Complex sentence: Sauropod feet that were discovered at the same quarry were added, a tail fashioned to appear as earlier Marsh believed it should with too few vertebrae, and a sculpted model of what the museum felt the skull of this massive creature might look like.
Split into simpler sentences: Sauropod feet that were discovered at the same quarry were added, as well as a tail fashioned to appear as Marsh believed it should, which had too few vertebrae. In addition, a sculpted model of what the museum felt the skull of this massive creature might look like.