Tetrapodophis – new four legged very basal, very tiny snake

A new paper by Martill, Tischlinger and Longrich (2015) brings us a really tiny, new Early Cretaceous snake, Tetrapodophis amplectus (Fig. 1, BMMS BK 2-2, ), with four limbs and all of its fingers and toes. The authors suggest this basal snake and thus all snakes evolved from burrowing rather than marine ancestors in accord with the  Longrich, Bullar and Gauthier (2012) assessment of another tiny snake, Coniophis, which is known from only a few skull parts. (Also see below.)

Unfortunately Tetradopodophis (so far based on skull traits only) nests in the large reptile tree between Adriosaurus + Pontosaurus and DinilysiaPachyrhachis + Boa, so an aquatic origin is recovered from the cladogram despite the extremely tiny size of Tetrapodophis (skull length about 1 cm, total length about 16 cm). Martill et al. used mosasaurs and several incomplete taxa (Eophis, Diablophis, Portugalophis and Parviraptor, none included in the large reptile tree) for outgroups and nested Tetrapodophis as a sister to Coniophis and basal to Najash, Dinilysia and all other snakes. The authors note, “As the only known four-legged snake, Tetrapodophis sheds light on the evolution of snakes from lizards. Tetrapodophis lacks aquatic adaptations (such as pachyostosis or a long, laterally compressed tail) and instead exhibits features of fossorial snakes and lizards: a short rostrum and elongation of the postorbital skull, a long trunk and short tail, short neural spines, and highly reduced limbs.”

I wonder if Tetrapodophis is a hatchling? Or does it represent yet another example of phylogenetic miniaturization at the origin of a major clade? It is similar in size to Jucaraseps, a more primitive lizard with snake affinities. Tetrapodophis may be a late surviving (Early Cretaceous) very basal snake with likely origins in the Middle Jurassic. DGS (digital graphic segregation) was helpful in pulling out details (Fig. 1) overlooked or ignored by the original authors.

Figure1. The skull of Tetrapodophis in situ and colorized (middle) as originally interpreted (below) and reconstructed using DGS (above). I have not seen the fossil, but examination of the photograph using DGS permits more details to be identified. This image will be tested for validity Monday. Only the major bones were identified here. The skull is about 1 cm in length.

Figure1. The skull of Tetrapodophis in situ and colorized (middle) as originally interpreted (below) and reconstructed using DGS (above). I have not seen the fossil, but examination of the photograph using DGS permits more details to be identified. This image will be tested for validity Monday. Only the major bones were identified here. The skull is about 1 cm in length.

The preparator did an excellent job on such a tiny (16 cm) specimen, unless it split naturally into part and counterpart. The specimen was in a private collection for decades before getting its museum number.

Like non-snakes, Tetrapodophis retained a postorbital, squamosal and lacrimal. A broken jugal was also found. Palatal fangs were present along with a deep coronoid process. There is a mass at the back of the throat that makes it difficult to identify the posterior palatal bones. The authors report, BMMS BK 2-2 is distinguished from all other snakes by the following combination of characters: 160 precaudal and 112 caudal vertebrae, short neural spines, four limbs, metapodials short, penultimate phalanges hyper elongate and curved, phalangeal formula 2?-3-3-3-3? (manus) 2-3-3-3-3 (pes).”

Although DGS was able to pull lots of details out of this specimen, don’t expect the DGS detractors to applaud this example, although It would be nice to get a tip of the hat for this one. It’s a pretty striking example and only took an hour or two to do.

Figure 2. Tiny Tetrapodophis at full scale if your monitor produces 72 dpi images (standard on many monitors).

Figure 2. Tiny Tetrapodophis at full scale if your monitor produces 72 dpi images (standard on many monitors).

This is a major find and congratulations are due to the authors. More on this specimen in future blog posts.

References Longrich NR, Bullar B-A S and Gauthier JA 2012. A transitional snake from the Late Cretaceous period of North America. Nature 488, 205-208. Martill DM, Tischlinger H and Longrich NR 2015. A four-legged snake from the Early Cretaceous of Gondwana. Science 349 (6246): 416-419. DOI: 10.1126/science.aaa9208

Invagination and erosion of the turtle cranium

Turtles have no temporal fenestra,
but some of them have enlarged their jaw muscles by greatly enlarging the cranium, or by invagination of the cranium from the occiput, or both (Fig. 1). Skull temporal fenestra are important traits to categorize most reptiles, but turtles do not follow other clade morphologies. That has made turtles difficult to categorize and nest in traditional studies.

Figure 1. Macrochelys (Macroclemys) skull colorized. Most workers label the bone above the curled quadrate as a squamosal, but here it is considered a supratemporal, which has horns in basal turtles.

Figure 1. Macrochelys (Macroclemys) skull colorized. Most workers label the bone above the curled quadrate as a squamosal, but here it is considered a supratemporal, which has horns in basal turtles. This skull shows a minimum of occiput invagination, but note the great height of the cranium.

Some paleontologists
think turtles are diapsids related to placodonts, but that is not supported by the large reptile tree.

Other paleontologists
think turtles are anapsids related to Eunotosaurus, but that is not supported by the large reptile tree.

Still other paleontologists
USED to think turtles are anapsids related to pareiasaurs, and that IS supported by the large reptile tree. Basal turtles, like pareiasaurs and all basal tetrapods, have both an external (dermal) skull  surrounding and protecting the smaller internal (braincase) skull.

Basal turtles have a solid cranium – with horns!
Elginia and Meiolania are basalmost turtles they have horns and at least we know that Meiolania had a solid carapace and plastron. The outgroup, Sclerosaurus, has horns, but no shell and no broad ribs. In Meiolania the large, horned supratemporal sends a ventral process to contact the quadratojugal leaving a hole for the quadrate and stapes (ear bone). The supratemporal is a large bone in basal turtles that does not go away in derived turtles. Rather, the squamosal continues to shrink.

Figure 2. Elginia and Meiolania, two basal horned turtles without skull invagination.

Figure 2. Elginia and Meiolania, two basal horned turtles without skull invagination. In Meiolania the supratemporal sends a ventral process to contact  the quadratojugal leaving a hole for the quadrate and stapes (ear bone). The supratemporal is a large bone in basal turtles that does not go away in derived turtles. Rather, the squamosal continues to shrink.

Proganochelys (Fig. 3) has long been recognized as a basal turtle. It has no horns or skull invagination, so, in this context, it is not a basal turtle, but a transitional turtle, between horned and invaginated-skull turtles.

Figure 2. The skull of Proganochelys, a basal turtle without skull invagation and without horns.

Figure 3. The skull of Proganochelys, a basal turtle without skull invagation and without horns. Note the identification of the supratemporal on the right matching that of basal turtles like Elginia and Meiloania in figure 2.

Softshell turtles
have an invaginated cranium, no horns and sometimes reduce their bony shells. A basal turtle with teeth, Odontochelys, nests with a soft-shell turtle, Trionyx, in the large reptile tree. The cranium of Trionyx is invaginated from the occiput, creating space for large jaw muscles. The skull of Odontochelys (Fig. 7) is difficult to study with available data, but it appears to have large round holes in the crushed cranium. At least it does not appear to have the solid cranium that was illustrated originally (Fig. 7). Rather the cranium appears to be so badly crushed, even in the low resolution image available, that it may indeed have had a more fragile, less box-like, Trionyx-like cranium. I requested high rez images, but was informed that another paper focusing on the skull of Odontochelys is in progress. Looking forward to that!

Figure 3. Trionyx, a softshell turtle with bones colorized.

Figure 3. Trionyx, a softshell turtle with bones colorized.

Other tested turtles have a an increasingly invaginated cranium
Chelonia,
the sea turtle, is a basal turtle that has a rather solid skull with a little posterior invagination.

Macrochelys, the alligator snapping turtle (Fig. 1), has a deeper invagination and a much taller cranium.

Pelomedusa and Foxemys are similar to the snapping turtle, but without the grand enlargement of the cranium.

Terrapene (Fig. 5), the box turtle, has lost most of its original cranium, revealing a braincase, like a mammal, snake, amphisbaenid or bird.

Figure 4. Terrapene, the box turtle, with skull bones colorized. Note the lack of a dermal skull and the appearance of the cranial skull, the braincase.

Figure 5. Terrapene, the box turtle, with skull bones colorized. Note the lack of a dermal skull and the appearance of the cranial skull, the braincase, as in birds, mammals, snakes and amphisbaenids.

The large reptile tree
nests Kayentachelys between the soft-shell turtles, Trionyx and the hard-shelled turtles, like Chelonia (Fig. 6). Kayentachelys has a complete cranium without invagination. Separate nestings of soft-shell and hard-shell turtles with skull invagination indicate this trait was convergent, not homologous. Such a tree topology has not been recovered before, but then no prior study (that I can recall) has included Sclerosaurus, Elginia and Stephanospondylus.

Figure 1. Turtle phylogeny showing extent of horns and cranial invagination. Here the skull invagination of soft-shell turtles is convergent with that of most other turtles.

Figure 6. Turtle phylogeny showing extent of horns and cranial invagination. Here the skull invagination of soft-shell turtles is convergent with that of most other turtles.

Parts of the skull of Odontochelys cannot be accurately reconstructed with available data (Fig. 7). There are apparent temporal fenestrae in the in situ specimen exposed in dorsal view. These would ordinarily have the appearance of diapsid openings and would lend credence to the diapsid hypothesis of turtle origins. Instead, let’s wonder if these holes represent either: 1) geological erosion; or 2) erosion of the posterior cranium in spots transitional to the morphology seen in Trionyx. There’s nothing else I can say at present until better data comes along.

There is a large circular plate
(Fig. 7) in the palatal view of the smaller Odontochelys that was labeled a possible squamosal. I don’t think there is room on the skull for that bone at present. So that elliptical bone may be from elsewhere, perhaps on the carapace or plastron.

Most turtles have anterior nares.
The anterolateral placement of the large naris in Odontchelys is different from all other turtles and similar only to Elginia (Fig. 2).

Figure 7. Data and tentative interpretations of skull elements for Odontochelys. I can't make more sense than this of the bones. Sorry. Gray areas appear to represent holes in the cranium.

Figure 7. Data and tentative interpretations of skull elements for Odontochelys. I can’t make more sense than this of the bones. Sorry. Gray areas appear to represent holes in the cranium. Note the difference between the original drawing and the photo with color overlay. The skull bones of Odontochelys appear to be more fragile than boxy turtle skulls are.

The skull of Stephanospondylus (Fig. 8) is a good starting point for both pareiasaur and turtle skulls. It nests (Fig. 7) at the base of both clades.

Figure 2. Stephanospondylus skull in two views. Note the rotation of the post parietals to the dorsal skull along with the transformation of the supratemporals into small horns.

Figure 8. Stephanospondylus skull in two views. Note the rotation of the post parietals to the dorsal skull along with the transformation of the supratemporals into small horns.

Perhaps more taxa
will someday unite soft-shell turtles with hard-shell turtles, but at present, the convergence is remarkable among all turtles with an invaginated skull. With regard to Odontochelys, I think we’ll see a strong revision of the original drawing.

References
Li C, Wu X-C, Rieppel O, Wang L-T and Zhao L-J 2008. An ancestral turtle from the Late Triassic of southwestern China. Nature 456: 497-501.

Urumqia – a very basal lepidosauromorph

Urumqia liudaowanensis (Zhang et al. 1984) ~20 cm snout-vent length, Lower Permian.

Figure 1. Urumqia liudaowanensis (Zhang et al. 1984) ~20 cm snout-vent length, Late Permian.

Here’s a gephyrostegid/basal amniote/basal lepidosauromorph
you may not have heard of. (Remember lepidosauromorphs in the large reptile tree constitute about half of all amniotes). It is considered China’s oldest known tetrapod.

Urumqia liudaowanensis (Zhang et al. 1984, Fig. 1) ~20 cm snout-vent length, Late Permian Lucaogou Formation), was originally considered a discosaurid seymouriamorph. Here it nests at the base of the lepidosauromorph reptiles. Shifting Urumqia to the discosaurid seymouriamorphs adds 39 steps to the large reptile tree.

Derived from 
Gephyostegus bohemicusUrumqia was basal to Bruketererpeton, Thuringothyris, and all lepdiosaurs, turtles, diadectids, pterosaurs and other various lepidosauromorphs starting with Saurorictus and Cephalerpeton. Phylogenetically Urumqia must have made a first appearance in the Viséan (335 mya, Mississipian, Carboniferous) despite its late appearance in the Late Permian (255 mya).

Figure 1. Basal amniotes to scale. Click to enlarge.

Figure 2. Basal amniotes to scale. Click to enlarge. Urumqia nests on the right hand column with Cephalerpeton and Thuringothyris.

Distinct from G. bohemicus,
Urumqia had shorter limbs, longer (but not long) posterior dorsal ribs and a robust tail with elongate caudals. The palate included a suborbital fenestra. The cheek may have included a small lateral temporal fenestra convergent with others. The carpals and tarsals were poorly ossified.

Figure 4. Extant lizards, A. gravid, B. in the process of laying eggs, C. with egg clutch.

Figure 3. Extant lizards, A. gravid, B. in the process of laying eggs, C. with egg clutch.

Notably
the posterior dorsal ribs were much shorter than the gastralia. So the gastralia create a wide posterior torso, ideal for carrying large amniote eggs (Fig. 3), as we learned earlier.

The new topology of basal reptiles
is based on the inclusion of several more species based taxa not previously considered. This new topology show that synapsids were not the first clade to branch off. Rather all taxa closer to archosaurs (here considered the new Archosauromorpha) split from all taxa closer to lepidosaurs (here considered the new Lepidosauromorpha) at the onset of the Reptilia (=Amniota).

References
Zhang F, Li Y, and Wan X. 1984. A new occurrence of Permian seymouriamorphs in Xinjiang, China. Vertebrate Palasiatica22(4):294-306.

Comments from readers

I don’t get very many comments from readers.
Rarely do any of my blogposts get any feedback. The few rare comments I do get usually arrive whenever I make a mistake among the bird-like theropod dinosaurs, who have their own large fan base. Oddly, many of those readers also become further angered whenever I correct those mistakes, something I thought they were encouraging me to do! In the world of the Internet, and scientific discovery, such feedback is par for the course and must be expected. People in general, and scientists in particular, like their paradigms and don’t want outsiders tampering with them.

As a matter of practice, 
I try to be very specific and show images in my comments on the work of others, keeping anger and other negative emotions out of it.

Even more rarely
do I get replies that include specific instructions and data on how to correct my tracing errors. That has probably happened less than ten times in 1350 blog posts. Nevertheless, all of those rare comments are gratefully appreciated and acted upon. As my readers know, I’m only trying to get everything right, hoping only to provide new ideas to colleagues, whether they like those ideas or not. In Science, testing is supposed to be an okay thing to do. And if the tests are not valid, they can be done again and again until they are valid.

After 4+ years of reptileevolution.com
and pterosaurheresies.wordpress.com, I still haven’t seen any other paleontologist attempt to provide large gamut reptile cladograms based on specimens and species, now hovering around 560 taxa (exclusive of the pterosaur cladogram). The bird, dinosaur, croc and lizard paleontologists have done similar large gamut work, so I’m trying to avoid those well-studied clades, concentrating only on their origins. Let’s face it, a large gamut study of the basal reptiles needs to be published. The problem is, no PhD is interested or capable (time and travel constraints) of doing so, so far. Perhaps one is in progress.

The ‘hate mail’ I get reminds me of the 1961 Yankees
and specifically of the plight of Roger Maris, who, in 1961 approached and ultimately exceeded Babe Ruth’s hallowed 60 home runs in a season record. Teammate Mickey Mantle (Fig. 1) was also in that race that year that also featured an extended season. No one liked the fact that Maris, an outsider, was doing something so important.

Figure 1. Roger Maris and Mickey Mantile in 1961, two Yankees with a chance to break Babe Ruth's home run record.

Figure 1. Roger Maris and Mickey Mantile in 1961, two Yankees with a chance to break Babe Ruth’s home run record. The press and the fans were not kind to Maris during that season or to Mantle several years earlier.

Wikipedia reports, “In 1956, the New York press had been protective of Ruth when Mantle challenged Ruth’s record for most of the season. When Mantle fell short, finishing with 52, there seemed to be a collective sigh of relief from the New York traditionalists. The New York press had not been kind to Mantle in his early years with the team; he struck out frequently, was injury prone, was a true “hick” from Oklahoma, and was perceived as being distinctly inferior to his predecessor in center field, Joe DiMaggio. Mantle, however, over the course of time (with a little help from his friend and teammate Whitey Ford, a native of New York’s Borough of Queens), had gotten better at “schmoozing” with the New York media, and consequently gained the favor of the press. This was a talent that Maris, a blunt-spoken Upper Midwesterner, never attempted to cultivate. Maris was perceived as surly during his time on the Yankees.

“More and more, the Yankees became “Mickey Mantle’s team” and Maris was ostracized as an “outsider” and “not a true Yankee.” The press at that time seemed to be rooting for Mantle and belittling Maris. Mantle, however, was felled by a hip infection causing hospitalization late in the season, leaving Maris as the single remaining player with the opportunity to break Ruth’s home run record.”

Much of the same sort of human psychology is at play here.
In this case, yours truly, an outsider, not a true paleontologist, and not a PhD, has created a large gamut set of cladograms for reptiles and pterosaurs. The expanded data recovers a different topology than smaller studies, often handicapping themselves by using suprageneric taxa. And not all of those smaller studies match one another. The new topologies featured here and here were due in large part to taxon inclusion that was not attempted in the smaller studies. No one should see this as a threat.

That same outsider (yours truly) also broke a cardinal rule among paleontologists, “You have to see the fossil.”  Due to the large number of specimens involved, I have not seen every fossil, nor will anyone else in my lifetime. Referencing the literature is also common practice. That’s what it is there for!

Instead, after concentrated study,
I have reconstructed every included fossil and compared one with another graphically. That is something most paleontologists don’t do or do only rarely. As you should expect of such a large cladogram, all sister taxa actually look like they could be related, something that is too often lacking at certain nodes in certain other traditional cladograms.

In my attempt at making sure all the data was verifiable,
I have traced photos of in situ specimens and reconstructed them. That, evidently, is a sin, but one that is getting to be increasingly popular. And like most paleontologists, I have made a few mistakes along the way. These seem to happen most often when working with images of low resolution. When alerted to those mistakes, and provided better data, I have made corrections. That’s should be considered, “a good thing,” just as it is with the new data on Pluto (note the earlier fuzzy images that still have/had scientific value). Unfortunately, like Roger Maris’s situation in 1961, the jeers keep coming, but the large gamut reptile studies have not arrived yet.

I encourage more reader feedback,
but please, make replies constructive and include data if you have it. I don’t want anybody to be embarrassed by brash comments as future data and cladograms confirm current findings. And if you find two taxa that should not nest together, please let me know where the errant one should nest. If there are any mistakes in my presentation, I want to fix them.

 

 

Germanodactylus cristatus ventral reconstruction

Every so often
old reconstructions get updated. This time Germanodactylus cristatus gets the treatment with a new ventral view, matching the exposure of the cervicals and anterior dorsals (Fig. 1).

Figure 1. Germanodactylus cristatus in ventral view, wings outspread.

Figure 1. Germanodactylus cristatus in ventral view, wings and legs outspread. in that configuration the legs act as horizontal stabilizers and create their own lift. The torso appears to have been wider than deep. The prepubes were fused medially. The pelvis and three toes are conjectural based on matrix impressions, perhaps buried bones.

Note
the femoral heads are nearly at right angles to the femoral shafts. This gives the hind limbs more of an erect configuration, which may have aided this taxon in terrestrial stalking, something we talked about earlier here.

Figure 2. Germanodactylus cristatus in lateral view, bipedal/quadrupedal configuration.

Figure 2. Germanodactylus cristatus in lateral view, bipedal/quadrupedal configuration. The pelvis and three toes are based on matrix impressions.

References
Plieninger F 1901. Beiträge zur Kenntnis der FlugsaurierPaläontographica 48, 65–90 and pls 4–5.
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.
Wiman C 1925. Aus dem Leber der Flugsaurier. Bulletin of the Geological Insititute of the University of Uppsala 19: 115-127.

wiki/Germanodactylus

DGS Embryo Lizards at PLOS

I’m happy to show you
examples of professional paleontologists using digital equipment to render bones, segregate bones and reconstruct fossil taxa. This one is from Fernandez et al. 2015.

Figure 1. Fossil lizard eggs rendered after CT scanning. Colors represent various parts of the body. Their digital segmentation is the same as my digital segregation, only hi-tech . THIS is the way to render bones in roadkill fossils. Let's make this standard practice.

Figure 1. Fossil lizard eggs rendered after CT scanning. Colors represent various parts of the body. Their digital segmentation is the same as my digital segregation, only hi-tech . THIS is the way to render bones in roadkill fossils. Let’s make this standard practice.

The above eggs are totally scrambled.
Lucky for us Fernandez et al. put in the effort to segregate, identify and reconstruct every bone in the egg. They did an excellent job!

From the Discussion:
“The digital segmentation of the two least crushed eggs (SK1-1 and SK1-2) shows that both embryonic skeletons are mostly disarticulated, but assembled into clusters reflecting the original position.” (Fig. 1). These workers used a CT scanner to reassemble this scrambled egg.

Along the same lines
and lacking a CT scanner, I use Photoshop, but the idea is the same: to extract as much data as possible from difficult specimens.

And after the bones are digitized
they can be moved about and reconstructed (Fig. 2). I want to encourage all workers to adopt the practice of coloring each bone in situ. Much better than simply drawing a line to the center of each bone and leaving the shape of the bone to the reader’s imagination.

Figure 2. Reconstructed embryo lizard skull from digitized data.

Figure 2. Reconstructed embryo lizard skull from digitized data.

Which lizard is it?
Just eyeballing it here, but Liushusaurus (Fig. 3) and Bahndwivici are close matches and the former is a contemporary. Not a perfect match, but close enough for now.

Figure 3. The basal scleroglossan, Liushusaurus, is a close match to the lizard embryo.

Figure 3. The basal scleroglossan, Liushusaurus, is a close match to the lizard embryo. The post cranial bones are likewise quite similar. Note the rostrum does not elongate here, another example of isometric growth.

Both are basal scleroglossans.
Based on sister taxon first appearances, both had been around since the Late Permian.

Figure 5. Bahndwivici, a basal anguimorph, scleroglossan squamate similar to the embryo in the egg.

Figure 4. Bahndwivici, a basal anguimorph, scleroglossan squamate similar to the embryo in the egg.

Npw, about those eggs
The authors noted these eggs had gekko-like hard eggshells, but attributed them to anguimorph lizards (monitors, mosasaurs, etc.). In the large reptile tree Liushusaurus nests just basal to geckos AND anguimorphs. So, the diversity described in the paper’s headline is maybe… not so much. Bahndwivici nests basal to anguimorphs like monitors and mosasaurs.

And please note
the embryo is an isometric match to its adult counterpart. So isometry can and does occur in the growth of certain lepidosaurs, like pterosaurs.

And on that note
Wills someone please fix the Wikipedia entry for Aurorazhdarcho. It includes a wide variety of pterosaurs of all shapes and sizes, some with small rostra and some with elongate rostra, all attributed to one genus based on the false paradigm of allometry during isometry in pterosaurs.

References
Fernandez V, Buffetaut E, Suteethorn V,  Rage J-C, Tafforeau P and Kundrát M 2015. Evidence of Egg Diversity in Squamate Evolution from Cretaceous Anguimorph Embryos. PLoS ONE 10(7):e0128610. doi:10.1371/journal.pone.0128610

Stalking or wading azhdarchids (part 3)

Witton and Naish (2013) proposed a terrestrial stalking mode of operation for azhdarchid pterosaurs (Fig. 1). We looked at various aspects of that earlier here and here. Today, a few more details need to be considered.

Figure 1. Click to enlarge. On right from Witton and Naish 2013. On left reconstruction from Cai and Wei 1994 of Zhejiangopterus.

Figure 1. Click to enlarge. On right from Witton and Naish 2013. On left reconstruction based on data from Cai and Wei 1994 of Zhejiangopterus. Compare right stalking image with figure 3 wading image. Consider the great weight of that big skull on the end of that long skinny neck supported by those tiny fingers. All those problems are solved when wading (Fig. 3).

The following notes are retrieved from the boxed captions surrounding the Witton and Naish image (Fig. 1), which you can enlarge to read. 1. Reclined occipital face – Head perpetually angled towards ground when neck is lowered. – True of all wading pterosaurs and most pterosaurs in general. 2. Neck anatomy and arthrology – Long neck reduces effort to produce large movements; range of motion allows easy access to the ground. – True of all wading pterosaurs and most pterosaurs in general. 3. Skull shape and hypertrophied jaw tips – Skull morphology most similar to terrestrial feeding generalists, such as ground hornbills and modern storks; jaw elongation reduces neck action required to reach ground level – True of all wading pterosaurs and most pterosaurs in general.

Figure 3b. Zhejiangopterus fingers. Witton and Naish want you to believe that these three fragile fingers on three spaghetti-thin metacarpals are suitable weight-bearing bones - OR that mc4 is a weight-bearing bone. Neither is true. Metacarpal 4 NEVER makes an impression. The wing finger NEVER makes an impression. They were both held above the substrate in ALL pterosaurs.

Figure 2. Zhejiangopterus fingers. On left based on Cai and Wei 1994. On the right, according to Witton and Naish who want you to believe that these three fragile fingers on three spaghetti-thin metacarpals are suitable weight-bearing bones – OR that mc4 is a weight-bearing bone. Neither is true. Metacarpal 4 NEVER makes an impression. The wing finger NEVER makes an impression. They were both held above the substrate in ALL pterosaurs. The Witton Naish metacarpal is over rotated in order to allow fingers 1-3 to hyper-extend laterally, but that means the wing finger also opens laterally, not in the plane of the wing! Their mc 1-3 are pasted against mc 4, dorsal sides to dorsal side following the false Bennett model. Their fingers don’t match ichnites.

4a. Large coracoid flanges: distally displaced crests. Enlarged anchorage and increased lever arm for flight muscle; powerful takeoff ability. – Actually azhdarchids have relatively small pectoral complexes and small humeri. Witton and Naish employed a juvenile sample for their humerus. 4b. Enlarged medial wing length, decreased wing finger length. Increased forelimb stride; enlarged medial wing region and greatest lift; reduced risk of snagging wingtips on vegetation. – This is also true of all wading bottom feeders, and most pterodactyloid-grade pterosaurs in general. Also note that these traits are present in tiny Solnhofen pterosaurs (Fig. 3). Decreased wing finger length reaches a nadir in JME SOS 2482, a flightless pterosaur with a big belly and definitely NOT a stalker of terrestrial vertebrates.  5. Robust digit bones. Adaptations to weight bearing. – Obviously not true. The free fingers of Zhejiangopterus are both small and gracile and have no obvious adaptation to weight bearing. So, why are they bearing nearly all the weight of Zhejiangopterus (Fig. 1) in the Witton and Naish reconstruction? Instead, think of pterosaur forelimbs like ski poles, good for steadying (Fig. 3), especially while feeding in moving waters (Fig. 4. All weight bearing runs through the hind limb. Here is a Zhejiangopterus matched to tracks (Fig. 3). Witton and Naish make no effort to match a manus and pes to the tracks they use. 

Figure 2. The large azhdarchid pterosaur, Zhejiangppterus. is shown walking over large pterosaur tracks matched to its feet from Korea (CNUPH.p9. Haenamichnus. (Hwang et al. 2002.)

Figure 3. The large azhdarchid pterosaur, Zhejiangppterus. is shown walking over large pterosaur tracks matched to its feet from Korea (CNUPH.p9. Haenamichnus. (Hwang et al. 2002.)

6. Elongate femur (>1.6 humeral length). Increases stride efficiency; decreases attitude of axial column during feeding. In azhdarchids the femora is not relatively longer than in precursor taxa. The humerus is relatively shorter than in most pterosaurs and shorter than azhdarchid precursors like n42 in particular (Fig. 4). The torso is also relatively shorter, but this is also true of tiny precursor azhdarchids, like n42.  l7. Narrow-gauge trackways (Haenamichnus). Sub-vertical limbs providing efficient carriage when walking. – The Witton and Naish drawing overlooks the shallow angle of the femoral head relative to the shaft that would have produced a relatively sprawling, lizard-like femoral angle, as preserved in situ. Even so, the ankles would have remained below the body so long as the knees were below the acetabulum. It is also clear that pterosaur knees were bent during terrestrial locomotion, as in virtually all tetrapods.  8. Compact, padded pes and manus. Maximizes outleaver forces during step cycle; cushioning and increased traction on firm ground. – Witton and Naish based this claim on such loose and sloppy ichnites that individual toes were not distinct. Pads are also not distinct other than in the original drawing. When you look at the actual pes of Zhejiangopterus (Fig. 1) the metatarsus is indeed compact, narrower than in all other pterosaurs. 

Quetzalcoatlus scraping bottom while standing in shallow water.

Figure 4. Quetzalcoatlus scraping bottom while standing in shallow water. Note the attempt here to shift weight posteriorly while the neck is extended anteriorly. Keeping the wing finger close to the forelimb reduces the exposed wing area, important for underwater stability. The air-filled skull is weightless when in water. Not so when terrestrial stalking.

If, on the other hand, azhdarchids were waders, as were their tiny ancestors, like n42 (Fig. 5), then we can see not only their original tall, thin, morphology and their gradual evolution to great size while maintaining their wading niche (Fig. 5), but also a reason for getting bigger; gradually deeper water access. Unfortunately, Witton and Naish make no attempt to nest azhdarchids phylogenetically and certainly make no reference to their tiny ancestors.

Sisters to Microtuban

Figure 5. Sisters to Microtuban include No. 42 (more primitive) and Jidapterus (more derived).

The actual trackmaker of Haenamichnus had fingers (digits 1-3) as long as its foot. That is not found in Zhejiangopterus, but is found in Jidapterus (Fig. 5), a precursor azhdarchid.

Azhdarchids and Obama

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

We already have pterosaurs that could have been terrestrial stalkers, like ground hornbills. We call them germanodactylids (Fig. 7). And THEY have horny/bony crests and a sharp, dangerous beak like a hornbill!

Germanodactylus and the Dsungaripteridae

Figure 7. Germanodactylus and the Dsungaripteridae. Click to enlarge. If any pterosaurs were like ground hornbills, these even had horn bills!

The beak tip of azhdarchids is a better pick-up tweezers than a stabbing knife. Better for picking up defenseless invertebrates than for stabbing terrestrial prey capable of fighting back or running away. Remember, when you go back further in azhdarchid phylogeny, you come to dorygnathids, a clade that also gave rise to wading ctenochasmatids. The devil is in the details Witton and Naish give us a pterosaur metacarpus with the false Bennett configuration (Fig. 8) in which metacarpals 1-3 are rotated as a set, like a closed draw bridge, against the anterior (formerly dorsal) surface of mc 4. That provides no space for all four extensor tendons. Now to get those fingers to hyper-extend laterally, Witton and Naish over rotate mc4 by another 90 degrees (Fig. 2). But now their wing opens laterally, no longer in the plane of the wing, as all fossils indicate.

Pterosaur finger orientation in lateral view

Figure 8. Pterosaur finger orientation in lateral view, the two hypotheses. On the left the Bennett hypothesis. On the right the Peters model that is supported by all fossil pterosaurs. These images graphically show how gracile metacarpals 1-3 were and why they could not support the weight of the pterosaur during terrestrial locomotion. The Bennett migration of the metacarpals is another problem. Witton and Naish take the Bennett mc4 one step further by rotating it another 90 degrees in order to produce lateral finger impressions. during hyperextension.

Witton and Naish give us a metacarpus and wing finger that should impress the substrate, but no pterosaur ichnite ever shows an impression of mc4 or the wing finger. So we know those two elements were held aloft during terrestrial locomotion, no matter how much Witton and Naish (and others see figure 9) wish otherwise. Witton and Naish give us a pteroid (Fig. 2) articulated to the preaxial carpal (another Bennett mistake) when the pteroid actually articulates with the radiale. Only soft tissue connects the pteroid and preaxial carpal. Witton and Naish give us pterosaur free fingers that don’t match tracks and don’t match bones. Witton and Naish illustrated from their imagination, both in shape and orientation. Witton and Naish currently hold court on pterosaur morphology, but I think you’ll agree they do so with false reconstructions. These two need to adopt strict and precise standards in which the bones agree with the ichnites and vice versa. Witton and Naish support the forelimb launch in all pterosaurs including giant Quetzalcoatlus. Considering the strain that would run through the three tiny fingers and three slender metacarpals, why do so many smart people take this idea seriously? Earlier we noted the morphological falsehoods artists added to the hand of an anhangueird pterosaur (Fig. 9) to make their forelimb launch hypothesis more logical and appealing by reducing the three free fingers and hoping the giant mc4 and wing finger made an impression in the substrate — but they don’t.

Errors in the Habib/Molnar reconstruction of the pterosaur manus

Figure 9. Errors in the Habib/Molnar reconstruction of the pterosaur manus. This manus uses the false Bennett reconstruction adopted by Witton and Naish and shortens the fingers. Corrections are provided in the lower images.

BTW I’m not blackwashing ALL of the output of Witton and Naish, just the above dozen or so problems. References Witton M and Naish D 2013. Azhdarchid pterosaurs: water-trawling pelican mimics or “terrestrial stalkers”? Acta Palaeontologica Polonica. available online 28 Oct 2013 doi:http://dx.doi.org/10.4202/app.00005.2013