Marsupial lions, also known as thylacoleonids, are an extinct family of marsupials that were present in Australia from about 24 million years ago up until the end of the Pleistocene era, about 30,000 years ago. At present, the thylacoleonid family contains nine species, five of which belong to the genus Wakaleo.
The distinguishing feature of marsupial lions is the presence of lengthened premolar teeth that form a pair of secateur-like blades. This feature – massively developed in the most recent member of the family, Thylacoleo carnifex – led to them being named a “marsupial lion” by the 19th century palaeontologist Sir Richard Owen.
A new species was discovered by fossil remains in 2017. Wakaleo schouteniwas the size of a Collie dog and weighed about 23 kilograms.