IIRC the original Shuttle design called for an ejection mechanism around the entire cockpit. During STS-1 and I believe STS-2, which was also Colombia, there were extra emergency mechanisms present, but I don’t think the seats themselves ejected through the roof like a fighter pilot’s would. For the most part though these were useless as they could not be used above 30,000 feet or something like that so it could only be used during the first minute or two of the flight.

Several of the safety mechanisms and other things that were going to be part of the original design that had not already been scrapped for weight (like jet engines for powered decent) were scrapped for weight when the DOD stepped in and offered NASA extra money for the Shuttle if the Shuttle could hit very specific, higher and less fuel efficient, orbits. This came from an offhand comment that Jimmy Carter made, and then had to make good on the threats and implications of.