Genre Hallensia Franzen & Haubold, 1986 Hallensia Franzen & Haubold, 1986: 37. TYPE SPECIES. — Hallensia matthesi Franzen & Haubold, 1986 by original designation. INCLUDED SPECIES. — Hallensia parisiensis, Franzen, 1990; Hallensia louisi, Hooker, 1994. EMENDED DIAGNOSIS. — Perissodactyl of medium size (basicranium length: 175 mm) with brachyodont and bunolophodont dentition. Dental formula 3.1.4.3/3.1.4.3. Nasal incisure extending at the posterior border of the I3 alveolus. Upper molars with or without mesostyle and without postprotocrista. Strong cingula on upper molars. M3 with strong hypocone. Upper and lower M3 larger than M2. Lower molars without paraconid. Hypoconulid of m3 relatively large. COMMENT Hallensia is a perissodactyl with a very characteristic morphology. This primitive morphology pushed Franzen & Haubold (1986) to classify it within the phenacodontid condylarths. The discovery of a complete skeleton of H. matthesi in Messel (Germany) indicates that it is a perissodactyl (Franzen 1990), mostly because of the saddle-shaped navicular facet of its astragalus, a synapomorphic feature of perissodactyls (Radinsky 1966).

Published as part of Bronnert, Constance & Métais, Grégoire, 2023, Early Eocene hippomorph perissodactyls (Mammalia) from the Paris Basin, pp. 277-326 in Geodiversitas 45 (9) on page 303, DOI: 10.5252/geodiversitas2023v45a9, http://zenodo.org/record/8037926