A new voltzian seed cone from the early cretaceous of mongoliaand its implications for the evolution of ancient conifers

Premise of research. Abundant fossil and molecular evidence suggests that all extant conifer families wereestablished by the Early Cretaceous. However, the recognition and understanding of the lineages that lead to theevolution of these extant families remain incomplete. Late Paleozoic to Early Mesozoic Voltziales conifers-also known as transitional conifers, usually with multilobed ovuliferous scales-have been hypothesized tobe among the stem lineages of modern crown conifers. This article describes an exquisitely preserved voltzianseed cone from the Aptian-Albian of Mongolia that introduces new taxonomic diversity and morphological datainto the complex pattern of conifer evolution.Methodology. Bulk lignite samples collected from the Tevshiin Govi locality were disaggregated in water,cleaned with hydrochloric and hydrofluoric acids, washed, and dried in air. Fossils were examined using LM,SEM, and X-ray microtomography.Pivotal results. Krassilovia mongolica gen. et sp. nov. has seed cones with helically arranged, imbricated,and tightly interlocked bract-scale complexes. Each mature bract-scale complex consists of an inconspicuousbract partially fused to the stalk of a five-lobed scale. Three of the lobes are distal (always pointing away fromthe cone base), while the other two are proximal (always pointing toward the cone base). Up to five invertedwinged seeds are present on the adaxial side of the ovuliferous scales. A systematic review of Late Paleozoic to Early Cretaceous multilobed ovuliferous scales-together with a morphological cladistic analysis-supportsthe placement of the Mongolian material in a new genus within the voltzian clade of the Voltziales.Conclusions. Krassilovia mongolica provides evidence of the additional diversity of extinct voltzian conifersand shows that some persisted to inhabit forest-moor swamp environments in eastern Asia during the Early Cretaceous. The new fossil taxon also shows novel morphological adaptations of the bract-scale complexesand the cone (i.e., imbrication and interlocking) for the protection of the ovules/seeds that are broadlyconcurrent with the appearance of new insect and other animal feeding strategies.