Don't remove the moon. A large moon relative to the planet (Say 1:6 mass ratio as our is) stabilizes the axis of rotation, making for a stable set of repeating seasons that the animal and plant life can grow with. Will also want moon to revolve around the planet more slowly than the planet spins.
A very short distance from its star or moon will also affect rotation due to the tidal lock forcing one face to always be pointed toward which ever one has the greatest effect of gravity on it. (The moon always has the same part facing the earth for this reason, and eventually the moon will slow the earth's rotation and the earth will speed the moon's revolution enough that they'll synchronize so that the same part of earth faces the moon at all times - around 45 current earth days.)
Rotation rate about its axis determines length of day as does planet diameter and thickness of atmosphere. A planet with a large diameter or thick atmosphere will appear to have longer days since the star's rays will continue to pass through and bend in the atmosphere to keep it light even as the star dips below the horizon. This can be seen on earth every day.
Angular momentum and gravity are of concern when you change the rotation speed. Our acceleration due to gravity is 9.8m/s/s or 1g. Increase either or both the rotation rate and diameter but keep the mass the same and the inhabitants will feel less gravity. Decrease either and they'll feel more gravity. it's a balance between the three. If the mass is increased as well as the spin rate, but the diameter is kept the same, the force of gravity can remain the same if you want that.
These all affect tides of any body of water on the planet as well as weather. The faster storms caused by the rotation would likely help equalize the temperatures but most likely will cause bands of pressure and temperature like those on Jupiter.
Keep in mind that during the time of the dinosaurs, the earth had only 23 hour days, not 24 and probably had 2-3 hour days when the moon was formed. Life arose early but complex life only arose in the past half billion years or so, so rotation rate would have been probably longer than 18 hours through most of it.
Lots of numbers to crunch, but ask any engineer friend and they can run them for you pretty quickly so you get what you need for your story. We all use these equations in our college studies, so none of it should be hard for them.
Good luck, and if your story gets published, my name is J-P for your contributions page! :)