Abstract Detail


Richmond, Dean [1], Lupia, Richard [2], Philippe, Marc [3].

Protocedroxylon from the marine shales of the Upper Jurassic Knoxville Formation, Tehama County, California.

A tracheidoxyl with growth rings is retained by the University of California, Berkeley. The sample was found in the marine shales of the Upper Jurassic Knoxville Formation in Tehama County, California. The majority of North American Upper Jurassic fossil woods reported are from the Morrison Formation of the intermountain west. This fossil provides a unique opportunity to evaluate wood from the western margin of North America. The wood is described herein as Protocedroxylon Gothan.
In the transverse section, the tracheid cells are circular in shape. The tracheid walls of the earlywood are relatively thin (2‒3 μm) with a median lumen radial diameter of 42 μm. The median earlywood perimeter is 155 μm with a median area of 1699 μm2. Latewood tracheid median perimeter is 115 μm with a median area of 773 μm2. The latewood to earlywood transition is gradual comprising up to 30 tracheids with a maximum width of 800 μm. Latewood can be divided into transition latewood and late-season latewood. Transition latewood cells, which comprise the majority of the latewood, have walls about 7 μm thick with a median lumen radial diameter of 28 μm. Late-season latewood walls are approximately 10 μm thick with a median lumen radial diameter of 22 μm.
In the tangential section, the medullary rays are homogeneous, homocellular, uniseriate, never biseriate nor multiseriate. Ray heights vary from 368 to 1467 μm, with a median height of 280 μm. In a random 100-ray count, the number of cells per ray varies from 2 to 58 with a median ray count of 13. The median ray cell vertical diameter is 23 μm. No bordered pits on the tracheid tangential walls were observed.
In the radial section, the wood displays variable pitting. Bordered pits are round, uniseriate, noncontiguous, and distant. In some cases, however, the bordered pits are contiguous. Bordered pits have a median width of 17.9 µm and a median height of 17.0 µm, resulting in a median height/width ratio of 0.97. Pits are rarely biseriate, usually occurring in an opposite configuration, but an alternate configuration does occur. A few crassulae are present. Cross-fields have one piceoid oculipore per field.
The wood washed offshore from the western coast of North America and was preserved in the Knoxville marine shale at a paleolatitude of 44oN. The presence of the genus along the western coast suggests a cool/wet climate for this region during the Late Jurassic period.

1 - University Of Oklahoma, 100 E. Boyd St., Sarkeys Energy Center Suite 710, Norman, OK, 73007, United States
2 - UNIVERSITY OF OKLAHOMA, Sam Noble Museum, 2401 Chautauqua Avenue, Norman, OK, 73072, United States
3 - Claude Bernard University Lyon 1, Cnrs, Umr 5023 , Villeurbanne, Lehna, F-69622, France

Knoxville Formation

Presentation Type: Poster
Session: P, Paleobotany Posters
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 5:00 PM Time and date to be determined
Number: PPB001
Abstract ID:224
Candidate for Awards:None

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