Barinophyton Citrulliforme (Barinophytales Incertae Sedis, Barinophytaceae) From the Upper Devonian of Pennsylvania

Abstract

Barinophyton citrulliforme is definitely proven to be a tracheophyte. The vascular cylinder of the main axis is an exarch protostele composed of tracheids having a continuous secondary wall folded into protrusions into the cell lumen. These protrusions delineate the position of annular thickenings which were deposited earlier than the continuous secondary wall. Between successive protrusions, the later-deposited secondary wall is interrupted by minute pitlike structures. It is suggested that the secondary walls of the tracheids were laid down in a twophase depositional sequence. The fertile system of B. citrulliforme consists of a main axis bearing spirally arranged strobili. The strobilus consists of an axis that bears two alternate rows of sporangiferous appendages. The sporangiferous appendages are borne laterally along the strobilar axis and recurve abaxially around the axis. The sporangia are attached along the inside curve of the appendages, one sporangium per appendage, each containing both microspores and megaspores. This species thus exhibits sporangial heterospory which is considered to be an adaptation to an aquatic habit and the sporangia are considered to be functional analogs of the sporocarps of Marsilea, The interpretation of the strobilus is morphologically identical to Ananiev's interpretation of the strobilus of Pectinophyton bipectinatum ; consequently P. hipectinaturn is here transferred to Barinophyton as B. robustius comb. nov.

Techniques for preparation of pyrite and limonite permineralizations

“…We have also noticed a fine-scale reticulate network in nearly all of our demineralized thin-sections of Millboro shale material. These patterns are similar in scale and generally equivalent in organization to reticulate networks of inferred biological origin in other plant fossils (Hartman and Banks, 1980;Brauer, 1980), but also in some instances interpreted as a preservational artifact (Beck, 1978;Hartman, 1978). In the case of our material, encompassing plants in widely divergent taxonomic groups, the pattern of reticulations we see are clearly not of biological origin, but appear instead to be related to the orientations of crystal faces present in the material before demineralization.…”

“…Specimens permineralized with iron oxides can be peeled, but more commonly sections have been cut and the surfaces prepared for observation with incident light, either with (Matten, 1966;Skog and Banks, 1973;Scheckler, 1978;Brauer, 1980) or without (Leclercq, 1951(Leclercq, , 1957; Leclercq ~Instead of waxed paper, we commonly use glassine.…”

Frasnian (Upper Devonian) evidence for multiple origins of seed-like structures

“…The arrangement of Sphinxia on the parent plant can only be surmised on the basis of the pairs of structures illustrated in Figure 1, possibly reflecting a elongated, conelike structure, as in Barinobhyton citrullijime (Brauer, 1980). However, from the specimens examined it is dimcult to ascertain which end of Sphinxia was the point of attachment to the parent plant.…”

“…Barinophyton bore sporangia containing numerous megaspores of variable size in an arrangement similar to that envisaged for Sphinxia (Pettitt, 1965;Brauer, 1980). These, however, have no indication of integumentation; merely an encirclement of the sporangium by the subtending axial branch.…”

Earliest record of megaphylls and leafy structures, and their initial diversification

“…Some dichotomous appendages are alternately borne at the basal areas of the fertile axes. Dibracophyton resembles Barinophyton and Protobarinophyton [46][47][48]. Their sporangia have two valves and distal dehiscence (sporangial characters were demonstrated in B. norvegicum and Dibracophyton), and possible unvascularized bracts.…”