page_title: Agathaeromys
section_title: Jaws
hierarchical_section_title: Agathaeromys / Description / Jaws
caption_attribution_description: English: Mandible of the fossil oryzomyine rodent Agathaeromys praeuniversitatis from Seroe Grandi, Bonaire (Pleistocene), in labial view. Collection of the Netherlands Center for Biodiversity Naturalis.
context_page_description: Agathaeromys is an extinct genus of oryzomyine rodents from the Pleistocene of Bonaire, Netherlands Antilles. Two species are known, which differ in size and some details of tooth morphology. The larger A. donovani, the type species, is known from hundreds of teeth, found in four localities that are probably 900,000 to 540,000 years old. A. praeuniversitatis, the smaller species, is known from 35 teeth found in a single fossil site, which is probably 540,000 to 230,000 years old.
  Although material of Agathaeromys was first described in 1959, the genus was not formally named and diagnosed until 2010. It probably belongs to "clade D" within the oryzomyine group, together with many other island-dwelling species. The molars of both species possess several accessory crests in addition to the main cusps. In addition to some differences in features of the chewing surface of the molars, A. donovani has more roots on its lower molars than does A. praeuniversitatis.
context_section_description: The maxilla (upper jaw) is known only for A. donovani. In these fossils, the back margin of the incisive foramen (an opening in the palate) is about at the same level as the front of M1, and the back margin of the zygomatic plate (a bony plate at the side of the skull, connected to the zygomatic arch) is also close to the front of M1. Mandibles (lower jaws) of both species are known. The mental foramen (an opening in the front of the jaw bone) opens towards the labial side of the bone, except in one mandible of A. praeuniversitatis, in which its opening is located higher. There is a well-developed capsular process—a raising in the bone that houses the root of the lower incisor. The masseteric ridges (two ridges on the labial side of the bone that anchor some of the chewing muscles) are joined into a single crest towards the front and reach to a point below the front of m1.
  A single mandible from Porto Spanjo (one of the sites where fossils of A. donovani have been found), without preserved molars, differs from all Agathaeromys dentaries and is thought to represent an unknown different sigmodontine rodent. This jaw is more slender than A. donovani dentaries, has a shorter diastema (gap) between the incisors and molars, have the incisor less shifted lingually relative to the molars, and has more roots under the molars, as shown by the preserved alveoli.
caption: A left mandible (lower jaw) of Agathaeromys praeuniversitatis, seen from the outer side. All the teeth are missing.
exif: {}