Hayden's redwood (Sequoia haydeni)

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Sequoia haydeni - Fossil Redwood Species | Botanical Encyclopedia

Excavated from Eocene and Oligocene sedimentary layers, the fossil taxon Sequoia haydeni provides critical insights into the prehistoric distribution of redwood lineages in North America. These ancient trees dominated the forest canopy during the warm Eocene and Oligocene epochs, approximately 34 million years ago.

Paleobotanists study these fossil remains to understand the evolutionary history of the genus Sequoia and the climatic shifts of the Cenozoic era. Their preservation in fine volcanic ash has allowed for exceptional detail in the studied specimens.

Taxonomy

  • ∟ царство Plantae
  • ∟ division Tracheophytes (Vascular Plants)
  • ∟ subdivision Spermatophytes (Seed plants)
  • ∟ superclass Gymnospermae (Gymnosperms)
  • ∟ division Pinophyta
  • ∟ subclass Cupressidae
  • ∟ order Cupressales (Cypresses and junipers)
  • ∟ family Cupressaceae (Cypress Family)
  • ∟ subfamily Sequoioideae (Sequoias)
  • ∟ genus Sequoia (Coast redwood)
  • ∟ species Sequoia haydeni (Hayden's redwood)

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Morphology

The vegetative structures of this ancient species are identified through compressed foliage and petrified wood samples. The leaves demonstrate a distinct dimorphic habit similar to modern coast redwoods, adapting to varying light conditions within the forest canopy.

Key diagnostic features include:

  • Needle-like leaves: The foliage features linear, decurrent needles arranged spirally but flattened into two ranks on lateral branchlets.
  • Fossilized cones: Small, woody seed cones are globose to ovoid, displaying peltate scales with distinct transverse ridges.
  • Trunk anatomy: Fossilized stumps indicate a massive trunk growth with thick, fibrous bark designed to withstand environmental disturbances.

Applications

Specimens of this species serve as important biostratigraphic markers for dating terrestrial sedimentary sequences. They help researchers reconstruct the terrestrial paleoclimates of the Eocene-Oligocene transition period.

Additionally, their wood structure helps calibrate models of ancient atmospheric carbon dioxide levels. Analyzing the density of stomata on the fossilized needles provides a proxy for historical climate variations.

Interesting facts

Some of the most spectacular petrified tree stumps of this redwood are preserved in the Florissant Fossil Beds National Monument in Colorado. These massive fossilized stumps measure up to 4 meters in diameter, indicating trees of colossal size.

Volcanic mudflows, known as lahars, rapidly buried the bases of these standing trees millions of years ago. This sudden oxygen-deprived burial prevented decay and initiated the petrification process that preserved their cellular structure.

Geography of distribution

  • США, Колорадо (эоцен)

Sources

  • Global Biodiversity Information Facility (GBIF): Sequoia haydeni (https://www.gbif.org/species/41019893)
  • The World Flora Online (WFO): Sequoia (http://www.worldfloraonline.org)
  • Paleobiology Database (PBDB): Sequoia haydeni (https://paleobiodb.org)

Technical Information

External Databases: GBIF

See also

Coast Redwood

Coast Redwood

Sequoia sempervirens

The coast redwood (Sequoia sempervirens) is a massive conifer native to coastal California and Oregon. …

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True Araucarias

True Araucarias

Araucaria sect. Araucaria

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