Editing Transitional fossil (section)

===''Runcaria''===
[[File:Runcaria megasporangium and cupule drawing.jpg|thumb|80px|The [[Devonian]] fossil plant ''[[Runcaria]]'' resembles a seed but lacks a solid seed coat and means to guide pollen.]]
{{Main|Runcaria|Evolution of plants#Seeds}}

A Middle Devonian precursor to [[Spermatophyte|seed plant]]s has been identified from Belgium, predating the earliest seed plants by about 20&nbsp;million years. ''Runcaria'', small and radially symmetrical, is an integumented [[Sporangium|megasporangium]] surrounded by a [[Calybium and cupule|cupule]]. The megasporangium bears an unopened [[distal]] extension protruding above the multilobed [[Integument#Botanical usage|integument]]. It is suspected that the extension was involved in [[Anemophily|anemophilous pollination]]. ''Runcaria'' sheds new light on the sequence of character acquisition leading to the seed, having all the qualities of seed plants except for a solid [[seed coat]] and a system to guide the pollen to the seed.<ref>{{cite journal |last1=Gerrienne |first1=Philippe |last2=Meyer-Berthaud |first2=Brigitte |last3=Fairon-Demaret |first3=Muriel |last4=Streel |first4=Maurice |last5=Steemans |first5=Philippe |date=29 October 2004 |title=Runcaria, a Middle Devonian Seed Plant Precursor |journal=[[Science (journal)|Science]] |volume=306 |issue=5697 |pages=856–858 |bibcode=2004Sci...306..856G |doi=10.1126/science.1102491 |issn=0036-8075 |pmid=15514154 |s2cid=34269432 |display-authors=3 }}</ref>