Hello Mindy
Without access to the original creator of the Dynascape file, my knowledge says your options are pretty thin.
1. If you did have that access, they of course would be able to re-export as a dwg or dwf… or at the very least they can create a PDF from within Dynascape that you can import to AC and then draw over. You may be able import the PDF into Corel Draw, Ungrouped (exploded, if it was a vector-based PDF), then re-save as a dwg. This would save the long drawing over step.
2. You may try to find a free trial version of Dynascape. These are not easily available but they are out there. fileguru.com is one source for dynascape v4.3. As always, exercise caution with any free download site.
Probably not much help, but good luck. If you find an interesting solution, it would make a great post.
Mitch