Agnotherium is a genus of large sized carnivoran mammals, belonging to the Amphicyonidae ("bear dogs"), which has been found in Western Europe, and possibly China and Northern Africa, and lived during the Late Miocene epoch. Despite only being known from fragmentary remains, the genus notable for hypercarnivorous adaptions, which have been said to represent the "apex" among its family.[1]
The genus Agnotherium was created by Johann Jakob von Kaup, based on a single molar (HLMD Din 1143) found in the Eppelsheim Formation, more well known as Dinotheriensande, located in southwestern Germany. Kaup, who described many Eppelsheim mammals, including such famous ones as Deinotherium, Machairodus and Chalicotherium, named the fragmentary material Agnotherium antiquum.[2] He noted that he only reason he gave a name to this fragmentary taxon was to "draw naturalists' attention to this genus" since it has teeth unlike any animal he had ever seen before. Over the next 180 years the genus was involved in taxonomic uncertainty, with various material being assigned to it, of which most was later thrown out. Kaup himself added to the confusion by renaming his found into "Agnocyon", since the name Agnotherium was "not fitting for a predator".[3] Kuss[4] synonymized the genus Tomocyon with Agnotherium, which led to a second species, A. grivense, being recognized by several authors.[5][6] This, however, has been disputed since,[7][8] and Agnotherium is now regarded as monotypic.[1][9]
In 2017, more material belonging to Agnotherium was unearthed in Eppelsheim, and designated as its paratype (MNHM Epp 117–2017).[1] It consists of a partial left juvenile mandible, with several teeth being either in eruption or still in the crypt. This find served to clarify the understanding of this obscure genus, and even allowed for a reconstruction, the first of its kind, to be made and displayed in the Naturhistorisches Museum Mainz.[10] The new remains also allowed for the confirmation of fossils assigned to Agnotherium from Switzerland,[11] consisting of a partial mandibular ramus (NMB CM 242) and the fragment of a right ulna (NMB CM 243) respectively, and a few isolated teeth (MNCN 79044a-c) from Spain[12] to the genus.[1]
Several remains from Africa, including Kenya[13] and Morocco,[14] have been attributed to Agnotherium, as species A. kiptalami, in the past, but have since been moved to the genus Myacyon.[15][16] Only material from Tunisia[7] has been tentatively assigned to cf. Agnotherium antiquum by Morlo et al.,[1] although if the authors state hat they can't confidently demonstrate that it belongs to the genus, due to the lack of definitive Agnotherium upper teeth to compare them to, while other authors consider it too to belong to Myacyon cf. kiptalami.[15] The Tunisian material consists of a right maxilla fragment (NOM T-370), proximal left radius fragment (NOM T-179) and a metatarsal V (NOM T-2269).
A medium-sized, hypercarnivorous amphicyonid from the Guonigou Fauna of the Linxia Basin has been tentatively assigned to Agnotherium sp.[17]
The name is derived from the Ancient Greek from Greek ἁγνός agnos, "chaste" and θηρίον therium "beast",[18] although it alternatively has been translated as "unknown beast". This translation does not seem to be grammatically correct, but Kaup's original description puts a lot of emphasis on how scarce the remains actually are, so it may be closer to his intention. The species name antiquum come from Latin, and means "old" or "ancient".