AMNH animated pterosaur takeoffs

On YouTube the American Museum of Natural History (AMNH) has placed two new pterosaur take-off sequences in their video, “Meet the Paleontologists,” part of last year’s pterosaur exhibit. One snippet features Jeholopterus (Fig. 1) and the other features Quetzalcoatlus (Fig. 2). Both purport to demonstrate the forelimb take-off method that Mike Habib’s team present here and I critiqued here and here.

IMHO, pterosaurs, like birds used multiple downbeats of their powerful wings to create thrust and lift as shown here.

Th AMNH snippets takes the opposite tack,
that pterosaurs used their folded forelimbs to push them off the ground, supposedly, but not quite like a vampire bat, (no height is generated at lift-off) and fractions of moments later, they unfold their wings and glide upward (!!!), evidently tossing out the effects of gravity and drag and the need to add thrust, forward momentum and airspeed. The originator of this hypothesis, Mike Habib, appears in the AMNH video. So I assume he had some input. I can’t image that Mike would approve these, as they break several rules of physics, as noted above.

Because the camera moves
in each animation, in both video snippets frames were realigned to remove that camera movement. If you’ve read this far without seeing the videos, refresh the page to start them over.

GIF movie 1. Jeholopterus. Each frame is 5 seconds and there are 7 frames. Click to animate if necessary.

GIF movie 1. Jeholopterus. Each frame is 5 seconds and there are 7 frames. Click to enlarge and animate if necessary. It recycles only once. As this movie starts with the page opening, you may wish to refresh the page.

The animated Jeholopterus (GIF move 1)
does not leap skyward with its spring-like forelimbs then unfold its wings like a vampire bat. Rather it simply leans forward off the rock with hind limb thrust, glides while unfolding its big wings then produces an upbeat before a downbeat. Not sure how it managed to rise during the upbeat. It must be a bubble in a breeze. All that thrust prior to the first downbeat had to come from the original hind limb push-off, but they gave Jeholopterus such puny legs. Nothing here makes sense.

GIF movie 2. Quetzalcoatlus take off. Each frame is 5  seconds. 7 frames total. Recycles once. Click to animate and enlarge if necessary.

GIF movie 2. As this movie starts with the page opening, you may wish to refresh the page. Quetzalcoatlus take off. Each frame is 5 seconds. 7 frames total. Recycles once. Click to animate and enlarge if necessary. Here the giant animal appears to rise and accelerate without one downbeat of its wings. Watch the shadow to see where the wings are in the middle frames.

In the Quetzalcoatlus movie (GIF movie 2
there is indeed a recoil prior to takeoff, but once again the leap doesn’t elevate the pterosaur. Rather the pterosaur again appears to be light as a bubble as it rises only after opening its wings without a downbeat, then accelerates and rises. Where does all this thrust come from?

In the alternate hypothesis
(Fig. 3), Quetzalcoatlus flaps its wings while gaining airspeed with its legs, as in many large birds. So plenty of airspeed is generated from both sets of limbs and the wings are already extended and beating like crazy prior to takeoff.

Quetzalcoatlus running like a lizard prior to takeoff.

Figure 1. Quetzalcoatlus running like a lizard prior to takeoff. Click to animate. The difference between this wing in dorsal view and the wing in figure 2 come down to the angle between the bones.

Key to the AMNH pterosaur problems
is their inability to imagine pterosaurs getting up on their hind limbs and standing bipedally to flap their wings like birds. Yet if they did their reconstructions in strict accordance with the bones they would find that pterosaurs could balance themselves on their hind limbs — even those that left quadrupedal imprints. We know this because their feet extended as far forwards as their center of balance, at the wing root, their shoulder joints — even those that walked quadrupedally. Pterosaurs were quite capable in every mode they found themselves in, from flying, to walking, to swimming. They weren’t awkward, as commonly portrayed.

The second problem with the AMNH animations
is their lack of faith in the thrust of the each downbeat of the wing. Bats do it. Birds do it. Why not let pterosaurs do it? Pterosaurs had to toss down a lot of air to get airborne, especially when they did not have sufficient forward airspeed to generate lift with Bernoulli’s principle. No matter how hollow their bones are, pterosaurs are not bubbles!

Quetzalcoatlus in dorsal view, flight configuration.

Figure 2. Quetzalcoatlus in dorsal view, flight configuration. The hind limbs were not uselessly trailing. They were extended laterally acting like horizontal stabilizers on an airplane — and they contributed to lift, but not thrust.

The third problem
is their lack of accuracy in their reconstructions. Beside the bone issues, the hind limbs should be extended laterally in flight where they contributed to lift and acted like horizontal stabilizers. The AMNH did not get the ‘blueprint’ right for either pterosaur. All they needed to do is pay attention to the details — and remember it takes a lot of power to overcome gravity.

Figure 4. Jeholopterus in dorsal view. Here the robust hind limbs, broad belly and small skull stand out as distinct from other anurognathids. Click to enlarge.

Figure 3. Jeholopterus in dorsal view. Here the robust hind limbs, broad belly and small skull stand out as distinct from other anurognathids. Click to enlarge.

People are also bitching about the Jurassic World dinosaurs, but that’s a franchise that wants to sell merchandise and the original merchandise did not have feathers on their ‘raptors’. On the other hand, the AMNH is a museum. They should have the resources and experts to get things right in flight technique and morphology.

 

Breeze: important for takeoff. Acrobatic leaping : not so much.

Pterosaur take-off analog
In this video of a glider with legs you can see it just takes a long set of wings and a stiff breeze to become airborne – not an elaborate acrobatic forelimb leap sequence. This is a good model, a good niche and a good location, for ornithocheirid and pteranodontid pterosaurs to rest, nest and take off. The invisible, but very present breeze is key to this aerie. It provides the lift. Gravity, when the nose of the aircraft is pointed down, provides the thrust.

 Click to play 48-second video of glider launching by airspeed alone caused by a stiff breeze.

Figure 1. Click to play 48-second video of glider launching by airspeed alone caused by a stiff breeze. This should put to rest all thoughts for the necessity of a dangerous and odd forelimb leap for pterosaurs, especially the big winged ones, the ornithocheirids and pteranodontids. As in airplanes, forward speed is increased by tipping the nose down.

But wait! There’s more!
Pterosaurs, of course, provided their own thrust when they flapped. So, really, why go through goofy acrobatics when all you have to do is stretch out and flap those big wings!

I mean, really!!
It’s this simple and much less risky than the alternative.

Two unlikely forelimb launching pterosaurs

Today we’ll look at two very different pterosaurs and wonder how it was even possible that these should be considered to be forelimb launchers.

The first is the basal pterosaur, MPUM 6009 (Fig. 1). It has the longest hind limbs compared to fore limbs. In these pterosaurs the hind limb leap alone would obviate the need for further spring off the forelimbs. Moreover, putting the short forelimbs on the substrate demands an awkward butt-high configuration unlikely to provide any sort of efficient launching. Phylogenetically all pterosaurs following this one had longer forelimbs capable of touching the substrate without losing balance over the toes.

MPUM 6009 with red and orange layers applied to show muscles. The hind limbs are well muscled, fully capable of leaping. The forelimbs are incapable of touching the ground without a very awkward butt-high configuration.

Figure 1. MPUM 6009 with red and orange layers applied to show muscles. The hind limbs are well muscled, fully capable of leaping. The forelimbs are incapable of touching the ground without a very awkward butt-high configuration.

Basal pterosaurs, derived from long-legged flapping fenestrasaurs like Longisquama, had longer hind limbs than forelimbs. This legacy of this hind limb leaping cannot be ignored.

 A completely different situation here with Nyctosaurus bonneri, in which the forelimbs are much longer than the hind limbs. Could those forelimb muscles provide a sufficient leap to clear the ground with those giant wing fingers before it comes crashing back to earth. Better to extend the wings while bipedal on those meaty thighs, then start flapping, running and leaping.

Figure 2. A completely different situation here with Nyctosaurus bonneri, in which the forelimbs are much longer than the hind limbs. Could those relatively small forelimb muscles provide a sufficient leap to clear those giant wing fingers before crashing back to earth? Better to extend the wings while bipedal on those meaty thighs, then start flapping, running and leaping, adding thrust with each wing flap.

When the forelimbs are much longer than the hind limbs
Nyctosaurus (Fig. 2) is the prime example of pterosaurs with the opposite morphology: longer forelimbs than hind limbs. Here it is hard to imagine this pterosaur becoming airborne without extending its wings for lift. The meaty thighs could have kept this pterosaur balanced over its toes while the wings unfolded. The meaty thighs could also have provided an initial leap or run to launch. Such large wings would have provided extra thrust, but only while extended. The triceps muscles appear to be pitifully too small to rapidly extend the forelimb to launch the pterosaur like a super pogo-stick.

Most other pterosaurs have a more balanced configuration with forelimbs and hind limbs more closely related in terms of length and the placement of joints. Even these were able to raise their forelimbs off the substrate to unfold the wings without losing balance over the toes.

Causes of the problem
Shortchanging the muscles of the pelvis, prepubis and femur by Witton (2013) and others is only one cause of their false paradigm. Creating poor reconstructions that disfigure real morphology is the second problem. Putting faith in imaginary ancestors with odd and improbable morphologies rather than verifiable fossil ancestors with real bones is the third cause.

That’s why I’m here, to encourage change based on evidence.

Scathing Book Review – Pterosaur hind limb muscles and the prepubis: Witton vs Peters

Earlier here, here and here we had a critical look at the hypotheses regarding various aspects of pterosaur phylogeny and morphology. Today we’ll look at the muscles of the pterosaur hind limb and how Witton (2013) emaciated them.

Pterosaur hind limb muscles according to Witton (2013, above) and based on lizard musculature (Fig. 2).

Figure 1. Pterosaur hind limb muscles according to Witton (2013, above) and based on lizard musculature (Fig. 1, below and Figs. 2, 3). Witton does not extend femoral muscles to the prepubis or the anterior ilium. Evidently it’s important for those who do not want pterosaurs to exhibit any bipedal abilities to denigrate hind limb muscle strength, as shown by the emaciated appearance Witton gives them and by reducing their anchorage.

Make sure those hind limbs look emaciated
if you want to convince others that pterosaur hind limbs were not capable of providing bipedal locomotion (in step with quadrupedal locomotion for most) or hindlimb leaping/launching/takeoff. Witton 2013 emaciates his pterosaur femoral muscles and reduces their points of origin on the ilium and prepubis. Why? He supports the forelimb launch hypothesis for pterosaurs big time.

Two dead lizards, dorsal and ventral views. Note the meaty thighs.

Figure 2. Two dead lizards, dorsal and ventral views. Note the meaty thighs. Same as in birds and crocs. Witton emaciates them.

Real lizard femoral muscles are robust and meaty (Figs. 2,3 ). The muscles get thicker at mid thigh. This even happens in birds and crocs! Why would Witton emaciate them?

Lizard muscles according to Romer (1956. 1062,1971). Ilium muscles in red. Pubis and ischium muscles in blue. Caudal muscles in yellow.

Figure 3. Lizard muscles according to Romer (1956. 1062,1971). Ilium muscles in red. Pubis and ischium muscles in blue. Caudal muscles in yellow. Curious that no muscles arise from the posterior ilium.

No Prepubis Anchor
Pterosaurs extend their ventral muscle anchorage by adding a prepubis, which can be very long indeed in Rhamphorhynchus (Fig. 2) and Campylognathoides (Fig. 3). No muscles attach to the prepubis in Witton’s version (Fig. 1). One wonders why not, especially when the prepubes and femora are aligned during normal locomotion (Figs. 2-4).

Instead Witton 2013 follows Claessens et al. (2009) mistake when he reports the prepubes “were capable of moving up and down with each breath taken by their owner.” This “rotating prepubis” hypothesis was falsified earlier based on the Claessen et al. use of a flipped and partial prepubis to support their hypothesis. They got the bone upside down!! No other prepubes in any other pterosaurs support the Claessen et al. hypothesis. The pubis/prepubis joint is a butt joint in all pterosaurs. So it basically cannot move. The prepubis acted as an extension to the pubis. Pubofemoralis muscles probably extended down the prepubis as if it were an elongated pubis. Respiration occurred by expansion of the ribs, as in all tetrapods, not by the rotation of the prepubes. Correctly configuration shown below (Figs. 2-4).

The darkwing Rhamphorhynchus JME SOS 4785

Figure 2 The darkwing Rhamphorhynchus JME SOS 4785. Note the depth of the prepubis. Even if this prepubis could rock back and forth it would not further deepen the torso.

 The Pittsburgh specimen of Campylognathoides. This pterosaur had the largest prepubes of all pterosaurs. Note the ventral orientation, aligned with the femora during normal standing.

Figure 3. The Pittsburgh specimen of Campylognathoides. This pterosaur had the largest prepubes of all pterosaurs. Note the ventral orientation, aligned with the femora during normal standing. Note the butt joint between the pubis and prepubis.

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

Figure 4. The Triebold Pteranodon, one of the most complete ever found. I have this skeleton cast. The prepubes extend ventrally, in line with the femora and unable to expand the torso during respiration. Expanding ribs, as in all tetrapods, provided all the necessary torso expansion for respiration.

Witton's prepubis mistakes, based on mistakes by Claessen et al. 2009. (Above) in Rhamphorhynchus the prepubis is waaaay too small. In both the prepubis is incorrectly oriented and incorrectly attached to the pubis.

Figure 5. Witton’s prepubis mistakes, based on mistakes by Claessen et al. 2009. (Above) in Rhamphorhynchus the prepubis is waaaay too small. In both pterosaurs the prepubis is incorrectly oriented and incorrectly attached to the pubis.

Elongate ilia
And why would the all pterosaur ilia extend so far anterior (especially so in Sos 2428), framing so many sacrals (Fig. 1), without bringing a few muscles with them? After all, that’s what mammals and dinosaurs do. And the muscles arising from the ilium in lizards concentrate anteriorly. Finding homologies and analogies is how we find the most parsimonious answer.

The missing caudofemoralis
Lizards and most dinosaurs have a robust tail with elongate transverse processes and deep chevrons. These are muscle anchors for the caudofemoralis, tail muscles that pull the femur posteriorly, contributing to the step cycle. In birds and pterosaurs these muscle anchors are largely, but not completely missing. The pelvis (and prepubis) have taken over those duties. The caudofemoralis is largely, but not completely missing in birds and probably pterosaurs. As in birds, pterosaur the anchoring transverse processes are vestigial or missing and their chevrons, where present, extend parallel to the caudal centra, not ventrally. In pterosaurs, chevrons are not caudofemoralis anchors, but secondarily adapted as tail stiffeners. They are essentially absent in basal pterosaurs, like MPUM6009. They redevelop in several taxa. These same caudal patterns (attenuated tails) are found in pterosaur precursors, the fenestrasaurs, evolving from less attenuated tails in tritosaur lepidosaurs, a key trait that ties them all together.

It’s important to examine living animals to see their muscle patterns in order to reconstruct them in prehistoric animals. It’s important to know what new bones, like the prepubis, are used for (not respiration). It’s important to note the details in a skeleton, establishing articular surfaces and creating accurate reconstructions.

References
Claessens, LPAM, O’Connor PM and Unwin DM 2009. Respiratory Evolution Facilitated the Origin of Pterosaur Flight and Aerial Gigantism. PLoS ONE 4(2):e4497.http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004497
Romer AS 1971. The Vertebrate Body (shorter version). WB Saunders Co. 452 pp.
Witton M. 2013. Pterosaurs. Princeton University Press. 291 pages.x

New Bipedal Tapejara Take-Off Video

A bipedal pterosaur video!
Just ran across this Tapejara skeleton take-off, fly and land video from the Huffington Post – and its a bipedal takeoff! The original came from the Sankar Chatterjee lab at Texas Tech in November 2012.

Click to animate. Tapejara take-off, flight and landing by the Sankar Chatterjee lab. Red arrows point to morphology problems. 1. Bend humerus back further. 2 Bend elbow more. 3. Pteroid goes to carpals, not the finger joint, unless that's a metacarpal lacking fingers. 4. Knees should be splayed 5. Extend hind limbs laterally.

Figure 1. Click to animate. Tapejara take-off, flight and landing by the Sankar Chatterjee lab. Nice to see. So many things are right about this animation. Yet, red arrows point to minor morphology problems. 1. Bend shoulder back further. 2 Bend elbow forward more. 3. When the elbow is bent, the pteroid angles out from the radius, framing the propatagium better. 4. Metacarpal lacking free fingers. 4. Knees should be splayed 5. Extend hind limbs laterally in flight.

The Huffington headline reads: Pterosaur ‘Runways’ Enabled Huge Prehistoric Flying Animal To Get Airborne, Study Suggests. By: Douglas Main, LiveScience Contributor
Published: 11/08/2012 03:01 PM EST on LiveScience.

How did pterosaurs takeoff and fly?
According to Main, “A new computer simulation has the answer: These beasts used downward-sloping areas, at the edges of lakes and river valleys, as prehistoric runways to gather enough speed and power to take off, according to a study presented Wednesday (Nov. 7) here at the annual meeting of the Geological Society of America.’First the animal would start running on all fours,'” Texas Tech University scientist Sankar Chatterjee, a co-author of the study, told LiveScience. “Then it would shift to its back legs, unfurl its wings and begin flapping. Once it generated enough power and speed, it finally would hop and take to the air,” said Chatterjee, who along with his colleagues created a video simulation of this pterosaur taking flight.

Unfortunately Chatterjee doesn’t give pterosaurs the credit they deserver when he reports, “This would be very awkward-looking,” he said. “They’d have to run, but also need a downslope, a technique used today by hang gliders. Once in the air, though, they were magnificent gliders.” 

So, a downslope was necessary and flapping was rare, evidently, in Chatterjee’s view. Unfortunately, Chatterjee, like the other pterosaur experts, has a built-in bias regarding pterosaurs in that he sees them too weak to run to take-off speed, except downhill, and too weak to flap sufficiently to create enough thrust without a runway, and too weak to flap with vigor while gaining altitude. The caption (Fig. 1) includes a few reconstruction suggestions.

Bipedal lizard video marker

Figure 2. Click to play video. Just how fast can quadrupedal/bipedal lizards run? This video documents 11 meters/second in a Callisaurus at the Bruce Jayne lab. just think what a pterosaur could attain, even without its wings.

Living bipedal lizards are anything but awkward-looking.
In fact they look incredibly like graceful bullets, faster than a rabbit  and impossible to see on film unless greatly slowed down, as shown here in the Bruce Jayne lab films.

Pterosaurs have what bats and birds have
The ability to flap and fly vigorously. Huge pectoral  and upper arm muscles, fur-covered body, independent wings and legs. Gosh, I feel like I’m looking out for the little guy (pterosaurs) here, having to defend them from pterosaur experts.

Doggone it. 
I realize everyone has their pet ideas and given those its important to trash the ideas of others. But this is Science and we can come to certain agreements. Nice to see Chatterjee showing that Tapejara could run bipedally! That’s a first step. Hopefully the round table at the Pterosaur Symposium in Rio in May will bring forth broad agreements on several issues without resorting to shoe throwing.

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.

New Tapejara Take-off Video

A bipedal pterosaur video!
Just ran across this Tapejara skeleton take-off, fly and land video from the Huffington Post -and its a bipedal takeoff! The original comes from Texas Tech in November 2012.

Click to animate. Tapejara take-off, flight and landing by the Sankar Chatterjee lab. Red arrows point to morphology problems. 1. Bend humerus back further. 2 Bend elbow more. 3. Pteroid goes to carpals, not the finger joint, unless that's a metacarpal lacking fingers. 4. Knees should be splayed 5. Extend hind limbs laterally.

Figure 1. Click to animate. Tapejara take-off, flight and landing by the Sankar Chatterjee lab. Red arrows point to morphology problems. 1. Bend humerus back further. 2 Bend elbow more. 3. When the elbow is bent, the pteroid angles out from the radius, framing the propatagium.4. Metacarpal lacking free fingers. 4. Knees should be splayed 5. Extend hind limbs laterally in flight.

The headline reads: Pterosaur ‘Runways’ Enabled Huge Prehistoric Flying Animal To Get Airborne, Study Suggests. By: Douglas Main, LiveScience Contributor
Published: 11/08/2012 03:01 PM EST on LiveScience.

How did pterosaurs takeoff and fly?
According to Main, “A new computer simulation has the answer: These beasts used downward-sloping areas, at the edges of lakes and river valleys, as prehistoric runways to gather enough speed and power to take off, according to a study presented Wednesday (Nov. 7) here at the annual meeting of the Geological Society of America.” This is Sankar Chatterjee’s hypothesis. “First the animal would start running on all fours,” Texas Tech University scientist Sankar Chatterjee, a co-author of the study, told LiveScience. Then it would shift to its back legs, unfurl its wings and begin flapping. Once it generated enough power and speed, it finally would hop and take to the air, said Chatterjee, who along with his colleagues created a video simulation of this pterosaur taking flight.

Chatterjee goes over the edge when he reports, “This would be very awkward-looking,” he said. “They’d have to run but also need a downslope, a technique used today by hang gliders. Once in the air, though, they were magnificent gliders.”

Unfortunately, Chatterjee, like the other pterosaur experts, has a built-in bias regarding pterosaurs in that he sees them too weak to run to take-off speed, except downhill, and too weak to flap sufficiently to create enough thrust without a runway, and too weak to flap with vigor while gaining altitude.

Living bipedal lizards are anything but awkward-looking.
In fact they look incredibly like graceful bullets, faster than a rabbit  and impossible to see on film unless greatly slowed down, as shown here in the Bruce Jayne lab films.

Hovering pterosaurs?

Hovering pterosaurs?
Well, maybe, maybe not… but let’s explore the concept. I’ve animated the possibility  (Figs. 1, 2). Let’s look for problems.

Click to animate. Hovering pterosaur in fast motion.

Figure 1. Click to animate. Hovering pterosaur in fast motion. Perhaps animated not nearly as fast as necessary, here restricted by GIF animation standards. This animation has been reduced to 3 frames at 558 dpi width. The scale bar at 72 dpi is actual size, so this pterosaur is actual size here.

Hovering tiny pterosaur, BMNH 42736, provided with a much larger sternal complex than other tiny pterosaurs.

Figure 1. Click to animate and enlarge. Hovering tiny pterosaur, BMNH 42736 in slow motion (15 frames in the cycle). Here we see either the take-off or the landing phase, with most of the thrust of the wing elevating the pterosaur above the substrate. The hind limbs are foreshortened because they are extended toward and away from the viewer. As in hovering birds and bats, thrust/lift is generated throughout the flapping cycle.

Take-off
Perhaps all pterosaurs were able to hover only briefly, especially at take-off and landing. A vertical take-off would have facilitated lift-off from water, if floating prior to flying.

Landing
Hovering would also have facilitated accurate landings on small runways, like branches, by rapidly reducing forward airspeed by “raising the nose,” presenting the maximum area for drag and rotating the thrust component downward.

Rotation to the minimum drag flight configuration
From the hovering mode, simply dropping or extending the skull anteriorly, especially in long-necked forms, would have rotated the pterosaur to the traditional flight configuration, reducing drag to a minimum and rotating the thrust vector to the horizontal to maximize airspeed.

Tiny vs. giant
Perhaps certain tiny pterosaurs with a large sternal complex, like BMNH 42736, would have found hovering easier due to their tiny size. We can only image a giant pterosaur hovering at present. Perhaps it is unlikely or impossible, as in large birds.

The ability to hover must be considered the acme of flight in vertebrates, requiring the most sensitive and energetic sort of morphology and metabolism. We know that pterosaur wings were imbued with nerves and blood vessels, so there would have been a constant stream of instructions and feedback traveling back and forth to the brain.

Sternal complex variations
The sternum in birds differs greatly, from the giant sternum in hummingbirds, to the much smaller one in ostriches. Similarly, in pterosaurs the sternal complex varies greatly, from the giant broad one in Dendrorhynchoides to the rather tiny ones in Dorygnathus. This may have something to do with hovering and vertical take-off.  Not sure. Makes sense.

Flight membrane
This hypothesis and model is shown with the narrow-chord wing membrane found in all known pterosaurs that preserve the wing membrane. A narrower wing membrane can flap more quickly due to less drag.

I really don’t see any problems having tiny pterosaurs hover — especially during take-off and landing — and thus for only short periods of time. Perhaps the best of them had the deepest or largest sternal complex. Perhaps these could hover for longer periods of time.

Notably, the vampire pterosaur, Jeholopterus, had a very small sternal complex. So, given this hypothesis, it is unlikely that it hovered the way Dendrorhynchoides and other anurognathids could have. Instead, Jeholopterus more likely landed with a thud.

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.

“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

Walking on water – birds and lizards

With a nod to Mike Habib, there are (at least) three tetrapods that can walk on water, each in their own way.

1. The famous Basilisk, otherwise known as the Jesus Christ lizard.

Basilisk walking on water.

Figure 1. Basilisk walking on water demonstrating just how fast lizards can move those hind legs.

2. The Stormy Petrel, which actually just flies or glides (with a nice headwind) so close to the water that it dips its toes in.

Stormy Petrels gliding into a headwind, dipping their toes in the water while feeding.

Figure 2. Click to see video. Stormy Petrels gliding into a headwind, dipping their toes in the water while feeding.

3. The western Grebe, which, like the basilisk, actually gets up and runs on water (Fig. 3). Looks strenuous. Ends in a cool dip. Hope these guys get lucky because it is a mating ritual designed to show their skills. The wings are semi deployed and do not provide lift during this excursion, but this is not a flightless bird.

Western Grebe walking on water

Figure 3. Western Grebe walking on water. Click to see video.

Another video of grebes from the BBS here.

Using the same technique (rapid leg movements) here is another video of yet another grebe ritual, performed belly to belly, largely out of the water.

These odd birds also have an unusual way of walking on the beach seen here in video (Fig. 4).

Grebe walking.

Figure 4. Grebe walking. A little ungainly, seems to tire easily as it plops down on its belly. Click to see video. Note the toes are beneath the center of balance in this flying animal, the root of the wings.

Western Grebes, like Jesus lizards, move their feet incredibly rapidly to remain above the water. I haven’t seen such rapid foot movements in large birds that actually takeoff from the water. I have searched for video of grebes taking off to no avail.

Addendum: January 4
Here is a video of the largest bird that can fly, the Kori bustard. The thing you may not be able to see unless you stop and start the video several times is the frantic kicking of the hindlimbs during the strenuous high angle take-off and acceleration to normal flight speed. It is reminiscent of the toe touches we’ve already seen pelicans do during takeoff, but there’s no water around. It’s just residual frantic leg movements timed with wing beats. So, is the pelican gaining speed with every toe touch on the water, or is it just more of the same frantic leg movement before the “landing gear” are finally stowed away at cruising speed? 

Finally, an image of a duck spanking the water on its first downstroke (Fig. 5) and using the recoil to propel it into the sky. I’m sure the feet are also moving like crazy, but are they moving together, as in a leap, or are they running? It happens so fast, it’s all a blur.

duck take off

Figure 5. Duck take off as it spanks the water on the first downstroke (evidently the feet did not cause it to leap free from the water). Click to see video. Takeoff is at the very end.

All of these are instructive with regard to pterosaurs and their ability to take off from a floating configuration.

The grebe shows that an apparently top-heavy tetrapod can still get about on two legs and take-off from the water.

The duck shows that laterally extended wings can spank the water and contribute to a quick take-off.

The petrel shows that a headwind can provide enough airspeed to achieve flight at a very low to no groundspeed.

The basilisk shows a non-webbed foot moving rapidly in a sprawling configuration can achieve no-wind takeoff speeds. Pterosaurs had webs. All of these expand the possibilities for pterosaurs.

We’ll be taking a look at pterosaur thighs in the near future. [Rated P-G. ]

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.

Water takeoff in a pelican (part 2 with reference to pterosaur water takeoffs)

Mike Habib, famous for his pterosaur forelimb take-off scenario, sent a short note recently for which my reply here is aided with illustrations.

M. Habib wrote, “Incidentally, pelicans do not launch using wing power. The launch using a series of pushes from the hindlimbs, which are essentially leaps. Their launch is basically saltatorial. Most of the power is provided by the final leap, as evidenced by the fact that the last “splash” is the largest – they displace more water, not less, as the feet push, so the wings are not picking up more power as they go. Animals do not launch like airplanes.”

Earlier I posted a pelican take-off composite photo that stitched together several scenes from a video from YouTube here (redux in figure 1) in which a Sea of Cortez pelican became airborne from a floating configuration.

Pelican take-off sequence from water.

Figure 1. Pelican take-off sequence from the Sea of Cortez. Click to enlarge. Full video linked above in text.

Thankfully there’s another YouTube video newly posted in slow-motion here that is even more instructive.

In both videos, you’ll note that the pelican slowly unfolds its wings (as in figure 1) preparing for flight. With one mighty downstroke it becomes airborne (#4 and #5 in figure 1, note the belly is clear of the water). Beneath the waves no doubt the feet have provided some thrust, as we can see by their position as they rise above the waves in the first (slow-motion) 7 seconds (#5 in figure 1) fully extended posteriorly. The wings continue to beat in sync with the feet cycling back, pulling the water backward, using every limb in its power to achieve greater airspeed. But note from the start (#4 in figure 1), the pelican is airborne and flying. Wings are dry. Feet are too, except for occasional dips (leaps? or simply gaining traction?). To my eye the foot motion looks more like a pull (swimming stroke, paddling, thrust from the entire interaction of foot and water), than a push (as in leaping, thrust only from the moment of last contact with the substrate).

Not sure, given the relative sizes of the feet and wings, how M. Habib can say, “pelicans do not launch using wing power.” Looks to me like they use everything they have, with the majority contribution from the enormous wings (and who knows how much added headwind  from the breeze). Certainly it takes five and a half foot contacts with the water before the pelican has enough airspeed to rise above the “ground (in this case water) effect” in which the wings benefit from more lift in closer association with the ground (water). And the last splash was the least, not the greatest in both videos.

The key seems to be: one downstroke and everything but the feet leave the water.

All of these musings on pelican water takeoff refer back to my thoughts on convergent water take off in pterosaurs first mentioned earlier and duplicated below (figure 2).

Pterosaur water launch

Figure 2. Ornithocheirid pterosaur water launch sequence in the pattern of a pelican launch. LIke ducks, geese and pelicans, pterosaur probably floated high in the water. Here the wings rise first and unfold in an unhurried fashion, keeping dry and unencumbered by swirling waters. Then the legs run furiously, like a Jesus lizard, but with such tiny feet, they were not much help in generating forward motion. The huge wings, however, did create great drafts of air, thrusting the pterosaur forward until sufficient airspeed was attained, as in the pelican. Considering the pelican’s abilities, perhaps the relatively lighter pterosaur could have arisen free of the water on the first downstroke, without much fuss from the hind limbs, especially aided by a light marine headwind.

Another video of a skimming pelican here brings to mind Nyctosaurus and Pteranodon feeding activity over the Niobrara Sea.

And yet another video of an origami Pteranodon here. Amazing. I better stop there. YouTube can be fascinating and distracting.