New Como Bluff (Latest Jurassic) pterosaurs

Bits and pieces
of new Latest Jurassic pterosaurs are coming out of aquatic deposits in western North America according to McLain and Bakker 2017. The material is 3D and not very mineralized, so it is extremely fragile.

Specimen(s) #1 – HMNS/BB 5027, 5028 and 5029
“One proximal and two distal femora match a complete femur (BYU 17214) referred to Mesadactylus. Unexpectedly, both of the BBF distal femora possess a large intercondylar pneumatopore. BYU 17214 also possesses an intercondylar pneumatopore, but it is smaller than in the BBF femora. Distal femoral pnuematicity is previously recognized only in Cretaceous azhdarchoids and pteranodontids.”

The Mesadactylus holotype and referred specimens reconstructed to match the flightless pterosaur, Sos2428.

Figure 1. The Mesadactylus holotype (Jensen and Padian 1989) nests with the North American anurognathids. Several referred specimens (Smith et al. 2004), when reconstructed nest at the base of the azhdarchidae, with Huanhepterus and the flightless pterosaur SOS 2428.  The new BYU 17214 femur is essentially identical to the femur shown here.

Earlier we looked at two specimens referred to Mesadactylus. One is an anurognathid (Fig. 1). The other is a basal azhadarchid close to Huanhepterus, not far removed from its Dorygnathus ancestors in the large pterosaur tree. Instead McLain and Bakker compare the femora with unrelated and Early Cretaceous Dsungaripterus, which convergently has a similar femur. The better match is to the basal azhdarchid, so distal femoral pneumaticity does not stray outside of this clade. By the way, it is possible that Mesadactylus was flightless.

Specimen(s) #2 – HMNS/BB 5032 (formerly JHU Paleon C Pt 5)
“A peculiar BBF jaw fragment shows strongly labiolingually compressed, incurved crowns with their upper half bent backwards; associated are anterior fangs. We suspect this specimen is a previously undiagnosed pterosaur.”

These toothy specimens were compared to two Early Cretaceous ornithocheirids, one Middle Jurassic dorygnathid, and one Latest Jurassic bird, Archaeopteryx. None are a good match. A better, but not perfect,match can be made to the Early Jurassic pre-ctenochasmatid, Angustinaripterus (Fig. 2) which has relatively larger posterior teeth than does any Dorygnathus specimen.

The HMNS BB 5032 specimen(s) probably belong to a new species of Angustinaripterus or its kin based on the relatively large posterior teeth not seen among most Dorygnathus specimens.

The HMNS BB 5032 specimen(s) probably belong to a new species of Angustinaripterus or its kin based on the relatively large posterior teeth not seen among most Dorygnathus specimens.

As before,
we paleontologists don’t always have to go to our ‘go to’ taxon list of familiar fossils. Expand your horizons and take a fresh look at some of the less famous taxa to make your comparisons. You’ll find a good place to start at ReptileEvolution.com

References
McLain MA and RT Bakker 2017. Pterosaur material from the uppermost Jurassic of the uppermost Morrison Formation, Breakfast Bench Facies, Como Bluff,
Wyoming, including a pterosaur with pneumatized femora.

Allkaruen koi was overlooked as a proto-Pterodaustro

A new pterosaur described by Codorniú et al. 2016
somehow escaped my notice until today. Allkaruen koi (Figs. 1,3,4) is the new genus. It was originally nested between basal (long-tailed) pterosaurs and the Darwinopterus clade + ‘Pterodactyloidea’ using an antiquated cladogram modified from Lü e al 2010, itself modified from Unwin 2003. We’re going to critically examine this paper, applying logic, creating reconstructions, calling on overlooked data and including more than a few previously excluded taxa.

Figure 1. Allkaruen elements as originally published.

Figure 1. Allkaruen elements as originally published. Some of the scale bars are different by 94% and 117%, resized to the same scale below in figure 3. Why couldn’t they all be drawn to the same scale, and in relation to one another? You’ll see how well that works in figure 3.

The holotype of Allkaruen koi includes:

  1. MPEF-PV 3613 (Museo Paleontológico Egidio Feruglio)  braincase,
  2. MPEF-PV 3609 mandible
  3. MPEF-PV 3615 cervical vertebrae (Fig. 1)

The stratigraphic horizon
in which Allkaruen was found was labeled by Codorniú et al.: “latest Early-early Middle Jurassic.” Let’s just call it “Middle Jurassic.”

From the Codorniú et al. abstract
“Here we report on a new Jurassic pterosaur from Argentina, Allkaruen koi gen. et sp. nov., remains of which include a superbly preserved, uncrushed braincase that sheds light on the origins of the highly derived neuroanatomy of pterodactyloids and their close relatives. A mCT ray-generated virtual endocast shows that the new pterosaur exhibits a mosaic of plesiomorphic and derived traits of the inner ear and neuroanatomy that fills an important gap between those of non-monofenestratan breviquartossans (Rhamphorhynchidae) and derived pterodactyloids.”

The diagnosis:
“Small pterosaur diagnosed by the following unique combination of skull characters present in the holotype (autapomorphies marked with asterisk):

  1. frontal with large pneumatic foramen on the postorbital process
  2. dorsal occiput faces posterodorsally and occipital condyle faces posteroventrally
  3. long, rod-like basipterygoid processes diverging at approximately 20–25 degrees.

The referred mandibular and vertebral materials also show a unique combination of characters that include:

  1. a long lower jaw with a concave profile in lateral view
  2. four-five large, septated, and well-separated anterior alveoli followed by a posterior alveolar groove*;
  3. mid-cervical vertebrae elongate with low neural arch and blade-like neural spine; pneumatic foramina on lateral surface of the centrum and peduncle of the neural arch
  4. reduced diapophyseal process lacking articular surface
  5. absence of accessory zygapophyseal processes.”
Codornií cladoram nesting Allkaruen between basal pterosaurs and derived pterosaurs.

Figure 2. Codornií cladoram nesting Allkaruen between basal pterosaurs and derived pterosaurs. Note that a dinosaur is the outgroup here. There are 59 taxa above. Note the close relationship of Dorygnathus and Allkaruen and Pterodaustro in this cladogram. It gets even closer in figure 6.

The Codorniú et al. phylogenetic analysis
Codorniú et al. added Allkaruen to the cladogram of Lü et al 2003 (the Darwinopterus study) based on Unwin 2003. They recovered Allkaruen basal to their ‘Monofenestrata, which was basal to their ‘Pterodactyloidea’. Both clades were found to be invalid in the large pterosaur tree.

Figure 3. Reconstruction of Allkaruen atop a more complete Pterodaustro to the same scale demonstrating a close match-up of elements.

Figure 3. Reconstruction of Allkaruen atop a more complete Pterodaustro to the same scale demonstrating a close match-up of elements that was somehow overlooked by the original authors. The amount of material missing between the mandibles and the cranium is unknown. See figure 4 for a closer look at the cranium. Note the tooth grooves and anterior alveoli in the top view of the dentary.

A reconstruction
missing from the original paper, but provided here (Fig. 3) provides an overlooked answer to the affinities of Allkaruen. This Middle Jurassic taxon closely matches Albian (latest Early Cretaceous) Pterodaustro, the only other South American pterosaur with a dorsally concave dentary (#1), an alveolar groove (#2), similar mid-cervical vertebrae (#3) and maybe traits #4 and #5, (hard to tell from the available data). The dorsal appearance of the cranium of Allkaruen also closely matches that of another ctenochasmatid, Gnathosaurus. Most to all Pterodaustro specimens are preserved in lateral view, so the dorsal appearance must be gained from closely related taxa. like Gnathosaurus, by phylogenetic bracketing.

Figure 4. Closeup of the cranium and brain scan of Allkaruen atop a ghosted to scale image of Pterodaustro demonstrating a close affinity that was somehow overlooked originally.

Figure 4. Closeup of the cranium and brain scan of Allkaruen atop a ghosted to scale image of Pterodaustro to scale demonstrating a close affinity that was somehow overlooked originally with that short taxon list.

Pterodaustro is distinct from other ctenochasmatids
in that it has typical tetrapod vertically oriented mandibles, rather than flattened (wider than tall) mandibles typical of other ctenochasmatids (Fig. 7). In addition Pterodaustro has upwardly curved jaw tips, a trait documented in Allkaruen, in which we can see the transition from a toothy dentary to one with grooves to accommodate the hundreds of needle-like filter teeth found in Pterodaustro. Not sure why, but this similarity was overlooked by Codorniü et al. It’s doubly puzzling because Dr. Codorniú has published extensively on Pterodaustro. The only time Pterodaustro was mentioned by Codorniú et al. was when they wrote, “The cavities that invade the basicranium are also large, equivalent to those observed in pterodactyloids such as Pterodaustro.”

Figure 4. Chronological evolution of Pterodaustro via Allkaruen, Angustinaripterus (Early Jurassic) and Dorygnathus (late survivor in the Middle Jurassic).

Figure 5. Chronological evolution of Pterodaustro via Allkaruen, Angustinaripterus (Early Jurassic) and Dorygnathus (late survivor in the Middle Jurassic).

The pterosaur phylogeny presented
by the large pterosaur tree (LPT, subset Fig. 5) provides a fast track evolution from derived dorygnathids, already demonstrating a wide radiation in the Early Jurassic, to ctenochasmatids like Allkaruen (Middle Jurassic) and Ctenochasma (Late Jurassic) that does not include the Darwinopterus clade as transitional taxa. In the LPT four clades evolved a complete set of pterodactyloid-grade traits. Two other clades, Anurognathidae and Wukongipteridae, independently evolved an incomplete set of pterodactyloid-grade traits. These led to invalid claims by Andres, Clark and Xu 2014 that anurognathids were basal to pterodactyloids and Unwin 2003 + Lü et al. 2010 that wukongopterids were basal to pterodactyloids. These claims were made with short, incomplete taxon inclusion lists that were shown to be lacking in pertinent taxa by the LPT.

Fig. 5. Subset of the LPT focusing on Dorygnathus clades that evolved to become ctenochasmatids and azhdarchids. This is what you get when don't exclude taxa the way Codorniú did.

Fig. 6. Subset of the argePT focusing on Dorygnathus clades that evolved to become ctenochasmatids and azhdarchids. This is what you get when don’t exclude taxa the way Codorniú did.

It’s no surprise that Allkaruen has transitional traits.
In the LPT it represents a transitional stage in the evolution of Pterodaustro from Angustinaripterus ancestors. Allkaruen nests with Pterodaustro in the LPT, but due to the headless D2514 ‘not Eosipterus‘ specimen adding Allkaruen creates a polytomy (Fig. 6). As earlier, no claim of ‘mosaic evolution‘ can be made by Codorniú et al. ‘Mosaic evolution’ has not been shown to exist in large gamut cladograms. Such claims by Codorniú et al. and others are the result of small cladograms grossly lacking in pertinent taxa.

A selection of valid Ctenochasma skulls

Figure 7. A selection of valid Ctenochasma skulls together with the two interpretations of Sos 2179 (in gray below). Note the phylogenetic miniaturization following Angustinaripterus.

Professional bias among paleontologists
and a refusal to test competing hypotheses of relationships (Peters 2000, 2007) led to the phylogenetic disaster presented by Codorniú et al. 2016. No one will ever be convinced that pterosaurs arose from Euparkeria + HerrerasaurusWorkers who do so open themselves up to ridicule. We don’t want that. It makes us all look bad. Adding taxa should solve the phylogenetic problems found in Codorniú et al. The LRT and LPT offer suggestions, but workers must put forth the effort. In Peters 2000 Cosesaurus, Sharovipteryerx and Longisquama were documented to demonstrate closer relationships to pterosaurs than dinosaurs and archosaurs can offer.

Was Allkaruen transitional between basal pterosaurs and pterodactyloids?
No. There is no valid monophlietic clade of pterodactyloids. At present, the best we can say is: Middle Jurassic Allkaruen is (time wise) transitional between Early Jurassic Angustinaripterus and Early Cretaceous Pterodaustro (Fig. 5). Allkaruen is a ctenochasmatid, plain and simple. It points to an earlier radiation of ctenochasmatids than the Solnhofen Late Jurassic. The cranial elements of Allkaruen might someday be matched to post-cranial elements now represented by the lower Yixian D2514 specimen wrongly attributed (by Lü et al. 2006) to Eosipterus. Or not. A complete specimen (crania + post-crania) would settle this  issue.

I can’t be the first pterosaur worker to notice
the Allkaruen/Pterodaustro connection. If others preceded me, please let me know so I can congratulate and confirm them.

Everyone, including Codorniu et al., is looking for
that one transitional taxon, that ‘missing link’ between long-tailed pterosaurs and short-tailed pterosaurs. Andres, Clark and Xu 2014 failed when they mistook small parts of a skinny dorygnathid for a much smaller pterodactyloid. Lü et al. 2010 failed when they added Darwinopterus to a small gamut cladogram. Codorniú et al. failed when they promoted Allkaruen to that position. The authority to state that these PhDs failed comes from a large gamut cladogram, the LPT, that tests their short taxon lists with a much larger taxon list. The LPT documents four appearances of pterodactyloid-grade clades and so will competing studies when they expand their lists, create reconstructions and have a third party certify their scores are correct.

Ironically, no one’s looking for
that one transitional taxon, that ‘missing link’ between pre-volant pterosaur ancestors and basal pterosaurs. Do you wonder why that is? I can only suppose no one wants to confirm the published work of an amateur from 17 years ago (Peters 2000). There’s no reward in it for PhDs. No one wants to admit they were wrong and needlessly parochial for 17 years.

References
Andres, B, Clark J and Xu X 2014. The Earliest Pterodactyloid and the Origin of the Group. Current Biology. 24: 1011–6.
Codorniú L, Carabajal AP, Pol D, Unwin D and Rauhut OWM 2016.
 A Jurassic pterosaur from Patagonia. and the origin of the pterodactyloid neurocranium. PeerJ 4:e2311; DOI 10.7717/peerj.2311
Lü J-C, Gao C-L, Meng Q-J, Liu J-Y, Ji Q 2006. On the Systematic Position of Eosipterus yangi Ji et Ji, 1997 among Pterodactyloids. Acta Geologicia Sinica 80(5):643-646.
Lü J, Unwin D, Jin X, Liu Y, Ji Q 2010. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceeding of the Royal Society B 273:383389.
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 2003. On the phylogeny and evolutionary history of pterosaurs. In:Buffetaut E, Mazin J-M, eds. Evolution and Paleobiology of Pterosaurs, vol. 217. London: Geological Society, Special Publications, 139190.

wiki/Allkaruen

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 it is interpreted as a rostrum and mandible, both with parallel rami.

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.

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

Another look at a possible pterosaur wingtip ungual

Figure 1. The Yale specimen of Rhamphorhynchus phyllurus with preserved wingtip ungual highlighted. See figure 2 for closeup.

Figure 1. The Yale specimen of Rhamphorhynchus phyllurus with preserved wingtip ungual highlighted. See figure 2 for closeup.

The Yale specimen of Rhamphorhynchus phyllurus (Figs. 1, 2; VP 1001778) has one painted wing tip and one that may include another wingtip ungual.

Figure 2. Closeup of Rhamphorhynchus phyllurus in figure 1 focusing on the preserved wingtip ungual.

Figure 2. Closeup of Rhamphorhynchus phyllurus in figure 1 focusing on the preserved wingtip ungual. Was this carved in? Or is it real? Note the cylindrical tip of the penultimate wing phalanx (m4.4). The wingtip was buried deep within the matrix and had to be exposed.

The wingtip
was buried deep within the matrix and had to be exposed. So the question is: was it carved? Or is it real? If it was carved, why was it carved? Traditionally pterosaurs are not supposed to have wing tip unguals, but I’ve found them in several specimens.

You might remember
we looked at this wing tip earlier with a different provided image. The present one appears to offer more clues.

One of the largest Pterodaustro specimens had stomach stones

aka: Gastroliths.
And that’s unique for pterosaurs of all sorts. So, what’s the story here?

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

Figure 1. The MIC V263 specimen compared to other Pterodaustro specimens to scale. Its one of the largest and therefore, most elderly.

One of the largest Pterodaustro specimens
MIC V263 (Figs. 1-5), was reported (Codorniú, Chiappe and Cid 2013) to have stomach stones (gastroliths). That made news because that represented the first time gastroliths have been observed in 300 Pterodaustro specimens and thousands of pterosaurs of all sorts.

Unfortunately,
Codorniu, Chiappe and Cid followed tradition when they aligned pterosaurs with archosaurs, like dinos (including birds) and crocs. Those taxa also employ gastroliths for grinding devices. According to Codorniú, Chiappe and Cid, other uses include as a personal mineral supply, maintaining a microbial flora, elimination of parasites and hunger appeasement. Shelled crustaceans may have formed a large part of the Pterodauastro diet and stones could have come in handy on crushing their ‘shells’ according to the authors.

FIgure 2. Pterodaustro specimen MIC V263 in situ and as originally traced.

FIgure 2. Pterodaustro specimen MIC V263 in situ and as originally traced.

The authors also noticed
an odd thickening of the anterior dentary teeth and the relatively large size of the MIC V 263 specimen (Fig. 1) and suggested their use as devices for acquiring stones.

The wingspan of this big Pterodaustro is estimated at 3.6 meters.

Figure 1. Pterodaustro elements from specimen MIC V263.

Figure 3. Pterodaustro elements from specimen MIC V263.

Unfortunately,
the authors overlooked a wingtip ungual (Fig. 4), or so it seems… The confirming wingtip ungula is off the matrix block. But they weren’t looking for it…

Figure 2. One wing ungual was preserved in this specimen of Pterodaustro. The other is missing off the edge of the matrix.

Figure 4. One wing ungual was preserved in this specimen of Pterodaustro. The other is missing off the edge of the matrix.

The authors overlooked a distal phalanges on the lateral toe (Fig. 5). It is hard to see. And they were not looking for it. Note the double pulley joint between p2.1 and p2.2. That’s where the big bend comes in basal pterosaurs.

Figure 5. Pterodaustro MIC V263 pes in situ and with pedal digit 2 reconstructed from overlooked bones.

Figure 5. Pterodaustro MIC V263 pes in situ and with pedal digit 2 reconstructed from overlooked bones.

The authors overlooked a manual digit 5, the vestigial near the carpus (Fig. 6) displaced to the disarticulated carpus during taphonomy. Again, easy to overlook. And they were not looking for it…

Figure 6. Carpus of the Pterodaustro specimen MIC V263 withe elements colorized. Manual digit 5 elements are in blue on the pink ulnare.

Figure 6. Carpus of the Pterodaustro specimen MIC V263 withe elements colorized. Manual digit 5 elements are in blue on the pink ulnare. Not sure where carpal 5 is.

The authors
labeled the unguals correctly (Fig. 7), but some of the phalanges escaped them. Note the manual unguals are not highly curved, like those of Dimorphodon and Jeholopterus. And for good reason. Pterodaustro is a quadrupedal beachcomber with the smallest fingers of all pterosaurs. It’s not a tree clinger. And for the same reason, pterosaurs with long curved manual claws are not quadrupeds. Paleontologists traditionally attempt to say all pterosaurs are quadrupeds, rather than taking each genus or clade individually. Beachcombers made most of the quadrupedal tracks. It’s also interesting to note that Pterodaustro fingers bend sideways at the knuckle, in the plane of the palm, probably in addition to flexing toward the palm. It’s easier for lizards to do this, btw. Not archosaurs. That’s how you get pterosaur manual tracks with digit 3 oriented posteriorly, different from all other tetrapods.

Figure 7. Pterodaustro MIC V 263 fingers reconstructed and restored.

Figure 7. Pterodaustro MIC V 263 fingers reconstructed and restored. Pterodaustro is unusual in having metacarpals 1 > 2 > 3. Note the flat tipped manual unguals. Not good for climbing trees, like those of many other pterosaurs.

So the question is: why did this specimen have stones inside—
when other pterosaurs do not? Since MIC V263 is larger, it is probably older, closer to death by old age. Was it supplementing an internal grinding structure that had begun to fail? Was this some sort of self-medication for a stomach ailment? It’s not standard operating procedure for pterosaurs to have stomach stones. So alternate explanations will have to do for now. Let’s not assume or pretend that all pterosaurs had gastroliths. They don’t.

Figure 8. Elements of the MIC V263 specimen applied to the smaller PPVL 3860 specimen scaled to the length of the metacarpals. At this scale the large Pterodaustro had a shorter wing and shorter fingers with smaller unguals.

Figure 8. Elements of the MIC V263 specimen applied to the smaller PVL 3860 specimen scaled to the length of the metacarpals. At this scale the large Pterodaustro had a shorter wing and shorter fingers with smaller unguals.

Compared to the largely complete and articulated Pterodaustro specimen,
PVL 3860, there are subtle differences in proportion (Fig 8) to the larger MIC V263 specimen. If metacarpals are the same length, then the wing is shorter in the larger specimen. This follows a morphological pattern in which no two tested pterosaurs are identical. Still looking for a pair of twins.

References
Codorniú L, Chiappe LM and Cid FD 2013. First occurrence of stomach stones in pterosaurs. Journal of Vertebrate Paleontology 33:647-654.

New Perspectives on Pterosaur Palaeobiology volume

The 2015 pterosaur meeting in Portsmouth, England
brings us several new papers. The meeting and abstracts were previewed here and reported on here by a participant.

From the intro: “The field of pterosaur research in palaeontology continues its rapid growth and diversification that began in recent decades. This volume is a collection of papers on these extinct flying reptiles that includes work on their taxonomy, behaviour, ecology and relationships.”

Oddly, the number of abstracts far exceeded the very few papers this time.

Palmer 2017 wrote:
“The preservation of the wing membrane of pterosaurs is very poor and the available fossil evidence does not allow its properties to be reconstructed. In contrast, the fossil record for the wing bones is relatively good and the advent of CT scanning has made it possible to build high-fidelity structural models of the wing spar. The bending strength of the wing spar of a 6 m wingspan ornithocheirid pterosaur is used to infer the likely membrane tension. The tensions required to suppress aeroelastic flutter and to minimize ballooning of the membrane under flight loads are also estimated. All three estimates are of similar magnitude and imply that the membrane must have contained high-modulus material, supporting the view that the reinforcing aktinofibrils were keratinous.”

Contra Palmer’s unfounded assertion, there are several specimens of pterosaurs that provide an excellent view of the wing membrane. For the most part wing shape designs continue to be stuck in the Dark Ages among several pterosaur workers with some actually flipping the wing tips. Those problems need to improve before further work on pterosaur wings.

Dalla Vecchia 2017 wrote:
“An incomplete bone from the latest Cretaceous dinosaur site of Villaggio del Pescatore (Trieste Province, Italy) is definitely a wing metacarpal of a pterodactyloid pterosaur. It represents the only Italian Cretaceous pterosaur remains known, as well as the only pterosaur from the Adriatic Carbonate Platform. With an estimated minimum length of 136 mm, it belongs to a relatively small individual relative to the standard of latest Cretaceous pterodactyloids. It is not as elongated and gracile as azhdarchid wing metacarpals and shows a mix of features found in Pteranodon and some more basal pterodactyloids. It is one of the very few remains of putative non-azhdarchid pterosaurs from the upper Campanian–Maastrichtian worldwide and supports the view that the Azhdarchidae were not the only pterosaur clade existing during latest Cretaceous times.”

Always good to see the gamut of pterosaurs increase.

Witton 2017 wrote:
“Understanding the ecological roles of pterosaurs is a challenging pursuit, but one aided by a growing body of fossil evidence for their dietary preferences and roles as food sources for other species. Pterosaur foraging behaviour is represented by preserved gut content, stomach regurgitates, coprolites and feeding traces. Pterosaurs being eaten by other species are recorded by tooth marks and teeth embedded in their fossil bones, consumer gut content and regurgitate, and their preservation entangled with predatory animals. This palaeoecological record has improved in recent years, but remains highly selective. The Jurassic rhamphorhynchid Rhamphorhynchus, Cretaceous ornithocheiroid Pteranodon and azhdarchid pterosaurs currently have the most substantial palaeoecological records. The food species and consumers of these taxa conform to lifestyle predictions for these groups. Rhamphorhynchus and Pteranodon ate and were eaten by aquatic species, matching expectations of these animals as sea-going, perhaps partly aquatic species. Possible azhdarchid pterosaur foraging traces alongside pterosaur tracks, and evidence that these animals were eaten by dinosaurs and Crocodyliformes, are consistent with hypotheses that azhdarchids foraged and lived in terrestrial settings. Fossil evidence of pterosaur palaeoecology remains rare: researchers are strongly encouraged to put specimens showing details of dietary preferences, foraging strategies or interactions with other animals on record.”

When Pteranodon is no longer considered an ornithocheiroid by ptero workers, I will celebrate.

Bennett and Penkalski 2017 wrote:
“Four specimens of the pterosaur Pteranodon exhibit patterns of irregular alternating light and dark bands on the lateral surfaces of the upper jaw anterior to the nasoantorbital fenestra. Examinations reveal that the maxilla and premaxilla of Pteranodon consisted of two thin sheets of bone interconnected by regularly spaced septa with the spaces contained within presumably pneumatized, resulting in a structure analogous to modern honeycomb sandwich panels. The alternating light and dark bands resulted from waves of bone deposition moving anteriorly along the external surface of the lateral sheet of bone and laying down thin laminae of new bone while bone was simultaneously resorbed from the internal surface of the lateral sheet to maintain its thickness. The specimens that exhibit the bands were immature males and no banding was found in mature specimens or immature females. Therefore, the presence of the bands in immature males is interpreted as correlated with the enlargement and reshaping of the rostrum as males approached and attained sexual maturity.”

Wonder if those immature males were really just more primitive species with smaller size and smaller crest? Earlier Bennett erred by considering the morphological differences in various Pteranodon specimens ontogenetic, rather than phylogenetic. He failed to realize that Pteranodon specimens don’t get to giant size with giant crests without going through transitional mid-size specimens derived from certain small, crestless Germanodactylus specimens. The lamination of pterosaur skull bones is something first described here with the anterior extension of the jugal nearly to the tip of the rostrum. However, what these two workers are describing appears to be another thing entirely.

Martill and Moser 2017 wrote:
“Six specimens accessioned to the Bavarian State Collection for Palaeontology and Geology in Munich, Germany, in 1966 are identified as coming from a gigantic pterodactyloid pterosaur. The previously undescribed material was obtained in 1955 by Jean Otto Haas and compares favourably in size with the type specimen of the Late Cretaceous (Maastrichtian) azhdarchid pterosaur Arambourgiania philadelphiae (Arambourg 1959) from the same locality/region. The material represents fragments of two cervical vertebrae, a neural arch, a left femur, a ?radius, and a metacarpal IV and bones of problematic identity, and does not duplicate the type material of Arambourgiania. The timing of its collection and its locality of Ruseifa, Jordan suggest it might pertain to the same individual as the holotype.” 

Interesting. More parts for the same specimen? That’s like more pieces to the same puzzle. On the other hand, when the term ‘pterodactyloid’ pterosaur falls by the wayside, I will also celebrate. Azhdarchids are not closely related tp Pterodactylus.

Rigal et al. 2017 wrote:
“A specimen of a pterodactyloid pterosaur from the Upper Tunbridge Wells Sand Formation (Early Cretaceous, Valanginian) of Bexhill, East Sussex, southern England is described. It comprises a small fragment of jaw with teeth, a partial vertebral column and associated incomplete wing bones. The juxtaposition of the bones suggests that the specimen was originally more complete and articulated. Its precise phylogenetic relationships are uncertain but it represents an indeterminate lonchodectid with affinities to Lonchodectes sagittirostris (Owen 1874) which is reviewed here, and may belong in Lonchodraco Rodrigues & Kellner 2013. This specimen is only the third record of pterosaurs from this formation.”

England is famous for excellent preservation of pterosaur bits and pieces, mostly jaws, as is the case here. The specimen is named Serradraco and has been known for over 150 years.

Henderson 2017 wrote:
“Simple, three-dimensional, digital models of the crania and mandibles of 22 pterosaurs – 13 pterodactyloids and nine non-pterodactyloids (‘rhamphorhynchoids’) – were generated to investigate gross-level mechanical aspects of the skulls as they would related to feeding behaviour such as bite force and speed of jaw motions. The key parameter was the determination of second moments of area of the mid-muzzle region and the computation of the bending moment relative to the occiput. The shorter, stockier skulls of basal ‘rhamphorhynchoids’ were the strongest for their size in terms of potential resistance to dorso-ventral bending, and this finding correlates with their robust dentitions. More derived ‘rhamphorhynchoids’ showed the start of a trend towards weaker skulls, but faster jaw adduction was interpreted to be an adaptation for the snatching of small prey. Pterodactyloids continued the trend to lengthen the skull and to reduce its cross-sectional area, resulting in less stiff skulls, but more rapid opening and closing of the jaws. Changes in the rear of the skulls and the development of coronoid eminences on the mandibles of all the pterodactyloids are correlated with the reduction in bite force and a concomitant increase in jaw closing speed.”

This makes sense, though I worry that ‘simple digital models’ by Henderson have not fared well in the past.

Hone, Jiang and Xu 2017 wrote: 
“After being inaccessible for a number of years, the holotype and other specimens of the dsungaripterid pterodactyloid pterosaur Noripterus complicidens are again available for study. Numerous taxa assigned to the Dsungaripteridae have been described since the erection of Noripterus, but with limited comparisons to this genus. Based on the information from Young’s original material here we revise the taxonomic identity of N. complicidens and that of other Asian dsungaripterids. We conclude that N. complicidens is likely to be distinct from the material recovered from Mongolia and this latter material should be placed in a separate genus.”

Okay. Wonderful. Thought I think some of us knew that already based on photo data.

And speaking of southern England…
did the U. of Leicester clade ever find the grad student they advertised for to prove the pterosaur quad leap hypothesis?

References
2017. New Perspectives on Pterosaur Palaeobiology. Hone  DWE, Witton MP and Martill DM editors. Geological Society, London SP455.
Bennett SC and Penkalski P 2017. Waves of bone deposition on the rostrum of the pterosaur Pteranodon.
Dalla Vecchia FM 2017. A wing metacarpal from Italy and its implications for latest Cretaceous pterosaur diversity.
Henderson DM 2017. Using three-dimensional, digital models of pterosaur skulls for the investigation of their relative bite forces and feeding styles.
Hone DWE, Jiang S, and Xu X 2017. A taxonomic revision of Noripterus complicidens and Asian members of the Dsungaripteridae.
Martill DM and Moser M 2017. Topotype specimens probably attributable to the giant azhdarchid pterosaur Arambourgiania philadelphiae (Arambourg 1959).
Palmer C 2017. Inferring the properties of the pterosaur wing membrane.
Rigal S, Martill DM, and Sweetman SC 2017. A new pterosaur specimen from the Upper Tunbridge Wells Sand Formation (Cretaceous, Valanginian) of southern England and a review of Lonchodectes sagittirostris (Owen 1874).
Witton MP 2017. Pterosaurs in Mesozoic food webs: a review of fossil evidence.

 

Liaodactylus, a new gnathosaurine pterosaur

Figure 1. Liaodactylus (in color in in situ compared to Gnathosaurus.

Figure 1. Liaodactylus (in color in in situ compared to Gnathosaurus. The portion of the rostrum above the antorbital fenestra remains unknown. A short crest may or may not have been present.

Liaodactylus primus (Zhou et al. 2017) was considered the earliest filter-feeding pterosaur. Here it nests with the Solnhofen specimen of Gnathosaurus. Distinctly, Liaodactylus has short premaxillary teeth and longer dentary teeth than maxillary teeth. The skull was small, only half the length of Gnathosaurus, but with similar proprotions. The jugal was not elevated and so did not shrink the orbit.

FIgure 2. Subset of the large pterosaur cladogram focusing on the clade Dorygnathia and the clade within it, the Ctenochasmatidae.

FIgure 2. Subset of the large pterosaur cladogram focusing on the clade Dorygnathia and the clade within it, the Ctenochasmatidae. Here Liaodactylus nests as a sister to Gnathosaur, a basal ctenochasmatid.

Zhou et al. did not provide
a specimen-based phylogenetic analysis. but used only one taxon for each genus and so missed out on the gradual accumulation of traits that nested Liaodactylus with Gnathosaurus. Instead they nested it with Ctenochasma.

Zhou et al. used the data matrix
of Andres, Clark and Xu 2004, which nested Kryptodrakon as the basalmost pterodactyloid. As we learned earlier, those authors reconstructed the few bits and pieces of Kryptodrakon as a small Pterodactylus-like pterosaur, when it should have been reconstructed as a larger, but very gracile Sericipterus, which was found in the same deposits, but would not have made so many headlines.

References
Andres B, Clark JM and Xu X 2010.A new rhamphorhynchid pterosaur from the Upper Jurassic of Xinjiang, China, and the phylogenetic relationships of basal pterosaurs, Journal of Vertebrate Paleontology 30: (1) 163-187.
Andres B, Clark J and Xu X 2014. The Earliest Pterodactyloid and the Origin of the Group. Current Biology (advance online publication)
DOI: http://dx.doi.org/10.1016/j.cub.2014.03.030
Zhou C-F, Gao K-Q, Yi H, Xue J, Li Q and Fox RC 201. Earliest filter-feeding pterosaur from the Jurassic of China and ecological evolution of Pterodactyloidea. R. Soc. open sci. 4: 160672. http://dx.doi.org/10.1098/rsos.160672