Complex sentence: At the Yale Peabody Museum, a skeleton was mounted in 1931 with a skull unique from all the others, while at the time most museums were using "Camarasaurus" casts, the Peabody Museum sculpted a completely different skull.
Split into simpler sentences: At the Yale Peabody Museum, a skeleton was mounted in 1931 with a skull unique from all the others. While at the time most museums were using "Camarasaurus" casts, the Peabody Museum sculpted a completely different skull.