Gastornis

gastornis was a large predatory bird of the eocene epoch. it didn't have alot of competition exept for creodonts mesonychians arctocyonids and crocodiles. it hunted leptictids and paleotheres like propaleotherium. with animals like propaleotherium it could kick it over with it's powerful legs peck at it with a bone shatering force. it died out when forest started to give way to open grasslands along with mammals like uintatheres pantodonts and condylarths. while the modern mammals continued to thrive and at that time cetaceans took over the oceans.