Thunderbird 'Giant Goose' fossil

Thunderbirds (or dromornithids) are a uniquely Australian family of extinct, giant flightless birds that existed during the Miocene epoch, some 23 to 5 million years ago. This dromornithid specimen, known as Bullockornis planei, stood at 2.5 metres tall and weighed over 250 kg and is a common fossil at the 12 million year old Bullock Creek site in the Northern Territory of Australia. It is believed that they are distantly related to geese and ducks. Due to their massive beaks, Thunderbirds were once thought to be carnivorous predators. There is now strong evidence, such as a lack of claws, that indicates they were probably plant-eating herbivores.