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MY TRIP TO THE ZOO



This week I took a trip to the National Zoo in DC, a place my Grandpa used to
take me to when I was a wee one (the best part was when the car went over the
bridge that was UNDER Rock Creek, alas that road no longer exists). This trip
was intended to gather information on two interesting creatures. 

The first was the kiwi. As I have noted earlier, these are among the most
theropod like of birds, with the narrowest nasal passages, least developed
air-sacs, fur-like feathers, the slowest growth, and they are of course
flightless as well as fairly large at up to 7 lbs. (When the keeper held a
kiwi it looked like a strange mammal, with whiskers and all. But don't get
one as a pet, they are rather nasty birds.). The first toe is not fully
reversed and is high up on the foot as in theropods. The metabolic rates of
kiwis are four times higher than those of reptiles, and equal or approach
those of some raptors, wallabies and canids. Body temperatures are high at
around 38C. The kiwi keeper disabused me of any notions that kiwis are more
sluggish than other birds. The one I watched was frenetic in the avian
manner, constantly probing the litter for food. Kiwis may offer a much better
model for dinosaur energetics than reptiles. 

Speaking of which, I also got to see a 4 year old Komodo monitor close up. A
most impressive beast in some ways. But it moved with that somewhat slow
motion speed typical of reptiles. It also showed that these big reptiles grow
very slowly, being no bigger than a medium sized dog after 4 years. It is
also being observed that the growth of the captive oras is highly dependent
upon food consumption. Captive reptiles can also be kept constantly warm,
further boosting growth rates. As a result captive reptiles - especially
those grown on farms where rapid weight gain is a priority - can grow at
least twice as fast as their wild counterparts, even those that live in
tropical locations with abundant food. This exposes a serious problem with
the work of Owerkowicz on growth of reptiles in his laboratory. Just because
reptiles can grow rapidly and deposit mammal-like bone when fed lots of food,
kept warm, and exercised by humans does not mean that the same can be
achieved under natural conditions. In the wild finding large amounts of food,
keeping warm, and exercising require the expenditure of large amounts of
energy both on an immediate basis, and in the long term energy budget. This
is probably why only birds and mammals can grow rapidly. As for dinosaurs, at
least some seem to have grown more rapidly than living reptiles, and none
lived at Harvard, so it is probable that they did not have reptilian
energetics. 

GSPaul