Complex sentence: These finds extend considerably the known body size range of Mesozoic mammals, "Repenomamus", in fact, were larger than several sympatric small dromaeosaurid dinosaurs like "Graciliraptor".
Split into simpler sentences: These finds extend considerably the known body size range of Mesozoic mammals. In fact, "Repenomamus" was larger than several small sympatric dromaeosaurid dinosaurs like "Graciliraptor".