They are definitely of a similar profile. Was one of them the first, like was it a sudden new style, that was copied by others or just an aerodynamic evolution from the race cars that preceded it?
Discussion
It more an evolution of designs from the past. You started to see hints of the curvy body style as early 1948 with open wheel roadsters like the Jaguars. It wasn't till around the mid-50's did you see more direct similarities to the cars above at least for coupes. By the early 60's this design style for race cars was in full swing. The style changed again sometime around the mid-70's to be less curvy like you see in the above pics.
Your passion and knowledge is infectious. My lack of interaction with cars means I'm probably only looking at the styling of the car without appreciating the beastly engines that are the real meat. When I was in my early twenties I worked in a boatyard and spent a lot of time stripping down outboard motors, so I'm no stranger to being a grease monkey. The boatyard was shared by a car mechanic and we spent many an hour standing around the beefed up cars that turned up for work. One car that sticks to mind was a Ford Sierra Cosworth, this was in the early 90s, which had been adapted heavily with nitrous, quality brakes etc. In fact it was my bosses' car and we spent a lot of time with me as the wing man as he raced it around town. Sitting at a traffic light at 1am, Skyline pulls up next to us and my boss was all in.... He said, "Watch this".......we left that Skyline in the dust!
Keep posting car stuff.