Why did the sigillaria plant become extinct?

The sigillaria plant became extinct primarily due to significant climatic changes during the late Paleozoic era, particularly the transition from the Carboniferous to the Permian period, which led to widespread environmental shifts. These changes included a decline in the humid, swampy conditions that favored the growth of these large, tree-like plants. Additionally, increased competition from other plant species and the impact of herbivorous animals contributed to their decline, ultimately resulting in their extinction.