Early Carboniferous Tree Species Had Unique Crown Shape

Feb 5, 2024 by Natali Anderson

Sanfordiacaulis densifolia is an extinct tree species that existed between 359 and 347 million years ago (Carboniferous period) in what is now New Brunswick, Canada. Its architecture consisted of an unbranched, 16-cm-diameter trunk with compound leaves arranged in spirals of 13 cm and compressed into 14 cm of vertical trunk length. Compound leaves in the upper 0.75 m of the trunk measured over 1.75 m in length and preserved alternately arranged secondary laterals beginning at 0.5 m from the trunk; the area below the trunk had only persistent leaf bases. Sanfordiacaulis densifolia shows that Early Carboniferous vegetation was more complex than realized, signaling that it was a time of experimental, possibly transitional and varied, growth architectures.



Sanfordiacaulis densifolia. Image credit: Tim Stonesifer.

Trees first appear in the mid-Devonian period (393 to 383 million years ago), although modern woody trees don’t appear until about 10 million years later.

Evidence of arborescence (tree-like structure) is based primarily on mudcast, sandcast, or permineralized stumps or extensive rooting structures in fossilized soils.

Under unique preservational circumstances, these early trees were fossilized with rooting-and-crown structures attached to their trunks.

“The way in which Sanfordiacaulis densifolia produced hugely long leaves around its spindly trunk, and the sheer number over a short length of trunk, is startling,” said Dr. Robert Gastaldo, a paleontologist at Colby College.

“The forms taken by these 350-million-year-old trees look something like a fern or palm, even though palms didn’t arise until 300 million years later.”

“However, the functional leaves in ferns or palm trees cluster at the top and are relatively few.”

“In contrast, Sanfordiacaulis densifolia preserves more than 250 leaves around its trunk, with each partially preserved leaf extending 1.75 m from it.”

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Actual and reconstructed tree heights and biostratigraphic ranges of Middle Devonian to Pennsylvanian trees. Image credit: Gastaldo et al., doi: 10.1016/j.cub.2024.01.011.

More:
https://www.sci.news/paleontology/sanfordiacaulis-densifolia-12656.html