Angiosperm fruiting axes were discovered from the Upper Jurassic of China. Angiosperms are defined by carpels enclosing ovules, a character demonstrated in this fossil. This feature is lacking in other fossils reported to be earliest angiosperms. The fruits are small follicles formed from conduplicate carpels helically arranged. Adaxial elongate stigmatic crests are conspicuous on each carpel. The basal one-third of the axes bore deciduous organs of uncertain affinities. No scars of subtending floral organs are present to define the individual fertile parts as floral units, but the leaf-like structures subtending each axis define them as flowers. These fruiting axes have primitive characters and characters not considered primitive.

The Late Paleogene surface height and paleoenvironment for the core area of the Qinghai-Tibetan Plateau (QTP) remain critically unresolved. Here, we report the discovery of the youngest well-preserved fossil palm leaves from Tibet. They were recovered from the Late Paleogene (Chattian), ca. 25.5 ± 0.5 million years, paleolake sediments within the Lunpola Basin (32.033°N, 89.767°E), central QTP at a present elevation of 4655 m. The anatomy of palms renders them intrinsically susceptible to freezing, imposing upper bounds on their latitudinal and altitudinal distribution. Combined with model-determined paleoterrestrial lapse rates, this shows that a high plateau cannot have existed in the core of Tibet in the Paleogene. Instead, a deep paleovalley, whose floor was <2.3 km above mean sea level bounded by (>4 km) high mountain systems, formed a topographically highly varied landscape. This finding challenges prevailing views on tectonic processes, monsoon dynamics, and the evolution of Asian biodiversity.