page_title: Posterolateral palatal pits
section_title: Sigmodontinae
hierarchical_section_title: Posterolateral palatal pits / Sigmodontinae
caption_attribution_description: English: Skull of a specimen of Oryzomys peninsulae in ventral view, with the posterolateral palatal pits (recessed into a fossa in this species) indicated by a red circle.
context_page_description: In anatomy, posterolateral palatal pits are gaps at the sides of the back of the bony palate, near the last molars. Posterolateral palatal pits are present, in various degrees of development, in several members of the rodent family Cricetidae. Many members of the family lack them or have only simple pits, but Arvicolinae and Oryzomyini have more highly developed posterolateral palatal pits. Posterolateral palatal pits are also present in some other rodents, including Glis, Jaculus, Hystrix, Abrocoma, Ctenomys, Chinchilla, and Lagidium.
context_section_description: Many members of the mainly South American cricetid subfamily Sigmodontinae have posterolateral palatal pits.
  In Oryzomyini (rice rats), the largest tribe of the Sigmodontinae, all but some species—Mindomys hammondi and Sigmodontomys aphrastus usually have only one small pit on each side of the palate—have prominent posterolateral palatal pits, often more than one on each side of the palate. In many oryzomyines, the pits are located in a deep depression or fossa. This depression has been termed the "palatal fossa" in the genus Cerradomys; its varying depth serves as a diagnostic character separating some of the species. The presence of complex posterolateral palatal pits is a synapomorphy either of Oryzomyini or of Oryzomyini minus Mindomys. Members of the genus Nephelomys usually have complex posterolateral palatal pits, recessed into deep fossae, but N. caracolus and N. nimbosus have simpler pits. One of the putative subdivisions within Oryzomyini, Clade D, has posterolateral palatal pits recessed into a fossa as one of its synapomorphies, although the feature is reversed in several subgroups. The extinct island endemic Noronhomys vespuccii also had smaller pits, perhaps because of its short palate.
  Among members of the tribe Thomasomyini, posterolateral palatal pits are small or absent. Aepeomys lacks them, but Rhagomys longilingua does have posterolateral palatal pits. The possible thomasomyine Abrawayaomys chebezi has small posterolateral palatal pits.
  Members of the Phyllotini tribe always have posterolateral palatal pits. In some species, they are displaced to the back from their usual position just before the mesopterygoid fossa into the fossa. The condition of the pits has been used to separate species of Phyllotis.
  The tribe Ichthyomyini is characterized by inconspicuous posterolateral palatal pits.
caption: The western Mexican oryzomyine Oryzomys peninsulae (skull, seen from below, with left posterolateral palatal pits indicated by a red circle) has the pits recessed into a fossa.[4]
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