cycadeoids

Cycadoids are an extinct group of seed-bearing plants that flourished during the Mesozoic Era. They are characterized by their stout, woody trunks, often unbranched, topped with a crown of large, compound leaves. These leaves, while superficially resembling those of modern cycads, are structurally distinct. Fossil evidence suggests that cycadoids were dioecious, meaning individual plants bore either male or female reproductive structures, called strobili. These strobili were often cone-like and varied in size and shape depending on the species.

The phylogenetic placement of cycadoids has been a subject of considerable debate among paleobotanists. Historically, they were grouped with cycads due to their similar overall appearance. However, modern analyses, incorporating detailed anatomical and morphological studies of fossil specimens, suggest that cycadoids represent a separate lineage within the seed plants, potentially more closely related to conifers or other gymnosperm groups. Their ecological role was significant; they formed a prominent component of Mesozoic vegetation, particularly in warmer, drier environments. Examples of well-known cycadoids include the genera Cycadeoidea and Beania. Their extinction is thought to have occurred by the end of the Cretaceous period, likely due to a combination of environmental changes and competition from more evolutionarily advanced flowering plants.