Paleontologist Thomas R. Holtz, Jr. penned “The Twelve Days of Darwin” in the days before Darwin Day on February 12th:
“The Twelve Days of Darwin”
Lyrics by Thomas R. Holtz, Jr., to the Tune of “The Twelve Days of Christmas” (Traditional)
Composed on 5-8 February, 2009, in honor of the Bicentennial of the Birth of Charles Robert Darwin (12 February 1809)On the Twelfth day of Darwin my true love gave to me
Twelve speciations,
Eleven clades converging,
Ten branches diverging,
Nine variations,
Eight ancient fossils,
Seven atolls forming,
Six males displaying,
Five finch beaks,
Four mockingbirds,
Three breeds of doves,
Two tortoise shells,
And a grandeur in this view of life.
The Dispersal of Darwin 
It doesn’t scan!
What doesn’t scan?
“Lyrics by Thomas R. Holtz, Jr., to the Tune of “The Twelve Days of Christmas” (Traditional)”
In several places the given text does not fit the melody of The Twelve Days of Christmas.
Okay, it isn’t an exact fit. Evolution is about “what works best at the moment”, not optimal perfection… 🙂
(That said, in some cases it works by breaking a quarter note into two eighth notes, and so forth).
Thony C.: You must adapt to the textual environment…