More on the Origin of Turtles – Lyson et al. 2010

Lyson et al.  (2010 – available online) put together their hypothesis on the origin of turtles. In their abstract, they wrote, “We reanalysed a recent dataset that allied turtles with the lizard–tuatara clade and found that the inclusion of the stem turtle Proganochelys quenstedti  and the ‘parareptile’ Eunotosaurus africanus  results in a single overriding morphological signal, with turtles outside Diapsida.”

Milleretta (RC14 specimen) and the Lyson et al. 2010 tree on the origin of turtles.

Figure 1. Milleretta (RC14 specimen) and the Lyson et al. 2010 tree on the origin of turtles. Note the broad ribs already developing in Milleretta, a sister to Acleistorhinus and Eunotosaurus. On its face this seems like a slam dunk for Eunotosaurus and turtles. However, according to the large reptile tree the origin of turtles parallleled the origin of Eunotosaurus. Missing from the Lyson et al. 2010 analysis is Romeria primus and Stephanospondylus, which are closer to the lineage of turtles. A sister to Romeria primus is the last common ancestor of Eunotosaurus and turtles.

Unfortunately,
Lyson et al. (2010) did not include Romeria primusOrobates (Fig. 2) and Stephanospondylus, three taxa found to be closer to the origin of turtles than Eunotosaurus, a terminal taxon with only one known sister, Acleistorhinus. Unfortunately we have no post-crania for Romeria primus (other than slender manual digits) or Acleistorhinus. That lack of data makes it less obvious how they are related to other taxa, but still the large reptile tree nested them in that fully resolved tree. Stephanospondylus was also the sister to the pareiasaurs, a derived clade previously and correctly associated with turtles, but only at the bases of both clades.

Click to enlarge. These skulls are arranged phylogenetically according to the results recovered from the large reptile tree.

Figure 2. Click to enlarge. These skulls are arranged phylogenetically according to the results recovered from the large reptile tree. This was first published a few days ago.

Would be nice to find the common ancestor of both pareiasaurs and turtles, something a little less turtle-like than Stephanspondylus. For now, Orobates(in yellow, Fig. 2) is the best candidate, and prior to that, Romeria primus (in pink). Orobates and Stephanospondylus are Early Permian. The two turtles are Late Triassic. That gives 60-70 million years to evolve a carapace and plastron, plenty of time for transitional taxa to be discovered in. 

Eunotosaurus

Figure 3. Eunotosaurus, a milleretid not related to turtles, but converged with them in several ways. Actually Eunotosaurus is closer to Acleistorhinus and the Caseasauria, which makes sense if put these two together, like Clark Kent and Superman.

Lyson et al. 2012 did find turtle genes closer to lizard genes, while others did not.

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
Broom R 1924. On the classification of the reptiles. Bulletin of the American Museum of Natural History 51:39-45.
Geinitz HB and Deichmüller JV 1882. Die Saurier der unteren Dyas von Sachsen. Paleontographica, N. F. 9:1-46.
Gregory WK 1946. Pareiasaurs versus placodonts as near ancestors to turtles. Bulletin of the American Museum of Natural History 86:275-326
Kissel R 2010. Morphology, Phylogeny, and Evolution of Diadectidae (Cotylosauria: Diadectomorpha). Toronto: University of Toronto Press. pp. 185. online pdf
Li C, Wu X-C, Rieppel O, Wang L-T, Zhao L-J 2008. An ancestral turtle from the Late Triassic of southwestern China. Nature 456: 497-501.
Lyson TR, Bever GS, Bhullar B-AS, Joyce WG and Gauthier JA. 2010. Transitional fossils and the origin of turtles. Biology Letters 2010 6, 830-833 first published online 9 June 2010. doi: 10.1098/rsbl.2010.0371
Lyson TR, Sperling EA, Heimberg AM, GauthierJA, King BL, and Peterson KJ 2011. MicroRNAs support a turtle + lizard clade. Biol Lett 2011 : rsbl.2011.0477v1-rsbl20110477.abstract – online news story
Reisz RR and Head JJ 2008. Turtle origins out to sea. Nature 456, 450–451.
Rieppel O and deBraga M 1996. Turtles as diapsid reptiles. Nature 384:453-454.
Rieppel O and Reisz RR 1999. The Origin and Early Evolution of Turtles. Annual Review of Ecology and Systematics 30: 1-22.
Romer AS 1925. Permian amphibian and reptilian remains described as Stephanospondylus. Journal of Geololgy 33: 447-463.
Stappenbeck R 1905. Uber Stephanospondylus n. g. und Phanerosaurus H. v. Meyer: Zeitschrift der Deutschen Geologischen Gesellschaft, v. 57, p. 380-437.
Williston SW 1917. The phylogeny and classification of Reptilies. Journal of Geology 28: 41-421.

wiki/Stephanospondylus

ReptileEvolution.com – The Top 10 Most Popular Pages

I was curious myself so I looked this up.

Your top 10 most popular pages (with their number of views this year) on ReptileEvolution.com are:

  1. Lagerpeton 518
  2. The reptile tree 329
  3. Cosesaurus 255
  4. Ichthyostega 241
  5. Longisquama 232
  6. Sharovipteryx 210
  7. The home page 208
  8. MPUM6009 (the basal pterosaur) 208
  9. Whale evolution 199
  10. and Jeholopterus (the vampire pterosaur) 149

Lagerpeton lead the pack by far, perhaps because I am often picking on it.

Finally, a Poposaurus skull! Or is it?

With a new skull reconstruction, this post was modified Nov 2, 2013.
Previously Poposaurus (Fig. 1) was only known from post-cranial remains. A complete Poposaurus, lacking a skull and a few cervicals, was described by Gauthier 2012 (Fig. 1).

Recently Parker and Nesbitt 2013, reported on a partial maxilla, dentary and prearticular, along with associated pubis and ischium (PEFO 34865). They matched their new find to prior Poposaurus specimens (Fig. 2), such as YPM 057100. In consideration of the PEFO tooth they wrote, “We fully describe the cranial elements and demonstrate that P. gracilis was a toothed hypercarnivore.” 

Poposaurus (in gray) together with the new skull, the new pelvis and the skulls of sister taxa.

Figure 1A. Poposaurus (in gray) together with the new skull, the new pelvis and the skulls of sister taxa according to the large reptile tree, which, in this case, agrees with Parker and Nesbitt (2013). Shuvosaurus and Effiga, the toothless ones, are above. Pampadromaeusa and Silesaurus are below. Close to the neck are the new elements with the rest of the skull restored. The new pelvis floats above the nearly complete Gauthier et al. (2011) specimen, YPM VP 057100. For details on the new skull see figure 4.

There’s more than one way to rebuild that skull.

Figure 1. Revised skull reconstruction for the PEFO specimen. Here the anterior is considered a premaxilla. Those teeth are shaped like triangles, but they are very deeply rooted and  exposed very little, which casts doubts on its hypercarnivory.

Figure 1B. Added Nov. 2, 2013. Revised skull reconstruction for the PEFO specimen. Here the anterior is considered a premaxilla. Those teeth are indeed shaped like triangles, but they are very deeply rooted and exposed very little, which casts doubts on hypercarnivory.

The pelvis – is this a match?
The new pelvis, PEFO 34865, (Fig. 3) is indeed most similar to that of the YPM Poposaurus pelvis (among the pelves I’ve been able to see), but, they’re not the same. Several traits unite the two pelves including the kink in the anterior ilium, the widely diverging  ventral elements and the semi-open acetabulum (a dinosaur trait). The curved pubis and pubic medial flange with obturator foramen separates them. Rauisuchid taxa with a curved booted pubis include Arizonasaurus, which Parker and Nesbitt (2013) consider to be poposauroid. However, the large reptile tree separates Arizonasaurus from poposaurids.

Figure 1. Poposaurus pelves. In black YPM VP 057100. Above in halftone, the ilium and pubis of PEFO 34865. They may be closely related, but these are not the same species or genus.

Figure 2. Poposaurus pelvis below, Arizonasaurus pelvis above and the PEFO specimen in the middle.  They may be closely related, but these are not the same species or genus. The kink in the anterior ilium, the widespread pubis and ischium and the open acetabulum unites the PEFO and YPM pelves. The curve of the pubis and the higher posterior ilium unite the PEFO and Arizonasaurus pelves. The PEFO specimen appears to be unique and poposaurian, but not Poposaurus. To YPM pelves are shown. I don’t know which is correct the in-situ specimen with a ventrally open acetabulum and what appears to be an overlapping pubis, or the repaired one.

Hypercarnivory?
With regard to the Parker and Nesbitt statement about hypercarnivory, let’s take another look at the post-cranial skeleton of Poposaurus (Fig. 1, YPM specimen). Are those tiny harmless hands those of a hypercarnivore? By comparison, the hands of Postosuchus (Fig, 3) look equally harmless, except for that can opener claw on digit 1. The elongated metatarsals of Poposaurus are also traits shared with dinosaurs, especially phytodinosaurs that depend on fleeing to avoid predation. Postosuchus (Fig. 3), by contrast, has small feet and short metatarsals relative to the tibia. Take poposaurs out of the Rauisuchia (because they don’t belong) and there are no rauisuchians with long metatarsals.

Postosuchus.

Figure 3. Postosuchus. Hands and feet are rare in rauisuchids, but here manual digit 1 has a large trenchant claw and the other unguals are tiny. The hands of Poposaurus (Fig. 1) do not have any large claws.

Parker and Nesbitt (2012) report, “The remains of poposauroids have long been confused with those of early dinosaurs because of the striking convergences (Nesbitt & Norell 2006; Nesbitt 2007; Nesbitt et al. 2007; Gauthier et al. 2011). The extraordinary disparity of poposauroid body plans, locomotor styles and dentition is unique within Pseudosuchia; however, the evolutionary sequence of acquisition of these features as well as the loss of others within the clade is incompletely understood.”

 

Figure 4. The restored skull of the PEFO specimen referred to Poposaurus based on the Nesbitt identification of the anterior as a maxilla. The blue articular is not part of the PEFO specimen, but is described as a Poposaurus articular by Parker and Nesbitt (2013) scaled to fit. Their scale bars indicate it was 4x larger, which may be a typo. As is, the elements are part of a longer, more robust skull than any other poposaurid. See the revised skull reconstruction, figure 1B.

Figure 4. The restored skull of the PEFO specimen referred to Poposaurus based on the Nesbitt identification of the anterior as a maxilla. The blue articular is not part of the PEFO specimen, but is described as a Poposaurus articular by Parker and Nesbitt (2013) scaled to fit. Their scale bars indicate it was 4x larger, which may be a typo. As is, the elements are part of a longer, more robust skull than any other poposaurid. See the revised skull reconstruction, figure 1B.

About that ventrally concave (bent) maxilla…
Fellow poposaur, Silesaurus has a bent maxilla and a straight premaxilla ventral rim. Lotosaurus has a straight maxilla and a bent premaxilla. All rauisuchians have a convex ventral maxilla with longer teeth. 

About that tooth…
Sure that tooth has that carnivore look, but more than half is buried in the maxilla. That likely preserved the tooth with the bone. Ancestral taxa, such as Pampadromaeus, have similar sharp, even recurved teeth. More derived poposaurids do not. The teeth of the PEFO specimen trend toward less recurved and more symmetrical.  Daemonosaurus, nested with basal ornithischians, but has hyper-carnivorous teeth, so there is precedent and analogy.

About that antorbital fenestra…
Other poposaurids have a tall open antorbital fenestra. the PEFO specimen does not. It more closely resembles that of rauisuchians. However, a small, but not elongated, antorbital fenestra is found in Daemonosaurus and other ornithischians.

About that robust dentary…
Other poposaurids don’t have a robust anterior dentary, but Pisanosaurus does. Rauisuchids have a robust anterior dentary.

About that robust skull…
The robust skull of the PEFO specimen stands out from the more gracile skulls found in other poposaurids (Fig. 1), but this is not unheard of in other phytodinosaurs. The armored ornithischians, like Scelidosaurus, also reduce the antorbital fenestra. Perhaps the post-crainia of the PEFO specimen is likewise armored and perhaps secondarily quadrupedal.

The poposaur list – different here
Among their poposaurids, Parker and Nesbitt (2013) include the long-necked Qianosuchus. In the large reptile tree that taxon nests with Ticinosuchus and aetosaurs. Parker and Nesbitt include the sailbacks Arizonasaurus and Xilosuchus among the herbivorous poposaurids. The large reptile tree nests those with the similarly carnivorous rauisuchians.

Poposaurus should have a phytodinosaur (herbivore) skull
All known poposaurs recovered in the large reptile tree are either toothless or, like Pisanosaurus and Silesaurus, have a plant-eater morphology and teeth. However, the sisters of the ancestors of poposaurs (like Pampadromaeus) had teeth typical of carnivores. Among the ornithischia, Heterodontosaurus retained fangs. We should also expect the skull of Poposaurus to be relatively short, like that in Daemonosaurus, Heterodontosaurus and Lotosaurus, with a large orbit and either a large antorbital fenestra.

At the base of the Phytodinosauria the teeth do not yet reflect an herbivorous diet, whether in the sauropodomorpha, ornithischia or poposauridae. Dinosaurs were diverging rapidly. Less perfect designs became extinct more quickly than the better morphologies. The PEFO specimen is among these. It’s type did not last long.

So is PEFO 34865 a Poposaurus?
The pelvis of the PEFO specimen is very close to Poposaurus, but it is also distinct. What remains of the skull does not closely resemble any other taxon in the archosaur clade of the large reptile tree. The skull is robust, which is expected in consideration of the robust cervicals. The anteriormost dentary is missing. The question is, were paired predentaries present? Or just a continued uplift of the mandible tip?

Incomplete remains are always a challenge. Parker and Nesbitt (2013) write, “Poposauroids display a complicated pattern of unusual character suites unlike any other group of pseudosuchians or any other archosaur group in the Triassic.” Let’s keep this discussion going.

Final passing thoughts
Parker and Nesbitt (2013) report, “Interestingly, the morphology of the neural spines that make up the sail in Lotosaurus adentus differs significantly from those of Arizonasaurus and Ctenosauriscus, supporting the idea that it was independently derived (Butler et al. 2011; Nesbitt 2011).”  That was promoted long ago by the results of the large reptile tree. I’m glad to see others are finally starting to catch up to this. Now let’s get poposaurids back into the Dinosauria, where they belong1

References
Gauthier JA, Nesbitt SJ, Schachner ER, Bever GS and Joyce WG 2011. The bipedal stem crocodilian Poposaurus gracilis: inferring function in fossils and innovation in archosaur locomotion. Bulletin of the Peabody Museum of Natural History 52:107-126.
Mehl MG 1915. Poposaurus gracilis, a new reptile from the Triassic of Wyoming. Journal of Geology 23:516–522.
Parker WG and Nesbitt 2013. Cranial remains of Poposaurus gracilis (Pseudosuchia: Poposauroidea) from the Upper Triassic, the distribution of the taxon, and its implications for poposauroid evolution. Geological Society, London, Special Publications 379: 22 pp.

wiki/Poposaurus

Stan Winston’s JP3 pterosaur – What kind is it?

Jurassic Park III included a Pteranodon-like pterosaur attacking our intrepid heroes in a sort of a giant “bird” cage. On YouTube you can find an early test (Fig. 1) of this mechanized toothless pterosaur suit. In the film, teeth were added.

Stan Winston Pteranodon suit for Jurassic Park 3.

Figure 1. Stan Winston Pteranodon suit, sans teeth, for Jurassic Park 3. Click to see video. There appears to be a man inside and also one outside working the jaws, I suppose, with radio controlled servos. Note the big feet, large enough to house a person. The elbows are turned out obscenely laterally, which rotates the fingers anteriorly, which seems right, but is wrong. And finally, there’s that wrinkly blanket-like web membrane that refuses to go away.

So, is this Pteranodon? Looks close. Here’s a reconstruction of a real Pteranodon for comparison (Fig. 2) where a longer beak, a longer metacarpus and a shorter forearm (antebrachium) are present.

The Triebold Pteranodon, one of the most complete ever found.  The metacarpals are quite a bit longer here. So is the beak.

Figure 2. The Triebold Pteranodon, one of the most complete ever found. The metacarpals are quite a bit longer here. So is the beak.

For comparison, here’s a toothy, short metacarpal ornithocheirid, Anhanguera (Fig. 3). Like the JP3 pterosaur, this one has a longer antebrachium and shorter metatarsus.

Anhanguera and Ludodactylus (skull), two short metacarpal pterosaurs with teeth.

Figure 3. Anhanguera and Ludodactylus (skull), two short metacarpal pterosaurs with teeth.

The metacarpals, antebrachia and skull size of this ornithocheirid pterosaur are closer to the Stan Winston version. Teeth were also added in the movie version creating a specimen very much like the later discovered crested ornithocheirid, Ludodactylus (Fig. 3 upper, smaller skull).

 Jurassic Park 3 logo, including a nice Pteranodon in ventral view with narrow chord wings.

Figure 4. Jurassic Park 3 logo, including a nice Pteranodon in ventral view with narrow chord wings. Compare this to the Pteranodons in the PterosaurHeresies masthead (the faux book cover). Later I spread the legs and added uropatagia.

Movie-makers have often taken liberties with their dinosaurs and pterosaurs. Rather than bitching about ’em, you just gotta love ’em and snicker if you’re “in the know.” Here’s the scene, again from YouTube, of the JP3 pterosaurs in action (Fig. 5).

Click to play. Pterosaurs attacking our heroes in Jurassic Park 3.

Figure 5. Click to play. Pterosaurs attacking our heroes in Jurassic Park 3.

Basal Lepidosauromorpha – the story told with skulls

Sometimes it just helps
to see a bunch of taxa together to get an appreciation for the evolution of one to another to another and another. Well, here are the members of one branch of the basal reptiles, the early plant-eaters, the new Lepidosauromorpha, all taken from the large reptile tree (recently slightly revised).

Click to enlarge. These skulls are arranged phylogenetically according to the results recovered from the large reptile tree.

Figure 1. Click to enlarge. These skulls are arranged phylogenetically according to the results recovered from the large reptile tree.

Contrary to conventional thinking,
the Diadectomorpha and Chroniosuchia are nested here within the Reptilia rather than within the pre-amniotes. Contrary to conventional thinking, the Caseasauria are nested here within the Millerettidae, rather than the Synapsida. These, and other new relationships were determined by adding taxa and thereby expanding the gamut of opportunities for every taxon to nest most parsimoniously – where the changes between taxa are minimized echoing the actual tree of reptile evolution.

Central to these discussions
Romeria primus (Fig. 1 in pink) – is at the base of the millerettids that begat the bolosaurids, acleitorhinids (not related to Lanthanosuchus btw), and the caseasauria, which now has new basal members, Feeserpeton and Australothyris. Romeria primus was largely ignored in prior studies. Now, perhaps, its importance will no longer be overlooked.

Orobates (Fig. 1 in yellow) – is leading the way toward Tseajaia and Tetraceratops, Limnoscelis, Procolophon, the lineage of Diadectes, Chelonia beginning with Stephanospondylus, and not finally the Pareiasauria. Orobates, likewise needs to rise in importance and needs to be added to several more focused phylogenetic analyses.

Saurorictus, Macroleter and the lanthanosuchids, Romeriscus and Lanthosuchus.

Figure 2. Click to enlarge. Saurorictus, Macroleter and the lanthanosuchids, Romeriscus and Lanthosuchus.

I say not finally because the next clade includes Saurorictus and Nyctiphruretus (Fig. 2) and the remainder of the new Lepidosauromorpha, including lanthanosuchids (Fig. 2), owenettids and the Lepidosauriformes.

No strange bedfellows here.
All taxa demonstrated gradual transitions from one to another. With this new phylogeny and tree topology the taxa that may or may not be someday discovered can more accurately be predicted based on phylogenetic bracketing. Hopefully more discoveries will help find the sisters of Orobates that will help define the base of this new, hitherto unknown clade.

Not amphibians!
Hopefully readers will glean the important fact that limnoscelids, chroniosuchids and diadectids are not amphibians (pre-amniotes), which represents conventional thinking. No, they’re nested deep within the Reptilia, far from Gephyrostegus and its ancestors and their kin.

Eudibamus is notably absent
Because Eudibamus is not a bolosaurid. It is a basal diapsid close to Petrolacosaurus. Strong foot homologies and long suite of other traits nest it there, not with heavy, plant-eating bolosaurids.

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.

Quetzalcoatlus – Why so big? Why such a long neck?

Yesterday we looked at a bad YouTube video on the giant pterosaur, Quetzalcoatlus. Earlier we looked at the tiny predecessors, like No. 42, of mid-size to giant azhdarchids pterosaurs.Tiny taxa had roughly the same proportions and were formerly considered specimens of the unrelated Pterodactylus. Here, some thoughts on what made Q so big and with such a long neck.

This is where reconstructions really come in handy.
I made a rough model of Quetzalcoatlus based on Q. sp., took a photo, then manipulated the photo to various neck configurations (Figs. 1, 2). I added a fake water surface since ancestral taxa going back to No. 42 and Dorygnathus, were water waders and the lineage includes a flightless water wader, Sos 2428. It may be pertinent.

Quetzalcoatlus neck poses. Dipping, watching and displaying.

Figure 1. Quetzalcoatlus neck poses. Dipping, watching and displaying. Gray areas mark tendon soft tissue matching smaller long-necked pterosaurs. If height was important to Q for display, than raising the beak quickly and easily makes it appear even taller. This converges on similar behavior in certain modern stork-like birds. Simply having a tall neck provides a better survey of the environment, inherited from tiny predecessors, like n42 and n44. The long beak is necessary to reach the ground or lake bottom, where the food is. The neck is unable to bend ventrally. See figure 2 for the feeding posture.

Natural selection
Apparently some azhdarchids had greater mating success the taller they were. Females appear to have selected taller males. Taller ones were better able to spot enemies from greater distances and to threaten them back with a taller bluff-and-show on approach. Taller azhdarchids could also exploit deeper waters for food, temperature regulation and protection.

All this is well and good, but most pterosaur workers have tried to understand azhdarchids, like Quetzalcoatlus, from a feeding perspective.

Like vultures?
Azhdarchids were originally considered scavengers of dino carcasses (Lawson 1975) since Q. was discovered near dino bones.

Like sandpipers?
Langston (1981), who studied Q, thought azhdarchids fed on burrowing invertebrates by probing for them in the substrate. Such burrows were found near Q. fossils.

Like skimmers?
Nesov (1975) saw his Azhdarcho as a soaring skimmer. Unwin et al. (1997) agreed with this vision.

Like storks?
Paul (1987a) imagined Quetzalcoatlus, “probably patrolled water courses, like a three-meter-tall stork, picking up fish and small animals.” Padian (1988) agreed with the stok/heron-like image, but noted that Langston (1981) was probably correct. : – /

Like ground hornbills?
Witton and Naish (2008) agreed with the stork analog, but added ground hornbills and imagined that azhdarchids frequented terra firma due to the size of their feet (see below). Perhaps this is the paper that inspired the bad YouTube video featuring Q snapping up a baby T-rex because featured illustrations by M. Witton has Q fetching baby sauropods.

Feet too small to wade?
Witton and Naish (2008) noted that, “azhdarchid footprints show that their feet were relatively small, padded and slender, and thus not well suited for wading.” Unfortunately they overlooked the fact that storks, flamingoes, spoonbills, sandpipers and other waders are not known for their large wide feet. Nor did they consider the value of toe webbing. Nor did they quantify azhdarchid feet versus other pterosaur feet. I found the feet of Q sp. to be average is size for a pterosaur of its size. Among pterosaurs, Pterodaustro had large feet. Ornithocheirids had small feet. Azhdarchids had the long, closely bound metatarsals that fit azhdarchid-sized footprints along with toes that looked short by comparison to those long metatarsals.

Failing to divide azhdarchids from eopteranodontids
Unfortunately all prior authors failed to differentiate azhdarchids from their unrelated and convergent sisters, the eopteranodontids. Azhdarchids, derived from Dorygnathus and n42, among others, had flat beak tips, more like a spoonbill than a heron. Eopteranodontids, derived from Germanodactylus, had a tooth-tipped sharp beak, more like that of a heron than a spoonbill.  With flat, squared-off beak tips and small eyes, azhdarchids would have blindly felt for prey underwater. On the other hand, eopteranodontids used their large eyes to spot prey and their needle-sharp beaks to spear prey.

Quetzalcoatlus scraping bottom while standing in shallow water.

Figure 2. Quetzalcoatlus scraping bottom while standing in shallow water. Only a slight shift forward of the manus drops the front of the torso a little, which drops the long cantilevered neck and head deep enough so the beak can blindly scrape the bottom, here stirring up a little graphic mud. The neck would have been unable to descend any more than the straight line shown here. A series of tendons, preserved in other long-neck pterosaurs, supported the cervicals. 

Like geese and spoonbills?
Previously ignored, geese and spoonbills probably make better analogs for azhdarchids. These analogs are very close to the sandpiper hypothesis of Langston (1981, Fig. 2) in which food items are felt rather than seen and snapped up randomly rather than targeted and attacked. Azhdarchids had small eyes set far back on their skulls (Figs. 1, 2), not binocular and thus ill-suited for targeting prey. The flat bills would have been suitable for prey that did not fight back.

Breathing while probing?
In this pose (Fig. 2) it’s interesting to note that Q. could keep breathing while foraging with its long beak underwater, perhaps demonstrating one reason why the naris was greatly reduced to closed off completely in pterodactyloid-grade pterosaurs of many sorts.

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
Witton MP and Naish D 2008. A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology. PLoS ONE 3(5): e2271. doi:10.1371/journal.pone.0002271
Langston W Jr 1981. Pterosaurs. Scientific American 244: 92–102. online
Lawson DA 1975. Pterosaur from the latest Cretaceous of West Texas: discovery of the largest flying creature. Science 187: 947-948.
Nessov LA 1984. Pterosaurs and birds of the Late Cretaceous of Central Asia. Paläontologische Zeitschrift 1: 47–57. online
Paul GS 1987. Pterodactyl habits – real and radio controlled. Nature 328: 481. online
Unwin DM, Bakuhrina NN, Lockley MG, Manabe M and Lü J 1997. Pterosaurs from Asia. Paleontological Society of Korea Special Publication 2: 43–65. online

“Clash of the Dinosaurs” Quetzalcoatlus Needs Repair

YouTube Video from “Clash of the Dinosaurs” 
Pterosaurs (Flying Dinosaurs) is a relatively new video uploaded in July 2012 from Clash of the Dinosaurs a program, aired in 2009 and produced by Dragons LTD for the Discovery Channel. This episode features the largest of all pterosaurs, Quetzalcoatlus (Figs. 1-13), doing its thang, as described by several paleontologists, some of whom may be (or should be) cringing now based on the way this video was finally put together.

Quetzalcoatlus wing

Figure 1 . Quetzalcoatlus wing. Yes, this title says… Flying Dinosaurs. Obviously the paleontologists listed below did not approve this title, but that’s just the beginning of the long list of sins incorporated here.  They made the wing too long by making m4.2 too long. The fingers should be palmar side down, not forward. More below.

Featuring pterosaur experts Tom Holtz, Pete Larson, Larry Witmer, Mike Habib and Matt Wedel, this video mixes great data (enervated wing membranes connected to enlarged brain tissue) with conjecture without evidence (forelimb takeoff (Fig. 7) and general morphology problems (Figs. 1-10)). Unfortunately the conjecture without evidence now forms much of the conventional thinking embraced by most pterosaur workers. That’s why I’m here, to clear things up and set things straight. Now for the long list of boo-boos.

Quetzalcoatlus pteroid

Figure 2. Quetzalcoatlus pteroid. Unfortunately they put it on the distal carpal, not the proximal one, the radiale. And they forgot the preaxial carpal. We’ll overlook the oversimplification of the rest of the  carpal elements. The depth of the wing is WAY too deep when we compare it to great wing membranes like the dark-wing and Zittel Rhamphorhynchus specimens. Thankfully the radius is in the neutral position here, not the supinated position as championed by Bennett and Hone, but then why are the fingers palmar side foreword? According to conventional thinking, these two go hand-in-hand. Keep the forearm neutral, then the fingers will be palmar side down, exactly as in the human hand pretending to be a wing. (Go ahead and try it, no one is looking)

Quetzalcoatlus fingers

Figure 3. Quetzalcoatlus fingers. Here fingers 1-3 are anchored too far beyond mc4. The metacarpals should all be aligned distally. All the metacarpals should also be connected, as they are in all tetrapods. The palmar sides of fingers 1-3 should be ventral in flight. Looks like finger 2 is missing here. We’re also overlooking the lack of a big cylindrical joint at the distal mc4 than enables wing folding and through which the giant extensor tendon passes. The fingers above don’t allow that tendon the room it requires.

Quetzalcoatlus bones.

Figure 4. Quetzalcoatlus leg bones. The femoral head axis should line up with the lateral acetabulum axis. Here they don’t. The knees should be fully extended. Here they aren’t. When fully extended they create a horizontal stabilizer, a secondary wing that generates its own lift! (See figure 12).

Quetzalcoatlus landing

Figure 5. Quetzalcoatlus landing. Here the wing is way too broad, the humerus is too far anterior and the little fingers point the wrong way.

Quetzalcoatlus walking.

Figure 6. Quetzalcoatlus walking. Note when walking the feet are correctly palmar side down. However, while flying with lateral limbs the feet should be palmar side lateral, but they remain strangely ventral in the video.

On takeoff
Wedel repeated Habib’s original assertions that the takeoff was a sort of “super pushup,” with the “strongest limbs” providing the necessary initial thrust. We looked at that bad hypothesis earlier. The more heavily muscled limbs were the hind limbs. Here (Fig. 7) is the pterosaur takeoff according to the conventional experts and the Clash of the Dinosaurs video in which Q could leap way over twice its height on its tiny triceps and with sufficient forward speed to glide a dozen times its own length before applying the first thrust flap. This pterosaur acts more like an Oz bubble than a 400 lb animal the shape of a giraffe. Not even kangaroos can attain such initial leaps from a standing start. Certainly giraffes can’t do it either despite the similar limb bone segment lengths with Q.

Quetzalcoatlus quadrupedal takeoff

Figure 7. Quetzalcoatlus quadrupedal takeoff. Here the tiny triceps drive this 400 lb pterosaur to heights and lengths that much more strongly muscled kangaroos cannot attain on the first leap. In the video Q appears to be light as a bubble because once aloft, it never descends as it appears to do, but the perspective line reminds us that is not so. Imagine a stork or flamingo in such a wooded setting. Hard to do? That’s because they both prefer water, as does Q.

The better hypothesis, the bipedal hind limb takeoff plan  (Fig. 8), provides wing thrust immediately and tremendous takeoff speed, like a bipedal lizard on steroids!

Quetzalcoatlus running like a lizard prior to takeoff.

Figure 8. Quetzalcoatlus running like a lizard prior to takeoff. Click to animate if not already animated.

Quetzalcoatlus walking

Figure 9. Quetzalcoatlus walking. Way too much wrist bend here. See figure 11 for a better reconstruction. Why doesn’t the wing finger fold up against the forearm? That’s the way other pterosaurs are fossilized and it protects the membrane, which virtually disappears. See figure 11 for the way it should be.

We’ll call this the Jurassic Park syndrome
When film and video makers refuse to add the latest data to their models, feathers for velociraptors and pycnofibers for pterosaurs (Fig. 10), they mark their work as out-of-date on the day it appears.

Quetzalcoatlus no hair

Figure 10. Quetzalcoatlus with no hair? All pterosaurs had a sort of hair. The wings here are also so poorly muscled, Q looks emaciated. The neck, how was it supported? Smaller pterosaurs show tendons holding the neck in a curve, like a horse’s neck, not like a flamingo neck. And where’s the curvature of the wing seen in birds, bats and airplanes. Raise the elbows! That provides the aerodynamic curvature. And shorten that chord! This is pure imagination based on toys, not on fossil evidence.

Quetzalcoatlus and its ancestor, no 42, note scale bars.

Fig. 11. Quetzalcoatlus and its ancestor, no 42, note scale bars. These are not predators of anything but crustaceans and other invertebrates. The video positioned Quetzalocoatlus as a T-rex baby eater?? That’s just showbiz. Q descended from tiny pond waders and was found near an inland lake. So, frogs, little pond reptiles and fish were probably on its diet. Eyesight was not the primary tool for hunting prey. Likely the bill was a sensitive probe and Q never saw its prey, but felt it on the lake floor while wading. We’ll look more at this tomorrow.

Quetzalcoatlus in dorsal view, flight configuration.

Figure 12. Quetzalcoatlus in dorsal view, flight configuration showing the correct wing proportions. The skull was taller than shown in the video and in the inset photo.

So, in the end
whoever guided the construction of Q. in the video did a poor job. As a remedy, imagine a fully muscled Q. running with a blur of lizardy legs and flapping its way into the sky (Fig. 8), like any goose or flamingo. Imagine a wading Q. finding bottom-dwelling invertebrates without seeing them (I’ll show you this tomorrow). Imagine a walking Q standing upright, like a giraffe, or a stork, with an upraised neck and bright colored hair covering its body and an upright crest rising from its skull (Fig. 11). T-rex babies would have been safe from Q with its slender, sensitive, yard-stick-shaped beak capable of handling only food that did not fight back.

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
Witton MP and Naish D 2008. A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology. PLoS ONE 3(5): e2271. doi:10.1371/journal.pone.0002271
Langston W Jr 1981. Pterosaurs. Scientific American 244: 92–102. online
Lawson DA 1975. Pterosaur from the latest Cretaceous of West Texas: discovery of the largest flying creature. Science 187: 947-948.
Nessov LA 1984. Pterosaurs and birds of the Late Cretaceous of Central Asia. Paläontologische Zeitschrift 1: 47–57. online
Paul GS 1987. Pterodactyl habits – real and radio controlled. Nature 328: 481. online
Unwin DM, Bakuhrina NN, Lockley MG, Manabe M and Lü J 1997. Pterosaurs from Asia. Paleontological Society of Korea Special Publication 2: 43–65. online