Comparison of even-toed ungulate and cetaceans genetic material has shown that the closest living relatives of whales and hippopotamuses is the paraphyletic group Artiodactyla. Dan Graur and Desmond Higgins were among the first to come to this conclusion, and included a paper published in 1994.
Definition of roundâtrip. : a trip to a place and back usually over the same route.
Definition of travel for English Language Learners. : 1  to go on a trip or journey : to go to a place and especially one that is far away. : 2  to go through or over (a place) during a trip or journey. : 3  to move from one place to another.