Better together: Joint consideration of anatomy and morphology illuminates the architecture and life history of the Carboniferous arborescent lycopsid Paralycopodites

Abstract

Paralycopodites Morey & Morey, a Carboniferous-age arboreous lycopsid that grew in the tropical wetlands of Pangea, is the phylogenetically basalmost member of the Carboniferous stigmarian lycopsids to be conceptually reconstructed. We update its description through reciprocal illumination between anatomy (coal-balls) and gross morphology (adpressions). Revised assessment of its architecture and development shows that the determinate, columnar main trunk eventually underwent several isotomous divisions to form a crown. Two opposite rows of closely-spaced, compact lateral branches were initiated anisotomously throughout the trunk and crown, each branch further undergoing multiple anisotomous divisions to form an apparently planar scaffold for numerous bisporangiate cones. We infer that branches were initially emitted near-vertically, but rapidly moved to a more horizontal position; they were abscised after the cones had matured but before the continuous phellogen had produced a centripetal periderm. Leaves were not abscised, though anatomy and morphology both suggest a photosynthetic economy that was localized within the plant body. Character content and clarity of interpretation make Paralycopodites the preferred name for the reconstructed plant rather than Anabathra, Ulodendron, or Bergeria. Phylogenetic analysis of rhizomorphic lycopsids based on a reduced spectrum of features observable in adpression returns the same topology as that based on a full matrix combining both anatomical and externally visible traits, permitting adpression fossils to be assigned to anatomically-circumscribed genera rather than perpetuating an unnecessary parallel taxonomy.

Phylogeny of Merlin’s grass (Isoetaceae): revealing an “Amborella syndrome” and the importance of geographic distribution for understanding current and historical diversity

“…The sporangia are often wholly or partly covered by a thin tissue called velum, and a ligule is attached to the adaxial side of the leaf distal to the sporangia [ 4 – 6 ]. The presence of a ligule (a small often triangular extension of tissue on the adaxial side of the leaf, [ 4 ]), as well as heterospory, are characteristics that Isoetaceae share with their closest living relatives, the Selaginellaceae [ 10 , 11 , 12 , 13 ], as well as with their extinct relatives in the remaining Isoetales (the rhizomorphic lycopsids), a lineage that can be traced at least to the Late Devonian [ 1 , 10 , 11 , 14 , 15 , 16 ].…”

Escaping the voluntary constraints of “tyre‐track” taxonomy

“…In contrast, the six more recently devised characters are summarised as a table placed above the topology in Fig. 3, consisting of the five characters added by DiMichele & Bateman (2020) plus a new character, 121, summarizing the relative size of leaf scar versus the more extensive leaf base.…”

“…4B of Bateman & al., 1992). The overlying table summarises genus‐level scoring of six additional stem‐surface characters by Cleal & Wang (2002) and DiMichele & Bateman (2020). Question mark indicates cell unknown or inapplicable.…”

Collections‐based systematics and biogeography in the 21st century: A tribute to Dr. Vicki Funk

“…Phylogenetic systematics has progressed tremendously in the last decade with the additional sampling of characters as well as taxa. DiMichele & Bateman (2020) have updated the reconstruction of the Carboniferous tree‐clubmoss Paralycopodites Morey & Morey from disarticulated, anatomically preserved fossils to determine its phylogenetic position and to infer the developmental biology that dictated its remarkable architecture. Their biological and taxonomic conclusions on the phylogenetically basalmost member of the Carboniferous stigmarian lycopsids can be expanded to encompass the more widespread compression mode of plant preservation.…”