SDUST-V1003 is not Forfexopterus

Zhou, Wang and Zhou 2020 describe a new pterosaur specimen
based on a single articulated wing (SDUST-V1003; (Fig. 1), which they assigned to Forfexopterus (Fig. 2)… with this odd reservation: “It is only about 75% the size of the immature holotype.”

By contrast
in the large pterosaur tree (LPT, 251 taxa) the SDUST-V1003 (Fig. 1) nests with a slightly earlier and smaller Yixian Formation pre-azhdarchid pterosaur, Beipiaopterus (Fig. 3).

Figure 1. SDUST-V1003, formerly Forfexopterus, in situ and reconstructed.

Figure 1. SDUST-V1003, formerly Forfexopterus, in situ and reconstructed. Note the slender free fingers and giant unguals. The radius was taphonomically displaced. A tiny wing finger claw is present. Metacarpus 4 was split and splintered. perhaps during axial wing rotation during taphonomy.

Zhou, Wang and Zhou 2020 considered the following pterosaurs
ctenochasmatids. Most are not when you add more taxa, as in the LPT.

  1. EosipterusElanodactylus – Germanodactylidae
  2. Feilongus, Pterofiltrus, MoganopterusCycnorhamphidae
  3. Beipiaopterus, Forfexopterus  pre-Azhdarchidae
  4. Gegepterus, Gladocephaloideus – Ctenochasmatidae
  5. Cathayopterusnot tested yet
Figure 2. Forfexopterus compared to sisters Huanhepterus and Ardeadactylus and the BYU specimen of Mesadactylus.

Figure 2. Forfexopterus compared to sisters Huanhepterus and Ardeadactylus and the BYU specimen of Mesadactylus.

The SDUST pterosaur is known from
a slab containing a complete wing (lacking manual 2.2, 2.3, 3.2, 3.3 and 3.4; Fig. 1) with somewhat different proportions than the holoytpe Forfexopterus (Fig 2), The differences turn out to be enough to separate the two in the LPT. The referred specimen (SDUST V1003) nests two nodes apart from Forfexopterus, so the two cannot be congeneric.

Figure 3. Beipiaopterus to scale with the SDUST pterosaur. Beipiaopterus wing enlarged to match the SDUST pterosaur.

Figure 3. Beipiaopterus to scale with the SDUST pterosaur. Beipiaopterus wing enlarged to match the SDUST pterosaur. Note how relatively tiny the free fingers are in these taxa.

From the Zhou, Wang and Zhou abstract:
“In the Jehol Biota, the filter-feeding ctenochasmatid pterosaurs flourished with a high biodiversity. Here, we report a new wing skeleton of the ctenochasmatid Forfexopterus from the Early Cretaceous Jiufotang Formation in Jianchang, western Liaoning, China. The specimen exhibits the sole autapomorphy, the first wing phalanx shorter than the second and longer than the third.”

Other pterosaurs also share this trait. As long-time readers will readily realize, Zhou, Wang and Zhou were “Pulling a Larry Martin” by relying on this single trait, or a dozen traits.

“Interestingly, it exhibits a skeletal maturity with co-ossified elements, but it is only about 75% the size of the immature holotype.”

Here the authors reveal they were misinformed on the subject of pterosaur  phylogeny and ontogeny Pterosaurs are tritosaur lepidosaurs with isometric growth patterns and phylogenetic (not ontogenetic) ossification patterns. Thus for good reason, pterosaurs don’t follow archosaur growth and ossification patterns.

“This discrepancy reveals developmental variation of Forfexopterus, but its relationship with sexual dimorphism needs to be certain by more available material.”

Pterosaurs have not yet shown sexual variation in their skeletons. Not yet.

The holotype Forfexopterus jeholensis
(Jiang et al. 2016; Early Cretaceous; Fig. 2) was originally considered an Archaeopterodactyloid. There is no such valid clade in the LPT. Here Forfexopterus nests with Ardeadactylus and Huanhepterus (Fig. 2) and other tall, slender pterosaurs basal to Azhdarchidae.


References
Jiang S, Cheng X, Ma Y and Wang X 2016. A new archaeopterodactyloid pterosaur from the Jiufotang Formation of western Liaoning, China, with a comparison of sterna in Pterodactylomorpha. Journal of Vertebrate Palaeontology: e1212058.
Zhou C-F, Wang J and Zhou Z 2020. A new wing skeleton of Forfexopterus (Pterosauria: Ctenochasmatidae) from the Early Cretaceous Jehol Biota reveals a developmental variation. Fossil Record 23:191–196,

wiki/Huanhepterus
wiki/Forfexopterus
wiki/Ardeadactylus
wiki/Beipiaopterus

 

Reconstructing the Cretaceous azhdarchid Keresdrakon

Kellner et al. 2019
presented a new Early or Late Cretaceous (Aptian or Campanian) toothless pterosaur preserved as several 3D bones, far from complete (Fig. 1). Keresdrakon vilsoni (CP.V 2069) was considered an “azhdarchoid pterodactyloid.” Unfortunately, neither clade is monophyletic when more taxa are added in the large pterosaur tree (LPT, 251 taxa). The authors report, “Keresdrakon vilsoni gen. et sp. nov. was recovered as a sister taxon of the tapejaridae.”

Figure 1. All that is known of Keresdrakon layered on top of a Quetzalcoatlus sp. specimen and the same ghosted and reduced to the size of Keresdrakon.

Figure 1. All that is known of Keresdrakon layered on top of a Quetzalcoatlus sp. specimen and the same ghosted and reduced to the size of Keresdrakon.

Perhaps too little of Keresdrakon is preserved
to add it to the LPT, but layering elements atop a previously completed image of the six-foot-tall Quetzalcoatlus specimen results in a pretty close match (Fig. 1). Overall Keresdrakon is about 64% the size of Q. sp. Proportionately manual 4.1 is longer than in Q. sp.

Ontogeny
The authors note, “the presence of these growth marks suggests that this bone belongsto an ontogenetically less developed individual compared to others.”

Figure 8 in Kellner et al. 2019 has a few identification errors.

  1. a is the left ilium, not the left ischium
  2. b and c are ischia, not pubes
  3. d and e are pubes, not ischia

The coracoid identified in Kellner et al. 2020
is not co-osified to the scapula and is relatively small (Fig. 1). In pterosaurs ossification or lack thereof is phylogenetic, not ontogenetic. It’s also worth noting that basal taxa in the Azhdarcho clade also have an unfused scapula and coracoid with the coracoid often much smaller than the scapula. The tiny BSPG 1911 I 31 Solnhofen specimen is one such taxon.

Co-author, Alex Kellner, along with Wann Langston
published Q. sp. in 1996, so it’s a bit surprising that Q. sp. was not immediately seen as a close match to Keresdrakon.

Sympatry
Keresdrakon were found close to the tapejarid Caiuajara in desert sandstone.


References
Kellner AWA and Langston W 1996. Cranial remains of Quetzalcoatlus (Pterosauria, Azhdarchidae) from late Cretaceous sediments of Big Bend National Park, Texas. – Journal of Vertebrate Paleontology 16: 222–231.
Kellner AWA, Weinschütz LC, Holgado B, Bantim RAM and Sayão JM 2019. A new toothless pterosaur (Pterodactyloidea) from Southern Brazil with insights into the paleoecology of a Cretaceous desert. Anais da Academia Brasileira de Ciencias 91: e20190768. DOI 10.1590/0001-3765201920190768

wiki/Quetzalcoatlus
wiki/Keresdrakon

New Quetzalcoatlus northropi skeletal model from Triebold Paleontology

Short one today
… focusing on a tall pterosaur skeleton model.

Figure 1. A Quetzalcoatlus northropi model from Triebold Paleontology scaled up from a Q. sp. sculpture I made and sold to Triebold.

Figure 1. A Quetzalcoatlus northropi model from Triebold Paleontology scaled up from a Q. sp. sculpture I made and sold to Triebold. Maybe it is posed trying to cool itself off, by those wing fingers can fold up against the arms for membrane protection.

First time I’ve seen this. 
Although I heard rumors that Mike Triebold (Triebold Paleontology) had scaled up the Q. sp. model I sold him a few years ago (Fig. 2) to create a 3x taller Quetzalcoatlus northropi model (Fig. 1). Giants are fascinating.

Quetzalcoatlus neck poses. Dipping, watching and displaying.

Figure 2. Quetzalcoatlus neck poses. Dipping, watching and displaying. Yes, that was my living room.

The shorter original was held together by wire
so it could be manipulated into one pose after another, or stuffed away into a small box.

As a reminder,
the brevity of the wings (vestigial distal phalanges) and the top-heavy proportions otherwise mark this as a flightless pterosaur.

Quetzalcoatlus running like a lizard prior to takeoff.

Figure 3. Quetzalcoatlus running like a lizard unable to take off due to vestigial distal wing elements and proportions that sent the center of balance anterior to the wing chord.

Even so, those wings were powerful thrusters
for speedy getaways on land (Fig. 3). I realize this is heresy, but facts are facts. Clipped wings in birds and pterosaurs means they cannot fly. And only flightless birds and pterosaurs are able to achieve such giant sizes (Fig. 4).

Figure 1. Click to enlarge. The largest flying and non-flying birds and pterosaurs to scale.

Figure 1. Click to enlarge. The largest flying and non-flying birds and pterosaurs to scale.

Enigmatic 29cm Antarctic Late Cretaceous soft-shell egg

Legendre et al. (6 co-authors) 2020
report on an enigmatic egg they cannot identify. They nicknamed it “The Thing”. Without knowing anything else about it, my first guess, based on “giant” and “leathery or soft” is a giant azhdarchid (Fig. 1; first imagined in 2012). Let’s see if any clues guide us toward or away from that initial guess.

Quetzalcoatlus embryo and egg.

Figure 1. Hypothetical Quetzalcoatlus embryo and egg imagined in 2012. Compare to figure 2. The elongated shape and soft, thin shell were needed to encompass the elongated beak, neck and metacarpals. The long axis is ~35cm. See figure 4 for images of the mother.

Excerpts from the abstract
“Here we report a new type of egg discovered in nearshore marine deposits from the Late Cretaceous period (roughly 68 million years ago) of Antarctica. It exceeds all nonavian dinosaur eggs in volume and differs from them in structure.”

As in the azhdarchid hypothesis (Fig. 1).

“the new fossil, visibly collapsed and folded, presents a thin eggshell with a layered structure that lacks a prismatic layer and distinct pores, and is similar to that of most extant lizards and snakes (Lepidosauria).

As in the azhdarchid hypothesis (Fig. 1; Peters 2007).

“The identity of the animal that laid the egg is unknown, but these preserved morphologies are consistent with the skeletal remains of mosasaurs (large marine lepidosaurs) found nearby. They are not consistent with described morphologies of dinosaur eggs of a similar size class.”

Is taxon exclusion a factor here?

“Phylogenetic analyses of traits for 259 lepidosaur species plus outgroups suggest that the egg belonged to an individual that was at least 7 metres long, hypothesized to be a giant marine reptile, all clades of which have previously been proposed to show live birth.”

Perhaps taxon exclusion is a factor here. I will need to see the list of 259 lepidosaur species to see if it includes any pterosaurs.

“Such a large egg with a relatively thin eggshell may reflect derived constraints associated with body shape, reproductive investment linked with gigantism, and lepidosaurian viviparity, in which a ‘vestigial’ egg is laid and hatches immediately.”

As in the azhdarchid hypothesis (Fig. 1).

Now let’s look at the supplemental data
(writing this in real time as I do the research).

Specimen name: Antarcticoolithus bradyi.
The long axis is 29cm (Fig. 2). The short axis is estimated at 15cm. Compare that to the imagined 2012 azhdarchid egg (Fig. 1) with a long axis of 35cm. Just curl the embryo a bit and the guess = the discovery. The wider, but shorter Antarcticoolithus egg gives the developing azhdarchid? embryo a bit more room to move about. By the look of the egg, it appears to have a slit in it, as if it hatched already.

Figure 2. Antarcticoolithus bradyi from Legendre et al 2020.

Figure 2. Antarcticoolithus bradyi from Legendre et al 2020.

Figure 2b. Is that a slit in the egg shell? I am still awaiting the text of the study.

Figure 2b. Antarcticoolithus bradyi from Legendre et al 2020. Side two. Is that a slit in the egg shell from arrow to arrow? I am still awaiting the text of the study. (turns out to be a crack in the rock)

From the Supplemental Data:
“The first known remains of Late Cretaceous Antarctic pterosaurs were recently described (Kellner et al. 2019) however, the largest known pterosaur eggs with known taxonomic affinities (Pterodaustro guiñazui, egg length: ~60 mm; Fig. 3) belonged to a species with a ~2.5 m adult wingspan102. Hence, if the 290 mm-long Antarcticoolithus was a pterosaur egg, it would have been laid by a species with a wingspan of over 12 m, which is much larger than the maximum wingspan of 4–5 m described in known Antarctic pterosaurs.”

The known Antarctic pterosaurs include bits from one or two specimens (Fig. 6).

Figure 2. Original interpretations (2 frames black/white) vs. new interpretations (color).

Figure 3. Original interpretations (2 frames black/white) vs. new interpretations (color).

Now let’s check out the mother’s pelvis
(Fig. 4). Looks like 10cm in the short axis was about the maximum, unless the ischia were free to expand during egg-laying. It is also possible that the pliability of the egg itself might have enabled Antarcticoolithus to pass through a hypothetical pelvis of a giant Q. northropi, if similar in proportion to the small Q. species, which is no sure thing in these flightless giants., wingspan ~11m.

Quetzalcoatlus eggs

Figure 4. Quetzalcoatlus northropi (left) nd Q. sp. (right) to the same scale alongside hypothetical eggs and hatchlings. The egg-layer of Antarcticoolithus, if azhdarchid pterosaurian, might have had a larger cloacal opening than shown here.

Finally, let’s consider those Antarctic pterosaurs. What were they?
Hard to say because they are such small parts of the pterosaur wing (Fig. 5).

Figure 6. Antarctic pterosaur bones from Kellner et al. 2019. The elements appear to be too gracile to fit the hypothetical outline provided.

Figure 6. Antarctic pterosaur bones from Kellner et al. 2019. The elements appear to be too gracile to fit the hypothetical outline provided.

Conclusion:
Don’t overlook the possibility of a giant azhdarchid egg layer for Antarcticoolithus.

Legendre et al. report,
“Interestingly, the two specimens of pterosaurs in our sample fall within the range of soft-shelled lepidosaur eggs, despite one of them showing a prismatic calcareous layer.”

We’ve known since Peters 2007 that pterosaurs are lepidosaurs.

“Pterosaur eggs have been repeatedly described as soft-shelled due to the thin and pliable aspect of their eggshell. The first detailed description of a pterosaur egg microstructure, however, showed a conspicuous prismatic layer. Another specimen was reported to lack a calcareous layer, and be most similar in structure to a lepidosaur eggshell, but no description of its microstructure using microscopy techniques was provided, preventing a clear identification of a soft-shelled structure. Since these first descriptions, more specimens of exceptionally preserved eggs have been described for a handful of pterosaur species – some hard-shelled (Grellet-Tinner et al. 2014) some soft-shelled.”

Pterodaustro eggs (Fig. 3) can hardly be called ‘hard-shelled’ contra Grellet-Tinner et al. 2014. Eggs with deep infolds, like those of Antarcticoolithus are not filled to bursting with full-term embryos, as is formerly empty, sediment-filled egg shown in figure 2.

“There is currently no consensus on whether such a soft eggshell was widespread among pterosaurs, nor on the relationship of the structure of that soft eggshell to that of lepidosaur eggshells.”

No consensus, for reasons listed earlier, but Peters 2007 was the first worker to nest pterosaurs within lepidosauria simply by adding taxa.

“More studies on pterosaur eggshells are thus necessary to assess their potential microstructural similarity with extant soft-shelled eggs. While the possibility of Antarcticoolithus being a fossilized pterosaur egg cannot definitely be ruled out, it should be noted that no remains of giant pterosaurs likely to have laid such a large egg are known from Antarctic deposits, contrary to giant marine reptiles.”

Leave the options open. Always a good idea. This egg may belong to something else entirely, like a mosasaur (see NPR online below). As more information arrives, I will add data to this blogpost.


References
Grellet-Tinner, G. et al. 2014. The first pterosaur 3-D egg: Implications for Pterodaustro guinazui nesting strategies, an Albian filter feeder pterosaur from central Argentina. Geoscience Frontiers 5, 759–765.
Kellner AWA et al. 2019. Pterodactyloid pterosaur bones from Cretaceous deposits of the Antarctic Peninsula. Anais da Academia Brasileira de Ciências91,e20191300.
Legendre LJ, et al. (6 co-authors) 2020.
A giant soft-shelled egg from the Late Cretaceous of Antarctica. Nature Jun 17 https://doi.org/10.1038/s41586-020-2377-7
Peters D 2007.
The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

At ResearchGate.net:
A_new_lepidosaur_clade_the_Tritosauria

From NPR with mosasaur baby illustration
https://www.npr.org/2020/06/17/877679868/scientists-find-the-biggest-soft-shelled-egg-ever-nicknamed-the-thing

https://static-content.springer.com/esm/art%3A10.1038%2Fs41586-020-2377-7/MediaObjects/41586_2020_2377_MOESM3_ESM.mov

https://pterosaurheresies.wordpress.com/2012/02/21/an-egg-for-quetzalcoatlus/

Rethinking giant ‘Dracula’ LPB R-2347 as a Q-sized Azhdarcho

Updated March 25, 2020
with the strong possibility that this specimen (chimaera or not) has been named, Albadraco tharmisensis with the holotype specimen number: PSMUBB V651a, b. But that may be a mid-sized specimen, not the giant.

The largest pterosaur model in the world, nicknamed ‘Dracula’
is built on relatively few disassociated parts Fig. 1). The rest is imagined.

Figure 1. Highly speculative reconstruction of large azhdarchid from Romania, nicknamed 'Dracula' based on the few bones shown here.

Figure 1. Highly speculative reconstruction of large azhdarchid from Romania, nicknamed ‘Dracula’ based on the few bones shown here. One source says an ‘upper arm bone” was found. Another states a scapula was found. I will update this if in error here.

Even so,
this chimaera may be close to the real deal, perhaps slightly smaller and more gracile (Fig. 2) 
than the model-builders imagined (Fig. 1). If ‘Dracula’ was indeed a giant (or full grown) Azhdarcho (as  indicated here by matching bits and pieces, Fig. 2), then the skull should have been sculpted with less bone, the stance more erect, the femur shorter, the sternal complex smaller and the distal wing phalanges smaller. With denser bones and shorter wings than volant pterosaurs, ‘Dracula’ would have been flightless, like other azhdarchids with similarly clipped (still imaginary, but compared to Fig. 2) wings.

Figure 2. 'Dracula' elements match those from the much smaller Azhdarcho, here enlarged to the scale of Quetzalcoatlus northropi and Q sp.

Figure 2. ‘Dracula’ elements match those from the much smaller Azhdarcho, here enlarged to the scale of Quetzalcoatlus northropi and Q sp. The imagined torso may be much smaller., the hind limb larger.  Note the large size of the wing-metacarpal joint compared to Q. sp. Don’t trust these chimeric images further than intended here. Lots of guesswork.

Earlier we looked at the cervical #7 of ‘Dracula’.
Here we add the re-identified rostrum (Figs. 2, 3 with a central set of narrow vomers), originally described as a mandible portion. Granted, there is not much to work with here, but everything scales correctly and fits the Azhdarcho pattern. Other suggestions are welcome, by the way.

Figure 2. The former mandible of 'Dracula' here flipped to become a rostrum complete with palatal vomers. Compare to enlarged and to scale images of Azhdarcho rostrum and mandible tips.

Figure 2. The former mandible of ‘Dracula’ here flipped to become a rostrum complete with palatal vomers. Compare to enlarged and to scale images of Azhdarcho rostrum and mandible tips.

Earlier we looked at the purported mandible of LPB R 2347
which was originally imagined as the largest pterosaur ‘mandible‘ (Fig. 3). The authors compared their jaw segment to the mandible of Bakonydraco (Fig. 3). As shown in figure 2, the Romanian fragment is more likely a rostrum belonging to an adult or giant Azhdarcho

FIgure 1. LPB R 2347 largest pterosaur mandible compared to Bakonydraco.

Figure 3. LPB R 2347 was originally imagined as the largest pterosaur ‘mandible’ which the authors compared to Bakonydraco. As shown in figure 2, this is more likely a rostrum belonging to an adult or giant Azhdarcho.

Bakonydraco
nests with volant basal pteranodontids in the LPT. 

Eurazhdarcho
is a coeval mid-sized azhdarchid known from some wing phalanges and three anterior neck cervicals. 


References
Averianov AO 2010. The osteology of Azhdarcho lancicollis (Nessov, 1984) (Pterosauria, Azhdarchidae) from the late Cretaceous of Uzbekistan. Proceedings of the Zoological Institute RAS 314:264-317
Averianov AO 2013. Reconstruction of the neck of Azhdarcho lancicollis and lifestyle of azhdarchids (Pterosauria, Azhdarchidae) Paleontological Journal 47:203-209.
Buffetaut E, Grigorescu D and Csiki Z 2003. Giant azhdarchid pterosaurs from the terminal Cretaceous of Transylvania (western Romania) In: Buffetaut E, Mazin JM, eds. Evolution and palaeobiology of pterosaurs. London: Geological Society Special Publications. Vol. 217:91-104.
Kellner AWA and Langston Jr W 1996. Cranial remains of Quetzalcoatlus (Pterosauria, Azhdarchidae) from Late Cretaceous sediments of Big Bend National Park, Texas. Journal of Vertebrate Paleontology 16:222-231
Naish D and Witton MP 2017. Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators. PeerJ 5:e2908; DOI 10.7717/peerj.2908
Vremir MM 2010.
New faunal elements from the Late Cretaceous (Maastrichtian) continental deposits of Sebes area (Transylvania). Terra Sebus-Acta Museu Sabesiensis 635–684.
Nessov LA 1984. Upper Cretaceous pterosaurs and birds from central Asia. Paleontology Journal 1984(1):38-49
Vremir M, Kellner AWA, Naish D and Dyke GJ 2013. A new azhdarchid pterosaur from the Late Cretaceous of the Transylvanian Basin, Romania: implications for azhdarchid diversity and distribution. PLOS ONE 8:e54268
Vremir M, Witton M, Naish D, Dyke G, Brusatte SL, Norell M and Totoianu R 2015. A medium-sized robust-necked Azhdarchid Pterosaur (Pterodactyloidea: Azhdarchidae) from the Maastrichtian of Pui (Haţeg Basin, Transylvania, Romania) American Museum Novitates 3827:1-16
Vremir M et al. 2018. Partial mandible of a giant pterosaur from the uppermost Cretaceous (Maastrichtian) of the Haţeg Basin, Romania. Lethaia doi: https://doi.org/10.1111/let.12268 https://onlinelibrary.wiley.com/doi/abs/10.1111/let.12268
Witton MP and Naish D 2008.
A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLOS ONE 3:e2271

wiki/Albadraco

Short-necked azhdarchids? Probably not.

Naish and Witton 2017 bring their insight
to a short, but giant cervical from a Romanian azhdarchid (Fig. 1 inset). They reported, “we discuss a recently discovered giant azhdarchid neck vertebra referable to Hatzegopteryx from the Maastrichtian Sebes Formation of the Transylvanian Basin, Romania. This vertebra, which we consider a cervical VII, is 240 mm long as preserved and almost as wide. Among azhdarchid cervicals, it is remarkable for the thickness of its cortex (46 mm along its ventral wall) and robust proportions.”

Naish and Witton conclude:
“By comparing its dimensions to other giant azhdarchid cervicals and to the more completely known necks of smaller taxa, we argue that Hatzegopteryx had a proportionally short, stocky neck highly resistant to torsion and compression.”

Figure 2. Quetzalcoatlus has a long cervical 7 and a short cervical 8. Naish and Witton consider the Romanian cervical #7, creating a short neck. But see figure 2.

Figure 2. Quetzalcoatlus has a long cervical 7 and a short cervical 8. Naish and Witton consider the Romanian cervical #7, creating a short neck. But see figure 2. The tall neural spine on cervical 8 is speculative and may be absent.

If the Romanian cervical is similar to cervical 7 of Quetzalcoatlus,
(Fig. 1) then the authors’ extrapolation seems reasonable.

Figure 2. Azhdarcho cervicals 7 and 8 are both short, but the anterior cervicals are elongate.

Figure 2. Azhdarcho cervicals 7 and 8 are both short, but the anterior cervicals are elongate. The Romanian cervical may belong to a similar genus, only larger.

However, if similar to the shorter cervical 7 of Azdarcho,
(Fig. 2) then the authors’ extrapolation can only be considered inconclusive. The rest of the cervicals in Azhdarcho are long and slender, matching those of all other clade members. Azhdarcho comes from Uzbekistan, closer to Romania than Quetzalcoatlus (Fig. 1), which comes from Texas.

Naish and Witton suggest,
“This specimen is one of several hinting at greater disparity within Azhdarchidae than previously considered, but is the first to demonstrate such proportional differences within giant taxa.”

Given the anatomy of Azhdarcho,
that conclusion is premature at present. We need to see at least some short anterior cervicals.

Historically, Naish and Witton imagined giant azhdarchids
as world-wide soarers, able to quad launch with folded wings, and terrorizing terrestrial prey like tiny sauropods. All of these fanciful hypotheses have been invalidated, but remain popular with paleoartists.


References
Naish D and Witton MP 2017. Neck biomechanics indicate that giant Transylvanian azhdarchid pterosaurs were short-necked arch predators. PeerJ 5:e2908; DOI 10.7717/peerj.2908

Gregorius rexi: not a ratfish in the LRT

Revised November 07, 10 and 17 2019
with a revision to the LRT that moves Gregorius closer to Hybodus, basal to Placodermi.

Talk about a transitional taxon…
Gregorius rexi (Lund and Grogan 2004; 11cm long; Early Carboniferous; CM 35490) is a small fish from the famous Bear Gulch Formation in Montana. Traditionally it is considered a type of ratfish.

By contrast,
in the large reptile tree (LRT, 1593 taxa; Fig. 3), Gregorius is a late surviving member of an Early Devonian genesis representing the most primitive ray-fin fish splitting from Hybodus. Gregorius is the last common ancestor of all bony fish and placoderms. Ratfish are a bit more primitive.

Figure 1. Gregorius rexi enlarged and to to scale with its cousin in the LRT, Robustichthys. Gregorius still has a dorsal spine and an odd soft of diphycercal tail.

Figure 1. Gregorius rexi enlarged and to to scale with its cousin in the LRT, Coccosteus.  Gregorius still has a dorsal spine and an odd soft of diphycercal tail.

Gregorius is not far from catfish,
still tucked inside the placoderms. Thunnus, the tuna, is the most primitive extant ray-fin fish among taxa derived from a sister to Gregorius.

Figure 5. Subset of the LRT focusing on fish. Pachycormus nests at the base of the revised Telostei (green) clade.

Figure 2. Subset of the LRT focusing on fish. Pachycormus nests at the base of the revised Telostei (green) clade.

In the meantime,
I’ve been learning more about ray fin fish. Some taxa have moved around as mistakes are discovered and corrections are made. The four-eyed fish now nests with the mudskipper, as an example. The general topology of the tree has otherwise stayed much the same as the Bootstrap scores get better. When that portion is complete, we’ll review the changes.


References
Lund R and Grogan E 2004. Five new euchondrocephalan Chondrichthyes from the Bear Gulch Limestone (Serpukhovian, Namurian E2b) of Montana, USA. Recent Advances in the Origin and Early Radiation of Vertebrates 505-531.

https://people.sju.edu/~egrogan/BearGulch/pages_fish_species/Gregorius_rexi.html

Could this azhdarchid eat this baby dinosaur?

Artist and paleontologist Mark Witton, U of Portsmouth,
published an iconic image of an azhdarchid pterosaur biting a baby sauropod prior to eating and digesting it (Fig. 1, Witton and Naish 2008). While biting a baby dinosaur in this fashion certainly was possible, could this azhdarchid swallow and digest it? Let’s see.

Figure 1. Above: original art from artist M Witton showing azhdarchid biting baby sauropod. Below: Azhdarchid organs including stomach (green) do not appear to be able accommodate such a large meal. Gastralia prevent ventral expansion.

Figure 1. Above: original art from artist M Witton (Witton and Naish 2008) showing azhdarchid biting baby sauropod. Below: Azhdarchid organs including stomach (green) do not appear to be able accommodate such a large meal. Gastralia prevent ventral expansion.

A skeletal view of the same azhdarchid
to the same scale (Fig. 1 below) shows the approximate lungs (blue), heart (red), liver (brown), stomach (green), intestines (pink), kidneys (red brown) and bladder (yellow) along with the same  baby dinosaur reduced slightly due to perspective. The wing membranes are also repaired. The tiny sternum is shown on the chest of the biting azhdarchid, another factor in giant azhdarchid flightlessness.

Based on the given parameters
the azhdarchid stomach (green) does not appear to be able to accommodate such a large meal all at once.

The analogous saddle-billed stork
(Ephippiorhynchus senegalensis, Fig. 2) eats what appears to be a similar-sized meal, but note the abdomen of the bird is relatively much larger than that of the azhdarchid and the meal is relatively smaller, much more flexible, without limbs, largely meat/muscle content and wet. Unfortunately Witton and Naish did not consider stomach size in their PlosOne paper.

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.

Figure 2. In my opinion this saddle-bill stork (genus: Ephippiorhynchus) wading in water appears to be the bird closest to azhdarchid morphology and, for that matter, niche.

An alternative wading lifestyle,
(Figs. 2, 3) dismissed by Witton and Naish 2008, appears to be more appropriate, based on the stomach size and other wading stork-like traits evidenced by azhdarchids. In LiveScience.com writer Jeanna Bryner (link below) wrote, ‘Witton and Naish learned that more than 50 percent of the azhdarchid fossils had been found inland. Other skeletal features, including long hind limbs and a stiff neck, also didn’t fit with a mud-prober or skim-feeder. All the details of their anatomy, and the environment their fossils are found in, show that they made their living by walking around, reaching down to grab and pick up animals and other prey,” Naish said.

“Their tiny feet also ruled out wading in the water or probing the soft mud for food. “Some of these animals are absolutely enormous,” Witton told LiveScience. “If you go wading out into this soft mud, and you weigh a quarter of a ton, and you’ve got these dinky little feet, you’re going to just sink in.”

Quetzalcoatlus neck poses. Dipping, watching and displaying.

Figure 3. Quetzalcoatlus neck poses. Dipping, watching and displaying.

We don’t know how soft the mud was
wherever azhdarchids fed. Analogous herons and storks seem to deal with underwater mud very well with similarly-sized feet. Witton and Naish report, Some storks with relatively small feet are known to wade indicating that azhdarchids may have been capable of some wading activity, but the high masses of large azhdarchids may have limited their ability to wade on soft substrates. Moreover, other pterodactyloids with larger pedal surface areas (most notably ctenochasmatoids) were almost certainly better adapted waders than azhdarchids. In view of this evidence, we suggest that azhdarchids were not habitual, although perhaps faculatative, waders.”

Don’t you wish the authors had performed some sort of test
to show azhdarchids were not like storks? Perhaps they could have employed a tank full of water and a variety of mud-like, sand-like and pebble-like substrates with a model azhdarchid foot and hand (btw, halving the weight of the azhdarchid directed through the feet) pressed with increasing weight to gauge the amount of sink. Instead they relied on their imaginations and made suggestions based on their initial bias. Nor did they discuss the factor of the hands supporting half the weight, nor the possibility of floating on the surface, polling with the hands and feet (Fig. 4), producing manus-only tracks, which are documented.

Witton and Naish did not attempt to show the maximum size of an object an azhdarchid stomach could handle, shown above (Fig. 1). In hindsight, that would have negated their dinosaur-killer hypothesis and the reason for their paper.

Figure 1. The azhdarchid pterosaur Quetzalcoatlus floating and poling producing manus only tracks.

Figure 4. The azhdarchid pterosaur Quetzalcoatlus floating and poling producing manus only tracks.

Witton and Naish 2008 report,
“Scavenging storks and corvids manage to open carcasses quickly and bite off pieces of flesh without the aid of curved jaw tips. Therefore, it seems almost certain that azhdarchids would have been capable of feeding upon at least some elements of large carcasses, although their long skulls and necks would inhibit their ability to obtain flesh from the deepest recesses of a corpse. However, although carrion was a likely component of azhdarchid diets, they possess no anatomical features to suggest they were obligate scavengers.”

Now you can ask,
did this azhdarchid (Fig. 1) kill this baby sauropod and then pick the meat from the bone? It is important to consider this and other possibilities. If so, the best meat would have come from the base of the tail and proximal limbs, not the neck or ‘breast.’

Azhdarchids and Obama

Figure 5. Click to enlarge. Here’s the 6 foot 1 inch President of the USA alongside several azhdarchids and their predecessors. Most were knee high. The earliest examples were cuff high. The tallest was twice as tall as our President. This image replaces an earlier one in which a smaller specimen of Zhejiangopterus was used.

Phylogenetically
what azhdarchids did ever since they were the size of tiny pterodactylids (Fig. 5) in the Late Jurassic is nibbling on bottom-dwelling prey. Larger, older, later azhdarchids were able to feed further out from shore in deeper ponds than smaller taxa and younger azhdarchids.  Witton and Naish did not discuss azhdarchids in a phylogenetic context evolving from tiny wading taxa. That is unfortunate because phylogeny is the backstory that informs every taxon. Phylogeny solves so many issues. That’s why the LRT and LPT (large pterosaur tree) could be so important for paleo workers, but, so far, they prefer not to use it.

Still struggling,
Witton and Naish began their 2015 introduction with, “Azhdarchids are among the most aberrant and remarkable of pterodactyloid pterosaurs.” Not really, As figure 5 shows, azhdarchids were simply larger versions of their small to tiny Late Jurassic ancestors, some of whom were also flightless waders.


References
Witton MP and Naish D 2008. A reappraisal of azhdarchid pterosaur functional morphology and paleoecology. PLoS ONE 3(5): e2271. https://doi.org/10.1371/journal.pone.0002271
Witton MP and Naish D 2015. Azhdarchid pterosaurs: water-trawling pelican mimics or “terrestrial stalkers”?. Acta Palaeontologica Polonica, 60(3), 651-660

Seems everyone bought into this invalid hypothesis:
https://www.livescience.com/
https://www.theguardian.com

The Times (UK) declares: proof for ‘winged dinosaurs’ vaulting

According to The Times.co.uk,
“Isle of Wight find proves winged dinosaurs took off by ‘vaulting’ into the air. Following the discovery of a fossilised giant pterosaur, scientists may have resolved how the 650lb beasts took flight. The sheer size of such creatures has long baffled scientists because they seem too heavy to take off. Now research with a computerised 3D model suggests they used their massive leg and wing muscles to catapult themselves into the air.”

Figure 1. Image from The Sunday Times (UK) showing the Isle of Wight and an ornithocheird filled with helium on a smaller planet taking off by vaulting.

Figure 1. Image from The Sunday Times (UK) showing the Isle of Wight and an ornithocheird filled with helium on a smaller planet taking off by vaulting. See figure 2 for the 650 lb Hatzegopteryx. The human silhouette (gray at left) is way too small for this ornithocheirid, so they got their pterosaurs mixed-up.

“Robert Coram, a professional fossil hunter who made the find, said: “It might have been the largest flying creature that had ever lived up to that time.”

“Mr Habib explained: “Mathematical modelling indicates that launching from a quadrupedal stance — pushing off first with the hind limbs and then with the forelimbs — would have provided the leaping power giant pterosaurs required for takeoff.”

FIgure 2. From The Sunday Times (UK) showing a human to scale with a restoration of Hatzegopteryx.

FIgure 2. From The Sunday Times (UK) showing a human to scale with a restoration of Hatzegopteryx.

This article appears to follow a Witton 2019 SVPCA abstract
(coincidence?) discussing the flight capabilities of the giant azhdarchid, Hatzegopteryx, using Graphic Double Integration and Principal Component Analysis. AND this article coincides with a Scientific American cover story on pterosaurs by Dr. Habib, discussed earlier here.

The pterosaur experts talking to The Times are still not discussing
the much smaller phylogenetic ancestors of azhdarchids with longer wings, nor do they consider the reduced to vestigial distal phalanges that essential clip the wings of azhdarchids over 1.8 m (6 ft) tall, nor do they recognize the traits that attend small flightless pterosaurs.

Let’s stop promoting giant volant pterosaurs
until these objections are met and resolved. Perhaps a little backtracking and apologizing for earlier grand standing is in order here.

Figure 1. Estimating giant azhdarchid weight from estimated height and comparables with similar smaller taxa.

Figure 3. Estimating giant azhdarchid weight from estimated height and comparables with similar smaller taxa.

Let’s define giant pterosaurs
as those at least 2m or 7ft tall at the eyeball (sans crest if present). The rest are large (more or less human-sized) pterosaurs (comparable to Pelagornis, Fig. 4) or smaller pterosaurs comparable to some other extant bird (e.g. goose-, robin- or hummingbird-sized).

Figure 1. Click to enlarge. The largest flying and non-flying birds and pterosaurs to scale.

Figure 4. Click to enlarge. The largest flying and non-flying birds and pterosaurs to scale.

You might remember
an earlier post featuring a classified ad from U of Leicester, (UK) seeking a student to prove the vaulting pterosaur hypothesis by finding appropriate pterosaur tracks. The Isle of Wight includes several strata with dinosaur tracks. Perhaps someday they will deliver giant pterosaur tracks that suddenly end. Then we can argue if the pterosaur flew from that point on and how it did so.


References
Witton M 2019. You’re going to need a bigger plane: body mass and flight capabilities of the giant pterosaur. SVPCA abstracts.
Counter arguments based on facts appear here:

Cryodrakon boreas: new Canadian azhdarchid: pt. 2

Hone, Habib and Therrien 2019
bring us news of several bones from several individuals of various sizes of a new mid-sized Canadian azhdarchid, Cryodrakon boreas (Fig. 1). Earlier today we looked at the promotional materials for this paper. Now, praise and criticism for the authors.

The name is excellent.
“Cryodrakon derived from the Ancient Greek for ‘cold’ and ‘dragon,’ boreas from the Greek god of the north wind. This is therefore the ‘cold dragon of the north winds.’”

The authors uncritically cite Wellnhofer 1970 who,
“suggested that the cervical vertebrae of azhdarchids elongate during ontogeny (i.e., show positive allometry). If correct, this can make identification of positions of individual vertebrae, and comparisons between specimens and taxa, difficult when specimens are small.” 

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 1. 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.

Unfortunately,
this reliance on citation shows the authors’ lack of understanding about pterosaur isometric (lepidosaur-like) growth patterns, proven by the several growth series demonstrated in the azhdarchid, Zhejiangopterus (which they cite, Fig. 1), Rhamphorhynchus (the subject of a rejected paper), and Pterodaustro (not to mention the several pterosaur embryos known).

The authors discuss a very large cervical mid-shaft,
TMP 1980.16.1367, but do not show it. Dang.

The most complete specimen of Cryodrakon
TMP 1992.83 includes several disarticulated bones (Fig. 2) here reduced to x.70 to match tibias to scale with Quetzalcoatlus sp.

Figure 2. The most complete Cryodrakon compared to the most complete Q. sp. Most elements are identical in size when scaled x.70 to match tibia lengths, but the cervical, metatarsal and humerus are relatively smaller in Cryodrakon.

Figure 2. The most complete Cryodrakon compared to the most complete Q. sp. Most elements are identical in size when scaled x.70 to match tibia lengths, but the cervical, metatarsal and humerus are relatively smaller in Cryodrakon.

Bone thickness
The authors report, “A break in the humerus of Quetzalcoatlus sp. (TMM 47180) reveals that cortical bone thickness [1.07mm] is near identical to that of Cryodrakon [1.1-1.3mm] (for which cortical bone thickness data were obtained by computed tomography [CT] imaging).” Note that the cortical thickness ratio (x 0.82) nearly matches the scale difference x 0.70). Fact: Large flightless azhdarchids are not evolving more solid bones, distinct from giant flightless birds.

Back to the humerus
The authors report, “Overall, the humeri of Cryodrakon and Quetzalcoatlus are quite similar, varying in most proportions within the range that would be expected for intraspecific comparisons.” The images of both (Fig. 2) do not support that statement. The authors conclude, “The greatest difference in overall shape is the slightly exaggerated flaring of the humerus distally in Quetzalcoatlus.” 

You decide what the differences are.
The authors should have showed the two humeri side-by-side.

Flight
The authors report, “These similarities confirm that Cryodrakon and Quetzalcoatlus were likely of very similar size and build, and the two species likely shared similar flight performance characteristics and flight muscle fractions.” This assumes that azhdarchids of this size could fly, regardless of the vestigial distal wing phalanges (= clipped wings) that argue against that hypothesis in Q. sp. (Fig. 2; wingtip unknown in Cryodrakon).

Weight
The authors report, “Combined with the somewhat greater length of the humerus in Cryodrakon, it is likely that Cryodrakon was slightly heavier than Quetzalcoatlus but that their overall mass was likely similar.” Yes! True? But not so fast. Scaled to a similar tibia, pteroid and metacarpal length, the feet, neck and humerus were all smaller (Fig. 2). Then remember: to achieve that scale Cryodrakon was reduced to x 0.70 from its original size. So Cryodrakon had big legs, big hands, small feet (used as twin rudders in smaller taxa), a slender humerus… not really the traits you’re looking for in a volant pterosaur (by comparison, see Jidapterus below). Finally, weight is never the issue if you have plenty of thrust and lift. But those two factors are reduced in large azhdarchids, all of which had clipped wings (vestigial distal phalanges).

Cervical comparisons and bauplan
The authors report, “The cervical vertebrae of Cryodrakon are absolutely more robust than those of Quetzalcoatlus.” No. They are relatively smaller (Fig. 2). See for yourself.

It really does help to follow the scale bars,
placing the bones upon a good Bauplan (blueprint) to see how incompletely known taxa compare to more completely known taxa. This last graphic step is something the authors did not provide or experiment with. If they had done so, they would not come to such conclusions. The referees (Drs. Martill, Naish and Bever) could also have raised these issues or suggested graphic experiments (Fig. 2).

Cladistic analysis
The authors report, “The fragmentary nature of the material available, and possible ontogenetic trajectories, prevents us from conducting a cladistic analysis to determine the phylogenetic relationships of Cryodrakon boreas. Nevetheless, certain characteristics permit a preliminary assessment of the phylogenetic position of the taxon within Azhdarchidae. For example, it does lack distinct cervical zygapophyses for the middle cervicals, a trait that suggests that it does not lie within basal-most Azhdarchidae, but instead within the Jidapterus-Quetzalcoatlus clade.”

Figure 1. Jidapterus compared to the new Lower Cretaceous pterosaur tracks. It's a pretty close match.

Figure 3. Jidapterus compared to the new Lower Cretaceous pterosaur tracks. It’s a pretty close match.

Since the authors brought up Jidapterus
it is worth our while to see for ourselves the relative size of its humerus and wing in this small azhdarchid (Figs. 3,4). Note the relatively larger humerus in Jidapterus. Only wing phalanx 4.4 is shorter here, with a folded wing that extends higher than the shoulder girdle, distinct from the much larger flightless azhdarchids.

Azhdarchids and Obama

Figure 4. Click to enlarge. Here’s the 6 foot 1 inch President of the USA alongside several azhdarchids and their predecessors. Most were knee high. The earliest examples were cuff high. The tallest was twice as tall as our President. This image replaces an earlier one in which a smaller specimen of Zhejiangopterus was used.

Jidapterus and Chaoyangopterus represent the transitional ‘end of the road’
for flying in azhdarchids. What follows (Fig. 4) are shorter distal wings and much larger flightless taxa.

Let’s put an end to the myth
that large azhdarchids were the largest flying animals of all time, a myth promoted by pterosaur paleontologists who should know better, but have staked their professional reputations on showmanship (rather than science).  We still have long-winged pteranodontids and ornithocheirids to compete with long-winged Pelagoris, among the largest bird aviators. That’s the Bauplan nature insists on if you’re a big flyer.


References
Hone DWE, Habib MB and Therrien F 2019. Cryodrakon boreas, gen. et sp. nov., a Late Cretaceous Canadian azhdarchid pterosaur. Journal of Vertebrate Paleontology Article: e1649681 DOI: 10.1080/02724634.2019.1649681

www.nationalgeographic.com
www.newsweek.com