english: And he's looking at them by looking at the embryo genesis of birds and actually looking at how they develop, and he's interested in how birds actually lost their tail.
non_english: Zaoberá sa tým, že skúma pôvod embryí vtákov a sleduje, ako sa embryá vyvíjajú. Zaujíma sa tiež o to,  ako vlastne vtáky prišli o chvost.