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MORE ON THEROPOD LUNG UNREALITY



Still waiting for Rod Serling to show up. This, because the posts by Jones et
al replying to my post on the Ruben et al paper in the Nov 14 Science was
itself peculiar. 

It seems that Jones etc agree with my observation that there is breakage on
the main slab of the type Sinosauropteryx. This is astonishing, especially
because they made no mention of this in Ruben et al. In fact, in their Fig.
5A they show the tip of the topmost arrow ending exactly at the edge of the
breakage, leading to the impression that this is part of the supposed arc of
the septum. It is not! There is no way to tell what the shape of the dark
area is in this area, because we cannot see it (more prep work would be
useful). That the breakage was never mentioned in their paper, and an arrow
points to the break as a border, is deeply unsettling to say the least. 

Jones et al then go on to assert that the breakage in the type does not
really matter because it "is 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". They
also state that "members of the "dream team" (all of whom had the opportunity
to study these specimens under 'scopes) have corroborated all of these
obsevations". This appears to be in their tradition of A) commenting on
specimens they have not seen, B) making claims they cannot verify, C)
implying that other agree when they may not. I've received messages from two
people - one a member of the "dream team" - who have seen all three specimens
and carefully examined them, and in no way do they corroborate the
observations of Ruben et al. Larry Martin probably does, but do Jones etc
have endorsements from others dream team and others who have seen the
specimens? I saw a slide of the second Sinosauropteryx during Phil Currie's
talk at SVP - one person who does not agree with their observations - and
there was no trace of a septum. This is fact. All the Sinosauropteryx
specimens will soon be described properly and carefully. Do not count on the
claims by the Oregon State group being verified. 

Jones et al. try to defend their characterization of crocodilian pubes as
being "elongate". For the record, in Ruben et al. they state that "the
distinctive crocodilian pubis is robust and elongate (at least as long as the
liver is deep), much like the pubis in theropod dinosaurs (Fig. 4)". Lots of
problems here. First, I suggest all those interested refer to their Figs.
3&4. The pubes are not "at least as long as the liver is deep", the bone is
only about 60% as long as the liver is deep! The Twilight Zone theme creeps
in again as one wonders, don't they look at their own figures? In other
crocodilian specimens the pubis seems to be even shorter (only 30% liver
depth in H Duncker 1978). Now, Websters defines elongate as "stretched out"
or "long in proportion to width". Croc pubes are only about one tenth as long
as the trunk, and when articulated together are broader than they are long! I
am hard pressed to come up with archosaurs with pubes as short as those of
crocodilians, only a few "thecodonts" are similar. Most archosaur pubes are
more elongate. Fact, crocodilian pubes are not elongate. 

What are elongate - to an extreme among archosaurs - are the pubes of
theropods and birds. In theropods avian and non the pubes are fully one
quarter to one third trunk length, and when articulated together are three or
four times as long as they are wide. Now THAT'S elongate! 

It cannot be overemphasized how extremely different crocodilian and theropod
pubes are. In anterior view the latter become even narrower distally, and the
pubic boot when present faces entirely laterally and does not participate in
supporting the abdomen. In crocodilians the pubes become much broader
distally, because they form shovel shaped plates that help support the belly.
To see just how different they are compare Fig. 4A (croc pubis) in Ruben et
al. to Fig. 2d (theropod pubis) in F Nova & P Puerta (Nature 387:390 1997).
Of course, Ruben et al did not bother to illustrate croc and theropod pubes
in functionally equivalent, anterior views, doing so would have revealed the
profound difference.  

Because the theropod pubic boot faces entirely laterally, and the pubis is so
narrow transversely, it is not at all clear how the could support massive,
anteriorly directed respiratory muscles, as do the transverely broad pubes of
crocodilians. In addition to that, some theropods do not even have a pubic
boot! This includes primitive Triassic Coelophysis and near avian, Cretaceous
troodonts. The pubic boots of Archaeopteryx and some early birds are much
larger than those of some theropods - and are just as ill suited for
supporting respiratory muscles. There is no evidence that the pubes of
theropods had anything to do with a liver-pump system. 

On a related issue, Hou et al (1996 Science 274:1164) claim that "uncinate
processes hinging on the ribcage are found in all ornithurine birds", and
cite Ruben as asserting that the early birds that lack these processes would
not be able to ventialte the abdominal air-sacs. As a result, early birds
could not be endotherms. Today, at the Smithsonian, checked a number of
ribcages of screamers, which are peculiar relatives of ducks. Not a trace of
uncinate processes in any of them. Even rummaged through the box bottoms just
to be sure. Emus. They do not have them either. Well, one really big adult
did have one very short (about 7 mm) projection that was doing the best it
could to be an uncinate process. So, both flightless and flying birds do not
need to have ossified uncinate processes in order to ventilate their
air-sacs, and be endotherms. It is possible that uncinate processes have more
to do with bracing the ribcage than with respiration, the problem is poorly
understood. As for early birds without uncinate processes, they were heavily
insulated with body feathers. No small ectotherm is insulated, it prevents
them from readily absorbing the large amounts of environmental heat they
require. Only endotherms (i.e., vertebrates with MRs high enough to produce
the majority of their body heat internally) that need to retain their
internally generated heat are insulated. This is all so obvious, yet we
actually have people arguing that feathered, flying  birds had reptile-like
energetics. How very perplexing! Rather disturbing too. 

About feathers, kiwis have very long head feathers that consist mainly of a
simple shaft that looks just like cat whiskers. Probably serve similar
purposes. Looked at vulture heads, their heads have a thin fuzz of simple
fur-like feathers. Except for being thin, it looks like the bristles that
adorn Sinosauropteryx bodies, arms and legs. 

GSPaul