Flowering Plants Dominated Forests 10 Million Years Earlier Than Thought

For decades, the conventional view held that flowering plants (angiosperms) were minor, understory players throughout most of the Cretaceous. The dominant narrative was that they only became ecologically dominant after the K-Pg extinction event 66 million years ago, when the extinction of dinosaurs allowed mammals to radiate and begin dispersing large fruits .

The Dori's Tuff flora directly contradicts this "catastrophist" narrative. The fossil assemblage reveals a mature forest already dominated by angiosperm trees—including relatives of modern laurels and palms—growing alongside ferns and redwoods. The trees had large trunks and formed a dense canopy structure . This means angiosperms had achieved structural and ecological dominance in at least some environments millions of years before the asteroid struck.

Lead author and UC Berkeley PhD student Jaemin Lee stated: "Our results show that, at least in some hot and humid environments during the Late Cretaceous, well before the extinction boundary by 10 million years, angiosperms were already investing more resources into individual diaspores and forming dense forests."

Blueberry-Sized Fruits and a Diversity of Dispersal Strategies

The fossil cache includes hundreds of seeds and fruits (technically called diaspores), ranging from tiny seeds to surprisingly large, fleshy fruits. While typical Cretaceous angiosperm diaspores were the size of poppy seeds, the average diaspore size in this forest was comparable to a large blueberry—representing a more than 100-fold increase in volume .

Even more striking is the diversity of dispersal strategies. Some seeds were winged, clearly adapted for wind dispersal. Others were large, fleshy, and nutrient-rich, which is a classic adaptation for animal-mediated dispersal . This diversity of strategies was previously thought to have only evolved after the dinosaur extinction, in a world dominated by fruit-eating mammals and birds .

Dinosaurs Were Already Dispersing Angiosperm Seeds

The presence of large, fleshy fruits provides strong evidence that animals were acting as seed dispersers long before mammals took over the role. The study identifies likely dispersers including:

• Marginocephalian dinosaurs (ornithischian herbivores), depicted in the study's reconstructions as feeding directly on angiosperm fruits .
• Multituberculate mammals — early, rodent-like mammals that lived alongside dinosaurs and could have consumed and transported seeds .
• Other Cretaceous vertebrates could have also carried both winged and fleshy diaspores .

This finding challenges the long-held assumption that animal-mediated seed dispersal of large fruits only evolved after the K-Pg extinction as a response to the radiation of fruit-eating mammals, bats, and birds. Instead, the evidence shows that Cretaceous animals—including dinosaurs—were already consuming and dispersing angiosperm seeds more than 74 million years ago .

How This Changes the Story of Angiosperm Dominance

The "catastrophist" narrative that the asteroid impact cleared the way for flowering plants was a compelling story, but the Dori's Tuff flora tells a different tale. The evidence suggests three critical revisions to the evolutionary timeline:

1. Angiosperm-dominated forests existed 10 million years before the extinction. The plants were already investing heavily in large diaspores and forming dense canopy forests .
2. Animal-mediated dispersal of large fruits was already operating in the Cretaceous. Seed dispersal by vertebrates did not require the extinction of dinosaurs or the rise of modern mammal groups .
3. The K-Pg impact did not 'unlock' flowering plant dominance—it restructured it. Angiosperms were already successful; the extinction reset the competitive landscape but did not initiate their rise .

Broader Implications and Unanswered Questions

This discovery adds to a growing body of evidence that the Cretaceous world was more botanically complex than previously assumed. Earlier work, such as a 2018 study showing large angiosperm trees existed in North America by the Turonian (around 90 million years ago), had already hinted at earlier angiosperm dominance . However, the Dori's Tuff site is unique in combining exceptional preservation of reproductive structures with a clear snapshot of forest structure.

The site also adds to the global record of Cretaceous volcanic ash deposits that preserve ancient ecosystems. A similar "vegetational Pompeii" in Inner Mongolia, China, was previously studied to resolve the paleontology of Noeggerathiales, an extinct group of spore-bearing plants .

Still, questions remain. The Dori's Tuff forest represents a single location in a hot, humid, paratropical climate . Whether this pattern of early angiosperm dominance was widespread across other environments during the Late Cretaceous is a question that future fieldwork will need to answer. The research team from the Looy Lab at UC Berkeley continues to analyze the site .

Flowering Plants Dominated Forests 10 Million Years Earlier Than Thought

For decades, the conventional view held that flowering plants (angiosperms) were minor, understory players throughout most of the Cretaceous. The dominant narrative was that they only became ecologically dominant after the K-Pg extinction event 66 million years ago, when the extinction of dinosaurs allowed mammals to radiate and begin dispersing large fruits .

The Dori's Tuff flora directly contradicts this "catastrophist" narrative. The fossil assemblage reveals a mature forest already dominated by angiosperm trees—including relatives of modern laurels and palms—growing alongside ferns and redwoods. The trees had large trunks and formed a dense canopy structure . This means angiosperms had achieved structural and ecological dominance in at least some environments millions of years before the asteroid struck.

Lead author and UC Berkeley PhD student Jaemin Lee stated: "Our results show that, at least in some hot and humid environments during the Late Cretaceous, well before the extinction boundary by 10 million years, angiosperms were already investing more resources into individual diaspores and forming dense forests."

Blueberry-Sized Fruits and a Diversity of Dispersal Strategies

The fossil cache includes hundreds of seeds and fruits (technically called diaspores), ranging from tiny seeds to surprisingly large, fleshy fruits. While typical Cretaceous angiosperm diaspores were the size of poppy seeds, the average diaspore size in this forest was comparable to a large blueberry—representing a more than 100-fold increase in volume .

Even more striking is the diversity of dispersal strategies. Some seeds were winged, clearly adapted for wind dispersal. Others were large, fleshy, and nutrient-rich, which is a classic adaptation for animal-mediated dispersal . This diversity of strategies was previously thought to have only evolved after the dinosaur extinction, in a world dominated by fruit-eating mammals and birds .

Dinosaurs Were Already Dispersing Angiosperm Seeds

The presence of large, fleshy fruits provides strong evidence that animals were acting as seed dispersers long before mammals took over the role. The study identifies likely dispersers including:

• Marginocephalian dinosaurs (ornithischian herbivores), depicted in the study's reconstructions as feeding directly on angiosperm fruits .
• Multituberculate mammals — early, rodent-like mammals that lived alongside dinosaurs and could have consumed and transported seeds .
• Other Cretaceous vertebrates could have also carried both winged and fleshy diaspores .

This finding challenges the long-held assumption that animal-mediated seed dispersal of large fruits only evolved after the K-Pg extinction as a response to the radiation of fruit-eating mammals, bats, and birds. Instead, the evidence shows that Cretaceous animals—including dinosaurs—were already consuming and dispersing angiosperm seeds more than 74 million years ago .

How This Changes the Story of Angiosperm Dominance

The "catastrophist" narrative that the asteroid impact cleared the way for flowering plants was a compelling story, but the Dori's Tuff flora tells a different tale. The evidence suggests three critical revisions to the evolutionary timeline:

1. Angiosperm-dominated forests existed 10 million years before the extinction. The plants were already investing heavily in large diaspores and forming dense canopy forests .
2. Animal-mediated dispersal of large fruits was already operating in the Cretaceous. Seed dispersal by vertebrates did not require the extinction of dinosaurs or the rise of modern mammal groups .
3. The K-Pg impact did not 'unlock' flowering plant dominance—it restructured it. Angiosperms were already successful; the extinction reset the competitive landscape but did not initiate their rise .

Broader Implications and Unanswered Questions

This discovery adds to a growing body of evidence that the Cretaceous world was more botanically complex than previously assumed. Earlier work, such as a 2018 study showing large angiosperm trees existed in North America by the Turonian (around 90 million years ago), had already hinted at earlier angiosperm dominance . However, the Dori's Tuff site is unique in combining exceptional preservation of reproductive structures with a clear snapshot of forest structure.

The site also adds to the global record of Cretaceous volcanic ash deposits that preserve ancient ecosystems. A similar "vegetational Pompeii" in Inner Mongolia, China, was previously studied to resolve the paleontology of Noeggerathiales, an extinct group of spore-bearing plants .

Still, questions remain. The Dori's Tuff forest represents a single location in a hot, humid, paratropical climate . Whether this pattern of early angiosperm dominance was widespread across other environments during the Late Cretaceous is a question that future fieldwork will need to answer. The research team from the Looy Lab at UC Berkeley continues to analyze the site .