Great-leaved araucaria (Araucaria grandifolia)

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Araucaria grandifolia: Characteristics of the Extinct Conifer

The ancient conifer Araucaria grandifolia flourished during the Albian stage of the Early Cretaceous period. Paleontologists have recovered its fossilized remains primarily from the Punta del Barco Formation. It eventually went extinct at the close of the Early Cretaceous, leaving behind a rich fossil record.

Taxonomy

Morphology

Fossilized shoots of this plant exhibit well-preserved secondary xylem with homocellular rays arranged in single rows. The wood cells connect through cupressoid-type pits, which are highly characteristic of early conifers.

Its leaves are distinctly large, many-veined, and shaped like narrow triangles with pointed tips and decurrent bases. They overlap in a tightly packed spiral pattern and feature a strong central ridge on the lower surface.

Microscopic studies of the leaf cuticles reveal straight and wavy fibers, as well as elliptical stomata arranged in straight lines. Kidney-shaped guard cells and a lamellate cuticle structure serve as key identifying markers for this extinct species.

Interesting facts

This prehistoric tree grew in a temperate, humid, and warm climate. It typically populated river valleys characterized by volcanic soil, a result of recurrent volcanic activity in the region during that era.

Geography of distribution

  • Argentina

Sources

  • Wikipedia
  • GBIF