What is Leptostomia? So little to work with…

A new genus and species of little pterosaur
from the Early Cretaceous of Morocco, Leptostomia begaaensis (Smith et al. 2020; Figs. 1–3), is based on two, little 3D pieces of rostrum (FSAC-KK 5075) and mandible (FSAC-KK 5076) originally considered to belong to a new kind of azhdarchoid (an invalid polyphyletic clade in the large pterosaur tree; LPT, 251 taxa), that traditionally, but mistakenly includes unrelated tapejarids and azhdarchids. As usual, simply adding traditionally or specifically omitted taxa clarifies interrelationships.

Figure 1. At about twice life size, these are jaw portions from Leptostomia in several views.

Figure 1. At about twice life size, these are jaw portions from Leptostomia in several views.

The affinities of the jaw segments remain ‘unclear’
according to the authors. Once again this was due to taxon exclusion.

Figure 2. Photo of the Leptostomia rostrum fragment in several views. Colors added here.

Figure 2. Photo of the Leptostomia rostrum fragment in several views. Colors added here. Premaxilla = yellow. Maxilla = green. Vomer = purple.

Unfortunately 
Smith et al. omitted the tall, slender ctenochasmatid, Gegepterus (Fig. 3,4) from their comparables list. Gegepterus has a similar rostrum and mandible. Both are similar in size and (Fig. 4) both are from Early Cretaceous strata, one from Morocco, the other from China.

Figure 3. Leptostomia compared to coeval Gegepterus (see figure 4).

Figure 3. Leptostomia compared to coeval Gegepterus at the same scale  (see figure 4).

Most pterosaurs,
including azhdarchids and tapejarids, have a taller than wide rostrum along with a narrow premaxilla ascending process that extends to the dorsal orbit.

Figure 4. Similar to azhdarchids, Gegepterus was a tall, slender ctenochasmatid with long jaws, neck and legs.

Figure 4. Similar to azhdarchids, except for size, Gegepterus was a tall, slender ctenochasmatid with long jaws, neck and legs for an overall small pterosaur. Here it is shown 3/5 original size.

By contrast,
the Leptostomia rostrum has a wider rostrum and a wider premaxilla overlapping it. Worth remembering: both the rostrum and mandible fragments are less than 1cm wide on this small specimen and genus.

Figure 5. Leptostomia rostrum palatal view. Vomer = purple ridge. Mx = maxilla. Tiny remnant alveoli appear to be present on the lateral palatal ridge.

Figure 5. Leptostomia rostrum palatal view. Vomer = purple ridge. Mx = maxilla. Tiny remnant alveoli appear to be present on the lateral palatal ridge, overlooked by Smith et al.

Most ctenochasmatids
have long slender teeth arising from the jaw rims. No such teeth are preserved with or were collected with Leptostomia, A close view (Fig. 5) shows a line of small ovals that could be slender tooth alveoli. Or teeth may indeed be absent in this taxon.

Wiki authors describing Gegepterus in Wikipedia note:
“This is the first uncontroversial report of the Ctenochasmatidae from the Yixian Formation, as the fossils of other assumed ctenochasmatids have not preserved the dentition.”

Smith et al. note,
Leptostomia differs from other edentulous pterosaurs in possessing a remarkably low rostral lateral angle, endowing it with a very long and slender beak. Its lateral angle is also very low when compared with toothed pterosaurs with only some ctenochamatids having a similarly low lateral angle.”

Smith et al. propose a poorly informed guess,
“The new pterosaur adds to the remarkable diversity of pterosaurs known from the mid-Cretaceous, and suggests that pterosaur diversity remained under sampled.” No it doesn’t. Leptostomia looks like an omitted taxon, Gegepterus.

In the LPT there are few to no morphological gaps largely because it employs a much larger taxon list than any published by PhD workers and their students who refuse to include small taxa, more than one specimen assigned to a genus and valid pterosaur outgroups in their analyses. Same for the LRT.

Quetzalcoatlus scraping bottom while standing in shallow water.

Figure 6. Quetzalcoatlus scraping bottom while standing in shallow water.

Smith et al. state,
“The proposed probe-feeding strategy suggested by the rostrum morphology of Leptostomia has not previously been documented for the Pterosauria.” This is false. Just google, “pterosaur + probe” and a long list will appear. And there’s always this image (Fig. 6) of the man-sized Quetzalcoatlus probing, which has been online for awhile, following ‘suggestions’ from Langston 1981.


References
Langston W Jr 1981. Pterosaurs. Scientific American: 244,:122–126.
Smith RE, Martill DM, Kao A, Zouhri S and Longrich N 2020. A long-billed, possible probe-feeding pterosaur (Pterodactyloidea: ?Azhdarchoidea) from the mid-Cretaceous of Morocco, North Africa, Cretaceous Research, https://doi.org/10.1016/j.cretres.2020.104643.

wiki/Leptostomia
wiki/Gegepterus

New tiny ‘Ctenochasma’ at the Field: Lauer Foundation Collection

The Lauer Foundation for Paleontology provided
this tiny crushed Ctenochasma? elegans? Fig. 1) to the Field Museum, Chicago, USA. The foundation number is: #LF 2296. It enters the large pterosaur tree (LPT, 250 taxa; Fig. 2) distinct from all other tested pterosaurs.

Figure 1. A tiny Ctenochasama micronyx undergoes DGS here. Every bone is present, but no soft tissue this time. Note the tiny claws on all digits along with the slightly spoon-shaped rostrum and needle-like teeth.

Figure 1. A tiny Ctenochasama micronyx undergoes DGS here. Every bone is present, but no soft tissue this time. Note the tiny claws on all digits along with the slightly spoon-shaped rostrum and needle-like teeth.

Tiny, yes, but not a juvenile.
As we learned earlier, pterosaur hatchlings have adult proportions. Pterodaustro presents the phylogenetically closest example, in this case. Phylogenetic miniaturization is how we get tiny pterosaurs. And tiny pterosaurs are transitional taxa. That’s how we get derived pterosaurs. Note the tiny Ctenochasma? elegans specimens all nest together (Fig. 2). These tiny pterosaurs are adults that would have produced 8x smaller hatchlings, often about the size of house flies. and therefore unable to fly without risking desiccation due to a high surface-to-volume ratio. In other words, hatchlings of tiny pterosaurs could have flown, but needed to keep their wings folded. So they walked, picking up small prey in damp leaf litter. And that’s why so many pterosaur tracks are from pterodactyloid-grade pterosaurs, many of which continued to feet quadrupedally as they grew into phylogenetically larger genera.

Figure 3. Subset of the LRT focusing on ctenochasmatids and kin.

Figure 2. Subset of the LRT focusing on ctenochasmatids and kin.

Earlier we looked at the Fossilienatlas.de specimen
assigned to Ctenochasma elegans #204 (Fig. 4), which provides a similar morphology in reconstruction. No scale bars were provided with the Lauer Collection specimen, but the size can’t be too far off from this.

Figure 3. Click to enlarge. Private pterosaur #2042 together with St/Ei1, which nests at the base of the ctenochasmatidade, close to Angustinaripterus.

Figure 3. Click to enlarge. Private pterosaur #2042 together with St/Ei1, which nests at the base of the ctenochasmatidade, close to Angustinaripterus.

References
https://www.fieldmuseum.org/blog/meet-pterosaur-flock
https://www.lauerfoundationpse.org/about

SVP abstracts – Daylight and lowlight Solnhofen pterosaurs

Cardozo, Sobral and Rodriques 2019 bring us
a new look at the vision of Solnhofen (Late Jurassic) pterosaurs.

From the abstract:
“Recent taxonomic reviews suggest that up to twelve genera of pterosaurs might have been present there.” 
Up to? There are twice a dozen distinct Rhamph-like taxa in the first row of figure 1, ignoring the other Solnhofen ‘wastebasket’ taxa Pterodactylus, Scaphognathus, Ctenochasma, Archaeopteryx, etc.
Traditional workers don’t count the little ones. Specialists don’t look closely at all the specimens. They ignore many. Some distinct taxa are found within traditional taxa like, Pterodactylus, Rhamphorhynchus and other generic wastebaskets. According to the LPT, no two pterosaurs scoring the same except for a juvenile/adult pairing in the Rhamphorhynchus wastebasket (Fig. 1).
Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O'Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

Figure 1. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O’Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

Cardoza et al. continue:
“Even though many have been recovered from different chronostratigraphic 
units, the high taxonomic diversity and morphological disparity still suggest specializations that reflect distinct ecological roles. An endocast analysis of Pterodactylus antiquus, together with a literature review of the anatomy and ecology of these taxa, suggest interesting niche partitions.”
“Pterodactylus, Scaphognathus, and Rhamphorhynchus were generalist taxa that lived on
coastal areas and fed on fishes and small invertebrates.”
The authors are ignoring the distinct morphologies of these three genera and are not splitting up the small, medium and large taxa. Nor are they considering the distinct niches between adults and their 8x smaller hatchlings.
The descendants of Scaphognathus.

Fig. 2. The descendants of Scaphognathus. Note the size reduction followed by a size increase.

Cardoza et al. continue:
Their niche, however, did not overlap completely: our analysis corroborates a previous study that Pterodactylus had photopic
[daylight] vision, in contrast to the scotopic [dusk/night vision] type of Rhamphorhynchus. Scaphognathus was also photopic, but the different dentition indicates it was not preying on the same items as Pterodactylus.
Other taxa have been regarded as more specialists.
“Germanodactylus has been proposed as a durophage, based mostly on the lack of teeth on the tips of the rostrum and mandible, and therefore also likely preyed on different items than Pterodactylus. Anurognathus, Ctenochasma, Gnathosaurus, and Cycnorhamphus represent highly specialized taxa. Anurognathus was probably an aerial insectivore, with moderately curved unguals that are consistent with a scansorial habit, thus suggesting it inhabited forested areas. Ctenochasma and Gnathosaurus were filter feeders and their different sizes might have prevented, at least to some extent, niche overlap. The diet of
Cycnorhamphus is more disputed: it has been proposed as a durophage, a jellyfish specialist, or a generalist feeding on fishes and insects. In any case, its uniquely curved mandible with teeth only on the distal tip implies a different feeding niche from Solnhofen generalist pterosaurs. Lastly, the endocast of Diopecephalus kochi, a taxon that has been proposed as synonymous with Pterodactylus, was analyzed but poor preservation  prevented adequate assumptions on niche specializations.”
This is a list of old news, old traditions and old excuses. Where is the original thinking? Where are the pithy insights?
“Our preliminary analyses suggest that, although the Solnhofen archipelago was a rich pterosaur site, these taxa were not in direct competition, separated either by functional
anatomy or time. More data on paleoneurology is still needed to better understand niche occupation by Pterodactylus.”
In other words, we have nothing new to say, but wanted to come to Australia to make a presentation.

References
Cardozo FG, Sobral G and Rodriques T 2019. Ecological niches among pterosaurs from the Solnhofen archipelago. Journal of Vertebrate Paleontology abstracts.

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.

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.

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

 

It looks A LOT like Gladocephaloideus, but it’s not one

Among the long-necked ctenochasmatids
close to Gegepterus, is Gladocephaloideus (Lü et al. 2012), a taxon originally considered a cycnorhamphid. A new, smaller specimen with an equally impressive set of long cervicals was recently assigned to the same genus (Lü et al. 2016, Fig. 1) as a juvenile.

Figure 1. Gladocephaloideus (the holotype) compared to the new specimen referred to Gladocephaloideus and its two sister taxa in the large pterosaur tree. Long necks in ctenochasmatids made several appearances by convergence.  Of particular interest, note the size of the pelvis in the JPM specimen, no larger than that of the much smaller MB.R. specimen. Lü et al considered the pelvis incomplete and it may be. Sister taxa are illustrated here from figure 2.

Figure 1. Gladocephaloideus (the holotype) compared to the new specimen referred to Gladocephaloideus and its two sister taxa in the large pterosaur tree. Long necks in ctenochasmatids made several appearances by convergence.  Of particular interest, note the size of the pelvis in the JPM specimen, no larger than that of the much smaller MB.R. specimen. Lü et al considered the pelvis incomplete and it may be. Sister taxa are illustrated here from figure 2.

Unfortunately
the two specimens do not nest together in the large pterosaur tree (Fig. 2). Close, but separated by several nodes.

Before leaving Figure 1,
note the size of the relatively tiny pelvis in the JPM specimen, no larger than that of the much smaller MB.R. specimen with a relatively large pelvis of similar shape. This reconstruction was built from scraps that give the appearance of complete bones. Lü et al. 2016 considered the pelvis incomplete and did not attempt a reconstruction. No sacrum is associated with the pelvic elements to confirm or refute the present size reconstruction. New conspecific specimens will help.

Figure 2. Ctenochasmatids arise from these dorygnathids.

Figure 2. Ctenochasmatids arise from these dorygnathids.

Lü et al. amended the diagnosis of Gladocephaloideus
to accommodate the new smaller specimen. That’s not a good idea before determining that they are indeed conspecific. In order to obviate that prospect, in phylogenetic analysis Lü et al. created a chimaera of the two specimens eliminating any possibility of testing one against the other and against all other pterosaur taxa. In my experience it is extremely rare to find conspecific pterosaurs. That is why I try to nest only specimens, not chimaeras.

The pes of Gladocephaloideus

Figure 3. (Left) The pes of Gladocephaloideus compared to (right) the pes of Ctenochasma elegans (a smaller, more primitive Ctenochasma with fewer teeth). Compare to the pes in figure 1.

The feet
of the holotype and referred specimen are similar but not the same in proportion or appearance. They score differently. In pterosaurs, feet are like fingerprints, enabling one to lump conspecific taxa and split convergent look-alikes.

Figure 4. The JPM specimen in situ along with a reconstruction of its skull compared to the holotype of Gladocephaloides.

Figure 4. The JPM specimen in situ along with a reconstruction of its skull compared to the holotype of Gladocephaloideus. The anterior mandible was glued on in the wrong direction, as noted by Lü et al. 2016.

Lü et al. did not test
the MBR stem ctenochasmatid. Lü et al.  nest ctenochasmatids with cycnorhamphids, among other odd yet traditional nestings. This may be due to the low number of included taxa (67) vs. 215 in the large pterosaur tree.

The taxonomy and systematics get a little confusing….
the original Gladocephaloideus was assigned by Lü et al. 2012 to the Gallodactylidae (cycnorhamphids), but in consideration of the smaller specimen Lü et al. 2016 shifted it to the Ctenochasmatidae where it nests with Pterofiltrus, which nests as a cycnorhamphid in the large pterosaur tree. Moreover, Lü et al. include as related taxa, Elanodactylus (a derived germanodactylid, basal to pteranodontids), Beipiaopterus (a basal azhdarchid), Feilongus and Moganopterus (both cycnorhamphids). At the next level of closest kin Lü et al. include Pterodactylus longicollum (a pterodactylid), Gnathosaurus (a ctenochasmatid) and Cearadactylus (an ornithocheirid nesting far from other ornithocheirids).

This buckshot phylogeny only get worse, but I’ll stop here.

I applaud Lü et al.
for re-identifying the holotype Gladocephaloideus as a ctenochasmatid, as first reported here several years ago. But the rest of their phylogenetic analysis has to add taxa to get up to speed with current research. Their pterosaur tree recovered over 3000 MPTs compared to the fully resolved single tree at ReptileEvolution.com.

Juvenile? Big question that needs new insight to answer:
Lü et al. 2016 report, “The unfused contact between the extensor tendon process and the proximal end of wing phalange 1, as well as the poorly ossified epiphyses of the wing phalanges, indicates that JPM-2014-004 is an early juvenile individual.” It is hard to consider the JPM specimen a juvenile because in phylogenetic analysis it is larger than both proximal adult taxa. The more primitive MB.R. specimen, despite its size is an adult having undergone phylogenetic miniaturization from larger Dorygnathus and Angustinaripterus ancestors, an evolutionary process that often gives rise to new morphologies, in this case, the clade Ctenochasmatidae with all of its synapomorphies. Phylogenetically miniaturized pterosaurs retain, through neotony, juvenile bone microstructure. Lü et al. 2016 report woven bone structure and no LAGs or zones. This may occur in rapidly growing tiny (sparrow-to-hummingbird-sized) adults less than one year in age. Tiny pterosaurs, like tiny birds may have matured in far less than a year, just like small birds. Lü et al. 2016 note that LAGs are uncommon in pterodactyloids, but may be seen in larger specimens that presumably lived longer. Size matters in a phylogenetic context. This has to be considered before making statements about ontogenetic age estimates.

Tibial bone wall thickness
With a radius of 16 units (holding a cm scale up to my monitor) the tibial bone thickness was 5 units, leaving 11 units of hollow cavity. That is same cortex ratio as in the 2x larger (9x heavier) holotype specimen.

But wait! What’s this?? A long rostrum on a juvenile??? 
That can’t be so, IF you follow the work of Bennett, Witton, Wellnhofer and others. That would be internally inconsistent! However, if you follow ReptileEvolution.com and the Pterosaur Heresies you’ll note that many tiny adults AND embryos had long rostra and small eyes. No problem under the isometric growth hypothesis, which I hope will someday gain a little acceptance because it is demonstrably factual. 

References
Lü J-C, Ji Q, Wei X-F and Liu Y-Q 2012. A new ctenochasmatoid pterosaur from the Early Cretaceous Yixian Formation of western Liaoning, China. Cretaceous Research in press. doi:10.1016/j.cretres.2011.09.010.
Lü J, Kundrát M, Shen C 2016. New Material of the Pterosaur Gladocephaloideus Lü et al., 2012 from the Early Cretaceous of Liaoning Province, China, with Comments on Its Systematic Position. PLoS ONE 11(6): e0154888. doi:10.1371/ journal.pone.0154888

TIme to Flip Plataleorhynchus (a spoonbill pterosaur)

Howse and Milner (1995)
described a spoonbill rostrum lacking teeth in place. They correctly compared it to the much smaller pterosaur Gnathosaurus and called their English find Plataleorhynchus stretophorodon (Fig. 1, BMNH R 11957). As you can see, it was much bigger.

Figure 1. Plataleorhynchus stretophorodon as originally interpreted (at far left) as newly interpreted (near left) with comparisons to Gnathoosaurus (right). Note the exposure is in dorsal view, not palatal view, and the premaxilla includes only 4 teeth, as in other pterosaurs.

Figure 1. Plataleorhynchus stretophorodon as originally interpreted (at far left) as newly interpreted (near left) with comparisons to Gnathoosaurus (right). Note the exposure is in dorsal view, not palatal view, and the premaxilla includes only 4 teeth, as in other pterosaurs. Yes, the premaxilla ‘pops up’ three times from beneath the maxilla and nasals in Gnathosaurus. Click to enlarge.

Unfortunately
Howse and Milner did not realize they were looking at the rostrum in dorsal aspect. And for that reason, perhaps,  they did not correctly figure the lateral extent of the premaxilla (Fig.1). No pterosaur has more than four teeth erupting from the premaxilla and Plataleorhynchus was no exception. So the premaxilla had a very short anterior exposure, rather than encompassing the entire spoonbill, as Howse and Milner interpreted the fossil from firsthand observation.

Howse and Milner did correctly note differences in the rostral shape and relative tooth size between Plataleorhynchus and Gnathosaurus, and also correctly noted that no other known pterosaur was closer. So, by this evidence, some mistakes don’t matter in the end.

Like Gnathosaurus and other ctenochasmatids,
Plataleorhynchus had dorsally expanded maxillae that contacted one another over the premaxilla aft of the spoonbill. Due to their orientation mistake, Howse and Milner identified the second dorsal appearance of the premaxilla as the palatine.

Howse and Milner thought the palate had a horny pad based on the rugosity that was exposed. That rugosity, (here considered dorsal) is also present in Gnathosaurus, but not as prominent. The reason or origin for the rugosity on the dorsal tip of Plataleorhynchus is difficult to explain, but may be related to the further extent of the maxillae and perhaps some sort of small horny crest.

Also note
the palatal extent of the premaxilla is much smaller in the comparable Gnathosaurus than envisioned for Plataleorhynchus by Howse and Milner. In Gnathosaurus I’m not sure how the teeth were not shaken loose. The roots appear to be exposed on the palate (Fig. 1). They must have been held in place by soft tissue.

Considering this mistake, 
much has been made about the value of firsthand observation versus the examination of photographs and illustrations. Paleontologists are fond of dismissing interpretations made in the absence of the fossil itself. They forget that most of the credit or blame for a discovery happens not in the lab, but between the ears. You have to see things correctly from the start or all the dominoes start to fall the wrong way. Mistakes can happen to anyone (including yours truly). Howse and Milner 1995 (Fig. 1) is another example of a firsthand observation that went awry based on one initial mistake. And that was an easy one to make with that odd spoonbill rostrum. It was flat on both sides.

Like Cope vs. Marsh back in the day, I am, once again metaphorically, “putting the skull on the other end of the skeleton” by flipping over the rostrum of Plataleorhynchus. The correct response, of course, should be curiosity or gratitude, not embarrassment, anger or dismissal. However, if anyone out there thinks the rostrum exposure is still palatal, I’d like to hear from you.

References
Howse SCB and Milner AR 1995. The pterodactyloids from the Purbeck Limestone Formation of Dorset. Bulletin of the Natural History Museum London (Geology)51:73-88.

 

Focus on Angustinaripterus – transitional between Dorygnathus and Ctenochasma

Angustinaripterus (Fig. 1) has been difficult to classify for other pterosaur paleontologists. Here in the large pterosaur tree the reason becomes quite evident. Add a few taxa and Angustinaripterus become a transitional taxon between the more primitive Dorygnathus (R154) and the more derived Gnathosaurus and Ctenochasma.

Figure 1. Angustinaripterus as a transitional taxon between Dorygnathus and Gnathosaurus.

Figure 1. Angustinaripterus as a transitional taxon between Dorygnathus and Gnathosaurus. Seems pretty obvious. Phylogenetic analysis confirms.

This possibility flips out traditional pterosaurologists who have pinned their hopes on Darwinopterus, which doesn’t look much like either Ctenochasma or Dorygnathus.

But that’s not all
Here (Fig. 2) are the many other specimens that smooth the evolutionary transition, as we noted before. Here they are. And many of them are tiny.

Figure 2. The same sequence with the addition of Dorygnathus purdonti and four tiny pterosaurs variously misassigned to Pterodactylus and Ctneochasma.

Figure 2. The same sequence with the addition of Dorygnathus purdonti and four tiny pterosaurs variously misassigned to Pterodactylus and Ctneochasma. Black illustrations are to scale. Gray figures are enlarged to show detail.

Angustinaripterus is the reason why I delved deeper into pterosaur phylogeny than anyone has done before. At first glance it’s clearly something not quite Dorygnathus and not quite Gnathosaurus or Ctenochasma.

The next step after Angustinaripterus was to add in some…

Tiny pterosaurs
This (Fig. 2) is only one sequence of many in which tiny adult pterosaurs are transitional between larger forms, both more primitive and more derived. At first glance, and according to tradition, these tiny pterosaurs are only juveniles or hatchlings, which makes perfect sense—until you add them to your matrix—and you realize juvenile pterosaurs of other types are virtual copies of adults. So there was no allometric growth after hatching, but chiefly isometric growth.

But there’s an important clue here staring you right in the face: Note how the tiny pterosaurs are ALL the same size. As it turns out, this is the minimum size at which pterosaurs could fly, evidently, as we find no smaller pterosaurs in the fossil record. Smaller pterosaurs, all juveniles, must have been living in damper environments and probably not flying. Some hatchlings, like the IVPP embryo, were as large as these adult pterosaurs (Fig. 2) and other adult tiny pterosaurs, so they could fly immediately. 

References
He X-L, Yang D-H and Su C-K 1983. A New Pterosaur from the Middle Jurassic of Dashanpu, Zigong, Sichuan. Journal of the Chengdu College of Geology supplement 1: 27-33.

wiki/Angustinaripterus

Pterodaustro evolution

Earlier we looked at the evolution and variety of ctenochasmatids, focusing on the skulls. Here we take a look at Ctenochasma, Pterodaustro and a taxon that forms the best transition (Fig. 1). So far it has been called the Bamberg piece. Even so, in some traits the new taxon has also gone its own way (Fig. 1), as all sisters to transitional taxa do. We’ll call it ‘Propterodaustro’ for now, but a real generic name will be applied by its discoverers when the Bamberg specimen is officially published. For now it has only made its presence known online here and here.

 

Figure 1. The evolution of Pterodaustro from a sister to Ctenochasma. "Propterodaustro" , the Bamberg specimen, is a sister to the transitional taxon. As you can see, there is an increasing variety in this clade.

Figure 1. The evolution of Pterodaustro from a sister to Ctenochasma. “Propterodaustro” , the Bamberg specimen, is a sister to the transitional taxon. As you can see, there is an increasing variety in this clade.

Similarities
Like Ctenochasma, the new taxon has a long, but not hyperelongated, rostrum, as seen in Pterodaustro. Sizewise, the new taxon is midway between the two. The neck length is transitional. The curvature and depth of the mandible and the length of the tibia relative to the metacarpus in the new taxon is midway between the two (Fig. 1). Relative to the antebrachium, the metacarpus of the more derived Pterodaustro is phylogenetically shrinking, an oddity among derived pterosaurs.

Autapomorphies
The new taxon includes a few autapomorphies found in neither Ctenochasma nor Pterodaustro. A relatively taller skull is present. The torso is relatively shorter. The scapula is no longer than the coracoid chiefly because the coracoid is relatively larger. The humerus is much shorter than the femur. The ischium does not have two posterior processes. The deltopectoral crest is ever so slightly pinched. The sternal complex is uniquely shaped. Manual 4.2 is shorter than m4.1 (fairly common among pterosaurs, but not present in Ctenochasma or Pterodaustro.) The upper teeth are longer than the lowers with small thickened lobes. Perhaps you can spot additional unique traits.

This weekend
I’ll reconstruct the new Pterodaustro with stomach stones featured in JVP and put it up against the holotype to see what overall variation, if any, is present. The specimen is obviously a Pterodaustro, so there’s no reason to reconstruct it (traditional thinking), but if there is variation, there might be something of interest to post (test, test, test).

References
The pre-Solnhofen ctenochasmatid pterosaur was covered earlier here and announced earlier here and here. Quoting from those sources (below), the discoverers appear to think they have an azhdarchid ancestor, but they are not saying that for sure.

“The 155 million year old animal is different in physique from other known species – and its remnants are extremely well preserved. Scientists speak of a major discovery. The specimen had very long arms and long legs, almost like stilts. Fish remains are found in the belly.”

“The Bamberg piece shows that these giant pterosaurs had their origin in the Jurassic period,” reports Dr. Eberhard (Dino) Frey. Such a nesting, at the base of the azhdarchidae, is not confirmed in the large pterosaur family tree. It is certain that azhdarchids had their origins in the Jurassic, but not with the Bamberg specimen. Instead those ancestors were the tiny pre-azhdarchids, like no. 42 and no. 44 reported earlier here.