The cycads (Na'vi name: tsyorina'wll meaning "flour seed plant") on Pandora bears an uncanny resemblance to cycads that occur throughout the Earth's tropics. Cycads are ancient seed plants that are found in Earth's fossil record as far back as 208 and possibly even 325 million years ago. They were common during the age of the dinosaurs. Although it is possible that identical life-forms could have evolved on two separate planets, geological and atmospheric differences between Earth and...