Simplify the following text for a Grade 10 native English-speaking person.
Original: Although his collection still contained more than 13,000 specimens , Cope 's fossil hoard was much smaller than Marsh 's collection , which was valued at over a million dollars .
Simplified: While his collection contained more than 13,000 specimens , Cope 's fossil hoard was still much smaller than Marsh 's collection , valued at over a million dollars .