Flowering plants, or angiosperms, became a major part of terrestrial ecosystems, but their beginnings remain debated. The oldest unequivocal fossils of flowers and other angiosperm structures are Cretaceous. A 2026 study combining a large fossil-occurrence dataset with molecular evidence estimates that the living crown group began earlier, in the Late Jurassic.
These statements describe different kinds of evidence. A fossil shows that a recognizable plant existed by the age of the rock in which it was preserved. A molecular-clock estimate infers when lineages split by combining genetic differences, a phylogenetic tree and fossil-based calibrations. The two dates need not coincide if early members were rare, geographically restricted or unlikely to fossilize.
What the Cretaceous fossils preserve
Early Cretaceous rocks preserve pollen, leaves, seeds and exceptionally complete plant remains attributed to flowering plants. Fossil pollen is particularly useful because it is abundant and resistant, although early grains can be difficult to distinguish from those of other seed plants. Complete flowers or fruits provide more diagnostic combinations of features, but they are much rarer.
Through the Cretaceous, angiosperm pollen and plant fossils become more diverse and widespread. Their expansion happened within landscapes that still included ferns, cycads, conifers and other seed plants. A richer flower record does not mean that forests instantly became modern-looking or that all older plant groups disappeared.
What a molecular clock adds
Wu and colleagues' 2026 study used more than 25,000 fossil occurrences to estimate age distributions for plant lineages, then used those distributions to calibrate a molecular tree built from 83 genes across 644 living species. Their preferred analyses placed the origin of crown angiosperms in the Late Jurassic and inferred that diversification accelerated in the Early Cretaceous.
This is a statistical result, not a newly discovered Jurassic flower. It depends on fossil identifications, the assignment and ages of occurrences, the calibration model and assumptions about lineage history. The study offers one way to use many fossil occurrences rather than calibrating a molecular clock from only a few selected fossils; alternative analyses may produce different timelines.
Origin, first fossil and ecological expansion
The first unequivocal fossil, the inferred origin of a lineage and its later ecological expansion are separate milestones. A group can originate before its first secure fossil appearance, and it can remain uncommon long after it first evolved. This distinction helps explain why paleobotanists compare the fossil record with molecular clocks rather than treating either as a complete timeline on its own.
Flowering plants did not single-handedly remake every Cretaceous ecosystem. Changes in plant diversity interacted with insects, climate, soils and geography, and the strength of those relationships varies among regions. See the broader Cretaceous forest and angiosperm fossil record, the history of Mesozoic plant life and the Cretaceous Period.
Frequently asked questions
Are the oldest known flowering-plant fossils Jurassic?
Unequivocal angiosperm fossils are Cretaceous. A 2026 fossil-calibrated molecular-clock study estimates a Late Jurassic origin for the crown group, which is an inference rather than a Jurassic flower fossil.
What did the 2026 study add?
It used more than 25,000 fossil occurrences to construct age calibrations, then combined them with a molecular tree based on 83 genes from 644 living species.
Why can a lineage be older than its oldest fossil?
Early members may have been rare, geographically restricted or poorly preserved. The oldest fossil establishes a minimum age, not necessarily the true origin.
Did flowering plants replace ferns and conifers in the Cretaceous?
No. Angiosperms diversified while ferns, conifers and other seed plants remained important parts of many ecosystems.