From Fallen London Wiki
You're right, that one's totally new! Thanks for the tip, I've started the page here: <a href="/wiki/Support_the_Prehistoricist_Tracklayers%27_desire_to_build_a_Tracklaying_Beast" title="Support the Prehistoricist Tracklayers' desire to build a Tracklaying Beast">Support the Prehistoricist Tracklayers' desire to build a Tracklaying Beast</a>. It looks like the new option is only available after completing the railway, and doesn't require Cornelius but does require a charter. Just, y'know, for every who regrets not building a dinosaur.