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Macintosh Picture Format  |  1996-09-10  |  191.9 KB  |  640x310  |  8-bit (248 colors)
   ocr: fossils"). Because ammonites lived exclusively in marine environments, their presence also indicates the location of prehistoric seas. Some species of ammonites have complex partitions, or septa, separat- ing the chambers within the shell. Thecomplex shape makes the shell structure stronger, just as corrugated cardboard is stronger than a flat sheet. The shape may have allowed some animals to live in deep water where pressure is more intense. 33