This is Mazon Monday post #312.  What’s your favorite Mazon Creek fossil?  Tell us at  email:esconi.info@gmail.com.

---

Sigillaria tessellata is an extinct species of spore bearing, arborescent (tree-like) lycophyte from the Mazon Creek fossil deposit. Arborescent lycophytes (or scale trees) belong to the group Lepidodendrales. Sigillaria is known from as early as the Middle Devonian. It went extinct during the Early Permian Period.

From Wikipedia

Lepidodendrales (from the Greek for “scale tree”) or arborescent lycophytes are an extinct order of primitive, vascular, heterosporous, arborescent (tree-like) plants belonging to Lycopodiopsida. Members of Lepidodendrales are the best understood of the fossil lycopsids due to the vast diversity of Lepidodendrales specimens and the diversity in which they were preserved; the extensive distribution of Lepidodendrales specimens as well as their well-preservedness lends paleobotanists exceptionally detailed knowledge of the coal-swamp giants’ reproductive biology, vegetative development, and role in their paleoecosystem. The defining characteristics of the Lepidodendrales are their secondary xylem, extensive  periderm  development, three-zoned cortex, rootlike appendages known as stigmarian rootlets arranged in a spiralling pattern, and  megasporangium each containing a single functional megaspore that germinates inside the  sporangium. Many of these different plant organs have been assigned both generic and specific names as relatively few have been found organically attached to each other. Some specimens have been discovered which indicate heights of 40^[1] and even 50 meters^[2] and diameters of over 2 meters at the base. The massive trunks of some species branched profusely, producing large crowns of leafy twigs; though some leaves were up to 1 meter long, most were much shorter, and when leaves dropped from branches their conspicuous leaf bases remained on the surface of branches. Strobili could be found at the tips of distal branches or in an area at the top of the main trunk. The underground organs of Lepidodendrales typically consisted of dichotomizing axes bearing helically arranged, lateral appendages serving an equivalent function to roots. Sometimes called “giant club mosses”, they are believed to be more closely related to extant  quillworts based on xylem, although fossil specimens of extinct  Selaginellales from the Late Carboniferous also had secondary xylem.^[3][4]

Sigillaria tessellata was named by Adolphe-Theodore Brongniart (1801-1876) in 1828. Brongniart, a French paleontologist, is considered by many to be the father of paleobotany. He described many Carboniferous plants.

Sigillaria tessellata can be found on page 19 of Jack Wittry’s “A Comprehensive Guide to the Fossil Flora of Mazon Creek”

Sigillaria tessellata Brongniart, 1828

1828. Sigillaria tessellata Brongniart: p. 65,
1836. Sigillaria tessellata Brongniart: p. 436, pl. 162, figs. 1-4
1879-80. Sigillaria mamillaris Lesquereux: p. 483, pl. 72, fig. 5; non fig. 6
1884. Sigillaria mamillaris Lesquereux: p. 799, pl. 108, fig. 6
1938. Sigillaria tessellata Brongniart; Bell: p. 98, pl. 100, fig. 2
1938. Sigillaria tessellata var. emminens Bell: p. 98, pl. 100, figs. 1, 3; pl. 101, figs. 1, 2
1964. Sigillaria tessellata Brongniart; Crookall: p. 398, pl. 87, figs. 1-4
1967. Sigillaria tessellata Steinhauer; Bell: p. 55, pl. 51, fig. 4

DESCRIPTION: The ribs are convex and lack any surface pattern. The furrows are straight or only slightly undulating. The leaf scars are highly variable in overall shape, close vertically, less than a leaf-scar length apart, and are separated by a tranverse furrow. They are hexagonal, generally as wide or wider than tall, and take up between three-quarters and the full width of the rib. The three vascular scars are at the same level, about one-third down the leaf scar. The center scar is transverse and slightly arched, and the two lateral scars are straight or slightly arched. The subepidermal surface, also known as the Syringodendron condition (see Fig. 2), has vertical, rather course striae, which merge and split at a distance of more than 1 cm. The leaf scars are in the form of two contiguous elliptical marks up to 3 mm tall and 1.5 mm wide, which represent the vascular scars.

REMARKS: Sigillaria tessellata is very rare. Like all members of Sigillaria, this species grew in drier areas. Its rare appearance and generally small size in the Mazon Creek area speak to the fact that they were all washed in from some distance outside the coal swamp.

Specimens

Field Museum PP 57651

Field Museum PP 32622