As a starting point for development, consider the World of the Shapgapsh.
Astronomically, and geologically, it resembles Earth in the Triassic. The continents are arranged in a way plausible with the evidence extant for the period, the day lasts just over 21 hours, the year is 372.4 days, the lunar month is 26 days (giving 14.32 of them per year). the climate is very hot, and most of the planets are there as you would expect. Neptune isn't there, for some reason.
There is one Continent, stretching from pole to pole. There is a northern and a southern subcontinent at both ends of the continent, extending significantly eastwards into the Ocean, embracing a subocean. The continent is divided into five broad climatic zones: The north polar region, not extending far below 50°N (on Earth, about the latitude of London and Vancouver) has a pleasant temperate climate, high relief and a complex coastline featuring a 'mediterranean' inland sea, which hosts civilisation in the North, all serving to cool it down somewhat; a wide torrid zone extends from 50°N to 40°S, with a band of exceedingly hot tropical wetlands about 10°N to 20°N; The southern polar zone begins around 40°S. The relief is generally lower, and is marked by the absence of any major inland seas, although there is a substantial archipelago of a dozen or so islands around the pole.
Random river names: Cool, Refreshing, Mighty, Embarrassing, Cupful, Summery, Poison, Slaked, Acerbic, Diehard, Fond, Rhombus, Dormant, Junkyard, Pyramid, Honest, Funniest, Carbide, Special, Slurring, Abridged, Soybean, Humpback, Warlock, Log, Criminal, Bricklayer