Time of Evolutionof Angiosperms

Established

Using 2 ways:

1. Fossils

2. Molecular clocks.

Fossile pollen

130mya 1st pollen fossil found in Isreal.

125mya triporate fossil. Late Cretaceous. (248-213mya Triassic and jurassic pollen looks like it could belong to angiophytes [plants with flower-like and flower bearing structures, precursors of the angiosperm. Remains uncertain.])

125mya fossils from China. (Archaefrutus is the oldest known fossil fruit. This plant is aquatic).

Archaefructus

Carpels. Beginning of a bisexual flower. Stamens.

Sexual structure of the flower if interpreted as flower cladograms place if before Amborella then it supports the Euanthial theory but not woody magnoliid hypothesis.

Unisexual female flower. Inflorescence. Unisexual male flower. If sexual structure is an Inflorescence, cladograms place it in the waterline clade. Supports the pseudanthial theory and Paleoherbaceous hypothesis.

Theories

1. Euanthial: angiosperm flowers evolved from single unbranched stem.

2. Pseudanthial: compound, branched stem

Hydatellaceae

Morphologically similar to Archaefructus. 2nd most ancient living flowring plant at base of the waterlily clade. Interestingly fossils of waterlilies and amborella date back 130 mya.

Archeanthus

Another interesting flower of the mid Cretaceous (c.100mya). Is without a doubt related to Magnoliids.

Sanmiguela is a fossile that has be suggested to be related to angiosperms but botanists discount that.. has leaves reminiscent of palms.

Schmeissneria

Is a possible early angiosperm recorded from early Jurassic of Europe and middle Jurassic of China. Some think it the basal member of the angiophytes radiation

Problems using fossils

1. Sparse, random and chance findings

2. Hard to interpret structures and their functions.

3. Difficult to date some fossils accurately

4. Exact taxonomy of some fossils unknown