Cretaceous fossil forest reveals dinosaurs dined on large fruits and seeds

A groundbreaking study indicates that herbivorous dinosaurs, rather than just post-extinction mammals, were likely the universe’s first major fruit-eaters and seed dispersers

The discovery has overturned a long-held paleobotanical theory, revealing that flowering plants evolved large, fleshy fruits and seeds millions of years earlier than previously believed.

The peer-reviewed study, published in the journal Science, was co-authored by Dr. James Saulsbury, a postdoctoral researcher at the University of Kansas Biodiversity Institute and Natural History Museum, along with scientists from UC Berkeley, the Perot Museum of Nature and Science, and the University of Colorado.

Overturning the post-asteroid timeline

Flowering plants (angiosperms) first appeared on Earth roughly 136 million years ago. For decades, the prevailing scientific consensus held that, for most of the Cretaceous period, these plants remained small, weedy undergrowth that produced tiny, dust- or poppyseed-sized reproductive structures, primarily dispersed by the wind.

According to the old model, it was only after a giant asteroid wiped out the dinosaurs 66 million years ago that flowering plants supposedly moved into forest canopies and evolved large, fleshy fruits (like modern apples or avocados). This shift was thought to be an evolutionary response to the rapid diversification of mammals, which stepped into newly vacant ecological niches and began spreading seeds.

The new study proves this ecological transition began much earlier, well before the asteroid impact.

Discovery at a “Botanical Pompeii”

The researchers based their findings on extensive fieldwork conducted near Truth or Consequences, New Mexico. The site represents a rare taphonomic phenomenon known as a “botanical Pompeii.”

Around 74 million years ago, a volcanic eruption blanketed a dense forest in a layer of ash, which eventually solidified into a rock layer called tuff stretching over a kilometre. Because the ash fell rapidly and uniformly, it froze the ecosystem in time, preserving a precise spatial layout of the ancient forest and its plants exactly where they grew and died.

By sorting through hundreds of beautifully preserved fossil seeds and fruits, the team categorised them into “morphotypes” (groupings based on physical shape and structure). They discovered a remarkably diverse and structurally modern ecosystem characterised by:

• Unprecedented fruit volume:

  • The forest boasted an unusual variety of large, flesh-covered seed structures.

• Grape-sized fruits:

  • The largest fossil fruits found at the site were roughly the size of modern grapes. While grape-sized fruit may seem modest today, it is remarkably massive for the Late Cretaceous, shattering the idea that early fruits were limited to the size of tiny specks.

Dinosaur delectables and forest ecology

Fruit and seed size are tightly bound to the broader architecture of a landscape. Large-seeded plants typically thrive in moist, highly competitive environments with densely packed forest canopies. The presence of these grape-sized fruits proves that complex, modern forest structures were already thriving 74 million years ago.

Furthermore, the timeline shift completely changes how scientists view plant-animal interactions in the deep past. If diverse, fleshy fruits were already abundant in Cretaceous forests, they were not waiting around for mammals to evolve. Instead, these fruits were likely a standard part of the diet for small Cretaceous mammals, birds, and large, herbivorous dinosaurs.

By eating the fleshy pulp and passing the resilient seeds through their digestive tracts as they migrated, dinosaurs acted as the planet’s original seed-dispersal network, actively shaping the evolution and spread of the world’s first modern forests.