Posterolateral palatal pits

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In anatomy, posterolateral palatal pits are gaps at the sides of the back of the bony palate, near the last molars. [1] 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 (voles, lemmings, and relatives) and Oryzomyini (rice rats and relatives) have more highly developed posterolateral palatal pits. [2] Posterolateral palatal pits are also present in some other rodents, including Glis , Jaculus , Hystrix , Abrocoma , Ctenomys , Chinchilla , and Lagidium . [3]

Contents

Sigmodontinae

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. Oryzomys peninsulae skull ventral PPPs.png
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.

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. [5] 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. [6] The presence of complex posterolateral palatal pits is a synapomorphy either of Oryzomyini [7] or of Oryzomyini minus Mindomys. [8] Members of the genus Nephelomys usually have complex posterolateral palatal pits, recessed into deep fossae, but N. caracolus and N. nimbosus have simpler pits. [9] One of the putative subdivisions within Oryzomyini, Clade D, has posterolateral palatal pits recessed into a fossa as one of its synapomorphies, [10] although the feature is reversed in several subgroups. [11] The extinct island endemic Noronhomys vespuccii also had smaller pits, perhaps because of its short palate. [12]

Among members of the tribe Thomasomyini, posterolateral palatal pits are small or absent. [13] Aepeomys lacks them, [14] but Rhagomys longilingua does have posterolateral palatal pits. [15] The possible thomasomyine Abrawayaomys chebezi has small posterolateral palatal pits. [16]

Members of the Phyllotini tribe always have posterolateral palatal pits. [17] In some species, they are displaced to the back from their usual position just before the mesopterygoid fossa into the fossa. [18] The condition of the pits has been used to separate species of Phyllotis . [19]

The tribe Ichthyomyini is characterized by inconspicuous posterolateral palatal pits. [20]

Arvicolinae

Arvicolinae, a group that includes the voles and lemmings, usually have posterolateral palatal pits, but the configuration of the pits is variable. In some species, the pits do not extend to the ventral face of the palate. [21]

Neotominae

Posterolateral palatal pits are poorly developed or absent in many members of the mostly North American subfamily Neotominae, including Peromyscus (deer mice) and related genera. [22]

Cladistics

The presence and development of posterolateral palatal pits has been used as a character in cladistic analyses of oryzomyines by Weksler (2006), [1] Carleton and Olson (1999), [23] and Carleton and Musser (1989); [24] neotomines by Carleton (1980); [25] and phyllotines by Steppan (1995). [26]

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Oryzomyini Tribe of rodents

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<i>Cerradomys</i> Genus of rodents

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Cerradomys scotti, also known as Lindbergh's oryzomys, is a rodent species from South America in the genus Cerradomys. It is terrestrial and is found in the cerrado (savanna) ecozone of south central Brazil, Bolivia and Paraguay. The species is common and appears to tolerate a degree of agricultural habitat modification.

Nephelomys caracolus, also known as the Costa Central oryzomys or caracol rice rat, is a species of rodent in the genus Nephelomys of family Cricetidae. It is found in cloud forest in the Cordillera de la Costa Central of Aragua, Miranda, and the Distrito Federal in north-central Venezuela at elevations from 1000 to 2500 m. It is nocturnal and terrestrial, and has a varied diet. In most Nephelomys species, the posterolateral palatal pits, perforations of the palate near the third molar, are conspicuous and receded into a fossa, but in N. caracolus and the Ecuadorian species N. nimbosus, the pits are much smaller.

Reigomys primigenus is an extinct oryzomyine rodent known from Pleistocene deposits in Tarija Department, southeastern Bolivia. It is known from a number of isolated jaws and molars which show that its molars were almost identical to those of the living Lundomys. On the other hand, the animal possesses a number of derived traits of the palate which document a closer relationship to living Holochilus, the genus of South American marsh rats, and for this reason it was placed in the genus Holochilus when it was first described in 1996. The subsequent discoveries of Noronhomys and Carletonomys, which may be more closely related to extant Holochilus than H. primigenus is, have cast its placement in Holochilus into doubt, and it was ultimately made the type species of a separate genus, Reigomys.

Hylaeamys acritus, formerly Oryzomys acritus, is an oryzomyine rodent of the family Cricetidae. The name is derived from the Greek word ακριτος 'confused, doubtful', because it could easily be confused with species such as H. megacephalus and Euryoryzomys nitidus. It is known only from northeastern Bolivia; its type locality is within Noel Kempff Mercado National Park. The rodent is terrestrial and is found in moist lowland semideciduous forest and savanna. It has olive brown coloration on its back; the cheeks and flanks are amber, and the top of the head is dark. The coat is 9 mm long at the center of the torso. Chest fur between the front legs is thick and 3 to 4 mm long. Abdominal hairs are gray at the base and white at the top.

Nephelomys nimbosus is a species of rodent in the genus Nephelomys of family Cricetidae. Its type locality is at San Antonio on the northeastern slope of the Tungurahua in the Andes of Ecuador, at an altitude of about 6,700 feet (2,000 m). The type series included five individuals.

Zygomatic plate Bony plate in rodent anatomy

In rodent anatomy, the zygomatic plate is a bony plate derived from the flattened front part of the zygomatic arch (cheekbone). At the back, it connects to the front (maxillary) root of the zygomatic arch, and at the top it is connected to the rest of the skull via the antorbital bridge. It is part of the maxillary bone, or upper jaw, which also contains the upper cheekteeth. Primitively, rodents have a nearly horizontal zygomatic plate. In association with specializations in zygomasseteric system, several distinct morphologies have developed across the order.

References

  1. 1 2 Weksler, 2006, p. 34
  2. ↑ Carleton, 1980, table 7
  3. ↑ Jenkins et al., 2005, appendix 3
  4. ↑ Gardner, 1918, plate I; Carleton and Arroyo-Cabrales, 2009, p. 116
  5. ↑ Weksler, 2006, p. 34; Weksler et al., 2006, p. 17
  6. ↑ Percequillo et al., 2008, table 1
  7. ↑ Voss and Carleton, 1993, p. 31
  8. ↑ Weksler, 2006, p. 124
  9. ↑ Weksler et al., 2006, p. 19
  10. ↑ Weksler, 2006, pp. 130, 138
  11. ↑ Weksler, 2006, pp. 131, 134
  12. ↑ Carleton and Olson, 1999, p. 37
  13. ↑ Voss et al., 2001, p. 129
  14. ↑ Voss et al., 2002, p. 12
  15. ↑ Luna and Patterson, 2003, p. 9
  16. ↑ Pardiñas et al., 2009, p. 45
  17. ↑ Hershkovitz, 1962, p. 23; Steppan, 1995, p. 38
  18. ↑ Steppan, 1995, pp. 38–39
  19. ↑ Hershkovitz, 1962, p. 348
  20. ↑ Voss, 1988, pp. 291, 320
  21. ↑ Hooper and Hart, 1962, p. 51
  22. ↑ Carleton, 1980, table 7; Carleton, 1989, p. 119
  23. ↑ Carleton and Olson, 1999, pp. 36–38
  24. ↑ Carleton and Musser, 1989, p. 50
  25. ↑ Carleton, 1980, p. 44
  26. ↑ Steppan, 1995, p. 39

Literature cited

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