[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: crocs and hadrosaurs (was science proect)



Stephen Throop wrote:

>I figured a running duckbill would be on two legs if only to keep its
>bill from bumping the ground.

I may be wrong about this, but: among living animals, most part-time bipeds
stand up on two legs to look around, to reach something, or to sniff the air
higher up, but when they want to run, they go down on four legs. This applies
to everything from lizards to bears to baboons -- though one notable exception
comes to mind: the basilisk lizard (basiliscus amoratus), which runs on two
legs VERY fast. But that's a very gracile animal, and hadrosaurs aren't.
        Besides, any animal moving on four legs is usually capable of keeping
its head off the ground. That's a problem you don't see very often.

>Anyway, it seems unlikely that the duckbill would run right into the
>croc's jaws.

Only as unlikely as a zebra running into a croc's jaws. Crocs have a way of
moving their jaws to where the prey is.

 If the duckbill didn't run into the croc, wouldn't the
>duckbill survive if it was a good enough swimmer to tire the croc before
>the croc could close the distance?

Have you ever seen a croc moving in the water? I doubt VERY MUCH that
a hadrosaur could outswim it. Crocs are built for swimming, and they're
real good at it.
>
>> Maiasaurs nested on lakeshores-not strictly a swamp, but pretty similar
>> conditions. Sort of like how modern flamingoes and storks nest in the
>> mudflats of the African savannahs after the rains.  Both of these can fly
>> to protect the adults, but they rely on the water to isolate and protect
>> the young.

Well, water is about the worst protection you can get against crocs.
>
>I wonder if there were crocs along the lakeshores.  Unless duckbills
>could nest where predators couldn't reach, they must have had a way to
>stand their ground against whatever predators were present.

If there were crocs along the lakeshores, you can bet they took their share
of Maiasaurs. That's why maiasaurs had large clutches of eggs -- herbivores
have to breed enough to keep up with predation.

>I figured my crow-like duckbills would raise a fuss before the croc
>struck.  When I was a teen, my uncle invited me to shoot crows who were
>eating his corn.  They weren't afraid of people.  I found that things
>were different when I was carrying a gun, even inconspicuously.
>Somehow, their sentry knew from a long way off.  Then, no matter what I
>did to get within range of the crows of the ground, he always knew where
>I was.

I don't know where the crow analogy came in, but I think you may be carrying
it a little far. Crows aren't afraid of people because they can fly away.
Hadrosaurs
had very poor flying abilities.

>I've read that if several men enter a blind individually over a period
>of time and leave over a period of time, crows will know it's occupied
>until the last man leaves.  Animals with similar mental capacity could
>be good at keeping track of the last known location of a croc and the
>locations where it might now be.

Even if we assume that crows can count (Counting Crows?), the crows
see you coming and going. When a croc swims in underwater, you don't
see it until it drags you under.

>Our Dobermans used barking and sometimes nips to keep predators away  .
>Subsequent dogs were less effective.  We started finding stray dogs,
>possums, coons, foxes, and egg-sucking snakes.

Dobermans can't really be compared -- they are also carnivores, competitors
rather than prey. Try to picture gazelles driving lions out of their
habitat, and
you get a more accurate (and less likely) analogy.

>If duckbills were endotherms, I think they would have had opportunities
>to stamp on sluggish crocs who had come ashore to warm up.

Yeah, and zebras could do the same to crocs onshore in Africa. Does it
happen? No. Why? Because prey animals are sensibly endowed with the
instinct to try to stay away from predators. The ones without that instinct
got eaten long ago.

Wayne Anderson