The Lion program was dropped in 1967 when the Webelos program became the 
program for 10 year-olds. The WEBELOS rank
replaced the Lion rank, and the Arrow of Light replaced the Webelos rank. 
Also, in 1967, the Bobcat cloth patch was
introduced.  

1973 - updated Cub Scout program introduced with new colorful insignia for Wolf
and Bear and NEW patch insignia (in addition to pin) for Bobcat.

1980 - Term "Den Mother" officially retired; all male and female leaders of
dens will now be simply called "Den Leaders" and "Assistant Den Leaders".

1986 -  Cub Scouting expands to a four-year program, to include a two-year
WEBELOS Cub Scout program.  Tiger Cubs implemented as separate Pack program 

(source: BSA Fact Sheet: Historical Highlights, BSA #2-551)
http://bsa.scouting.org/factsheets/02-511/index.html