Giant flying arboreal mammal-killer in the Jehol (Early Cretaceous, China)

So… this one has been under the radar since 2004
And you’ll see why.

Like a prehistoric eagle,
this was the largest flying predator in the Jehol biota (Early Cretaceous, China). It had no feathers. And it has gone unrecognized as a giant flying predator since Wang and Zhou 2004 announced it in Nature for other reasons.

At this time the only evidence
for this taxon comes in the form of a giant embryo anurognathid pterosaur, IVPP V13758 (Fig. 1) the size of other adult anurognathids. As an adult it would have been 8x larger (if similar to other pterosaur and based on the pelvic opening). The skull retains traits of the related, but more basal Dimorphodon from the Early Jurassic of England, but the giant anurognathid was coeval and similar in size to another Jehol predator, the pre-tyrannosauroid, Tianyuraptor, and larger than a coeval four-winged, flight-feathered ornitholestid, Microraptor (Fig. 1). It was also larger than the modern bald eagle (Haliaeetus leucocephalus). All the early Cretaceous toothed birds, like Yanornis, and Hongshanornis, were smaller.

Figure 1. Adult scaled version of the IVPP anurognathid pterosaur, with a skull similar in size to those attributed to Dimorphdodon. Bergamodactylus and Preondactylus are ancestral to Dimorphodon. Other Jehol predators are shown in white.

Figure 1. Adult scaled version of the IVPP anurognathid pterosaur, with a skull similar in size to those attributed to Dimorphdodon. Bergamodactylus and Preondactylus are ancestral to Dimorphodon. Other Jehol predators are shown in white.

If early Cretaceous mammals thought they were safe up in the trees,
think again. This giant anurognathid kept their numbers in check by going after them in the trees. That’s a big guess, but if you’re looking for a predator capable of snatching mammals out of the trees, there are no other candidates in the Early Cretaceous of China. Just look at those teeth!

Most anurognathids were small
because they ate small insect prey. Ask yourself if something as large as the IVPP embryo as an adult would have been satisfied eating insects. No, it was going after larger prey.

Figure 1. 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.

Figure 2. 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.

Unfortunately
Wang and Zhou 2004 (Fig. 3) didn’t know what sort of pterosaur their first embryo/egg was. Back then they thought pterosaur babies had a shorter rostrum that adults. Wrong. Back then they thought anurognathids were all small taxa. Wrong. Back then they didn’t spend much time tracing traits (Fig. 3) and reconstructions were largely guesswork. We fix all those problems here and at ReptileEvolution.com

The IVPP embryo pterosaur

Figure 3. Click to enlarge DGS tracing. The IVPP embryo pterosaur (far left) as originally traced, (near left) as originally reconstructed as a baby ornithocheirid, (near right) traced using the DGS method, (far right) adult reconstructed at 8x the embryo size.

We first looked at the IVPP embryo
here, several years ago and several times since.

Figure 4. The IVPP embryo anurognathid compared to other basal pterosaurs.

Figure 4. The IVPP embryo anurognathid enlarged to adult size and compared to other basal pterosaurs.

References
Wang X-L and Zhou Z 2004. Palaeontology: pterosaur embryo from the Early Cretaceous. Nature 429: 623.

http://reptileevolution.com/dimorphodon.htm
http://reptileevolution.com/ivpp-embryo.htm

https://pterosaurheresies.wordpress.com/2011/07/26/what-do-those-pterosaur-embryos-really-look-like/

Bergamodactylus (basal pterosaur) back ‘under the microscope’

This all started with Kellner 2015
who proposed 6 states of pterosaur ontogeny based on skeletal fusion of discrete elements. This hypothesis was tested in phylogenetic analysis and shown to be invalid. Pterosaurs don’t fuse bones during ontogeny. Fusion appears in phylogenic patterns. Oblivious to this fact, Dalla Vecchia 2018 dismissed Kellner’s hypothesis by writing, “Kellner’s six ontogenetic stages are an oversimplification mixing ontogenetic features of different taxa that probably had distinct growth patterns. Finding commonality across all pterosaurs is impossible, because there is much variation in pterosaur ontogeny and the available sample is highly restricted.” 

Neither Kellner nor Dalla Vecchia recognize
the lepidosaurian affinities of pterosaurs, and do not realize that as lepidosaurs pterosaurs mature differently than archosaurs. Some lepidosaurs continue growing after fusing elements (Maisano 2002). Others never fuse elements. Fusion of elements in pterosaurs is phylogenetic, not ontogenetic. Pterosaurs mature isometrically, not allometrically as proven by every full-term embryo and every known juvenile among a wide variety of pterosaur specimens. Plus, all of the small purported Solnhofen juveniles phylogenetically nest as key transitional taxa linking larger long-tail primitive pterosaurs to larger short-tail derived pterosaurs (Peters 2007). That’s how those clades survived the extinction events that doomed their fellow, larger, longer-tailed kin.

Kellner 2015 also
distinguished a small pterosaur MPUM 6009 from the holotype of Eudimorphodon and from Carniadactylus (MFSN 1797, Dalla Vecchia 2009; Fig. 1) and gave MPUM 6009 the name Bergamodactylus (Fig. 1) after Peters 2007 had done the same (without renaming MPUM 6009), in phylogenetic analysis. Neither Kellner nor Dalla Vecchia performed a phylogenetic analysis, but preferred to describe similar bones. That rarely works out well.

Figure 1. Bergamodactylus compared to Carniadactylus. These two nest apart from one another in the LRT.

Figure 1. Bergamodactylus (MPUM 6009) compared to Carniadactylus (MFSN 1797). These two nest apart from one another in the LRT. Contra Dalla Vecchia 2018, these two share relatively few traits in common. The feet, cervicals, sternal complex coracoids and legs are different.

Dalla Vecchia 2018 concludes, 
“The anatomical differences between MPUM 6009 and MFSN 1797 are too small to support the erection a new genus for MPUM 6009.” That is incorrect (Fig. 1). Several taxa nest between these two taxa in the large pterosaur tree (LPT, 232 taxa). Their feet alone (Fig. 1) were shown to be very different in Peters (2011).

Figure 1. Bergamodactylus compared to Cosesaurus. Hypothetical hatchling also shown.

Figure 2. Bergamodactylus compared to Cosesaurus. Hypothetical hatchling also shown.

From the Dalla Vecchia 2018 abstract
“Six stages (OS1-6) were identified by Kellner (2015) to establish the ontogeny of a given pterosaur fossil. These were used to support the erection of several new Triassic taxa including Bergamodactylus wildi, which is based on a single specimen (MPUM 6009) from the Norian of Lombardy, Italy. However, those ontogenetic stages are not valid because different pterosaur taxa had different tempos of skeletal development. Purported diagnostic characters of Bergamodactylus wildi are not autapomorphic or were incorrectly identified. Although minor differences do exist between MPUM 6009 and the holotype of Carniadactylus rosenfeldi, these do not warrant generic differentiation. Thus, MPUM 6009 is here retained within the taxon Carniadactylus rosenfeldi as proposed by Dalla Vecchia (2009a).” \

Dalla Vecchia is basing his opinion on comparing a few cherry-picked traits, possibly convergent, rather than running both taxa and a long list of other pterosaurs through phylogenetic analysis, to see where unbiased software nests both taxa among the others.

Plus, as mentioned above, both authors are working from an antiquated set or rules that no longer apply now that pterosaurs have been tested and validated as lepidosaurs.

Figure 2. Bergamodactylus skull colorized with DGS and reconstructed.

Figure 3. Bergamodactylus skull colorized with DGS and reconstructed. Palatal and occipital bones shown here were missed by Dalla Vecchia 2018 and prior workers who did not use DGS.

Phylogenetic analysis
employing a large gamut of taxa, like the large reptile tree (LRT, 1215 taxa), invalidates traditional arguments that pterosaurs arose without obvious precedent among the archosauriforms, which most pterosaur workers, including both Kellner and Dalla Vecchia, still cling to, despite no evidence of support. Pterosaurs arose from fenestrasaur tritosaur lepidosaurs (Fig. 7).

Figure 4. The skull of Bergamodactylus traced by Kellner 2015, Dalla Vecchia 2018 and by me using DGS.

Figure 4. The skull of Bergamodactylus traced by Kellner 2015, Dalla Vecchia 2018 and by me using DGS. See figure 2 for a reconstruction of the DGS tracing.  Prior authors missed all the palatal and occipital bones along with several others.

The metacarpus of Bergamodactylus
has a few disarticulated elements. When replaced to their in vivo positions the axial rotation of metacarpal 4 (convergent with the axial rotation of pedal digit 1 in birds) enables the wing finger to fold in the plane of the hand, not against the palmar surface. Manual digit 5, a vestige, goes along for the ride, rotating the dorsal surface of the hand (Fig. 5).

Figure 5. Metacarpus of Bergamodactylus (MPUM 6009) in situ and reconstructed.

Figure 5. Metacarpus of Bergamodactylus (MPUM 6009) in situ and reconstructed. Apparently the pteroid splintered apart, overlooked by those with direct access to the specimen. The distal carpals are not co-ossified, as they are in later pterosaurs. The laterally longer fingers, up to digit 4, is a tritosaur trait. Note ungual 1 lies on top of the posterior face of metacarpal 4. That was overlooked by those who had direct access to the specimen, which supports the utility of DGS.

 

Bergamodactylus, as the most basal pterosaur,
is itself a transitional taxon bridging non-volant fenestrasaurs with all other pterosaurs. And the wing (Fig. 6) was about the last thing to evolve.

Figure 6. Click to enlarge. The origin of the pterosaur wing and the migration of the pteroid and preaxial carpal. A. Sphenodon. B. Huehuecuetzpalli. C. Cosesaurus. D. Sharovipteryx. E. Longisquama. F-H. The Milan specimen MPUM 6009, a basal pterosaur.

Bergamodactylus to scale
with Cosesaurus and Longisquama (Fig. 7), demonstrate the variety within the Fenestrasauria. Pterosaurs arose more or less directly from a sister to Cosesaurus (based on overall proportions), but note that both Sharovipteryx and Longisquama have more pterosaurian traits than Cosesaurus does. This pattern is convergent with that of birds, of which several clades of Solnhofen bird descendants arose of similar yet distinct structure.

Figure 8. Taxa at the genesis of pterosaurs: Cosesaurus, Longisquama and Bergamodactylus.

Figure 7. Taxa at the genesis of pterosaurs: Cosesaurus, Longisquama and Bergamodactylus.

See rollover images
of Bergamodactylus in situ here. You’ll see how DGS is able to pull out post-cranial details overlooked by others in the chaos and confusion of layers of bones and impressions in MPUM 6009. Cranial details are best seen in figure 3 above, which is based on higher resolution images.

References
Dalla Vecchia FM 2009. Anatomy and systematics of the pterosaur Carniadactylus gen. n. rosenfeldi (Dalla Vecchia, 1995). Riv. It. Paleontol. Strat., 115: 159-186.
Dalla Vecchia FM 2018. Comments on Triassic pterosaurs with a commentary on the “ontogenetic stages” of Kellner (2015) and the validity of Bergamodactylus wildi.  Rivista Italiana di Paleontologia e Stratigrafia 124(2): 317-341. DOI: https://doi.org/10.13130/2039-4942/10099 https://riviste.unimi.it/index.php/RIPS/article/view/10099
Kellner AWA. 2015. Comments on Triassic pterosaurs with discussion about ontogeny and description of new taxa. Anais Acad. Brasil. Ciênc., 87(2): 669-689.
Maisano JA 2002. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrate Paleontology 22:268-275.
Peters D. 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification. Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605

Vesperopterylus (aka: Versperopterylus, Lü et al. 2017) did not have a reversed first toe

And this specimen PROVES again
that anurognathids DID NOT have giant eyeballs in the anterior skull.

Figure 1. Vesperopterylus in situ. There is nothing distinct about pedal digit 1.

Figure 1. Vesperopterylus in situ. There is nothing distinct about pedal digit 1.

Lü et al. 2017 bring us a new little wide-skull anurognathid
Vesperopterylus lamadongensis (Lü et al. 2017) is a complete skeleton of a wide-skull anurognathid. It was considered the first pterosaur with a reversed first toe based on the fact that in digit 1 the palmar surface of the ungual is oriented lateral while digis 2–4 the palmar surfaces of the unguals are medial. That is based on the slight transverse curve of the metatarsus (Peters 2000) and the crushing which always lays unguals on their side. In life the palmar surfaces were all ventral and digit 1 radiated anteriorly along with the others.

Figure 2. Vesperopterylus reconstructed using original drawings which were originally traced from the photo. Manual digit 4.4 is buried beneath other bones and reemerges to give its length. Pedal digit 1 turns laterally due to metacarpal arcing and taphonomic crushing. There is nothing reversed about it. 

Figure 2. Vesperopterylus reconstructed using original drawings which were originally traced from the photo. Manual digit 4.4 is buried beneath other bones and reemerges to give its length. Pedal digit 1 turns laterally due to metacarpal arcing and taphonomic crushing. There is nothing reversed about it.

Lü et al were unable to segregate the skull bones.
Those are segregated by color here using DGS (Digital Graphic Segregation). See below. Some soft tissue is preserved on the wing. Note: I did not see the fossil first hand, yet I was able to discern the skull bones that evidently baffled those who had this specimen under a binocular microscope. Perhaps they were looking for the giant sclerotic rings in the anterior skull that are not present. Little ones, yes. Big ones, no.

Figure 1. Vesperopterylus skull with bones identified by DGS (digital graphic segregation). Lü et al. were not able to discern these bones and so left the area blank in their tracing. Note the complete lack of a giant eyeball in the front of the skull. Radius and ulna were removed for clarity and to show a complete lack of giant eyeballs (sclerotic rings) in the anterior skull. 

Figure 1. Vesperopterylus skull with bones identified by DGS (digital graphic segregation). Lü et al. were not able to discern these bones and so left the area blank in their tracing. Note the complete lack of a giant eyeball in the front of the skull. Radius and ulna were removed for clarity and to show a complete lack of giant eyeballs (sclerotic rings) in the anterior skull.

This skull reconstruction
(Fig. 4) is typical of every other anurognathid, because guesswork has been minimized here. After doing this several times with other anurognathids, I knew what to look for and found it. No giant sclerotic rings were seen in this specimen.

Figure 4. Vesperopterylus skull reconstructed from color data traced in figure 3.

Figure 4. Vesperopterylus skull reconstructed from color data traced in figure 3. Due to the angled sides of the skull some foreshortening was employed  to match those angles. Original sizes are also shown.

With regard to perching
all basal pterosaurs could perch on branches of a wide variety of diameters by flexing digit 1–4 while extending digit 5, acting like a universal wrench (Peters 2000, FIg. 5). This ability has been overlooked by other workers for the last two decades,

Figure 1. The pterosaur Dorygnathus perching on a branch. Above the pes of Dorygnathus demonstrating the use of pedal digit 5 as a universal wrench (left), extending while the other four toes flexed around a branch of any diameter and (right) flexing with the other four toes. As in birds, perching requires bipedal balancing because the medially directed fingers have nothing to grasp.

Figure 1. The pterosaur Dorygnathus perching on a branch. Above the pes of Dorygnathus demonstrating the use of pedal digit 5 as a universal wrench (left), extending while the other four toes flexed around a branch of any diameter and (right) flexing with the other four toes. As in birds, perching requires bipedal balancing because the medially directed fingers have nothing to grasp.

I have not yet added Vesperopterylus
with the holotype of Anurognathus in the large pterosaur tree.

References
Lü J-C et al. 2017. Short note on a new anurognathid pterosaur with evidence of perching behaviour from Jianchang of Liaoning Province, China. From: Hone, D. W. E., Witton MP and Martill DM(eds) New Perspectives on Pterosaur Palaeobiology.
Geological Society, London, Special Publications, 455, https://doi.org/10.1144/SP455.16
Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods. 
Ichnos, 7: 11-41

 

Arcticodactylus a tiny Greenland Triassic pterosaur

Arcticodactylus cromptonellus (Kellner 2015, originally Eudimorphodon cromptonellus Jenkins et al. 1999, 1999; MGUH VP 3393) Late Triassic ~210mya ~8 cm snout to vent length was a tiny pterosaur derived from a sister to Eudimorphodon ranzii and phylogenetically preceded Campylognathoides and BSp 1994 specimen attributed to Eudimorphodon. Whether it was a juvenile or a tiny adult cannot be determined because juveniles and even embryos are identical to adults in pterosaurs. Note that that rostrum was not shorter and the orbit was not larger than in sister taxa. This specimen is one of the smallest known pterosaurs., but not THE smallest (Fig. 1) contra the Wikipedia article. That honor goes to B St 1967 I 276.

Figure 1. Articodactylus is evidently NOT the smallest pterosaur. That honor still goes to an unnamed specimen (not a Pterodactylus kochi juvenile) B St 1967 I 276.

Figure 1. Articodactylus is evidently NOT the smallest pterosaur. That honor still goes to an unnamed specimen (not a Pterodactylus kochi juvenile) B St 1967 I 276.

Distinct from E. ranzii,
the skull of Arctiodactylus had a rounder, less triangular orbit. The jugal was not as deep. The sternal complex did not have small lateral processes. The humerus was not as robust. The fingers were longer an more gracile. The prepubis was distinctly shaped.

Distinct from
Bergamodactylus the femur and tibia were smaller but the metatarsals were longer, compact and nearly subequal in length with IV smaller than III.

References
Jenkins FA Jr, Shubin NH, Gatesy SM and Padian K 1999. A primitive pterosaur of Late Triassic age from Greenland. Journal of the Society of Vertebrate Paleontology 19(3): 56A.
Jenkins FA Jr, Shubin NH, Gatesy SM and Padian K 1999. A diminutive pterosaur (Pterosauria: Eudimorphodontidae) from the Greenlandic Triassic. Bulletin of the Museum of Comparative Zoology, Harvard University 155(9): 487-506.
Kellner AWA 2015. Comments on Triassic pterosaurs with discussion about ontogeny and description of new taxa. Anais da Academia Brasileira de Ciências 87(2): 669–689

wiki/Eudimorphodon
wiki/Arcticodactylus

SVP 5 – Triassic pterosaur from Utah

Britt et al. (2105) found a Late Triassic pterosaur in Utah, described in the following SVP abstract.

From the abstract:
“We previously reported on a wealth of tetrapods, including multiple individuals each of a coelophysoid, a drepanosauromorph, two sphenosuchian taxa, and two sphenodontian taxa. All are preserved along the shoreline of  a Late Triassic oasis in the Nugget Sandstone at the Saints & Sinner Quarry (SSQ). Recently, we discovered a non-pterodactyloid pterosaur at the quarry, represented by a partial uncrushed, associated/articulated skull imaged via micro CT. The premaxillaries are spoon-shaped rostrally; the maxilla is a simple bar with a needle-like nasal process, the suborbital jugal/quadratojugal blade is high; the nasal is a short, narrow rectangle; and the fused frontals are wide with a moderately high, tripartite sagittal crest. The lower jaws are complete, with a long, slender dentary terminating rostrally in a downward-bend with a ventral expansion, a short postdentary complex and a short retroarticular process. The quadrate-articular joint is well above the tooth row. At least three, widely spaced, conical teeth are in the premaxilla; maxillary teeth are mesiodistally long (3 widely-spaced mesially and 7 close together distally); and on the dentary there are two apicobasally high, widely-spaced mesial teeth and ~20 small, multicusped, low-crowned distal teeth. The frontals and lower jaws are extensively pneumatized. With a 170 mm-long lower jaw, this is two times larger than other Triassic pterosaurs and only the second indisputable Triassic pterosaur from the Western Hemisphere (the other is from Greenland). This is the only record of desert-dwelling nonpterodactyloids and it predates by >60 Ma all known desert pterosaurs. Whereas most pterosaurs are known from fine-grained marine or lacustrine environments, and other Triassic forms are smaller, the SSQ specimen shows that early pterosaurs were widely distributed, attained a large size, and lived in wide range of habitats, including inland deserts far (>800 km) from the sea. Finally, the SSQ pterosaur corroborates the Late Triassic age of the fauna based on drepanosaurs because pterosaurs with multicusped teeth are presently known only from the Upper Triassic.”

The description
sounds like an early dimorphodontid, but withe the deep jugal of Raeticodactylus. The size of the skull is similar to both. Unfortunately, too few clues to go on. I’ll wait for the paper… eagerly!

References
Britt BB, Chure D, Engelmann G and Dalla Vecchia F et al.  2015.
A new, large, non-pterodactyloid pterosaur from a Late Triassic internal desert environment with the eolian nugget sandstone of Northeastern Utah, USA indicates early pterosaurs were ecologically diverse and geographically widespread. Journal of Vertebrate Paleontology abstracts.

 

 

The vampire pterosaur has a new sister: Daohugoupterus

Cheng et al. (2014)
present a new small, late Jurassic pterosaur, Daohugoupterus. They were not quite sure what it was, assigning it to Pterosauria incerta sedis. The specimen is represented by an articulated skeleton lacking hind limbs, the anterior skull and two proximal wing phalanges (Fig. 1). Wing tip soft tissue was preserved. I believe the ulna and radius are just beneath the surface based on the positions of the humerus and carpus/metacarpus. The rest of the wing is likely twisted beneath these elements as the distal two wing phalanges frame the soft tissue.

Figure 1. Click to enlarge. Daohugoupterus in situ, colorized (left) and as originally traced (right). You'll note that DGS pulled out more details than firsthand tracing.

Figure 1. Click to enlarge. Daohugoupterus in situ, colorized (left) and as originally traced (right). You’ll note that DGS pulled out more details than firsthand tracing.

From their abstract:
“Daohugou is an important locality of the Jurassic Yanliao Biota, where
only two pterosaurs have been described so far (Jeholopterus and
Pterorhynchus). Here we report a new genus and species, Daohugoupterus
delicatus gen. et sp. nov. (IVPP V12537), from this region, consisting
of a partial skeleton with soft tissue. The skull is laterally
compressed, differing from Jeholopterus. The antorbital fenestra is
larger than in Pterorhynchus. The upper temporal fenestra is unusually
small. The short cervical vertebrae bearing cervical ribs indicate
that it is a non-pterodactyloid flying reptile. The sternal plate is
triangular, being much wider than long. The deltopectoral crest of
humerus is positioned proximally and does not extend further down the
shaft, a typical feature of basal pterosaurs. Daohugoupterus also
differs from the wukongopterids and scaphognathids from the Tiaojishan
Formation at Linglongta, regarded to be about the same age as the
Daohugou Bed. The new specimen increases the Jurassic
non-pterodactyloid pterosaur diversity of the Yanliao Biota and is the
smallest pterosaur from Daohugou area so far.”

DGS
Digital Graphic Segregation was used to pull details out of the skeleton. While the original paper described small upper temporal fenestra (that are indeed there) the figure did not show this detail. No skull bones were identified. The vertebrae were outlined without details. Color tracing and reconstruction (fig. 2) help bring this specimen ‘back to life.’ The length of the rostrum is unknown, but after phylogenetic analysis nesting with Jeholopterus, the rostrum was reconstructed like it’s sister taxon.

Reconstruction
A reconstruction of all available elements resulted in a sister to Jeholopterus, sharing many traits including the strong reduction of anterior cervical vertebrae, robust cervical vertebrae posteriorly, wide ribs creating a pancake-like torso, and a fragile skull with very large orbit (Fig. 2). Notably, Jeholopterus was a contemporary from the same Late Jurassic formation.

Figure 2. Click to enlarge. Daohugoupterus reconstructed.

Figure 2. Click to enlarge. Daohugoupterus reconstructed.

If you take a bone-by-bone survey
of the the DGS tracing vs. the original tracing (Fig. 1), you’ll find many differences. This is a difficult fossil and the accuracy of my tracings depending to a large part on testing each part within an evolving reconstruction (Fig. 3). Attempting reconstructions of roadkill pterosaurs is something conventional paleontologists are loathe to do, and they never ask me to help. Hence this blog.

Figure 1. Jeholopterus in lateral view. Note the extreme length of the dermal fibers, unmatched by other pterosaurs.

Figure 3. Jeholopterus in lateral view. Note the wide ribs.

In a side-by-side comparison (Fig. 4)
Jeholopterus and Daohugoupterus do share many traits and are roughly the same size. Daohugoupterus does not have the robust limbs and surgically curved claws that Jeholopterus has, but Daohugoupterus does have enormous eyes, probably for night vison. They share a wider than deep torso which enables them to cram their bellies, but still keep an aerodynamic disc-like shape (also see Sharovipteryx for something similar). They also share a very robust neck that gets very gracile close to the skull. I presume this gives both pterosaurs a wider range of motion at the skull/neck juncture. But why does most of the neck have to be stronger than the dorsal vertebrae?

Figure 3. Jeholopterus and Daohugoupterus in side-by-side comparison to scale. The wings were relatively short in Daohugoupterus and the pelvis was small. The skull was relatively narrower, but the torso was just as broad.

Figure 3. Jeholopterus and Daohugoupterus in side-by-side comparison to scale. The wings were relatively short in Daohugoupterus and the pelvis was small. The skull was relatively narrower, but the torso was just as broad.

On a side note
Experiment.com has accepted by submission and my first crowd-source funding project has started today. See details at:
https://experiment.com/projects/the-reptile-evolution-project

References
Cheng X, Wang X, Jiang S and Kellner AWA 2014. Short note on a non-pterodactyloid pterosaur from Upper Jurassic deposits of Inner Mongolia, China. Historical Biology (advance online publication) DOI:10.1080/08912963.2014.974038

 

What is Faxinalipterus? (hint: not a pterosaur…)

Faxinalipterus minima (Bonaparte 2010) has been described from bits and pieces of a sparrow-sized archosaur. The holotype consists of short robust arm bones and much longer leg bones. A displaced maxilla with a large antorbital fenestra and narrow fossa is also referred to the specimen.

Wiki writes, “The describers have assigned Faxinalipterus to the Pterosauria, based on its long hollow limbs and saddle-shaped upper joint of the relatively short and robust humerus, suitable to perform a wing stroke. They see it as perhaps the oldest pterosaur known, as it possibly predates European finds from the Norian. That the possible age difference cannot be large, they see as an indication of rapid evolution in early pterosaurs. Because the Caturrita Formation consists of terrestrial sandstones, that evolution would have had its origins in a terrestrial, not coastal, habitat. They also concluded Faxinalipterus is the most basal known pterosaur, basal features including a lack of fusion between tibia and fibula, a thin radius and a coracoid that has not fused to the scapula. However, Alexander Kellner has suggested Faxinalipterus might be not be a pterosaur but a basal member of the Pterosauromorpha instead or, if the lack of fusion between tibia and fibula is plesiomorphic, even a sister taxon of the Ornithodira.”

Faxinalipterus matched to Scleromochlus. The former is more primitive, like Gracilisuchus, in having shorter hind limbs and more robust fore limbs. The maxilla with fenestra and fossa, plus the teeth, are a good match.

Figure 1. Click to enlarge. Faxinalipterus matched to Scleromochlus. The former is more primitive, like Gracilisuchus, in having shorter hind limbs and more robust fore limbs. The maxilla with fenestra and fossa, plus the teeth, are a good match. Faxinalipterus was not phylogenetically analyzed, but I’m not sure what other Triassic taxon could be closer.

This is going to get some people excited, others not
The maxilla assigned to Faxinalipterus (and I don’t doubt the assignment) has a large squarish antorbital fenestra surrounded by a narrow fossa. No pterosaur has a fossa. Basal pterosaurs always have an angled maxillary ascending process. Basal pterosaurs also have a much more slender fibula. And there are several other mismatches despite the few bones representing the animal. The putative coracoid is more likely a pubis or ischium.

The best match I found (not via phylogenetic analysis) is with Scleromochlus (Fig. 1) a basal bipedal crocodylomorph. Virtually every aspect of Faxinalipterus seems to be a good match, including chronological age and overall size, other than relative limb length. Faxinalipterus is just more primitive in having shorter hind limbs and more robust front limbs. Check out the distal tibia and fibula. A close match to bipedal crocs. Nothing like pterosaurs.

So, for those who like to match Scleromochlus with pterosaurs in the Pterosauromorpha and the Ornithodira, you now have another taxon that doesn’t look like a pterosaur!

Since every discovery can be discovered only once
it’s only human nature that a paleontologist finding a partial skeleton would jump on the most exciting possibility, like “the most primitive known pterosaur.” Unfortunately you also have to play by the rules and compare the new specimen to every other taxon sharing a majority of its traits (even if incomplete) and you have to go with the recovered results.

On the other hand…
Faxinalipterus
 does offer insight into the origin of Scleromochlus and basal crocs, and by extension, basal archosaurs. I’d like to see thefolks toying with Lagerpeton (a convergent biped close to Tropidosuchus) drop it in favor of these two croc bipeds at the base of the archosaur family trees.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Bonaparte JF, Schultz CL and Soares MB 2010. Pterosauria from the Late Triassic of southern Brazil. In S. Bandyopadhyay (ed.), New Aspects of Mesozoic Biodiversity, Lecture Notes in Earth Sciences 132:63-71.

Wiki/Faxinalipterus