Angiosperm plants first evolved and began to flourish during the Cretaceous Period. Angiosperms are flowering plants that produce seeds within an enclosure such as a fruit. Diverse angiosperm shrubs and smalldiameter trees thrived in the open-canopy Cretaceous Denali forests of gymnosperm trees. Menispermites is a fossil form name referring to leaves that look similar to those of the modern Menispermum (which means "moonseed"). Platanoid shrubs are related to modern members of the Platanaceae or "plane-tree" family.
Identification Level: Order and Genus
Alder is the common name for the genus Alnus. Some leaf fossils superficially resemble alder leaves, but they lack more evolved features that would assuredly link them to the modern alder. Menispermites leaves were preserved well enough to identify them to the fossil leaf form genus. Platanoid leaf forms were highly diversified during the Cretaceous. They exhibit affinities to two different plant lineages, the Hamamelidales and the Proteales.
Where do I live?
Alder-like shrubs lined the edges of streams, creeks, and lakes. The Menispermites vine thrived in the open canopy forest, weaving its way through the trees above the wet floodplain. Platanoid shrubs lived in the understory of those same gymnosperm forests and lined the channel banks.
How do we know I lived in Denali?
Menispermites leaf fossils have been found near Sable Mountain in Denali, typically in association with conifer tree remains. Alder-like shrub leaves have also been found near Sable Mountain. A variety of platanoid leaf forms have been found all over Denali.
Leaf fossils can be used to estimate what the ancient climate was like. There is an observed correlation between temperature and precipitation, and modern leaf characters such as toothed margins. This correlation can be applied to fossil leaves.
Last updated: August 15, 2016