File:Araucaria sp. (fossil conifer tree) (Mesozoic) 1 (49019751586).jpg

Fossil wood from the Mesozoic. (public display, Sternberg Museum of Natural History, Hays, Kansas, USA)

Plants are multicellular, photosynthetic eucaryotes. The oldest known land plant body fossils are Silurian in age. Fossil root traces of land plants are known back in the Ordovician. The Devonian was the key time interval during which land plants flourished and Earth experienced its first “greening” of the land. The earliest land plants were small and simple and probably remained close to bodies of water. By the Late Devonian, land plants had evolved large, tree-sized bodies and the first-ever forests appeared.

Seen here is a nice section of "petrified wood" from an ancient Araucaria tree. While buried in sediments, the wood had its microscopic porosity filled with minerals as groundwater percolated through. This fossilization process is technically known as permineralization ("petrified" is a horrible term - never use it in a scientific context). Permineralization can also occur with fossil bones. The most common permineralization mineral is quartz (~pure silica - SiO2), which is the most common mineral in Earth's crust.

Araucaria is a type of conifer tree, with about 20 species living today in the Holocene. Araucariaceans have a fossil record dating back to the Triassic. During the Mesozoic, they occurred in both Southern Hemisphere and Northern Hemisphere continents. Today, they are Southern Hemisphere plants.

From exhibit signage:

During the dinosaur era, a conifer tree called Araucaria dominated the forests. Now fossilized, this tree trunk weighs about 300 pounds. Several species of Araucaria survive today, including the monkey puzzle tree and Norfolk Island pine tree.

A growing tree acts like a tape recorder and documents climate season by season, year after year. Growth rings are produced when there are strong variations in temperature or water supply. Fossilized tree trunks from the Sahara do not have growth rings, suggesting that the climate during the dinosaur era was mild year round.

Classification: Plantae, Pinophyta, Pinopsida, Pinales, Araucariaceae

Stratigraphy & Locality: unrecorded/undisclosed

See info. at: <a href="https://en.wikipedia.org/wiki/Araucaria" rel="noreferrer nofollow">en.wikipedia.org/wiki/Araucaria</a> and