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Chatterjee and Templin 2004, review, part II (long)
Posture, locomotion, and paleoecology of pterosaurs
Geological Society of America
Special Paper 376, 2004 64pp.
Chatterjee, S. and Templin, R.J.
In part II of this long review we start with a heading entitled: Wing Design,
Comparative Morphology of the Wing
1. Chatterjee & Templin (C&T) compare the wings of bats, birds and pterosaurs.
Basic stuff. C&T state: â??Both pterosaurs and birds belong to the clade
Archosauria...â?? This statement comes four years after Peters 2000 showed that
pterosaurs do not belong in the clade Archosauria. No argument is given. More
importantly, no support is offered. Dropping pterosaurs into the Archosauria
has always been by default and a bad fit.
2. C&T follow that statement with: â??As a result, pterosaurs and birds show
closer phylogenetic similarity, as reflected in their anatomy and lifestyle.â??
What similarity??? Their closest common ancestor, assuming an archosaurian
origin would have been erythrousuchian, according to the lastest from the
â??Pterosaurs Are Archosaurs Peopleâ??. A diapsid opening and an antorbital
fenestra is no guarantee of a similar anatomy and lifestyle. Strangely, almost
every _other_ analogy in the book indicates that C&T think pterosaurs and bats
have a more similar anatomy. Hereâ??s a quote, â??Here we prefer the bat model
for pterosaur wings...â??
3. C&T follow Unwin et al. (1996) in supposing that the pteroid is a modified
first distal carpal. Again, a bad guess arrived at by default. No evidence is
given. Peters (2001) showed that ithe pteroid is derived from a central carpal.
The first distal carpal remains lined up behnd digit I. The central carpals are
missing having migrated anteriorly (medially) in nonvolant precursors.
4. Figure 12 shows the standard wing planforms of early and later pterosaurs
based on Sordes and Pterodactylus. Again arguments and drawings made by Peters
(2001) against these very same specimens were not argued against. Simply
ignored. (and yes, C&T reference the work.)
5. C&T report, â??In bats, the large membrane in front of the wing can be used
as a flap, another adaptation to low-speed flight.â?? Flaps always go on the
trailing edge of the wing. Those on the leading edge are called slats.
6. C&T state, â??No [pterosaur] specimen shows a clearly defined trailing edge,
attached unambiguously to the sidewall of the body.â?? Peters (2001) showed a
number of examples of just such a wing, and Sordes is another good example of
this. No argument was given by C&T. More samples have come to light since then.
Not one is different.
7. C&T follow this with: â??[in the narrow chord wing]...the long trailing edge
would remain free and dangling during flight without any mechanism of tensing
the membrane.â?? Peters (2001) and Schaller (1985) showed that the wing is
tensed between the wing tip and the elbow. No argument was given by C&T.
8. C&T report: â??Without leg attachment, there would be no angle of incidence
control and alteration of the wing planform.â?? First of all, most of the long
wing is beyong the control of the hind leg, even if attached. Second, the angle
of incidence control would be handled by shoulder muscles for the most part,
but also by the uropatagium beween the legs and tail acting in flight as a
horizontal stabilizer in an airplane, pitching the whole body.
9. C&T report: â??...the narrow, â??bird-likeâ?? wing without any leg
attachment would make the control of ptich and camber more difficult.â?? First
of all, birds donâ??t have any trouble controling pitch and camber with their
narrow â??bird-likeâ?? wings. Second, a toy ornithopter has no trouble flying
with a widely varying pitch and camber. Camber in a pterosaur wing could be
controlled by the elbow which rises above the plane of the wing and curves the
membrane like a circus tent, as in bats, but ornithopter toys show that even
this is not necessary.
10. C&T continue, â??...it would decrease the wing area slightly, thus
increasing the wing loading and bending stress on the spar.â?? C&T are grasping
at straws here. As a matter of fact, a narrow wing has much less drag (think of
a glider), and whatever the wing loading was, pterosaurs handled it.
11. C&T repeat Unwin and Bakhurina (1994) in stating: â??[Pedal digit V]
supported, tensed, and manipulated the uropatagium analogous with the calcar of
bats.â?? No one, whether in 1994, nor in 2004, has shown how this occurs. What
stretches, what rebounds, what are the limits, what are the abilities? This one
Nature paper has bamboozled more scientists into accepting its statements
without evidence and without testing them. A shame. Tischlinger & Frey (2002)
report on a perfectly preserved uropatagium extending from the distal metarsal
V to the tail base. Thatâ??s the pattern in all pterosaurs. This also was not
reported or argued by C&T, but the paper was referenced.
12. C&T report that â??...the wing of a pterosaur... is curved to produce
lift.â?? I donâ??t think camber has ever been preserved in stone. This might be
13. Figure 15 copies Bennett (2000) and his deep chord wing model bearing no
resemblance to the reality of the Zittel wing that shares the figure. According
to Bennett and now according to C&T: The propatagium attaches to the neck(
which is false). The trailing edge of the wing is oriented toward the hips
(which is false). And the elbow is over-extended. It is paramount that
paleontologists follow Nature (the maternal figure, not the magazine) and not
make up extended wing membranes and such just to please some horrible bat-wing
paradigm (which Padian warned about over ten years ago and never fully heeded).
By the way, Peters (2001) argued against these exact drawings with figures that
were more faithful to Nature and solved more problems.
14. C&T report that, â??In water spiders, small hairs on the body surface trap
air and act as a water repellant. It is likely that pterosaur hair might have
functioned in similar way [sic].â?? I think there are issues of scale here
regarding water tension and beading, arenâ??t there? If the hairs are
hydrophobic they will not get wet.
Wing adaptations for powered flight
15. C&T report, â??Unlike bats and birds, the clavicles are absent in
pterosaurs.â?? Wild (1993) identified pterosaur clavicles on the leading edge
of the sternal complex.
16. C&T report, â??The scapula and coracoid... are elongated, L-shaped and
fused together.â?? They are not fused together in a majority of pterosaurs.
Fusion is restricted to certain clades so it is a phylogenetic character. It
has not yet been shown to be an ontogenetic character despite Bennettâ??s
17. C&T report, â??In Cretaceous pterodactyloids, the upper end of the scapula
fits into a socket of the notarium to make the joint immobile.â?? Wrong on two
accounts. Not all Cretaceous pterodactyloids had a notarium. Think of
ctenochasmatids and many of the smaller germanodactylids. The notarial joint
was a ball-and-socket joint, with limited mobility, but still some.
18. Continuing: â??The coracoid is slightly longer than the scapula and is
braced strongly against the transverse sulcus of the sternum.â?? Here C&T are
thinking of their favorite pterodactyloids, not all of them. Some (tapejarids,
dsungaripterids, some germanodactylids) have a short coracoid.
19. Continuing: â??The sternal plate is wide and has a shallow ventral keel.â??
But not in Istiodactylus (deep keel). And not in Zhejiangopterus (narrow
plate), among others.
20. Continuing: â??In pterosaurs, there is a prominent acrocoracoid process on
the coracoid to serve the same pulley function of the supracoracoideus muscle
(Padian 1983). Yes, in Anhaguera and its kin there is a similar structure. No
in most other pterosaurs, suggesting that this is not a case of basic
convergence. Itâ??s the valley thatâ??s important for determining whether a
pulley function is present or not â?? the valley between the process and the
rest of the scapula. There is no valley in Dimorphodon, according to Padianâ??s
drawing. Just a slight convex rise. Again wishful thinking in 1983. Not tested
in 2004. Bennett also rebuilt pterosaur musculature without a pulley-like
supracoracoideus in 2003 and he used Anhanguera as an example.
21. C&T report: â??â?¦by flexing the knuckle joint during the upstroke to
reduce the drag.â?? Unfortunately, according to their wing model, this would
relieve all the tension in the wing, turning it into a high-drag flapping flag.
A sharp posterior bending of the wing works with birds. It might not work with
pterosaurs. Does it work with bats? Not sure. In any case, the narrow,
glider-like wing of pterosaurs already has a high-aspect ratio, which results
in a high lift/ low drag ratio. Flexing the knuckle as much as is shown in
Figure 17 would actually do more to destroy lift, rather than drag, which would
be useful in a dive.
22. C&T report that the base of the wing could not close any closer than 35Âº
in Anhanguera. Thatâ??s unfortunate, because in Istiodactylus, Pteranodon and
any number of smaller pterosaurs the wing finger is sometimes found closed
completely. Otherwise any wind on a grounded pterosaur is going to billow those
23. C&T hypothesize: The propatagium and pteroid bone might have acted as an
elastic strap to keep the body close to the trunk [of a tree].â?? Peters (2001)
referenced Brown, Baumel and Klemm (1995) who found that the propatagium in
birds passively prevents hyperextension of the elbow during flight as the wing
tip is subject to drag. The propatagium develops in leaping arboreal mammals
and it appears in Longisquama, another arboreal leaper and a sister taxon to
pterosaurs. Here the membrane forms a parachute to slow descent. Arm muscles
are used to keep the body close to the tree, not elastic straps.
24. Figure 19 , the flight muscles of Anhanguera, is a direct copy from
Wellnhofer 1991. Notably absent in both renderings are muscles that might
connect the anterior dorsal spines to the scapula. There should be layers of
25. Figure 20 shows a number of pterosaurs in various views and scales in
silhouette in order to compare wingspans and masses. Many were traced from
various popular and childrenâ??s books. Why didnâ??t C&T show a ventral view of
each of their wings to show they actually did the work?
Much of the middle part of this paper goes into the mathematics of flight,
Templinâ??s specialty. I note that because C&T chose a deep chord wing model,
as every study before them did, their regression lines and scatter clouds were
all a bit off from the bat and bird lines and clouds. A shallower chord would
have brought all the data closer together.
26. C&T state: â??In a shallow glide, in still air, there is no propulsive
thrust, but there is a component of gravity acting forward along the sloping
flight path.â?? In flight training we learned that gravity always acts
downward. Inertia or momentum carries the object forward until friction, or the
surface of the earth, stops it.
27. Figure 21 has the standard wing shapes missing from Figure 20 presented in
ventral view, along with a glider shape, a hangglider and a spread-eagle human
for scale. Notably no pterosaurs have uropatagia here. Why not? In addition,
the round tip wing shape C&T espouse earlier is absent in all these pictures
(only the largest preserve enough detail to tell). Why didnâ??t they fix this?
It only promotes an image they know to be false.
28. Figures 22 and 25, once again, if C&T would reduce the wing chord all the
pterosaurs would line up better with all the birds.
29. Table 5. Eudimorphodon ranzii, a specimen that has no wings, is species
number one in a basic terrestrial takeoff data table. How can this be? Maybe
theyâ??re thinking of another Eudimorphodon, probably MPUM 6009.
30. Figure 26 shows the glide polars for various pterosaurs. Dorygnathus comes
out as a better glider than Rhamphorhynchus despite the fact that it has a much
shorter relative wingspread and a much smaller sternal complex. Curious.
C&T spend many pages on hovering, steady flying and formation flying. Difficult
to comment on these mathematical hypotheses when the wing shape is wrong and
aerodynamics are not my specialty.
Takeoff and Landing
The question posed by C&T is simple: running start? or flying start?
31. C&T state: â??the heavier a pterosaur was, the more trouble it had during
takeoff and landing.â?? Define trouble. Does that mean effort or power
expended? Does that mean awkwardness? Obstacle avoidance? All of the above? Do
large birds have trouble taking off or landing, or are C&T mentally picturing
gooney birds in particular? Lots of storks, pelicans and eagles have no trouble
at all it seems to me.
32. C&T state that large pterosaurs needed a headwind or sloping surface for
extra power in addition to a takeoff run. Hmmm. I see an ideal ploy as a
predator. Not downwind, but down hill from my prey. Hey, give the pterosaurs
33. C&T state: â??Because of their long wings that were rooted to their hind
limb, pterosaurs could not flap during a takeoff.â?? I have never lived in the
Mesozoic, but that statement doesnâ?? t sound right. A creature with wings
unable to flap them? When C&T wrote this statement they should have pushed
their chairs away from their computers and gone back to the chalk board. Or
better yet, go rent â??Winged Migration.â??
34. C&T state: â??Long and wide runways would be needed...â?? The recent
abstracts from this Novemberâ??s SVP include a report of tracks documenting the
landing of a pterosaur. Took one tiny hop and stopped. With such large wings
and small bodies it is easy to imagine one half of one flap (from dorsal to
lateral) would send a body flying. Thatâ??s pushing a lot of air straight down.
Plus donâ??t forget those leaping hind limbs!
35. Figure 33 shows the take-off strategy of Quetzalcoatlus using a headwind
and a downslope (poor guy!). First of all, this Quetzalcoatlus doesnâ??t match
the skeleton seen earlier in figure 4. The neck is too short, the beak is too
long, the wings are too long, the legs are too short, the metacarpus is too
short. Itâ??s horrible! Plus, the way itâ??s running, carrying its wings half
open creates twin high-drag parachutes. No wonder it had to plow downhill.
36. C&T note that large pterosaurs might have used ground effect. Thatâ??s
good. They might have. But probably unnecessary. It would be good to re-ask
this question when the wing shape is right.
Sexual Dimorphism and Aerodynamic Function of the Head
37. C&T state: â??Among flying vertebrates, the most unusual feature of
pterosaur anatomy is its immense skull, often dominated by a huge sagittal
crest.â?? Here C&T are openly displaying their bias again. Very few pterosaurs
had an immense skull. Fewer still had a huge crest.
38. Here C&T repeat Bennettâ??s (1987, 2003) subjective guess to allocate large
crests to supposed males because they supposedly also had narrow pelvic
openings. The one Pteranodon that has a crest and a pelvic opening preserved in
one specimen (the Triebold specimen) has a short crest and a small opening. So
no cigar. The pelvic opening samples provided by Bennett, when scaled the same,
are about the same diameter. The large pelvis has a narrow opening. The small
pelvis a larger opening, both about 4 cm. No advantage in passing eggs
therefore. Turns out other characters of the pelvis turn this into a
phylogenetic problem. The two sample pelves were not the same species or genus.
He was comparing apples to oranges, or Pteranodon to Nyctosaurus. Again, C&T
could have tested Bennettâ??s assumptions, as I did, and in half an hour
discovered the fatal flaws. No, they accepted without testing. Large crests, it
turns out to no oneâ??s surprise, are only found at the end of phylogenetic
lineages of â??no crestsâ?? leading to â??small crestsâ?? leading to â??large
39. Continuing: â??The crest was developed last in ontogeny during sexual
maturity.â?? Kind of like Bambi? No. Females and juvies probably had them too.
There is no way to tell gender in a pterosaur unless thereâ??s a baby
alongside. Crest development late in phylogeny? Yes. And that can be
demonstrated in a cladogram. Thatâ??s the best answer we have for now that can
be scientifically demonstrated.
40. C&T state: â??...all pterodactyloids had a proportionately enormous skull
that was longer than the body length.â?? The micro-pterodactyloids close to
Scaphognathus did not have a skull > torso. In G. cristatus + dsungaripterids
it was subequal to the torso, not longer, and certainly not longer than the
post-cranial body length. So that means not â??all.â??
41. C&T state: â??The primary function of the enormous head of pterodactyloids
appears to be associated with a yawing or steering mechanism.â?? Birds donâ??t
do this. Bats donâ??t do this. Airplanes donâ??t do this. Pterosaurs with small
heads donâ??t do this. Many pterodactyloids do not have an enormous head. C&T
are blindly repeating bad dogma and focusing on their personal favorites
again. All flying things bank to turn, which tilts the lift vector to that side
and the turn continues infinitely until an opposite bank is applied.
Ecology and Evolution
42. C&T state: â??The origin of and phylogeny of pterosaurs are still poorly
understood.â?? What can I say? They read Peters (2001) but they could not
overcome their archosaur paradigm and refused to accept. Or better yet, test!
43. C&T hypthesize: â??During swimming they could raise their wings vertically
upward like a sailboat using wind energy to travel large territory for
foraging.â?? Their own drawings actually limit the ability to lift the humerus
to 20Âº from vertical. C&T hypothesize a locking mechanism (never found) for
soaring, but this isnâ??t that. This is different. So theyâ??re asking the
floating pterosaur to raise its wing(s) to its most dorsal position and hold it
stiff while sailing? Once again, show me. Seems implausible at first glance.
Seems tiring too.
44. Hereâ??s a problem in logic that could have been solved just by re-reading
the manuscript: C&T state: â??The skeletal design of pterosaurs does not
suggest a diving adaptation (Brower 1983). Similar to brown pelicans, many
small and medium-sized pterosaurs (M < 8kg) with good flying ability could
forage by _plunge diving_ from the air into the water.â?? [emphasis mine]
44. C&T report: â??Apparently, pterosaurs spent a great deal of time eating.
The enormous skull and narrow snout facilitated the large intake of food.â??
Again, not all pterosaurs had an enourmous skull and narrow snout. C&T are
picking personal favorites again. And like the pelican, some pterosaurs beak
can hold more than its belly-can. So, maybe more time searching for food and
enjoying the afternoon. Maybe not â??a great deal of timeâ?? actually eating.
Not even sure that whales spend a great deal of time eating. Crinoids do. Boas
45. C&T report on the various hypotheses concerning the origins of pterosaurs.
Scleromochlus is considered then rejected as too close to theropods (not true -
crocs). Atannassovâ??s dissertation on two Dockum archosaurs is mentioned,
again both are apparently crocodilian. Bennettâ??s 1996 â??radicalâ??
hypothesis that pterosaurs come out close to erythrosuchids is mentioned.
Closer, but still no cigar. C&T mention my report on Sharovipteryx as a
possible ancestor, and ignore Unwinâ??s work along the same lines. They also
ignore the other three protorosaur taxa that would work if for any reason
Sharovipteryx was made ineligible to wear the crown. Wildâ??s (1983) imagined
parachute lizard is discussed by C&T as if it was a possibility. That model is
wrong. Peters (2000, 2001, 2004) showed that pterosaurs descended from
protorosaur bipeds and that the wings came last after almost all the other
modifications were in place, almost as in birds.
46. C&T report that pterosaurs range down to sparrow-size. Actually the
smallest hummingbird or bat is the lower size limit.
47.C&T discuss K selection vs. r selection, then state: â??Early pterosaurs
with small size showed preference for r selectin, where production of large
numbers of offspring was insurance against juvenile mortality or environmental
catastrophe. Later pterosaurs exhibited K selection, with large size and long
generation of time where the full resources of environments were exploited
safely.â?? This is nothing but guesswork told as fact. No broods or clutches
have been found for pterosaurs. Furthermore, this was at the printer before the
discovery of the single pterosaur in the egg which turned out not to be an
embryo after all.
48. C&T discuss Copeâ??s Rule, reject Copeâ??s Rule then show the effects of
Copeâ??s Rule. To do this, C&T plot a mere ten pterosaurs on a guesstimated
weight vs. guessitmated phylogeny graph to show Gouldâ??s (1996)
â??Drunkardâ??s Walkâ??. To make the chart work terminal taxa were flipped left
to right and some closely related taxa, such as Nyctosaurus and Pteranodon were
separated. Not good science from the start. Thereâ??s no discussion of size
squeezes, which have not yet appeared in the literature, except in this chart.
49. C&T discuss increased oyxgen levels in the Late Cretaceous leading to
gigantism in pterosaurs. C&T â??believe that an increased oxygen supply may
enhance repiratory efficiency... enabling them to takeoff without switching to
anaerobic physiology.â?? As if thatâ??s a bad thing!
50. C&T conclude by discussing various Late Cretaceous extinction scenarios,
suggesting that â??huge tsunamis produced by the impact would have destroyed
shallow-marine habitats across the globe, devastating the sanctuary for the
Maastrichtian pterodactyloids.â?? While birds had ecological superiority over
pterosaurs. This is more guesswork, estimating where pterosaur nests were
stationed and what destroyed them all.
51. C&T report: â??Large-bodied pterosaurs had two disadvantages: they
generally had smaller populations and lower reproductive rates than
smaller-bodied bird species.â?? Again, where does this data come from? This is
guesswork. Not all pterosaurs were giants at the end of the Cretaceous. Donâ??t
forget the nyctosaurs.
In the end, Chatterjee and Templin have given us a largely uncritical review of
past literature, some novel flight theory and little else that isnâ??t tainted
with bad data and guesswork. I cannot recommend this literature. There is
little here that need be referenced in future work. Largely disappointing.
Padian and Bennett were among the colleagues who reviewed the work prior to