Cretaceous chloranthoids: early prominence, extinct diversity and missing links

Area of Science:

• Paleobotany
• Angiosperm Phylogeny
• Evolutionary Biology

Background:

• Chloranthaceae, comprising four genera, exhibits simple flowers and diverged early in angiosperm evolution.
• The phylogenetic placement of Chloranthaceae relative to other major angiosperm groups remains uncertain.
• Fossil evidence, particularly from the Early Cretaceous, significantly enhances our understanding of the family's evolutionary history.

Purpose of the Study:

• To describe three new genera of Early Cretaceous chloranthoids.
• To summarize current knowledge on the extinct diversity of the Chloranthaceae family.
• To elucidate the evolutionary relationships and morphological gaps among extant Chloranthaceae genera.

Main Methods:

• Analysis of Early Cretaceous mesofossils (flowers, fruits, seeds, inflorescences, stamens) from Portugal and North America.
• Examination of Late Cretaceous fossil androecia.
• Comparative morphological analysis of fossil and extant Chloranthaceae taxa.

Main Results:

• Diverse early chloranthoids, related to extant Hedyosmum and the Ascarina, Chloranthus, Sarcandra clade, were identified from the Early Cretaceous.
• Distinctive fossil androecia related to extant Chloranthus were found in the Late Cretaceous.
• Three new genera of Early Cretaceous chloranthoids are described, expanding the known extinct diversity.

Conclusions:

• The Early Cretaceous Chloranthaceae record is rich, providing early evidence of angiosperm reproductive structures.
• Extinct chloranthoids bridge morphological gaps between extant genera and illuminate the evolution of their unique features.
• Chloranthaceae fossils are crucial for understanding early angiosperm diversification, ecology, and phylogeny.