This is the first printing of the original omnibus edition of Mark's Xenozoic Tales. This sports Mark's original cover illustration which was replaced for the 2013 reprint.
From the publisher:
After the ecological cataclysm, the last men and women fight to survive a prehistoric nightmare! Xenozoic combines lush and richly realized ink-and-brush artwork with a pulp-fueled narrative to create an action-packed fantasy -- an unrelenting adventure that also serves as a subtle cautionary fable concerning the unforeseen consequences that shortsighted present decisions might have upon future generations.
Introduction by Craig Elliott.