Just throwing this out there (I'm uncertain if this has been posted before and apologise in advance if I'm just covering old topics) but I have been thinking lately about how a massive change in rotational speed caused possibly by the asteroid presumed to have wiped out the dinosaurs may help explain certain aspects regarding the Cretaceous-Tertiary mass extinction and also the rise of mammals and other species. Firstly I want to ask of what the environment and conditions of the Earth were like prior to the impact, and the consequences that would result from such an event "If the Earth was rotating at twice it's current speed before the strike". The Earth rotates at approximately 1070 miles/hr which means if the Earth was rotating twice as fast we would be spinning at approx 2140 miles/hr and an Earth day would be 12 hours. So from what I understand (with only a basic understanding of astrophysics) gravity holds us to the Earth but is also compensated by centrifugal force which is created from the spinning action of the planet and it is this balance of forces which creates the effects that keep us from not flying off the planet as we spin and also not having crushing gravitational forces upon our bodies. So if the mass of the Earth was basically the same (prior to the event) as present time but the rotational speed was doubled prior to the event as I have suggested, in theory would the effect of gravity be far less? So basically theorising the impact not only suddenly slowed the rotational speed of the Earth but also inflicted massive gravitational forces upon the Earth environment in a short time frame. Now looking at the body shapes of massive dinosaurs and how seemingly massive cumbersome designed creatures were so prolific during the Cretaceous Period makes me question whether an environment with less gravitational forces (Prior to the Impact) could explain their design and when they were subjected to sudden massive gravitational forces as well as the massive ash clouds soon after the impact occurred they were unable to sustain ease of mobility to escape the disaster (Including ocean species). They would simply be to heavy to maintain their previous speed and strength and in most cases would basically fall where they stood or perish soon after (Which also may explain archaeological discoveries locations and positioning). This could then lead to the survival of less cumbersome species such as mammals and also this may explain why species prior to the impact were often led to evolve for flight as with less gravitational force would encourage animals to the sky and our modern birds are simply evolutionary adaptations from those early flighted species. Perhaps the sudden gravitational forces inflicted also is what invited our early primates ancestors from the trees to the land as it was no longer as simple to jump from tree to tree. Ouch!!! On a metaphysical aspect perhaps now having a day lasting twice as long also inspired early primates to creatively think more as they now had twice as much time during the day to utilise as they were no longer restricted to a 12 hour day night cycle and also they didn't have those pesky dinosaurs to worry about *I am only using the 1/2 speed rotation measure purely as just a reference and I don't claim to estimate what the possible rotational speeds may have been prior to the impact according to the theory just the consequences. Anyway it is just a theory and I am by no means stating this is fact but I am looking forward to your input and your ideas and hope at the least it is some food for thought. Again I apologise if this has been covered or it is in the wrong forum section.