits that. The pterosaur puzzle piece continues to fit perfectly and wonderfully in the fenestrasaur tritosaur lepidosaur slot.

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References
Bantim RAM et al. (5 co-authors) 2020. Osteohistology and growth pattern of a large pterosaur from the lower Cretaceous Romualdo formation of the Araripe basin, northeastern Brazil. Science Direct https://doi.org/10.1016/j.cretres.2020.104667
Maisano JA 2002. The potential utility of postnatal skeletal developmental patterns in squamate phylogenetics. Journal of Vertebrate Paleontology 22:82A.
Maisano JA 2002.Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

https://pterosaurheresies.wordpress.com/2013/05/14/phylogenetic-fusion-patterns-in-pterosaurs/

Hone et al. 2020 vs. Rhamphorhynchus

Long one today.
Summary, for those in a hurry:
Hone et al. 2020 bring us their views
on Rhamphorhynchus ontogeny (= growth from hatchling to adult). Unfortunately, this study is based on several invalid assumptions. Lacking a phylogenetic context, Hone et al. made the mistake of comparing small adults to large adults. No juveniles were tested. Subsequent ontogeny comparisons to birds and bats were thus rendered moot.

Figure 2. Rhamphorhynchus specimens to scale based on results from the LPT. No two are alike — except the juvenile Vienna specimen and the adult n81.

Before we get started, you might remember:

1. A competing paper has been online for 2 years: ‘First Rhamphorhynchus juvenile recovered by phylogenetic analysis’ in which only one juvenile/adult pairing was found among all 31 specimens shown in figure 1. Among the rest, no two are alike. The small ones in the top row are not juveniles, but phylogenetically miniaturized adult basal Rhamphorhynchus species. (Perhaps someday, someone will re-name them all appropriately.)
2. All pterosaurs (so far tested) develop isometrically (with the exception of tapejarid crests) because that’s what lepidosaurs do.
3. Hatchling pterosaurs are typically 1/8 as tall as adults.
4. Only hatchlings of a certain minimum size can fly. Hatchlings below this hypothetical size risk desiccation due to a high surface-to-volume ratio. That’s when quadrupedal locomotion enters pterosaur clades. Extradermal soft tissue that limits desiccation first appears on tiny, flapping pre-pterosaurs like Cosesaurus.
5. New pterosaur clades often begin with a series of phylogenetically miniaturized transitional taxa (as in Fig. 1). This only appears in phylogenetic analyses when small and large taxa are analyzed together. That has not happened yet in published analyses because other workers make the same mistake as they consider small adult taxa to be mismatched juveniles (thereby destroying the Hone et al. isometry hypothesis).

The Hone et al. 2020 paper was announced today on
Dr. Hone’s email list. After a short comparison to Pteranodon, Hone continues:
“However, if we turn to Rhamphorhynchus we have only a fraction of the number of specimens but pretty much all the other issues are absent. They also cover a near order of magnitude in size with everything for animals of c 30 cm wingspan up to nearly 2 metres and include everything from putative hatchling-sized animals to a couple of genuine outliers that are much bigger than other known individuals.”

A good sample of Rhamphorhynchus taxa are shown above (Fig. 1) in phylogenetic order. Note this genus has its genesis as a phylogenetically miniaturized series following Campylognatoides in the large pterosaur tree (LPT, 250 taxa). The sole juvenile shown above is the Vienna specimen, nesting with one of the ‘genuine outliers that are much bigger.’ This adult and juvenile pairing nest together with virtually identical scores, despite the great difference in size.The LPT was able to lump and split all tested Rhamphorhynchus taxa. So it can be done. Hone et al. omitted this all important step and ruined their paper.

Hone continues:
“The numbers of course are not tiny, well over 100 good specimens, and that alone would make them an exceptional sample of most terrestrial Mesozoic archosaurs.”

Our first red flag! Hone et al. do not realize that when taxa are added, pterosaurs move over to lepidosaurs. On another note: relative to ‘100 good specimens’, 31 are shown above (Fig. 1).

Hone explains
that Wellnhofer (1975) featured 108 specimens. Hone’s group looked at 129, but, as Hone confesses, “The ‘real’ total is actually a little lower.” Oddly, in the text of the paper, Hone et al. report testing 135 specimens of R. muensteri.

Hone continues:
“This post inevitably marks the publication of an analysis of growth in Rhamphorhyunchus. In a lot of ways, this mirrors Chris Bennett’s fantastic 1995 paper on this genus where he convincingly demonstrated that all specimens belonged to a single species and not multiple ones as previously thought, and part of his arguments for doing this looked at the relationships between various elements based on Wellhofer’s dataset.”

Our second red flag! Bennett’s 1995 paper likewise did not include a phylogenetic analysis. When several specimens of Pteranodon were added to the LPT, no two nested together as conspecific taxa (Fig. 2). Small specimens were closer to the genesis of Pteranodon following Germanodactylus. Large specimens split into several clades.

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.

Hone is delighted to announce
“Chris’ point [in Bennett 1993, 1995] was that while there were some discreet clusters of specimens (which he attributed to year classes) most of the alleged differences between the putative species vanished when you put them on a graph and the rest were classic ontogenetic traits like the fusion of the pelvis in large individuals of big eyes in small ones. So while he didn’t really deal with growth as such, he was already showing similar patterns to what I and my coauthors confirm now – Rhamphorhynchus was weirdly isometric in growth.”

Our third red flag! Dr. Hone does not appear to realize that ALL pterosaurs  develop isometrically during ontogeny. They do this because pterosaurs are lepidosaurs. By contrast, archosaurs develop allometrically. I’m also going to throw in the objection that a graph or two (as in Bennett 1993, 1995, Hone et al. 2020] is no substitute for a thorough phylogenetic analysis.

Hone continues:
“In other words, in the case of the vast majority of their anatomy, young animals are basically just scaled down adults.”

This is an odd statement to make considering the fact that Hone et al. are looking at phylogenetically miniaturized adults (Fig. 1) and regarding them as juveniles. That Hone considers the little specimens, “basically carbon copies of the adults” makes one question the precision of their observations. They did cherry-pick two similar taxa (Figs. 3, 4), avoiding the wider variation of other specimens. A competing online analysis (subset Fig. 5) was able to split and lump all Rhamphorhynchus specimens.

For comparison, Hone et al. also looked at ontogeny in bats,
noting hand/wing development accelerated close to sexual maturity (= shortly after weaning). He notes, “This is the pattern we would expect.”

Our fourth red flag! Since Hone et al. have blinded themselves to the possibility that pterosaurs are lepidosaurs (Peters 2007) they don’t look at lepidosaurs for comparison. Here’s why they should: pterosaurs hatch with adult proportions from leathery eggs held within the mother’s body longer than in any archosaur.

Hone continues:
“Birds are functionally poor analogues of pterosaurs but are much closer phylogenetically and are the only other powered flying tetrapod so we also looked at some existing datasets for them too.”

More traditional myth perpetuating here. I find this all so disheartening. Colleagues, just add taxa. If I can do it as an outsider, you can do it as a PhD. Do not be afraid to do the work of constructing a cladogram.

Hone continues:
“If you grow isometrically you wings will get longer and wider but your weight will increase much faster since you as a whole will get longer and wider and deeper. Birds increase penumaticity as they grow and there’s evidence this is the case in other pneumatic clades too and if so for pterosaurs, then the mass increase in adults would also be offset somewhat by a proportionally lower mass in adults for a given volume than juveniles.”

Very good point. But I’m ot sure of any pneumaticity studies comparing hatchling and adult pterosaurs.

Hone continues:
“Precociousness has been suggested in pterosaurs before based on the evidence for them flying while young, but it has also been challenged. It suggested that to be flying at that size would require a huge amount of effort and this would leave little energy for growth.”

Wait a minute! Didn’t he just say the weight would increase by the cube in adults? That means juveniles were that much lighter.

Hone continues:
“That’s largely true, but overlooks that there could be post hatching parental parental care. That is normal for archosaurs (including dinosaurs) and we would expect it for pterosaurs.”

If only pterosaurs were archosaurs, but at this point they still nest with lepidosaurs. Most lepidosaurs fend for themselves after hatching, and if pterosaur hatchlings could fly, then they would be able to fly off on their own shortly after hatching. Best not to ‘expect’ anything without a valid phylogenetic context, evidently lacking in Hone et al. 2020.

Hone continues:
“So in short, Rhamphorhynchus is perhaps the best pterosaur for large studies about populations and growth and this genius at least grew isometrically, and this may or may not be the same for other pterosaurs.”

But for the present, every pterosaur known from embryo, juvenile and adult shows strict isometric growth (except for tapejarid crests).

“But it does imply that young pterosaur could fly, and fly well.”

Sadly, Hone et al. seem to be looking at small adults (Fig. 1) and calling them ‘young’. Of course these adult pterosaurs can fly well!

Apparently Hone et al. are comparing linear measurements and graphing them. That method produced false positives for Bennett 1995. There is no substitute for phylogenetic analysis.

In this topsy-turvy world of pterosaurs,
myths are popularized by PhDs while comprehensive phylogenetic analyses compiled by amateurs are ignored and suppressed. Not sure why this problem is not more widely recognized. For other missteps made by Dr. Hone with regard to pterosaurs, click here or use the keyword ‘Hone’ for that long list.

Moments ago the paper itself arrived.
In my morning email was a message from Dr. Hone: “Attached” along with a PDF of their Rhamphorhynchus paper. Two sets of graphs are present, but only a single figure combining bat allometry and Rhamphorhynchus isometry (isolated in Fig. 3).

Figure 3. Image from the only non-graph figure in Hone et al. 2020. Identification and permission note from that caption. Compare these taxa to those in figures 1 and 4.

Figure 4. Lateral view of Hone et al. 2020 Rhamphorhynchus taxa taken from ReptileEvolution.com (Fig. 1). Hone et al. cherry-picked these two somewhat similar by convergence taxa assuming the smaller one was a juvenile of the other other. Phylogenetic analysis separates these two (see Fig. 1). Note the differences in pedal element proportions.

From the paper:
“We test whether pterosaurs show a similar pattern of rapid forelimb growth during post‐hatching/ontogeny to that of bats and birds, and thus infer when in ontogeny R. muensteri would have become volant.”

Sounds laudable. Let’s see how they do it.

From the paper:
“All Rhamphorhynchus specimens from Bavaria are now considered a single species (Bennett 1995).”

No. That’s why figure 1 was created and a phylogenetic analysis of pterosaurs was run (subset Fig. 5), to see how specimens could be lumped and separated. Like Hone et al., Bennett likewise eschewed the use of phylogenetic analysis. Sadly, Hone et al. adopted without further consideration Bennett’s invalid assumption, rather than testing Rhamphorhynchus with a phylogenetic analysis.

Figure 5. Subset of the LRT focusing on Rhamphorhynchus.

From the paper:
“Four lines of evidence suggest that the smallest R. muensteri specimens were very young animals and potentially hatchlings.

1. Histology reveals incomplete ossification of long bones in the smallest specimens tested (Prondvai et al. 2012),
2. A disproportionate number of known specimens are small, consistent with high juvenile mortality (Bennett 1995; Hone & Henderson 2014)
3. Late‐stage embryos of pterosaurs had well‐developed, ossified wings (Wang & Zhou 2004; Codorniú et al. 2018)
4. and finally while few fossilized pterosaur embryos are known, the ratio by which adults are larger than embryos (Lü et al. 2011; Wang et al. 2017) is similar to the size ratio between the largest R. muensteri specimens and the smallest.”

Incomplete ossification: the smallest specimen studied by Prondvai et al. (2012) was BSPG 1960 I 470a = n9 (Figs. 1, 5) is also the second most primitive tested specimen (next to n28) in a phylogenetic miniaturization series that began with Campylognathoides. Among the neotonous / juvenile traits retained was incomplete ossification of the long bones. Lacking a phylogenetic context, neither Prondvai et al. nor Hone et al. were aware of the miniaturized adult status of n9.

Figure 5. the B St 1960 I 470a specimen of Rhamphorhynchus (at right)  is the second most primitive and one of the smallest phylogenetically miniaturized specimens attributed to Rhamphorhynchus. One of the neotonous traits was incomplete ossification. Hatchlings were 1/8x the size of adults, similar to house flies in size.

Disproportionate number of specimens are small: lacking a phylogenetic context, Hone et al. were not aware of the phylogenetic miniaturization that preceded the evolution of larger Rhamphorhynchus specimens. In the LPT only one Rhamphorhynchus specimen is a valid juvenile nesting with larger adults.

Late‐stage embryos of other pterosaurs had well‐developed, ossified wings: So did miniaturized adults.

Size ratio of largest R. muensteri specimens to smallest similar to embryo vs adult sizes in other pterosaurs: lacking a phylogenetic context, Hone et al. were not aware of the phylogenetic miniaturization that preceded the evolution of larger Rhamphorhynchus specimens. Hone et al. made the mistake of labeling small adults as juveniles. Notably, Hone et al. did not try to match their purported juveniles with adults phylogenetically. Other tiny Rhamphorhynchus specimens have juvenilized proportions (smaller rostrum, larger orbit), but these were ignored by Hone et al., who cherry-picked two comparative taxa out of 135.

From the paper:
“We tested for isometric versus allometric growth across 135 specimens of R. muensteri using bone length and composite measures (e.g. total wing length and total leg length) relative to: (1) total body length, from rostrum tip to the end of the tail; (2) skull length; and (3) humerus length.”

Lacking a phylogenetic context (available online for several years), Hone et al. made the mistake of comparing adults to adults. No juveniles were tested. Subsequent comparisons to birds and bats were thus rendered moot.

From the paper:
“Our results suggest that even the smallest Rhamphorhynchus had adult skeletal proportions and thus wings sufficient for flight.” This confirms the conclusions of Peters (2018) using a phylogenetically validated juvenile Rhamphorhynchus, rather than a dataset full of large and small adults.

From the paper:
“Wang et al. (2017) noted that in embryos of the pterodactyloid Hamipterus, although there was greater ossification of the limbs and vertebrae than the head, including of the shafts of longbones, there was limited ossification of some other parts of the skeleton that may have related to flight. They hypothesize in this case that hatchlings may have been able to walk before they could fly, though still imply relatively early flight for these animals.”

These were not hatchlings, but embryos still developing within the egg, within the mother in the tradition of lepidosaurs.  Eruptive gases killed flocks en masse. Details here.

From the paper:
“Pterosaurs, like almost all other archosaurs, probably provided parental care (Witton 2013), and precocial flight need not preclude this possibility.” 

This is myth. We’ve known since Peters 2007 that adding taxa moves pterosaurs to nest within Lepidosauria.

From the paper:
“Thus, while Rhamphorhynchus apparently flew at a young age, such volant offspring may have plausibly received parental care, including provisioned food, as they became independent foragers.” 

There is no evidence for this bit of speculation. But it cannot be ruled out. According to Gans 1996, “Many aspects of reptilian reproductive patterns prove to be vagile among the vertebrates. Reversals complicate, and may even invalidate, the characterization of broad trends. Furthermore, the 7000 species of reptiles show dozens of modes that seem to enhance the fitness of their offspring, thereby providing a vast opportunity of testing the reality of these adaptations.”  (‘vagile’ = able or tending to move from place to place or disperse)

In summary:
Hone et al. assumed that phylogenetically miniaturized adults at the genesis of Rhamphorhynchus were juveniles. While testing small adults against large adults (Figs. 1–5) the authors determined that Rhamphorhynchus ontogeny proceeded isometrically.

Ironically this confirms earlier findings by Peters (2018 and elsewhere in this blog) using the only known phylogenetically validated juvenile and a matching adult Rhamphorhynchus. As longtime readers know, all other pterosaurs develop isometrically because they are lepidosaurs arising from taxa close to late-surviving Huehuecuetzpalli, known from matching juvenile and adult specimens.

Dr. Hone needs to show more leadership. He needs to create reconstructions of the specimens under study so visual comparisons can be made by his team and readers. Roadkill specimens are too difficult to compare otherwise. He also needs to run a phylogenetic analysis to determine interrelationships between pterosaur taxa and within all amniotes to see where pterosaurs nest. At present he’s perpetuating old myths and traditions that were invalidated twenty years. He’s that far behind the times.

I’ll never forget the day several decades ago
when Dr. Kevin Padian and Dr. Chris Bennett told me, “nothing can be known about a taxon until it is put into a phylogenetic context.” I took that advice to heart. That is why the LRT and LPT now include more than 2000 taxa.

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References
Bennett SC 1993. The ontogeny of Pteranodon and other pterosaurs. Paleobiolgy 19(1):92-106.
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.
Gans C 1996. An overview of parental care among the Reptilia. Advances in the Study of Behaviour 25:145–157.
Hone DWE, Ratcliffe JM, Riskin DK, Hemanson JW and Reisz RR 2020. Unique near isometric ontogeny in the pterosaur Rhamphorhynchus suggests hatchlings could fly. Lethaia. Paywall access here.
Hone 2020. Email post. How to grow your dragon – pterosaur onotgeny [sp]
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Peters D 2018. First juvenile Rhamphorhynchus recovered by phylogenetic analysis. PDF here.
Prondvai E, Stein K, Ösi A, Sander MP 2012. Life History of Rhamphorhynchus Inferred from Bone Histology and the Diversity of Pterosaurian Growth Strategies. PlosOne. online pdf
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.

wiki/Rhamphorhynchus

https://pterosaurheresies.wordpress.com/2012/03/23/not-another-rhamphorhynchus-growth-series-without-a-phylogenetic-analysis/

 

Fresh data on little Ningchengopterus (not a baby pterosaur)

Yesterday we looked at a new paper on an old topic,
the ability of ‘large enough’ pterosaur hatchlings to fly shortly after hatching (Unwin and Deeming 2019). I say, ‘large enough’ because some fly-sized hatchlings of hummingbird-sized adults were not large enough to avoid desiccation due to their high surface/volume ratio. This was likely the origin of quadrupedal locomotion from bipedal pterosaur ancestors. Such tiny hatchlings had to remain within high humidity leaf litter environs until reaching that minimum size for flight. And they probably drank a lot of water.

On the publicity tour for Unwin and Deeming 2019,
the NYTimes.com published an article that contained a rather high-resolution picture of a small Late Jurassic pterosaur, Ningchengopterus (Figs. 1-3; Lü 2009) that is several magnitudes better than the originally published line drawing.

Figure 1. ?Ningchengopterus in situ. Note the narrow-at-the-elbow wing membrane and manual digit 5 near the wrist. There is no wing membrane connection to the lower leg or ankle, only a ‘fuselage fillet’ inside the elbow.

Ningchengopterus? liuae (Lü J 2009) CYGB-0035 was originally considered a “baby”, even though it had an adult crest. Here, in the large pterosaur tree (LPT, 238 taxa) Ningchengopterus was derived from a sister to the larger Painten pterosaur and it phylogenetically preceded Pterodactylus antiquus? AMNH 1942 (No. 20 in Wellnhofer (1970). Here it appears that Ningchengopterus was actually a basal Pterodactylus and therefore congeneric.

Despite the additional data and several scoring changes,
the nesting of Ningchengopterus in the LPT did not change. So crappy data sometimes work. Crappy character lists sometimes work. Taxon exclusion never works. Let’s treat every pterosaur specimen as a taxon, like the LPT does, and see which taxa are associated with many times larger adults… and which nest with other tiny pterosaurs under phylogenetic miniaturization.

Figure 2. Ningchenopterus reconstructed using DGS methods. Sure it’s small, but not much smaller than sister taxa after phylogenetic analysis.

Ningchengopterus preserves a complete proximal wing membrane
(Fig. 1) that confirms the findings of Peters 2002, in which evidence for a narrow chord pterosaur wing membrane that was stretched between the elbow and wing tip was presented for all pterosaurs in which the soft tissue is preserved, distinct from traditional bat-wing models proposed without evidence by several PhDs.

Figure 3. Finger 5 in Ningchengopterus is very clear, but overlooked by all other pterosaur workers.

Manual digit 5 on pterosaurs is a vestige
(Fig. 3) that has been overlooked by all prior pterosaur workers. Ningchengopterus preserves manual digit 5 without question.

Figure 4. The Painten pterosaur phylogenetically nests between two smaller specimens in the LPT. This is an earlier reconstruction of Ningchengopterus.

We’ve already established
(contra tradition enforced by several pterosaur professors) that pterosaur hatchlings were nearly identical to their 8x larger adults. So how do we determine if a pterosaur is a hatchling or an adult? The answer is phylogenetic analysis. A small adult pterosaur will nest with other small adult pterosaurs. A juvenile will nest with much larger adult pterosaurs, as demonstrated here with the first juvenile Rhamphorhynchus recovered by phylogenetic analysis, a paper the pterosaur referees did not want you to read, but you can read it here at ResearchGate.net for yourself.

Figure 5. Large anurognathids and their typical-sized sisters. Here the IVPP embryo enlarged to adult size is larger than D. weintraubi and both are much larger than more typical basal anurognathids, Mesadactylus and MCSNB 8950.

There is (so far) only one exception to the above rule:
The IVPP anurognathid embryo (Fig. 5) is the same size as several adult sister taxa, like MCSNB 8950 and Mesadactylus. So undiscovered adults will be giant basal anurognathids when found. One incomplete and mislabeled sister taxon, ?Dimorphodon weintraubi, is closer in size to the hypothetical adult of the IVPP embryo, demonstrating the possibility of a giant anurognathid is real. Again, phylogenetic analysis works out all such problems.

Figure 6. The Vienna Pterodactylus. Click to animate. Wing membranes in situ (when folded) then animated to extend them. There is no shrinkage here or in ANY pterosaur wing membrane. There is only an “explanation” to avoid dealing with the hard evidence here and elsewhere.

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References
Lü J 2009. A baby pterodactyloid pterosaur from the Yixian Formation of Ningcheng, Inner Mongolia, China. Acta Geologica Sinica 83 (1): 1–8.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Unwin DM and Deeming DC 2019. Prenatal development in pterosaurs and its implications for their postnatal locomotory ability. Proceedings of the Royal Society B https://doi.org/10.1098/rspb.2019.0409

wiki/Ningchengopterus

Prenatal development in pterosaurs

Unwin and Deeming 2019 report,
yet again, the hypothesis of pterosaur hatchling flight. They add this time, “the application of four contrasting quantitative approaches allows a more precise identification of the developmental status of embryos revealing, for the first time to our knowledge, the presence of middle and late developmental stages as well as individuals that were at term.”

Earlier
here, here and here middle, late and term developments were published online.

The authors add this time,
“We also identify a predicted relationship between egg size and shape and the developmental stage of embryos contained within. Small elongate eggs contain embryos at an earlier stage of development than larger rounder eggs which contain more fully developed embryos.”

Earlier
here, here and here, egg shape was matched to pterosaur rostrum length with the ctenochasmatid embryo, Pterodaustro (Figs. 3, 4) having the longer egg and the IVPP V13758 anurognathid (Figs. 1, 2) embryo having the rounder egg. It is also worthwhile to consider the alternate hypothesis presented earlier here for the varied sizes and shapes for Hamipterus eggs in a lepidosaur context (see below).

The authors add this time,
“Early ossification of the vertebral column, limb girdles and principal limb bones involved some heterochronic shifts in appearance times, most notably of manus digit IV, and facilitated full development of the flight apparatus prior to hatching.”

This has been known
since the first appearance of the IVPP anurognathid embryo (Figs. 1, 2) in 2004 and reported nearly immediately thereafter by Unwin and Deeming. That’s really stretching out a single idea over more than a decade.

Figure 1. Click to enlarge. A magnitude of more detail was gleaned from this fossil (the IVPP egg/embryo) using the DGS method.

Over the last two decades, workers must have vowed
not to touch any lepidosaur/fenestrasaur hypotheses for fear of confirming an amateur’s findings. Nor have they added tiny pterosaurs to phylogenetic analyses.

Figure 2. The IVPP embryo anurognathid (lower right) compared to other basal pterosaurs, including an adult IVPP embryo, 8x larger.

Unwin and Deeming follow the invalidated hypothesis
that pterosaurs were archosaurs that laid and buried their eggs at an early stage of development, much as birds and crocs do. Not only do workers openly admit they lack pterosaur precursors within Archosauria, birds and crocs follow an allometric growth trajectory after hatching with a short snout and large eyes.

Figure x. Added a few hours after publication. Figure from Unwin and Deeming 2019. Apparently these authors saw fewer details in these pterosaur eggs than were present. Compare to figures 1 and 3. No reconstructions were attempted by Unwin and Deeming, so they didn’t realize the embryos had adult proportions (Fig. 2) or could be scored in a phylogenetic analysis. So much potential. So little study.

On the other hand,
pterosaurs, like other lepidosaurs, follow an isometric growth series (Figs. 4, 5). as documented most clearly by Zhejiangopterus online here and Pterodaustro here, but also in a large Rhamphorhynchus juvenile here (‘the Vienna specimen’ and see citation below).

Figure 3. Original interpretations (2 frames black/white) vs. new interpretation using DGS (color). Note: the premaxilla is in the lower right corner. The back of the skull is in the upper right corner. And see figure 4 for a growth series.

In the SuppData, the authors report,
“While most recent studies have concluded that pterosaurs belong within Ornithodira [S3, S4] some analyses have located them outside this clade, although still within Archosauromorpha [S5, S6]. Here, we accept the majority view, that pterosaurs are ornithodirans, with an extant phylogenetic bracket consisting of crocodiles and birds.”

You might think they cited Peters 2000
as their ‘minority view.’ If so, you would be wrong. No citation to Peters 2000 was mentioned. S5 is Bennett 1996 where he nested pterosaurs tentatively with Scleromochlus. That was invalidated by Peters 2000 who simply added several taxa to Bennett’s published matrix of taxa and characters, and those of three other workers. S6 is Bennett 2012/13, where Bennett also ignores taxa proposed by Peters 2000, 2007.

If you’ll recall,
Bennett 2012/2013 reports that pterosaurs nested between the lumbering and aquatic archosauriforms Proterosuchus and Erythrosuchus. That moves the nesting away from Scleromochlus, proterochampsids and parasuchians, the previous archosaur ‘favorite candidates for most pterosaur workers. I shudder when I peek into their minds.

Thus Bennett’s curse,
“You will not be published, and if you are published, you will not be cited,” comes true once again. And now you know, once again, why I chose online publishing after seven or so academic publications. Not sure if not having a PhD is the issue, or if criticizing the hypotheses of PhDs is the real problem.

Figure 4. The V263 specimen compared to other Pterodaustro specimens to scale.

Readers need no reminding that phylogenetic analyses by Peters 2000
that tested prior pterosaur outgroup candidates has been enhanced online since 2011 with a steady stream of additional taxa. In that study pterosaurs nest with taxa identified by Peters 2000, and those taxa nest with taxa identified by Peters 2007, among them, the lepidosaur, Huehuecuetzpalli, all ignored by Unwin and Deeming. (You can download the Tritosauria paper here.)

Figure 5. 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.

Lepidosaurs generally carry their eggs longer within the mother
than birds or crocs do, sometimes until the moment of hatching. This is not only a more parsimonious hypothesis based on actual evidence (“lizard-like eggshell thickness and leathery lizardy texture in pterosaur eggs”), but hypothetically hatching in open air, without the need to resurrect itself from burial is much to be preferred in tiny pterosaurs with fragile, bat-like wing membranes… much more fragile than wet hatchling bird feathers found in precocial mound building birds. And what happen to pliable eggs that are buried. Might get a little tight inside those eggshells! Mom, on the other hand, always makes room for her growing babies in their eggs.

Unwin and Deeming supplementary material identifies
without phylogenetic analysis, a list of small pterosaurs the authors label juveniles. After phylogenetic analysis, many of these turn out to be small adults (Peters 2007 and here). Earlier we talked about pterosaur workers putting on their blinders and ruining/distorting our understanding of pterosaurs by employing taxon exclusion in phylogenetic analysis. Alas, it has happened once again.

If you are wondering,
I submitted a paper (now available on ResearchGate.net here) on isometric pterosaur growth patterns. The pterosaur referees rejected it for reasons that are clear given the present attitude toward conflicting hypotheses.

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References
Bennett SC 1996. The phylogenetic position of the Pterosauria within the  Archosauromorpha. Zoo. J. Linn. Soc. 118, 261–308.
Bennett SC 2012/13. The phylogenetic position of the Pterosauria reexamined.
Hist. Biol. 25, 545–563.
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 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27
Unwin DM and Deeming DC 2019. Prenatal development in pterosaurs and its implications for their postnatal locomotory ability. Proceedings of the Royal Society B https://doi.org/10.1098/rspb.2019.0409

Note: Prior to understanding pterosaurs were lepidosaurs, I fell back upon tradition and labeled the outgroup taxa ‘prolacertiforms’ in Peters 2000, to my eternal embarrassment and with the approval of my editors and referees. Worse yet, today, twenty years later, most workers are still caught up in that error. Phylogenetic analysis solves so many problems. It’s really a cure for nearly everything in paleontology.

From the NYTimes.com article:

“Other experts were convinced by the paper’s assessment of embryo development, but not its behavioral conclusions.

“In order to prove those, the study would need to compare the pterosaurs with megapodes, chicken-like birds from Australia that can fly from birth, said Edina Prondvai, a postdoctoral researcher at Ghent University in Belgium and the MTA-MTM-ELTE Research Group for Paleontology in Budapest. Kevin Padian, a biologist at the University of California, Berkeley, called the idea that hatchlings could support their own body mass in the air “quite a stretch,” based on studies of birds.

“Dr. Unwin replied that he would have liked to compare pterosaurs with megapodes, but could not find enough data, and that “pterosaurs are not birds.

“He prefers it that way.

“It’s that sheer alienness of pterosaurs that is really fascinating about them,” Dr. Unwin said. “These were creatures that were really different than anything that’s around today.”

No, they are like lizards, bipedal lizards…(Peters 2000)
because they are lepidosaurs (Peters 2007). That has been validated by taxon inclusion. something Unwin and Deeming are loathe to do. Studying megapodes would be a waste of time, based on phylogenetic bracketing.

 

 

 

SVP 2018: Reproduction and Growth in Pterosaurs

Unwin and Deeming 2018 report,
“Pterosaur eggshells were pliable and occasionally bounded externally by a thin calcitic layer. Contact incubation seems impractical and eggs were likely buried and developed at ambient temperatures.”

Burial is not only unnecessary, but dangerous
given that pterosaurs are lepidosaurs and therefore able to retain eggs within the mother until just before hatching, something the authors continue to ignore. That’s why the eggs have lepidosaur-like ultra-thin external layers. No tiny fragile pterosaur wants to dig out of a buried situation. Too dangerous for fragile membranes. Unwin and Deeming are clinging to an archosaur hypothesis, ignoring all the data since Peters 2000 that nest them apart from archosaurs.

Figure 1. The V263 specimen compared to other Pterodaustro specimens to scale.

The authors report,
“Near term embryos were well ossified and hatchlings had postcranial proportions and well developed flight membranes that indicate a superprecocial flight ability.” 

As in lepidosaurs, not archosaurs.
Overlooked by the authors, cranial proportions are also adult-like in hatchlings (Fig. 1). Lepidosaurs hatch ready to eat and take care of themselves.

Regarding growth, they report,
“The growth rates recovered for pterosaurs are comparable to those reported for extant reptiles and a magnitude lower than in extant birds.” Here the authors are lumping turtles, lizards and crocs, when lizards will do.

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.

Note,
the authors do not address isometric growth in their abstract, as in lepidosaurs, not archosaurs. Nor do they address sexual maturity at half full growth, which facilitates rapid phylogenetic miniaturization or gigantism whenever needed due to changing environs.

We’ve heard this all before. Years ago.

Respecting the embargo
other SVP abstract posts will show up after the 20th. This one made the news, so its embargo is over. That article featured BMNH 42736 (Fig. 3) labeled as a hatchling or flapling. Actually it’s a hummingbird-sized adult female. We know this because it nests with other phylogenetically miniaturized taxa in the large pterosaur tree (not with a larger specimen) and… it’s pregnant.

Figure 6. Torso region of BMNH 42736 showing various bones, soft tissues and embryo.

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.
Unwin DM and Deeming C 2018. An integrated model for reproduction and growth in pterosaurs. SVP abstracts.

Live Science online

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.

Azhdarchid pterosaur flight issues

Pterosaurs,
as fenestrasaur tritosaur lepidosaurs matured isometrically. That’s a widely overlooked fact, even by pterosaur workers. Hatchlings had adult proportions with small eyes and long rostra — if their 8x larger parents had small eyes and long rostra. Hatchlings also had adult-proportioned wings. So presumably they were able to fly shortly after hatching (and drying out a bit) — if their parents were able to fly. But not all adult pterosaurs were able to fly…

Figure 1. GIF animation, 4 frames, showing three pterosaurs specimens in 3 sizes (see scale bars) with short, medium and long wings, drawn to the same torso length. The question is: did Quetzalcoatlus fly?

Flightless pterosaurs
Earlier we looked at two related pterosaurs, the no. 57 specimen (Sos 2482) and the no. 42 specimen in the Wellnhofer 1970 catalog (Fig. 1). Both are adults. Both are in the azhdarchid lineage that arose from a tiny pterodactyloid-grade dorygnathid, the no. 1 specimen (TM 10341) in the Wellnhofer 1970 catalog and ultimately gave rise to the giant pterosaur, Quetzalcoatlus (also in Fig. 1). A magnitude or more greater in size and with wings only half as long as the flying no. 42 specimen,

Quetzalcoatlus is widely considered a flying pterosaur.
Can that be verified? Other clades of large (larger than a pelican) pterosaurs all have elongate wings, ideal for soaring. Azhdarchids, apparently deep shoreline waders, did not. The distal two long phalanges (sans the ungual) were shorter in azhdarchids, but the wing was not otherwise reduced, as in the flightless pterosaur, no. 57 (Fig. 1). Witton and Naish 2008 provide a history of workers pondering this question. Unfortunately they provided a bat-wing membrane attached to the ankles or shins with anteriorly oriented pteroids, ignoring key references for pterosaur wing shape (Peters 2002, 2009 and references therein) while ignoring fossilized evidence of pterosaur wing tissue, as others have done.

As anything gets larger,
either ontogenetically or phylogenetically, they generally put on weight at the cube of their length. Air-filled pterosaurs were not as solid, so that ratio was undoubtedly lower.  Even so longer, larger wings on larger pterosaurs makes sense, as in living large birds that fly and are also air-filled.

But that is countered by the isometric growth of individual pterosaurs as they mature to adulthood. Whatever works for hatchlings and tiny pterosaurs, is working just as well for giant adults. Could that mean that all ontogenetic stages of Quetzalcoatlus could fly? Or none of them? Or only half-sized juveniles at about ten percent of the adult weight? With flight, it’s always a balancing act: thrust, lift, drag, weight.

Wings can still provide great thrust
for terrestrial excursions even if they cannot get a big pterosaur off the ground (Fig. 2). So that’s a possibility under consideration, too. After all, why not use all the thrust available?

Figure 10. Quetzalcoatlus running like a lizard prior to takeoff.

To prevent an extant flying bird, like a cockatiel, from flying, or flying well,
it’s surprising how little of the tips of the feathers need to be clipped. Link here. Basically its the difference between no. 42 and Quetzalcoatlus above (Fig. 1). With this in mind, I cannot join those who say giant Quetzalcoatlus could fly or fly between continents, until supporting evidence comes alone. Rather, giant azhdarchids become hippo analogs in this respect: they were probably constant deep waders (Fig. 3) capable of charging or running from danger. Storks, which azhdarchids otherwise resemble, tend to fly away because they have long, not truncated wings and can do so.

Figure 3. In my opinion this saddle-bill stork wading in water appears to be the bird closest to azhdarchid morphology and, for that matter, niche. It can fly from danger on elongate wings. Not so sure that Q could do the same. 

References
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing—with a twist. Historical Biology 15:277-301.
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.
Witton M and Naish D 2008.  A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology. https://doi.org/10.1371/journal.pone.0002271. online here.

Pangupterus: a juvenile Moganopterus

Lü et al. 2016
described a new tiny, long-snouthed pterosaur, Pangupterus liui (Jiufotang Fm., Liaoning, Aptian, Early Cretaceous; Figs. 1, 2). Lü et al. thought they had a mandible with a 30º divergence at the jaw symphysis 1/5 of the total jaw length (Fig. 1).

But then, they also report,
“The distal end of the rostrum is slightly expanded, and although it has been destroyed, it seems to have a bony process in the middle, which is similar to the case in Longchengopterus.” The paper has several authors. I don’t think they read each others input.

The color illustration of a restored Pangupterus
that was included with the paper does not follow the first description, but features extremely narrow jaws closer to the second description. The restored body was imaginatively based on a Pterodactylus bauplan.

Figure 1. Pangupterus in situ. Lü et al. had first hand access and considered this a mandible with a symphysis at 1/5 the jaw length. Here, based on this photo,  it is interpreted as a rostrum and mandible, both with parallel rami. If you’re looking at this on a 72 dpi monitor the image is 7/5 larger than life size.

Here, based on tracing
the photo in figure 1, a narrow rostrum lies at an angle to the equally narrow mandible. And the resulting reconstruction matches that of only one pterosaur, Moganopterus, except for its size. The skull of Pangupterus is only 1/4 as long as in Moganopterus (Fig. 2). A hatchling Monganoterpus, if it followed the pattern of other pterosaur hatchlings, would have been 1/8 the size of the adult (Fig. 2) or half the size of Pangupterus.

Figure 2. No other pterosaur has such narrow jaws tipped with slender teeth. Pangupterus is a good candidate to be a juvenile Moganopterus, as shown here.

Moganopterus zhuiana 41HIII0419 (Lü et al. 2012) Early Cretaceous was a large sister to Feilongus and the cycnorhamphids. The skull was extraordinarly stretched out. Feeble needle-like teeth lined the anterior jaws. A long crest that did not break the rostral margin appeared posteriorly. And the neck vertebrae were very much elongated. Likely this was a very tall pterosaur.

Several other blog spots
covered Pangupterus. Some reimagine it as a hummingbird-like specimen. See other images here, here, here and here.

This specimen
further confirms the presence of tiny, long-snouted pterosaurs, some of them juveniles of larger long-snouted pterosaurs, and the isometric ontogenetic growth of all pterosaurs.

References
Lü J-C, Pu H-Y, Xu i, WuY-H and Wei X-F 2012. Largest Toothed Pterosaur Skull from the Early Cretaceous Yixian Formation of Western Liaoning, China, with Comments On the Family Boreopteridae. Acta Geologica Sinica 86 (2): 287-293.
Lü J-C, Liu C, Pan L-J and Shen C-Z 2016. A new pterodactyloid pterosaur from the Early Cretaceous of the Western part of the Liaoning Province, Northeastern China. Acta Geologica Sinica (English) 90(3):777-782.

wiki/Moganopterus
/wiki/Pangupterus

Dr. David Unwin on pterosaur reproduction – YouTube

Dr. David Unwin’ talk on pterosaur reproduction 

was recorded at the XIV Annual Meeting of the European Association of Vertebrate Palaeontologists, Teylers Museum, Haarlem, Netherlands and are online as a YouTube video.

Dr. Unwin is an excellent and engaging speaker.
However, some of the issues Dr. Unwin raises have been solved at www.ReptileEvolution.com

The virtual lack of calcite in pterosaur eggs were compared to lepidosaurs by Dr. Unwin, because pterosaurs ARE lepidosaurs.  See: www.ReptileEvolution.com/reptile-tree.htm

Lepidosaurs carry their eggs internally much longer than archosaurs, some to the point of live birth or hatching within hours of egg laying. Given this, pterosaurs did not have to bury their eggs where hatchlings would risk damaging their fragile membranes while digging out. Rather mothers carried them until hatching. The Mrs. T external egg was prematurely expelled at death, thus the embryo was poorly ossified and small.

Dr. Unwin ignores the fact that hatchlings and juveniles had adult proportions as demonstrated by growth series in Zhejiangopterus, Pterodaustro and all others, like the JZMP embryo (with adult ornithocheirid proportions) and the IVPP embryo (with adult anurognathid proportions).

Dr. Unwin also holds to the disproved assumption that all Solnhofen sparrow- to hummingbird-sized pterosaurs were juveniles or hatchlings distinct from any adult in the strata. So they can’t be juveniles (see above). Rather these have been demonstrated to be phylogenetically miniaturized adults and transitional taxa linking larger long-tailed dorygnathid and scaphognathid ancestors to larger short-tailed pterodactyloid-grade descendants, as shown at: www.ReptileEvolution.com/MPUM6009-3.htm

Thus the BMNH 42736 specimen and Ningchengopterus are adults, not hatchlings. And the small Rhamphorhynchus specimens are also small adults.

Ontogeny and gender dimorphism in pterosaurs – SVP abstract 2016

Unfortunately,
and apparently, this is yet another study (Anderson and O’Keefe 2016) with a priori species assignations prior to a robust phylogenetic analysis and the creation of precise reconstructions. I hope I’m wrong, but no mention of phylogenetic analysis appears in the abstract. Nor do they mention creating reconstructions. Bennett (1993ab, 1995, 1996a, 2001ab, 2006, 2007) failed several times in similar fashion (with statistical analyses) to shed light on the twin issues of pterosaur ontogeny and dimorphism, coming to the wrong conclusions every time, based on results recovered by creating reconstructions and analyses. Further thoughts follow the abstract.

From the Anderson and O’Keefe abstract:
“The relationships of pterosaurs have been previously inferred from observed traits, depositional environments, and phylogenetic associations. A great deal of research has begun to analyze pterosaur ontogeny, mass estimates, wing dynamics, and sexual dimorphism in the last two decades. The latter has received the least attention because of the large data set required for statistical analyses. Analyzing pterosaurs using osteological measurements will reveal different aspects of size and shape variation in Pterosauria (in place of character states) and sexual dimorphism when present. Some of these variations, not easily recognized visually, will be observed using multivariate allometry methods including Principle Component Analysis (PCA) and bivariate regression analysis. Using PCA to variance analysis has better visualized ontogeny and sexual dimorphism among Pterodactylus antiquus, and Aurorazhdarcho micronyx. Each of the 24 (P. antiquus) and 15 (A. micronyx) specimens had 14 length measurements used to assess isometric and allometric growth. Results for P. antiquus analyses show modular isometric growth in the 4th metacarpal, phalanges I–II, and the femur. Bivariate plots of the ln-geometric mean vs ln-lengths correlate with the PCA showing graphically the relationship between P. antiquus and A. micronyx which are argued here to be sexually dimorphic and conspecific. Wing schematic reconstructions of all 39 specimens were done to calculate individual surface areas and scaled to show relative intraspecific wing shape and size. Finally, Pteranodon, previously identified having with sexually dimorphic groups, was compared with ln-4th metacarpal vs ln-femur data, bivariately, revealing similarities between the two groups (P. antiquus and A. micronyx = group 1; Pteranodon = group 2) in terms of a sexual dimorphic presence within the data sets.”

Figure 3. Click to enlarge. The Pterodactylus lineage and mislabeled specimens formerly attributed to this “wastebasket” genus

If these two workers actually had 24 P. antiquus specimens to work with,
then it was only because the labels told them so. Or they came across a cache on a slab of matrix I’m not aware of. Pterodactylus has been a wastebasket taxon for a long time (Fig.1) that, apparently the authors didn’t bother to segregate with analysis. Anderson and O’Keefe do not indicate they arrived at a large clade of P. antiquus specimens after phylogenetic analysis. Having done so, I can tell you that no other tested Pterodactylus is  identical to the holotype and no two adult pterosaurs I’ve tested are alike, even among Rhamphorhynchus, Germanodactylus and Pteranodon. The differences I’ve scored are individual to phylogenetic and they create cladograms that illuminate interrelationships, not sexual dimorphism or ontogeny. There are sequences of smaller species and larger ones. These can appear to be two genders, but that is a false result.

Embryo to juvenile pterosaurs
are isometrically miniaturized versions of their parents as the evidence shows time and again across the pterosaur clade. These facts have been known for over five years and it’s unfortunate that old traditions continue like this unfettered and untested under phylogenetic analysis… or so it seems… I could be wrong having not seen the presentation.

References
Anderson EC and O’Keefe FR 2016. Analyzing pterosaur ontogeny and sexual dimorphism with multivariate allometery. Abstracts from the 2016 meeting of the Society of Vertebrate Paleontology.
Bennett SC 1993a. The ontogeny of Pteranodon and other pterosaurs. Paleobiology 19, 92–106.
Bennett SC 1993b. Year classes of pterosaurs from the Solnhofen limestone of southern Germany. Journal of Vertebrate Paleontology. 13, 26A.
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 1996a. Year-classes of pterosaurs from the Solnhofen limestones of Germany: taxonomic and systematic implications. Journal of Vertebrate Paleontology 16:432–444.
Bennett SC 2001a, b. 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 review of the genus. Journal of Vertebrate Paleontology 26:872–878.
Bennett SC 2007. A review of the pterosaur Ctenochasma: taxonomy and ontogeny. Neues Jahrbuch fur Geologie und Paläontologie, Abhandlungen 245:23–31.