Complex sentence: Historically, three poorly defined species were recognised in the largetooth group, but in 2013 it was shown that "P. pristis", "P. microdon" and "P. perotteti" do not differ in morphologicy or genetics.
Split into simpler sentences: Historically, three poorly defined species were recognised in the largetooth group. In 2013, it was shown that "P. pristis", "P. microdon" and "P. perotteti" do not differ in morphologicy or genetics.