Demaryius Thomas is lucky to be alive today -- let alone healthy and ready to play in the NFL -- 'cause TMZ Sports has obtained pics of his car crash ... and the scene is gnarly.
Thomas was doing 70 MPH in a 30 MPH zone in Denver at around 12:20 AM on Feb. 16 when he lost control of his SUV and crashed it into a curb.
One witness tells us the car flipped several times before coming to a stop right-side-up ... dozens of yards from where it took off from.