126 ANIMALS OF THE PAST 
more difficult problem, since the pieces are not 
like so many checkers — all made after one pat- 
tern — but each has an individuality of its own. 
The total number of vertebrae must be guessed — 
at (perhaps it would sound better to say esti- 
mated, but it really means the same), and 
knowing that some sections are from the front 
part of the vertebral column and some from 
the back, we must fill in the gaps as best we 
may. ‘The ribs offer a little aid in this task, 
giving certain details of the vertebra, while 
those in turn tell something about the adjoin- 
ing parts of the ribs. We finish our Tricera- 
tops with a tail of moderate length, as indica- — 
ted by the rapid taper of the few vertebre 
available, and from these we. gather, too, that 
in life the tail was round, and not flattened, 
and that it neither served for swimming nor _ 
for a balancing pole. And so, little by little, — 
have been pieced together the fragments from | 
which we have derived our knowledge of the 4 
past, and thus has the paleontologist read the. 
riddles of the rocks; » : 
To make these dry bones live again, to 4 
clothe them with flesh and reconstruct the / 
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Set Le Teo 
se es Pe ge ee 
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Foe ee, SSS SE ee 
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