Mastodon have sadly had to cancel their tour with Dinosaur Jr "due to a critical situation of a member of the Mastodon family." They issued a statement, which reads:

Mastodon regrets to inform fans that due to a critical situation of a member of the Mastodon family, their upcoming tour with Dinosaur Jr. will be cancelled. Tickets and VIP upgrades will be refunded at point of purchase.

Mastodon would like to extend their sincerest thanks to their loyal fans as well as the fans of Dinosaur Jr. for their support and understanding at this time. The band hopes to make up these shows at a future time, but as of now, no plans for rescheduling have been set.

The tour was set to hit Port Chester, MD; Silver Spring, MD; Duluth, MN; Milwaukee, WI; Cleveland, OH; and more. All affected dates are listed below.

Mastodon / Dinosaur Jr -- 2018 Cancelled Tour Dates
09/01 – Edmonton, AB @ North Alberta Jubilee Auditorium
09/02 – Calgary, AB @ Grey Eagle Centre
09/04 – Saskatoon, SK @ O’Brians Event Centre
09/06 – Winnipeg, MB @ Burton Cummings Theatre
09/07 – Duluth, MN @ Duluth Heritage Center
09/08 – Sioux City, IA @ Anthem at Hard Rock Casino
09/11 – Milwaukee, WI @ Eagles Ballroom
09/12 – Cleveland, OH @ Agora Theatre
09/14 – Ft. Wayne, IN @ Clyde Theatre
09/15 – Grand Rapids, MI @ 20 Monroe Live
09/16 – London, ON @ London Concert Theatre
09/17 – Kitchener, ON @ Elements
09/19 – Hamilton, ON @ First Ontario Concert Hall
09/20 – Port Chester, NY @ Capitol Theatre
09/21 – Silver Spring, MD @ The Fillmore