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RE: Microraptor also ate fish
I hate to send this again but some of it was chopped out last time.
Just for clarity. So long and boring, so sorry!
From: owner-DINOSAUR@usc.edu [owner-DINOSAUR@usc.edu]
on behalf of Jason Brougham [email@example.com]
Sent: Wednesday, April 24, 2013 12:44 AM
To: firstname.lastname@example.org; "email@example.com"@listproc.usc.edu
Subject: RE: Microraptor also ate fish
Now this is a productive debate about Paleontology.
Your points are well made, well supported, succinct, and articulate.
Thank you. I really want to be as succinct but I will probably fall a little
One reason we are all so interested in Microraptor is that, thanks to its
its phylogenetic position, and its similarities to other paravian relatives,
retain some of the ancestral characters of the ancestors of birds. If so, it
a useful model for understanding the transitional forms between the non-flying
and flying dinosaurs, in any number of aspects of its biology.
As you note, I never said I could prove Microraptor could climb into a tree, I
we can't rule it out. You are probably annoyed with me for raising hypothetical
functional possibilities without unambiguous evidence. But is it unscientific
present a hypothesis, and then discuss with one's peers comparative methods
to test it? I must reply, with all respect, that you seem to have actually
a logical fallacy by categorically calling one of these hypotheses impossible
a priori grounds. That is where I think scientifically shaky ground and woolly
thinking entered into this conversation. If I may jokingly exaggerate to make a
you are saying that since we never found Amelia Earhart's body there is no way
she could be dead. Disproving that A = B doesn't prove if Not A then Not B.
ust because birds with strong halluces often nest in trees doesn't mean diving
which do not have halluces, can't nest in trees (in fact they do). Thanks to
observations from actual Zoology, we know for certain that behaviors without
theory. I am not saying that, if diving petrels were extinct, I could just
tell they climbed trees. But I never claimed certainty, you did. You feel that
you can say "no way" if the animals are "not adapted for" it without testing
conclusion, while I do not.
You may retort that analogies are speculative wastes of time. But isn't analogy
indispensable in evolutionary theory? Didn't Darwin apply the lessons of
Galapagos finches to apes to help understand all evolution?
Moreover, if we are considering evolutionary sequences, inference from context
will be relevant. In order for such highly evolved traits as opposed halluces
evolve, a feedback loop must be established where slight improvements in the
structure have real survival benefits to the inheritors. Far from there being
it is in fact indisputable that the behaviors must often precede the
else there must be exaptations. As you concede, the gripping of prey by the
digit which, according to dromaeosaur anatomy could probably flex enough to
its own foot pad, could be just such an exaptation. The fact that, unlike
Microraptor weighs the same as birds like ravens, pheasants, and tinamous that
in trees seems to me highly relevant.
>Unless you are arguing that _Microraptor_ could perch like a raven
>(and clearly you aren't), I would say that comparing _Microraptor_ to
>a raven is irrelevant and moot. _Microraptor_ has no morphological
>traits that are correlated with an ability to climb out on to terminal
>branches the way ravens do. Yes, _Microraptor_ might have done so.
>Animals often perform functions for which they are not adapted. But
>I'm trying to keep our inferences about an animal's behavior to a
>soundly scientific footing (so to speak). In short: What was
>_Microraptor_ actually *adapted* to do?
You say that Microraptor might have done so, but also that this is irrelevant
If two animals weigh the same, and the question is whether terminal branche
support them, you don't see any relevance? Two animals do not have to have THE
feet in order to hold on to branches. They just need to have feet that can
Do you reject the use of all analogs in comparative zoology and Paleontology?
Or do you accept that, if a Harbor Porpoise weighing 60 kg can breach the water
leap into the air, isn't this is one lineof evidence that an ichthyosaur
weighing 60 kg could
perform the same maneuver?
What was Microraptor actually adapted to do? What is your answer? No one knows
Microraptor is adapted to do because there are no four - winged animals with
unfused, finger and toe claws, long bony tails, and feathered integuments
alive today for
us to calibrate any correlates. This is why we are all so fascinated by the
animal. If you
rely solely on modern morphological correlates, it was adapted to do nothing.
Some measurements, of feather vane asymmetry, wing length and surface area,
size, estimated pectoral muscle mass etc. place Microraptor among powered
megachiropteran bats. Some wind tunnel tests showed that it was an efficient
glider and that,
even thought its leg feathers cut into the induced wind the wrong way, they
produce lift. That experiment even suggested Microraptor was adapted to
quickly tip up to
land on trunks. Other comparisons to living birds, like ornamental breeds of
the leg feathers had no aerodynamic function at all, and that this little thing
could have spent
its life darting around in thickets and covering its huge egg clutches with
its wings. I think all
of these are real possiblities, and I don't reject any of them a priori.
>This grasping pes may have been exapted in other lineages for arboreal
> perching; but it wasn't there yet. Not even close, IMHO.
I have photos of two different grouse chicks perching in trees by pinching
branches - between
the 2nd and 3rd toe with the left foot, and 3rd and fourth, on the left, in
both cases. I have
photos of turke
discussed the goats climbing trees. If all goats were extinct you would say
there was no
way they could climb trees, because they lack all skeletal correlates for
climbing, like thumbs.
But since they are alive we know that one correlate for climbing is being a
To repeat, I have never suggested that Microraptor was in the morphological
'perching' or 'arboreal'. Those two categories are highly derived states in
true bird evolution.
Instead, I observed that basal birds with body masses low enough (tinamous,
anatids) all have many representatives that roost in trees, often at night and
young. Some birds with NO halluces also nest in trees, and In some cases
estigial halluces and wild turkeys with elevated halluces) their feet even seem
for perching, so that, if they were extinct, you could go on the DML and argue
that there was
"no way" they could get into a tree, let alone with their chicks, since their
they were going in the other direction entirely, of being strictly ground birds.
If you look only at unambiguous correlates, how would you know an intermediate
you saw it? If we look at the jaw joint in Morganucodon, would you say that the
quadrate still participate in the jaw joint and that, lacking a purely
squamosal/dentary jaw joint,
Morganucodon lacks that correlate for being a Therian and thus has nothing to
tell us about
mammal evolution? Or can you see it in context, as a model for how the
may have progressed, even if it may not be an actual ancestor of true mammals?
>Regarding the manual claws, there is an issue regarding how it is
>difficult to distinguish predation from climbing ability (after all,
>both require gripping). This leaves scope for exaptation, if a
>predatory manus was co-opted for climbing, which is possible in small
>maniraptorans. This is an entirely scientific example of
Actually David Hone suggested in h
uld not be brought
together to grasp prey because of the primary feathers. I was skeptical, so I
tested it in my precise
scale model, and found that he was right. To bring the hands together a large
percentage of the
length of the primaries strikes the ground.
-Sullivan, C., Hone, D. W. E., Xu, X. and Zhang, F. The asymmetry of the carpal
joint and the
evolution of wing folding in maniraptoran theropod dinosaurs. Proceedings of
the Royal Society
B. Published online March 3, 2010. Figure 3
>But if we say that the manual claws or pes could be used for functions
>for which they were clearly not adapted, then we're on shaky ground.
>This is a way that "uncertainty" is mis-used. The foot of
>_Microraptor_ was *not* adapted for perching. No amount of discussion
>about wood ducks and ravens will convince me of otherwise.
Agreed. The foot of Microraptor does not have the adaptations of modern
But its anatomy is tantalizing precisely because we can't exclude the
possibility that it could
climb into trees. Not perch, but start on that sequence.
Are you suggesting that Microraptor has LESS gripping ability with the second
toe than larger
dromaeosaurs do? I am open to that possibility, has anyone measured that?
Now, you are right if you say that I may be wasting my time imagining the
lifestyle scenarios of
Microraptor, Archaeopteryx, Xiaotingia, Anchiornis, Epidexipteryx, and
that the real ancestral condition, and habits, may be revealed by as yet
or may never be revealed. But those taxa grade pretty well into Jeholornis,
and so on. They seem to reflect back to the real common ancestor of Paraves,
which was probably
small, winged, and just possibly could have climbed into trees to roost as
basal birds still do.
>I'd say the morphology of _Microraptor_ says "no way". It has no
>adaptations that correlate with an ability to grasp narrow branches,
>either with its hands or feet (or both together). If we are going to
>adapted, and that these behaviors were important to its life habits,
>then I think we're heading in the wrong direction.
Agreed, we must not claim this. But we must remain open - minded to plausible
And we must remember that claims of what Microraptor IS adapted to are also
and must be tested. There is no consensus on what T. rex was adapted to do
(scavenge or hunt),
nor Alvarezsaurs, nor sauropods, nor sabre toothed tigers. There are just
leading and minority
>... let's not use uncertainty as an invitation for woolly thinking.
Agreed. Let's not claim certainty a priori either. You see, that is why I so
often resort to real animals
rather than calculations or theoretical works. If Sokoloff et al. hadn't
finally buckled down and
performed surgery on some Starlings, we'd still all be saying that the
supracoracoideus is an
indispensable adaptation for take off from the ground. Thanks to him we know
that total loss of the supracoracoideus has disturbingly little effect on take
off performance. I would have bet my savings
they couldn't do it, but they did it with seeming ease. That humbled me, and
made me leery of relying
on the interpretation of adaptations to predict actual capabilities.
'There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.'
- Hamlet Act 1, scene 5