The following video makes a case for the idea that the diameter of the Earth is expanding. http://www.youtube.com/watch?v=VjgidAICoQI&mode=related&search . What's not mentined in the video, is the observed evidence that supports such a theory--the slowing of the Earth's rotational rate, which is observed to be decelerating at about 2 milliseconds per day per century --
The deceleration of the Earth's rotational speed is caused by the conversation of angular momentum--mass stays the same, diameter increases, so rotational velocity must decrease.
Given how much the diameter has increased from dinosaur days, the cross-sectional area of the Earth as viewed from the sun would have increased significantly. This increase in thermal flux would result in an increase in the temperature of the Earth, all things being equal. This change in thermal flux over time may help explain a lot of open ended questions about the history of the Earth's climate.