Exceptional preservation of tiny embryos documents seed dormancy in early angiosperms

Area of Science:

• Palaeobotany
• Evolutionary Biology
• Seed Biology

Background:

• The Early Cretaceous period (130-100 million years ago) saw rapid angiosperm diversification, altering terrestrial ecosystems.
• Existing hypotheses suggest early angiosperms were small, fast-cycling plants exploiting disturbed habitats.
• Direct fossil evidence on early angiosperm seed biology and germination is limited.

Purpose of the Study:

• To investigate the seed biology and germination ecology of Early Cretaceous angiosperms.
• To provide direct palaeontological data on early angiosperm reproductive strategies.

Main Methods:

• Discovery and analysis of exceptionally preserved angiosperm seeds from the Early Cretaceous.
• Synchrotron radiation X-ray tomographic microscopy to examine fossil embryos and nutrient storage tissues.

Main Results:

• Fossilized embryos from numerous taxa were found to be tiny at the time of dispersal.
• The nutrient storage tissues were modest, consistent with small overall seed size.
• These findings align with hypotheses based on extant plants regarding embryo size and seed dormancy.

Conclusions:

• Tiny embryos and seed dormancy appear to be fundamental traits of angiosperms.
• The small size of early angiosperm seeds and embryos supports their role as opportunistic colonizers of disturbance-prone habitats.
• This research offers crucial insights into the early life history and ecological strategies of angiosperms.