Re: (Fwd) Large Dino Growth

[Stan Friesen <swf@ElSegundoCA.ATTGIS.COM>]

>From:          rswigart@heartland.bradley.edu (Richard Swigart)
 > 
 >      Mike Yenga brought up an interesting subject when he ask
 > how long for a large Dino to reach adult size.

There is fairly solid evidence that Maiasaura took about 7 years
to reach full adult size (about 10 meters in length).

Presumably the true giants, like Brachiosaurus and so on took
longer.  How much longer is unclear at present.

 >      Then the thought hit me,  drawings of the super large 
 > adult Dino's (at least the late ones) show them pruning vegetation
 > from the very tops of trees.  Some are even shown standing on hind
 > legs so they can reach the very tippy tippy tops of the trees. 
 >      What in the world would the baby's be eating?  Having just
 > hatched from an egg the size of(or smaller) than an ostrich egg?
 > They certainly weren't reaching the tippy tops of any trees.  They
 > couldn't even reach the tops of a good size bush.  If the
 > vegitation is good enough down here to grow so large, why gro so 
 > large?

Competition, for one.  It is quite common for adults and young to
feed on different resources, and in different ways.

Also there is at least some possiblity that baby sauropods were
*fed* by their parents, thus obviating the need for foraging for
themselves at tha small size.  (Though this is debatable, as most
workers tend to assume that sauopods abandoned their nests after
laying the eggs).

 >      Another image just came to mind.  I have seen film of 
 > elephants, especially very large bull African Elephants pushing 
 > over quite large trees to get at the top vegetation.  Why would
 > an animal as heavy as a herd of elephants need to stand on its
 > hind legs to reach the tippy tippy tops of trees?  Why not just
 > push the darn thing over?

The thing to keep in mins is the sort of trees involved.  The trees
the elephants are pushing over are *small* savanna trees, no more
than 50 feet or so tall, and with trunks no more than 6-8 inches
in diameter.

At least along permanent water courses, the trees present along with
the sauropods may have been ancient relatives of modern trees like
redwoods and douglas fir. These can grow *very* large (douglas fir
can grow to a size only slightly smaller than a redwood).  Such
forest giants are much harder to plow over.  (However, the Morrison
climate was so arid, I doubt such large trees were very common,
really).
 

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.