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Re: THEROPOD LUNG UNREALITY (long)



        We urge that readers of the dino-list regard GSP's recent novella
("theropod lung unreality") with the skepticism it deserves.  All of the
objections/issues raised by him (as well as others) were raised and easily
dealt with in the course of  peer-review before the paper appeared in the 14
November SCIENCE.  Thus, for example:

1. ** The dorsal "imperfection" in the otherwise domelike outline of the
anterior portion of the abdominal compartment (see especially the Bejing
slab)** -- This imperfection actually represents an artifact (actually a
gouge on the Bejing slab and a corresponding raised area on the Nanjing
slab) created by local disruption of the otherwise mostly regular plane in
which the specimen was split.  Thus, the apparently "missing" portion of the
border of the dome-shaped liver is probably contained within the small
raised area on the Nanjing slab.  Members of the "dream team"  (all of whom
had the opportunity to study these specimens under 'scopes) have
corroborated our observations.  It is also important  that dinolist readers
realize that at least two distinct individuals of Sinosauropteryx  (one's
not published) exhibit similar diaphragm-related partitioning of the
visceral cavity.
2.  **Differences in pelvic girdle proportions between theropods and
crocodilians**-- remember, we specifically mention that the key here is the
pubis in all hepatic-piston breathers must be "...at least as long as the
liver is deep..."  in order to properly accommodate the ventral
diaphragmatic muscles (which insert on the ventral aspect of the liver).
Thus,  the fact that the pubis in a markedly dorsoventrally flattened animal
(i.e., crocs) is relatively shorter than the pubis in a markedly
laterally-compressed group (theropods) is irrelevant.
We could go on to refute all of  GSP's objections, but in the interest of
time we need to devote most of our energies to the peer-reviewed literature. 

>The following errors, omissions and other mistakes are present in Ruben et al
>Science 278:1193-1368. 
>
>It is important to understand that Ruben et al have not actually seen any of
>the Sinosauropteryx specimens, they are making guesses based on photos of
>just one specimen, photos that fail to show its 3-D complexity. In Fig. 5A
>they use a low resolution, out of focus photo to contend that there is a
>semi-circular anterior border to the abdominal cavity. There is no such
>thing. Examination of higher quality, larger format photos on the cover of
>the April 97 Audubon (counterslab) and Nov 14 97 Science (main slab) and the
>March 97 Episode (both slabs) show that much of the supposed border of the
>abdominal cavity is really an irregular break in the sediment! This is
>especially obvious in the superbly detailed Audubon photo, where the shallow
>rim of a large, semi-circular, light colored break under the spinal column is
>clearly delineated both by cast shadows, and obvious breakage of the ribs at
>that location, the rest of the ribs are complete. Ruben et al saw this photo
>since they cited it in their paper, yet they make no mention of the damage
>(either they missed it, or thought it unimportant). Yet  their arrow points
>to this break as the septum - i.e. they misidentify sediment damage as soft
>tissue anatomy.  On the main slab there also appears to be small,
>subrectangular break in the sediment projecting ventrally from the larger
>area, perhaps parallaling a rib. If so, then this break forms more of the
>border of the supposed abdominal cavity. Also, on the mainslab, a small part
>of the dark area extends more anteriorly than they indicate, resulting in a
>more pointed apex to the dark region than the nice gentle curve they
>indicate. The rest of the "abdominal cavity" just consists of vague,
>irregular, darkish stains with no particular pattern to them. Who knows what
>they represent. Perhaps thoroughly degraded abdominal tissue flattened to
>paper thinness, it will require careful examination and analysis of the
>specimen to determine so or otherwise, there may never be definitive results.
>The claim that the specimen shows a croc-like separation between the lung and
>belly cavities via a septum is absurd, it shows nothing of the sort. 
>      Severely crushed specimens are always badly damaged and can be very
>difficult to correctly interpret under the best of circumstances. Yet Ruben
>et al treat the flattened dinosaur - whose soft tissues are less well
>preserved than your well run over roadkill - as though it is one of their
>high tech CT scans of a carefully pickled carcasse. The damage to the ribcage
>area in the Sinosauropteryx specimen probably occurred when the slab was
>first split. This kind of damage is very common, yet can be hidden in 2-D
>photos unless the lighting happens to be at a low enough angle, and coming
>from the right direction, so the shallow topography is not washed out. Any
>person working with such photos should be very careful to watch out for and
>not be mislead by such obvious pitfalls. As it is, Ruben et al violated all
>of the necessary protocals.   
>     Basic rule of paleontology. It's always a good idea to actually SEE THE
>SPECIMEN, or at least have excellent stereo photos and/or a detailed
>description, before making dramatic claims concerning same in a major science
>journal. 
>
>According to Ruben et al birds "lack a crocodilelike or mammallike
>thoracic-abdominal subdivision (septum) of the visceral cavity". Duncker
>(1979) states that in "all birds the coelum (body cavity) is subdivided in a
>manner rather similar to reptiles and especially crocodiles" (he also notes
>the differences), and "ventrally the pleural (lung) cavity is bounded by the
>horizontal septum" (illustrated in Fig. 2.13). Schmidt-Nielsen (1972) states
>that "a membranous structure.....is located along the ventral surface of the
>lungs. This membrane arches slightly up into the lungs" (as shown by Fig.
>25). Interestingly, the septum is attached to the ribs via muscles. The
>septum is pierced by the bronchai leading to ventro-posterior air-sacs. Ergo,
>the presence of a septum does not interfer with the evolution of abdominal
>air-sacs. 
>
>Ruben et al assert that birds use a very large sternum articulated via
>ossified sternal ribs with the ribs to ventilate the large abdominal
>air-sacs. This is partly true, yet misleading because it applies to flying
>birds in which in flight ventilation rates are extraordinarily high, and the
>super sternum anchors enlarged flight muscles. Theropods did not fly, and
>their aerobic capacity was probably more similar to ground birds like the
>kiwi, which Ruben et al ignore. In the kiwi there are no extensive abdominal
>air-sacs, and the sternum is very short. Alas, so little work has been done
>on respiration in these birds, but it is clear that the sternum ventialtes
>only the antero-ventral most air-sacs. The majority of air-sac ventilation is
>via simple rib action. 
>
>Ruben et al contend that theropods lacked the adaptations needed to operate
>an air-sac complex. Au contraire. It is important to understand that the
>avian complex did not spring into being fully developed, it developed
>gradually in their theropod ancestors. It started with elongation and
>increased mobility (via well developed double heads of the posterior ribs in
>ceratosaurs. This trend increased in avetheropods, in which the anterior
>chest ribs also shortened, showing that ventilation was shifting from the
>lung itself to bellows action air-sacs. Ruben et al state that theropods
>"lacked an expansive sternum". In the real world that most of us live in,
>large ossified sternal plates - at least as large as those of kiwis - were
>described and figured in dromaeosaurs and oviraptors by Barsbold in 1983, and
>have been discussed and figured in many other publications! In an odd way
>this denial makes sense, in that Ruben et al 1997b use an out of date
>cross-section of the ribcage of a dromaeosaur - based on incomplete
>disarticulated remains - in a futile effort to deny/ignore the evidence
>provided by complete ribcages, that these near birds have large sternal
>plates. These big sternal plates articulated with the coracoids via a
>transverely long hinge joint which allowed to sterna to help ventilate the
>antero-ventral air-sacs. Ruben et al also ignore the ossified dromaeosaur
>sternal ribs published by Ostrom in 1969. They fail to mention the ossified
>uncinate processes present on the fighting Velociraptor. Why do not Ruben et
>al make any mention of the work by Britt (1994) or Reid (1996) showing that
>the pneumatic vertebrae of theropods are strongly indicative of the presence
>of pulmonary air-sacs? Fact is that advanced theropods had the most bird-like
>trunks of any tetrapods. 
>
>It is equally important to understand that theropods have none of the
>adapations associated with the crocodilian piston action respiratory complex.
>In the latter the pubes are short (only one tenth trunk length, so they are
>not "elongate" as Ruben et al claim), transverely broad (maximum
>breadth/height ratio ~0.6) plates, separate along most of their length, and
>they are MOBILE! The last is a bizarre adaptation that is critical to the
>function of the liver pump, in which the shovel shaped pubes help move the
>mass of the broad abdominal cavity during the breath cycle. In theropods the
>pubes are very long (about a third trunk length), transversely narrow (ratio
>~0.25), cojoined along most of their length, and immobile as in birds and
>everything else. Fig 4 in Ruben et al is very misleading, because the extreme
>difference in pubis structure between the dinosaurs and crocs is obscured by
>comparing the posterior view of the croc to the lateral view of the dinosaur
>pubes, and failing to show the dinosaur pubes in posterior or anterior view.
> There is not the slightest reason to think that theropod pubes anchored a
>liver pump system. 
>
>In crocodilians there is a well developed, rib free, broad lumbar region.
>This is critical in order to allow the abdomen to expand and contract as the
>liver-piston works. We mammals have a plump lumbar region for a broadly
>similar reason. Theropods not only lack a lumbar region, the posterior ribs
>are elongated as in birds, and the belly was narrow and deep. Lacking either
>a broad lumbar region to allow strong abdominal movement, or mobile, shovel
>pubes to help move the belly, the idea that an abdominal mass dominated
>system could operate in theropods is absurd. Crocs have long, narrow,
>flattened, flexible trunks with hyperelongated transverse processes on the
>vertebrae. Theropods, including birds, have short, deep, rigid trunks with
>normal transverse processes. You can hardly get a ribcage less similar to
>those of crocs than those of theropods. 
>
>In Ruben et al the pubes of Archaeopteryx are shown nearly horizontal. They
>state that the pubis has "occasionally" been restored more vertically. Again
>this is most misleading. There is no Archaeopteryx specimen that shows a
>subhorizontal pubis. In the London specimen the pubes are completely and
>entirely disarticulated from the ilia. In the Berlin specimen the pubis is
>retroverted about 45 degrees, not horizontal as Ruben et al imply. I used to
>illustrate the urvogel's pubis at 45 degrees, but all four other specimens
>consistently show the pubis nearly vertical. This includes the newest
>specimen, in which there is no evidence that the pubis is in any way
>displaced from the ilium. So the pubis was subvertical and its distal end was
>anterior to the tip of the ischium, like it or not. It is the Ruben et al
>reconstruction that is the now rare and obsolete Heilmann version, the modern
>consensus of the great majority of modern researchers is that the protobird's
>pubis was subvertical. Actually, it is in dromaeosaurs that the pubes are
>strongly retroverted (Barsbold 1983). 
>
>It is also worth noting that the sternal plates in Archaeopteryx were
>actually quite large, because there is a large gap between the coracoids and
>the first gastralia. It's just that only the anterior part of the plates
>ossified, a situation similar to some ratites. Because they sternum
>articulated with the coracoids via a hinge araangement, the sternum could
>help ventilate the more antero-ventral air-sacs. 
>
>Ruben et al are also internally inconsistent and illogical. They cite the
>presence of gastralia in theropods as evidence that they had a croc-like
>respiratory system, yet conclude that early birds with well developed
>gastralia had air-sacs. They contend that early birds were not endotherms,
>yet they argue that they had air-sac ventilation. Of course, functioning
>air-sacs would not be present unless the aerobic exercise capacity was
>elevated above the reptile level (a few reptiles seem to have air-sacs, but
>there is no evidence that they help ventilate the lungs). It is known that
>the early birds were fully insulated with feathers. This would only be true
>of the birds were endotherms that generated the majority of their body heat
>internally. It is also becoming increasingly apparent that small theropods
>were feather insulated endotherms. Indeed, if and when it is shown that the
>hollow bristles adorning Sinosauropteryx and Mononykus are made of feather
>type keration then the house of cards called the antidinosaur hypothesis of
>bird origins will be run over by a truck. 
>
>I suggest to all that they compare the paraoccipital process of Archaeopteryx
>(Fig. 6 stereo views in Whetstone 1983) to that of Dromaeosaurus (Figs. 1,3,9
>in Colbert & Russell 1969). They share a distinctive structure not observed
>in other tetrapods. This is because the urvogel is a diminutive, flying
>dromaeosaur. It is now known that the egg microstructure of ovirpators is the
>same as that of ratites. It is careful methodical comparisons of this sort -
>not superficial appraisals of photos or inherently ambiguous assumptions
>about finger counts in bird embyros - that reveal the reality of bird
>descent. 
>
>Reading Ruben et al reminded me of watching one of those old Twilight Zone
>episodes. You know, the one in which reality was distorted all out of
>recognition? Well, they were all like that.  But in this case there is no
>evidence of any kind that any dinosaur had a croc-like respiratory complex,
>there is a lot of evidence that they did not. Here is a more plausible
>scenario. The presence of a septum in crocs and birds suggests that this is
>the general archosaur condition. Therefore, a weakly developed abdominal pump
>system may have been present in basal archosaurs. This was taken to an
>extreme in crocodilians which adapt the liver as a powerful pump. In
>tridactyl footed theropods this system was suppressed as air-sac ventilation
>gradually developed in order to overcome the aerobic limitations inherent to
>septate lungs. As this occurred, the septum migrated dorsally as the lungs
>reduced in size, and air-sacs expanded posteriorly through the septum. The
>system was probably weakly developed in Coelophysis, intermediate in
>Sinosauropteryx, better developed in Archaeopteryx, and about as well
>developed in dromaeosaurs as in kiwis. Only as flight evolved to high levels
>in the Cretaceous did volant birds evolve a hyperenlarged sternum in order to
>support enormous flight muscles, and help ventilate oversized abdominal
>air-sacs. 
>
>Yet again an attempt to refute the dino-bird link fails completely. The
>evolution of the theropod-bird respiratory complex is strong evidence in
>favor of an ancestor-descendent relationship. 
>
>GSPaul
>
>Barsbold R 1983 Joint Soviet-Mongolian Palaeont. Exp. 19:1
>Britt B 1994 J. Vert Paleont 14(3) 18A
>Colbert E & Russell D 1969 Amer Mus Novitates 2380:1
>Duncker H 1979 39 in King A & McLelland J, Form & Function in 
> Birds I
>Ostrom J 1969 Bull Peabody Mus Nat Hist 30:1 
>Reid R 1996 BYU Geol Studies 41:25
>Ruben J et al 1997b 505 in Farlow J & Brett-Surman M, The 
> Complete Dinosaur
>Schmidt-Nielsen K 1972 How Animals Work 
>Whetstone K 1983 J. Vert Paleo 2:439 (the text is largely incorrect)
>
>
>
TDJ
:-{)>
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    Terry D. Jones                             Voice:  541/737-6120     
    Oregon State University              Fax:      541/737-0501          
    Dept. of Zoology                         JONEST@bcc.orst.edu
    3029 Cordley Hall
    Corvallis, OR  97331-2914
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