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parental care (was Re: RE: Dinosaur Planet, parts 3 & 4 )
Here is the problem, just because SOME extant vertebrates care for their your
is not PROOF that dinosaurs did. It is INFERRED that they did because some do
today. That is the big difference. An inference may be very logical but is
difficult to frame as a testable hypothesis. How would you prove parental care
from just the skeletons? Very difficult. Footprints may be a better bet, but no
one has yet found hatchling and adult prints together.
As for the underdeveloped joints, well I guess someone better tell young
chickens they can't walk. Next time you eat chicken look at the leg joints.
You'll see that they are poorly formed, especially if you get a small, young
thigh (KFC seems to have a lot of those). Everyone seems to forget that a
hatchling hadrosaur is very light, a few pounds (kg) at most. Cartilage is a
very strong substance and can easily support the few pounds of a baby.
>>> ANN SCHMIDT <firstname.lastname@example.org> 12/19/03 15:48 PM >>>
wrote:> From: email@example.com
[mailto:firstname.lastname@example.org]On Behalf Of
> Ken Carpenter
> I would take strong exception to this, noting that
> for parental care in the Dinosauria (even Jack's
> very weak and based mostly on inferences and
> evidence there is indicates that the smallest
footprints in track
> sites are half- or more adult size. There are NO
baby tracks with adults.
Doesn't it make sense that the infant-to-juvenile
sauropods and other very large dinosaurs would avoid
moving with groups of adults? The chance of trampling
would be too great I think. But this doesn't preclude
any parental care, especially with how fast they may
have grown. Many modern animals care for their young
for some time seperately from the main grup until
they are better able t move. Of course, these are
mammals whose young are much closer in size to the
adults than dinosaurs but it does show that the parent
can leave the group to care for their young.
However, doesn't the "spongyness" of the leg bones of
some types of infant dinosaurs make parental care a
necessity? Not to mention the distance between nests
being approximately equal to the size of Maisaura
adults. I wasn't aware of any serious rebuttals to
the evidence for Maisaura acting like their namesake.
Not to mention that parental care becomes more
widespread among living animals every year it seems.
Many creatures once thought to not care for their eggs
and young are being found to. All living crocodilians
and birds care for their young for varying periods in
varying ways (except for some kinds of mound nesting
birds in Australia and New Guinea which don't do
anything other than provide very large self-heating
nests for their young). Even Cuckoos devote quite a
bit to their young in terms of selecting other parents
Many monitor lizards are now being found to care for
their young in amazing ways. Several species incubate
their young via termite mounds, some of these having
the mother even come back to dig them out when they
hatch. Komodo Dragons also guard their nests until
near hatching time. Many amphibians care for their
eggs and young, even the giant salamanders of China
and Japan. I saw an African Bullfrog on one show that
was shown digging a small trench through the mud to a
nearby pool of water to save dozens of tadpoles that
were in an evaporating puddle.
Every vertebrate (and many invertebrate) group has at
least some members that exhibit parental care of eggs
and/or young (unless you consider sharks to be
vertebrates and not in remotely the same group as
other fish). So with all due respect it seems
inconceivable to me to think that dinosaurs did not,
to varying degrees. It seems that most any animal
that cant care for itself effectivey at bith has to
have some parental protection. And many animals that
can care for themselves at birth (crocodilians) still
exhibit parental care.