The recommendation of 95 degrees for the first week does not take in consideration the breed of chickens or whether large fowl or bantams. It is not a one temp fits all situation. My Australorps are very cold hardy, and when I put them in the brooder at exactly 95 degrees, they immediately started panting and holding their wings away from the body. I had to lower the temps to high 80's when they were two days old, and then quickly had to lower it even more.
Heat stroke is one of the frequent killers of chickens. At less than a week old, chicks cannot regulate their body temperature, so being in the sun could have caused them to die.
You mentioned 'body temp' of 85 degrees. A healthy chicken's body temp should be 103.6 to 110.5 degrees Fahrenheit.