This dinosaur skeleton is a good reminder of the square/cube scaling laws. How was it possible to have such large land animals, not to mention flying insects with a 2-foot wingspan? Well, one major factor is a much thicker atmosphere than now. More oxygen, easier breathing = larger animals. I think it was something like twice as thick during some portion of the dinosaur era. And CO2 levels were also much higher. If memory serves, the sun was also a bit brighter back then. So, imagine the “greenhouose effect” during that time! No wonder ice at the polar caps (called an ice age) is a relatively recent phenomenon! Next time someone tries to tell you the Earth is about to go the way of the next closer planet to tyhe sun (Venus) with their 800 degree Fahrenheit surface temps, let them know that even with twice the atmosphere, higher insolation, and many times the CO2 we have today, Earth was still a comfortable place to live, as long as you didn’t end up as dino-lunch! 