A good crop in this year

As you say, a good crop!  Nitpicks:

Adolph Hitler: Should be Adolf (Adolphus is a Latinized form, with -ph- by hypercorrection).

Appaloosa, n. This word for a white horse with dark patches is just begging to antedated: Needs a “be.”

house-train, v. Ostensibly used in reference to infants and dogs: Not sure what you mean by “ostensibly,” but it implies that it was not actually used about infants and dogs, which I suspect is not the case.  “Originally,” perhaps?

Corrections made. Thanks.

Lots of fun, as usual, and a few surprises too. I would have guessed that wisecrack, for instance, was much older.

I need some license

You’ve got it as far as I’m concerned, Dave! All the license in the world, so long as you keep up the game!

“First appearance in the OED” is a convenient way of putting a date to words that made it from other languages into English without being translated, such as lumpenproletariat, zeitgeist, élan, sang-froid, tortilla, etc. Is lumpenproletariat cited in italics? Perhaps the date when such words lose the italics could be considered the date on which they become English words. Or do they become English simply by appearing in the OED, italics or not?

(wishes once more that he had access to the OED. Sighs)

One nitpick I noticed:

Gottlieb Daimler and Karl Benz merge their companies to form Mercedes-Benz

Gottlieb Daimler died in 1900, so it was the companies that merged(Karl Benz was still around).

When a borrowing becomes an “English word” is rather subjective. In some cases, the first citation in the OED may reflect it, other times not. When it loses the italics or parenthetical definition is a good rule of thumb, but that happens at different times for different publications.

The license I was asking for was just for the initial paragraph, specifically lumping the actual Pangaea and velociraptor into the same “long time ago” bin. I want to be accurate when it comes to expressing the dates of the words themselves.

I’ve corrected the Daimler-Benz error. That’s an easy fix. Thanks.

I’m a few days behind, which is not unusual, but I have a quibble with one of the items in the “Events” section:

November: [...] film director Thomas Ince is shot dead by newspaper tycoon William Randolph Hearst

Shouldn’t there be a journalistic allegedly in there somewhere?  I don’t think it was ever conclusively proven that Hearst shot him, or even that he was shot at all.  Snopes labels it “Undetermined.”

While you can’t libel a dead man and I have no fear in that regard, I have corrected it to note that the shooting is “alleged.”