A multicarpellate fruit from Late Cretaceous sediments of South Bohemia, Czech Republic

Abstract

The gynoecium of most angiosperms consists of two or more united carpels and syncarpy is generally considered a key innovation. Multicarpellate-syncarpous gynoecia, i.e., with more than five united carpels, are overall rare, probably because of developmental and functional constraints. Based on scanning electron microscopy (SEM) and X-ray computed tomography (microCT), we here describe a new fossil taxon, Covidifructus multicarpellatus, from the Late Cretaceous (Late Turonian-Santonian) of Southern Bohemia (Czech Republic). The new fossil taxon is based on a single syncarpous gynoecium (an immature fruit) consisting of 10 carpels, each containing a single seed; no other floral organs are preserved. The gynoecium morphology of C. multicarpellatus is highly complex and involves an enclosed, undifferentiated floral apex, an empty space in the centre of the ovary formed by the postgenital union of the distal parts of the carpels, an irregular apical closure of the ovary, and possibly an extra-gynoecial compitum. Similar gynoecium morphologies have evolved convergently in various angiosperm lineages and are directly linked with the special developmental (architectural) challenges of forming a functional syncarpous gynoecium with many carpels. Among extant angiosperms, C. multicarpellatus is most similar to Dillenia (Dilleniaceae). However, a systematic assignment based on gynoecium characters alone would involve a high level of uncertainty, even if the gynoecial features of C. multicarpellatus are rare among other angiosperms.

Integrating Fossil Flowers into the Angiosperm Phylogeny using a Total Evidence Approach

“…Charcoalified flowers are most commonly represented in Cretaceous sediments, possibly due to increases in paleo-fire regimes during that period (Bond and Scott 2010). This type of fossils have been described mainly from localities in the Eastern United States (Drinnan et al 1990, 1991; Crepet and Nixon 1998; Gandolfo et al 1998; von Balthazar et al 2007; Crepet et al 2018; Friis et al 2020), Portugal (Friis et al 2001, 2019), Sweden (Friis and Skarby 1981; Schönenberger and Friis 2001; Friis and Pedersen 2012), the Czech Republic (Heřmanová et al 2021, 2022), and Japan (Takahashi et al 2001, 2008). The preservation of charcoalified flowers is often exquisite, allowing for the detailed study of morphological and anatomical floral traits.…”

Profile of a flower: How rates of morphological evolution drive floral diversification in Ericales and angiosperms

“…For example, the order comprises both actinomorphic (A-H) and zygomorphic flowers (I), different degrees of fusion between petals, and variable stamen numbers and arrangement (B, D, F, G). often observed that higher levels of synorganization are correlated with a relatively low number of organs in a whorl; for example, the evolution of syncarpous gynoecia constrains the number of carpels (Endress, 2014;Heřmanová et al, 2022). Flowers may also exhibit functional modularity tied to their interaction with pollinators, which may influence the evolutionary rates of characters in different developmental modules (Smith and Kriebel, 2018;Opedal, 2019).…”