How to rely on the unreliable: Examples from Mesozoic bryophytes of Transbaikalia

Abstract

Three new fossil bryophytes are described from Jurassic and Lower Cretaceous deposits of the Transbaikalia region of Russia. The complex thalloid hepatic Khasurtythallus monosolenioides gen. et sp. nov. belongs to the Marchantiidae, but its combination of characters precludes unequivocal placement in any of the five orders of this subclass, representing most likely an extinct lineage. Paleaethallus squarrosus gen. et sp. nov. is a thalloid plant with scales similar to those of complex thalloid hepatics, although their arrangement and the overall plant structure has little in common with any extant hepatics. Dispersed moss capsules, three of which have attached calyptrae, are described as a form genus Kulindobryum gen. nov. Despite incomplete preservation, some rare characters indicate possible relationship to the genus Tayloria of the Splachnaceae, an extant family of mosses adapted to grow on animal dung, dead bodies and bones. Notably, Kulindobryum co‐occurs with bones of the small feathered dinosaurs Kulindadromeus, which also supports an affiliation of Kulindobryum with the Splachnaceae. The most common and best known Mesozoic moss for the region, the genus Bryokhutuliinia, is appraised for its systematic position and probable affinities with the Dicranales. A scoring approach is introduced for the comparative method of taxonomic placement of fossils with partial suites of morphological characters at the family or order level.

Defying death: incorporating fossils into the phylogeny of the complex thalloid liverworts (Marchantiidae, Marchantiophyta) confirms high order clades but reveals discrepancies in family‐level relationships

“…3 and 4). Overall, these results challenge the view that liverwort fossils are troublesome for phylogenetic inference (e.g., Mamontov and Ignatov, 2019).…”

“…However, most of the presently known liverwort fossils are coalified compressions of gametophytes that preserve only a limited number of taxonomically informative characters (Tomescu et al, 2018). Since bryophyte fossils are considered highly incomplete, they were usually excluded from phylogenetic analyses (Mamontov and Ignatov, 2019) and little is known about their impact on phylogenetic inference. Here, the molecular data contributed more clearly to the inferred topology of reference (Figs.…”

“…Additionally, extinct Marchantiidae are known only from gametophytes. Therefore information on the sporophyte is missing (Tomescu et al, 2018), and integrating these fossils into phylogenetic analyses is challenging since they are either unambiguously or poorly scored (Mamontov and Ignatov, 2019). Thus, previous phylogenetic analyses of liverworts included only extant taxa and, therefore, the taxonomic affinities of fossils and their impact on our understanding of Marchantiidae phylogeny are both unclear.…”

Celebrating Research Devoted to Seed‐Free Land Plants

“…The first set consists of three contributions devoted to the study of the fossil record of SFLP during the Mesozoic and Cenozoic (Mamonto & Ignatov, ; Regalado et al, ; Sadowski et al, ). In recent years, major advances have been achieved in our understanding of the evolutionary history of these plants especially, but not exclusively, by studying amber inclusions.…”

“…The study by Sadowski et al () provides for the first time a critical review of the fern diversity recovered in Baltic amber, whereas the study by Regalado et al () added a further critical piece to resolve the remarkable fern diversity preserved in Cretaceous Burmese amber inclusions. The study on the bryophyte of the Mesozoic of Transbaikalia (Mamonto & Ignatov, ) expands the exploration of the fossil record to non‐amber fossils of the early Cretaceous and late Jurassic, including the vegetative body of thalloid liverworts and capsules of derived mosses.…”