Another ancient cone-bearing tree that was thought to be extinct but was later discovered growing in a remote valley of Central China is the dawn redwood (Metasequoia glyptostroboides). The genus Metasequoia was first described from fossil material by the Japanese paleobotanist Shigeru Miki in 1941. In 1948, paleobotanist Dr. Ralph Chaney of the University of California, Berkeley led a 10,000 mile expedition up the Yangtze River and across three mountain ranges to a lush, fog-shrouded valley where a thousand dawn redwoods were growing. Leaf imprints and petrified wood of ancestral dawn redwoods resembling the present-day species have been found in Cretaceous deposits throughout North America. Some of the fossils date back nearly 90 million years, from a time when the climate was much more humid than today. It has been estimated that the relict forest in China may have been surviving in this remote primeval valley for countless thousands of years. The seed cones and foliage of the dawn redwood superficially resemble our California coast redwood (Sequoia sempervirens), except that the dawn redwood is deciduous and loses its leaves during the winter months. All North American plantings of this superb cone-bearing tree came from the seeds (and their progeny) originally collected in China. Indeed this "living fossil" was brought back to its ancestral home.

The foliage and cones of the dawn redwood (Metasequoia glyptostroboides) superficially resemble the California coast redwood (Sequoia sempervirens). This lovely deciduous conifer once coexisted with dinosaurs in North America during the Cretaceous Period 90 million years ago.
A 25 million-year-old leaf of dawn redwood (Metasequoia) from the John Day Fossil Beds National Monument in Eastern Oregon. Close examination of the needles reveals that this extinct species is not a Sequoia, but is remarkably similar to our present-day Metasequoia. The soft brown shale is from ancient Miocene lake bed sediments made from layers of volcanic ash and silt. Many conifers and broad-leaf angiosperms have been identified from this fossil-rich shale (note other leaves in photo).

5. The Amazing Cycads:

Perhaps the most remarkable of all seed plants that flourished during the days of the dinosaurs are the cycads. These plants were so numerous in Mesozoic times (65 to 230 million years ago) that this era is often called the "Age of Cycads and Dinosaurs." Cycads are dioecious species with pollen cones and seed cones produced on separate male and female individuals. Cycad cones can reach 3 feet in length, the largest of all living cone-bearing plants. The most massive seed cones may weigh up to 95 pounds, and are produced by species of Lepidozamia and Encephalartos.

 
 
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