Figure 1.
Paleogeographic map and stratigraphy of Colorado Plateau region during Late Triassic.
A. Map showing Wolverine Petrified Forest (WPF), Utah and Petrified Forest National Park (PEFO), Arizona. Modified after Blakey [44]. B. Stratigraphy after [9], [10]; asterisks denote the stratigraphic position of Xylokrypta specimens.
Figure 2.
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.
Figure 3.
Sections of Xylokrypta from UMNH PB 1915.
Transverse (A–F) and tangential (G) sections of the wood substrate. All images oriented with proximal side of boring on the right of image. A. Holotype, composite photomicrograph just off-center from midline of boring. Frass and hematite-after-pyrite (py) line and fill the upper chamber and proximal shaft; quartz (qz) and calcite (cc) spar fill the center of the chamber. Margin of adjacent Xylokrypta (as in F) marked by arrow. B. Slab section through midline of boring, bisecting proximal and distal apertures. C, D. Holotype, slab sections of boring in making thin section in A. Image C is photo-reversed to match counterpart in D. E. Holotype, detail photomicrograph of A showing fragmented tracheids found under the word “frass”. F. Slab section showing outer portion of chambers of adjacent Xylokrypta borings. Holotype is the boring on the left. G. Slab section just below wood surface. All scale bars = 5 mm, except E, which is 50 microns.
Figure 4.
Oblique (A), transverse (B), tangential (C), and radial (D) views relative to wood substrate. E. Tangential view of typical Xylokrypta series. Long dash corresponds to transverse view in B, and short dashed line corresponds to radial view in D. F. Orientation of Xylokrypta series on wood cylinder. Decorticated wood reveals central chamber of Xylokrypta, which remains concealed if outermost xylem or inner bark are preserved (top left). Abbreviations: pa, proximal aperture; ps, proximal shaft; da, distal aperture; ds, distal shaft; e, encrustation of hematite-after-pyrite. Planes on cube in A marked R, radial; Ta, tangential; Tr, transverse.
Figure 5.
Field photographs of Xylokrypta in PEFO specimen.
A. Apertures containing fill. B. Series of Xylokrypta with brown lining and sparitized or hollow chambers. C. Cross section of boring showing lunate spar at center of boring. All scale bar intervals = 1 cm.
Figure 6.
Composite field photograph of PEFO log specimen containing borings diagnosed here as Xylokrypta.
Borings concentrated along longitudinal furrow. Scale bar at lower right is 10 cm, with 1 cm increments.
Table 1.
Morphometry of Xylokrypta borings from holotype specimen, UMNH PB 1915.
Figure 7.
Length and width measurements of 21 species of cupedid beetle (Archostemata: Cupedidae).
Minimum (−) and maximum (+) dimensions from individual taxa connected by grey line. Stippled field denotes diameter range of distal aperture in Xylokrypta.
Table 2.
Morphometry of Triassic cupedid beetles (Archostemata: Cupedidae).