A novel fossil seed roils botany theory
Seeds surfaced less than 100 million years after land plants evolved from their water-borne ancestors. These nutritional nuggets - the reproductive units of the world's most highly evolved plants - arose from spore-producing predecessors that lacked sophisticated structures for collecting pollen. Because all early fossil seeds found so far look almost identical in structure, most plant biologists assume that a single group of spore-spreading plants, or Pteridophytes, led to nonflowering seed-bearing plants, the gymnosperms, says paleobotanist Lawrence C. Matten of Southern Illinois University in Carbondale.
But two european paleobotanists recently put a kink in this theory. Sifting through sediments in southern France, they found an intact fossilized seed that looks like no other from the early Carboniferous-the period about 350 million years ago during which plants apparently acquired the seed-bearing habit. Whereas other fossil seeds feature a funnel designed to trap wind-carried pollen grains, this one sports a stub where the funnel should be, reports Jean L. Galtier of Universite des Sciences et Techniques in Montpellier, France.
The newly found fossil might represent the first evidence of an intermediate stage between pteriodphytes and early seed plants. …