Why is there a comma in "University of Texas, Austin" but not after?

Solution 1:

According to The Chicago Manual of Style, you need a comma both before and after Austin:

“There is broad agreement that the causes^* of the dinosaur and pterosaur extinctions were one and the same,” University of Texas, Austin, paleontologist Brian Andres says.

From 6.39: Commas with addresses (login required):

Some institutional names include place-names set off by commas. When such a name appears in the middle of a clause, a second comma is required to set off the place-name. See also 6.81.

California State University, Northridge, has an enrollment of . . .

but

The University of Wisconsin–Madison has an enrollment of . . .

This is the same for cities with states/countries in text:

Waukegan, Illinois, is not far from the Wisconsin border.

The plane landed in Kampala, Uganda, that evening.

And similar the comma before and after a year:

The performance took place on February 2, 2006, at the State Theatre in Ithaca.

Style guides may vary on this topic. Consult with your institution or editor as to which guide you should follow.

_{^*Since this is a quote, the writer and speaker both may be forgiven for not using causes plural in the original.}

Solution 2:

First of all, just in case there's any confusion, there are several schools all named "University of Texas," and this is the one in the city of Austin. This phenomenon is common in US States. So "University of Texas, Austin" is being used as one big phrasal noun. However, it appears that the most official form is "University of Texas at Austin", which would avoid the problem. And personally, I'd be inclined to hyphenate the whole thing: "... and the same,' University-of-Texas-at-Austin paleontologist Brian Andres says." (Wait, strike that, that's horrible. What's wrong with "... says Brian Andres, paleontologist at University of Texas at Austin"? (Aside from the at-at.))

But to answer your central question: No, even if this were a good construction, you wouldn't need to "close" the comma after "Austin." If you wrote: "Los Angeles, California, is a big city," you would be setting up "California" as an apposition, suggesting that it's the same thing as "Los Angeles." See also https://owl.purdue.edu/owl/general_writing/punctuation/commas/commas_with_nonessential_elements.html for using enclosing commas around "essential" phrases.

But while we're at it, there's a subject-verb disagreement in "the cause of ___ and ___ were one and the same," most likely because the author isn't actually thinking about the sentence but just reached reflexively for the plural because the preceding word, "extinctions," is plural. I don't think I'd put too much stock in how they handle a comma.