Can you provide a reference?

That's difficult to believe. Was this a diesel locomotive pulling a freight train or was it something smaller/lighter?

Not your correspondent, but trains are quite easy to derail, because they work by sliding orthogonality over the rail, and because otherwise there are way worse crashes.

The cow might not have caused the fatalities directly, but derailment, and a fast train crashing unbound through the landscape has a lot of kinetic energy.

I decided to do a little searching myself, now that I'm at my PC. In 1984 there was 13 killed from derailment from hitting a cow, but that was a "push-pull" train and it wasn't the locomotive that hit the cow, but a much lighter "control car".[1] Another case where the train hit a cow and launched it through the air, and it struck and killed someone.[2]

Also, in [1] there weren't any cowcatchers on the train either. All the trains (besides possibly an old steam locomotive, IDR) that I've seen in my life have cowcatchers and also a locomotive in the lead.

[1] https://mx-schroeder.medium.com/unholy-cow-the-1984-polmont-... [2] https://morningsidekick.com/indian-man-killed-in-freak-train...