The last "hot house" or period of increased temperature occurred

The last "hot house" or period of increased temperature occurred during the time of dinosaurs. The temperature in today's world is rising slowly but it is still miles away from the temperature that dinosaurs had to face during "hot house".  

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.