ORIGINAL ARTICLE
 
HIGHLIGHTS
  • The Early Devonian euphyllophyte Nebuloxyla recovered successfully from trauma
  • We reconstruct the dynamics of a discrete wounding event that occurred 400 myr ago
  • This occurrence demonstrates that even very small early tracheophytes were resilient
  • Early euphyllophytes were capable of recovery from trauma affecting the deep tissues
  • Early euphyllophytes had evolved complex wound response mechanisms
KEYWORDS
ABSTRACT
Anatomically preserved material from Lower Devonian strata of the Battery Point Formation (Gaspé Peninsula, Quebec, Canada) offers a rare opportunity to reconstruct the sequence of events in the life of a Nebuloxyla mikmaqiana plant (early euphyllophyte) that led to wounding and the plant’s recovery after wounding. Using serial sections from cellulose acetate peels of the Nebuloxyla axis and volume renderings of the affected tissues, we show that the wound, centered around a branch and caused likely by an herbivore, resulted in removal of the extraxylary tissues of the branch starting from its very base, associated with bending of the xylem strand that supplied the branch. Downward bending of the branch xylem toward the base of the main axis led to the separation and displacement of a significant portion of it, leaving a short portion of the xylem strand at the base of the branch in its original position. The displaced strand of branch xylem, after stripping of the extraxylary tissues along with some of its own thickness, was left protruding outwards from the open wound surface. Subsequent development of wound response tissue filled the gap left by the wound around the protruding displaced xylem strand, surrounding it with wound periderm. This specimen provides evidence that plants as old as Nebuloxyla had the capacity to endure and survive traumatic events, and to deploy effective and sophisticated response mechanisms that had already evolved in the euphyllophyte clade by Emsian time. More broadly, this occurrence re-emphasizes the importance of permineralized fossils in documenting details of plant anatomy and development, even allowing glimpses into minutia of their daily life, such as interactions with their environment and immediate responses to these interactions.
FUNDING
MAKL’s research is supported by a U.S. National Science Foundation Graduate Research Fellowship (#000922334).
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eISSN:2082-0259
ISSN:0001-6594
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