Enigmaleo
Enigmaleo is an extinct genus of carnivorous marsupial from northeast Australia. The genus contains a single species, E. archeri, known from an isolated premolar. It is the fourth thylacoleonid found from Early Miocene-aged deposits. This species is closely related to the diminutive Microleo.
Discovery and naming
The holotype and only known specimen of Enigmaleo, QM F24549, was recovered from the Dirk’s Towers Site at the Riversleigh World Heritage Area, in the Boodjamulla National Park of north-western Queensland. It consists of an isolated upper third premolar.In 2023, Anna K. Gillespie named and described Enigmaleo archeri as a new genus and species of thylacoleonid based on these fossil remains. The genus name is derived from the Greek word for "mysterious", a word specifically chosen to reference the lack of other information about this marsupial lion. The second part of the name is composed of the Latin word for "lion". The species name honours Michael Archer, for his contributions to Australian vertebrate palaeontology and leadership of the Riversleigh fossil project.
Description
The holotype tooth is 5.7 millimetres long. It is similar to other thylacoleonids in that it is blade-like. The anterior and posterior cusps are broadly separated from each other but are connected by a V-shaped longitudinal blade. This blade has a relatively deep notch just in front of the posterior cusp and, unlike in Microleo, is lingually bowed. The tooth's crown lacks buccal and lingual constriction just behind the anterior cusp. The anterior crest has a kink towards its middle, a feature not seen in species of Lekaneleo and Wakaleo. A small, concave longitudinal crest is present at the back of the tooth and is inclined at a moderate angle.Enigmaleo is one of the smallest thylacoleonids, with an estimated weight of 1.05 kg.