中国科学院南京地质古生物研究所机构知识库

Premise of research.Abundant fossil and molecular evidence suggests that all extant conifer families were established by the Early Cretaceous. However, the recognition and understanding of the lineages that lead to the evolution of these extant families remain incomplete. Late Paleozoic to Early Mesozoic Voltziales conifersalso known as transitional conifers, usually with multilobed ovuliferous scaleshave been hypothesized to be among the stem lineages of modern crown conifers. This article describes an exquisitely preserved voltzian seed cone from the Aptian-Albian of Mongolia that introduces new taxonomic diversity and morphological data into 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 inconspicuous bract partially fused to the stalk of a five-lobed scale. Three of the lobes are distal (always pointing away from the cone base), while the other two are proximal (always pointing toward the cone base). Up to five inverted winged seeds are present on the adaxial side of the ovuliferous scales. A systematic review of Late Paleozoic to Early Cretaceous multilobed ovuliferous scalestogether with a morphological cladistic analysissupports the 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 conifers and 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 complexes and the cone (i.e., imbrication and interlocking) for the protection of the ovules/seeds that are broadly concurrent with the appearance of new insect and other animal feeding strategies.