Bennettitales (the cycadeoids) were an order of seed plants that appeared in the Triassic period and became extinct toward the end of the Cretaceous. They lived about 250-70 million years ago.
Some were characterized by thick trunks and pinnately compound leaves that bore a superficial resemblance to those of cycads, differing primarily in stomatal arrangement.
Bennettitales consist two groups, the Cycadeoidaceae, represented by Cycadeoidea, Cycadella, and Monanthesia which had stout trunks and bisporangiate strobili (cones serving as their reproductive structures), and the Williamsoniaceae including Williamsonia, Williamsoniella, Wielandella and Ischnophyton which had slender, branching trunks and either bisporangiate or monosporangiate strobili.
At first Bennettitales were considered to be close relatives of the flowering plants but more detailed morphological studies have shown that they are actually more closely related to the cycads, ginkgo and conifers.