Complex sentence: The second phase of excavation, from 2013 to 2015, included the well-preserved skull "Aroeira 3", but the hardness of the sediment in which it was embedded lead to damage during recovery and had it to be partially reconstructed.
Split into simpler sentences: The second phase of excavation, from 2013 to 2015, included the well-preserved skull "Aroeira 3". The hardness of the sediment in which it was embedded lead to damage during recovery and had to be partially reconstructed.