A collection of plant fossils from volcanic layers in New Mexico challenges the idea that flowering plants remained minor elements in forests until the dinosaur extinction 66 million years ago. Analysis of sizable seeds preserved under ash roughly 74.6 million years ago shows a mature woodland already dominated by angiosperms that produced large, fleshy fruits. UC Berkeley researchers conclude that these plants invested heavily in individual seeds well before the asteroid impact. The findings question earlier assumptions that angiosperms expanded widely only after mammals such as rodents and bats began dispersing larger fruits. Flowering plants first appeared about 135 million years ago as small, weedy forms with tiny seeds. By the late Cretaceous they had diversified in size and form, yet seed dispersal methods were thought to have stayed limited. The New Mexico deposit instead reveals large-trunked flowering trees including laurel relatives and palms, together with many other angiosperms growing among ferns and redwoods. Average seed size here equals a large blueberry, more than one hundred times the volume of typical Cretaceous angiosperm seeds. The site formed when ash fell rapidly and preserved plants in place, similar to a botanical snapshot. Ground cover remains visible at the base, while leaves appear at various angles higher in the layer. The study appears in the journal Science.
