External surface views of Xylokrypta in Late Triassic petrified conifer wood.
All images of holotype-bearing log UMNH PB 1915, except C, IMNH-PB-055/1011. A. Xylem cylinder with several series of Xylokrypta preserved at various depths of erosion; red arrow marks proximal aperture, blue arrow marks distal opening. Scale bar = 2 cm. B. Detail of A, with inner bark preserved adjacent proximal apertures at top of image. Scale bar = 1 cm. C. Multiple series of deeply eroded Xylokrypta. Scale bar intervals = 1 cm. D. Two relatively uneroded Xylokrypta with proximal (right) and distal (left) apertures and central portion of chamber concealed below surface of wood. Vertical line marks edge of inner bark preserved at left side of image. Scale bar = 5 mm. E. Distal part of eroded Xylokrypta preserving light-colored frass fill of the distal shaft surrounded by dark-colored frass and hematite of the proximal and chamber cavity. Scale bar = 5 mm. F. Detail of E showing spiraled organization of coarse tracheid fibers comprising the distal shaft fill. Scale bar = 1 mm.