“Why didn’t the skeleton cross the road?”/“He didn’t have any guts.”

“Why did the chicken cross the road?”/“To get to the other side” is a classic riddle from the 19th century. A skeleton version is:
     
Q: Why didn’t the skeleton cross the road?
A: He didn’t have any guts.
   
The joke has been cited in print since at least 1972 and has been printed on several images.
   
“Why did the skeleton cross the road?”/“To get to the body shop” is a related riddle.
   
       
Newspapers.com
7 October 1972, Indiana (PA) Evening Gazette, “Mini Jokes,” The Mini Page, pg. 3, col. 1:
Q. Why didn’t the skeleton cross the road?
A. He didn’t have the guts.
Karen Strong—Brush Valley
 
10 February 1973, Progress-Bulletin (Pomona, CA), “More Mini Jokes,” The Mini Page, pg. 3, col. 4:
Q: Why didn’t the skeleton cross the road?
A: He didn’t have the guts.
Rebecca Pegdanganan, 9
Chaparral School
Claremont
 
19 November 1975, Austin (TX) American-Statesman, “Fun Time—The Riddle Box” by A. Leokum,  pg. 39, col. 5: 
Why didn’t the skeleton cross the road?
He didn’t have enough guts.
 
24 February 1977, The Morning Union (Springfield, MA), “Fun Time—The Riddle Box” by A. Leokum,  pg. 55, col. 2:
Why didn’t the skeleton cross the road?
He didn’t have the guts.
 
Google Books
March 1996, Boys’ Life, “Think & Grin,” pg. 57, col. 1:
Pee Wee: Why didn’t the skeleton cross the road?
Pedro: Beats me.
Pee Wee: Because he had no guts. — Tian Xie, Newton, Mass.
     
Google Books
Kids’ Nuttiest Jokes
By Mike Benny
New York, NY: Sterling Publishing Company, Inc.
2003
Pg. 11:
Why didn’t the skeleton cross the road?
It didn’t have the guts.
 
Google Books
The Super, Epic, Mega Joke Book for Kids
By Whee Winn
Grand Rapids, MI: Zonderkidz
2016
Pg. ?:
Why didn’t the skeleton cross the road?
He didn’t have any guts.
 
International Business Times
Halloween Jokes 2017: 25 Funny Riddles And Trivia To Share With Kids
BY SUMAN VARANDANI @SUMAN09 ON 10/25/17 AT 7:48 AM
(...)
3. Why didn’t the skeleton cross the road? Answer: He didn’t have any guts.