This is quite sudden, but have you heard of Archaeopteryx? It's an ancient animal of 150 million years ago. The first Archaeopteryx fossil was found in Germany. Seven fossil skeletons have been discovered so far. They look like birds, but also have characteristics of dinosaurs. Archaeopteryx might be an animal in the intermediate stage of evolution from dinosaurs to birds.
The same is true of trains. Please look at the top photo. It's set 3828 (hereafter 3828F) of the EMU Keisei 3700 series. 3828F has stainless-steel bodies with beads on the side surfaces. A gangway and a train type display are located in the center left of the front. They're the same as the standard sets of the 3700 series. On the other hand, the positions of two front lights are upper left and right. Tail lights and express lights are wider and longitudinally arranged on the front. They're different from the standard sets of the 3700 series. They're more like the younger model, namely the 3000 series. In conclusion, 3828F seems a train in the intermediate stage of evolution from the standard 3700 series to the newer 3000 series.
3828F was built in 2000 as the 6th batch of the 3700 series. The newer model, namely the 3000 series, was developed in 2002, just after the manufacturing of 3828F. The design of the new model was inherited from the 6th batch trains of the 3700 series including 3828F. As a trainspotter, it's fun for me to perceive fine differences between trains.
