Araucaria mirabilis (Conifer Cones)

Object/Artifact

-

Crater Rock Museum

Name/Title

Araucaria mirabilis (Conifer Cones)

Entry/Object ID

2009.57.1

Description

2 cones of the species Araucaria mirabilis in the matrix of a beige sandstone matrix. The cones are rusty-tan in color. Seventy-two silicified cone specimens of Pararaucaria patagonica Wieland from the Cerro Cuadrado (Jurassic) petrified forest in Patagonia were studied by use of thin sections and reflected light. Traces from the cone axis stele to the bract and ovuliferous scale are separate at their origins. In cross section the abaxially concave ovuliferous scale trace and massive circular bract trace branch half-way out into the cone-scale complex. Two triangular-shaped bundles of fibers follow the scale trace into the laminar part of the ovuliferous scale. Both surfaces of the ovuliferous scale possess hairs which may have assisted in cone closure. Cones typically contain one flattened, winged seed per ovuliferous scale. Multi-layered seed integuments are represented by an inner fleshy layer of large cells filled with a black amorphous material, a sclerotesta consisting of wedges or fan-shaped groups of sclereids oriented at right angles to the seed surface, and a thin, often crushed fleshy layer. Seed wings consist of anastomosing, branched cells resembling glandular hairs and containing many intercellular spaces. Well-preserved polycotyledonous embryos containing up to eight cotyledons are present in several cones. Tissues of the embryo including the shoot apex, calyptroperiblem, hypocotyl, and cotyledons are described. On the basis of anatomical and morphological features, specimens of P. patagonica are compared to members of both extant and extinct families of conifers including the Araucariaceae, Taxodiaceae, Pinaceae, Cupressaceae, and Cheirolepidaceae. Clade: Tracheophytes Division: Pinophyta Class: Pinopsida Order: Pinales Family: Araucariaceae Genus: Araucaria Species: †A. mirabilis Rock and Mineral Data (Silica) Assemblage Zone: sedimentary Chemical Composition: Si O2 Crystal System: Hexagonal Type of Fossils Present: Plants Grain Size: Fine Hardness: 7 Quartz Lithofacies: ash-flow tuffs Luster: Glassy Pressure: Low-Moderate Rock Color: Medium Rock Origin: Post-depositional Rock Type: Sedimentary Specific Gravity: 2.6 Surface Process: Not apparent Temperature: Low Texture: Fine grain Variety: Petrified pine cones in a sandstone matrix

Collection

Fossil Collection

Acquisition

Accession

2009.57

Source or Donor

Fossils received in 2009 from donation

Acquisition Method

Donation

Notes

"Lee Willms" (Williams?) is listed as the donor.

Dimensions

Dimension Description

Dimensions of overall specimen

Dimension Notes

"(7 x 6.25)," measurements and units not specified. Assumed length by width in inches. Dimensions taken at widest points.

Dimension Description

First Cone

Dimension Notes

"(1.5 x 1.75)," measurements and units not specified. Assumed length by width in inches. Dimensions taken at widest points.

Dimension Description

Second Cone

Dimension Notes

"(4.25 x 0.75)," measurements and units not specified. Assumed length by width in inches. Dimensions taken at widest points.

Location

Location

Container

Right

Drawer

2nd Shelf

Shelf

Right

Cabinet

Case #104

Wall

East Wall

Building

Mentzer Hall-Petrified Wood Room

Category

Permanent