Gerbillini
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Fat sand rat ( Psammomys obesus ) |
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| Scientific name | ||||||||||||
| Gerbillini | ||||||||||||
| JE Gray , 1825 |
The Gerbillini include here in the rank of a tribe the gerbils called "typical" and are divided into the "lower gerbils" (Gerbillina), the "higher gerbils" (Rhombomyina) and the bush-tailed gerbil . Depending on the system, a different rank is used for the "typical gerbils" or other gerbil species are assigned to them.
Its distribution area is northern and eastern Africa and Asia east to Mongolia , Manchuria and India . In Asia they are known from the Upper Miocene , possibly from the Lower Pliocene and from the Upper Pliocene to the Holocene , in Africa from the Upper Pliocene to the Holocene and in Eastern Europe from the Holocene.
With about three quarters of the species they make up the majority of the gerbils and they are very diverse. Regarding some essential features of the skull and molars, they include both the most generalized and the most specialized representatives of the gerbils.
Body features
skull
In contrast to those of most taterillins and the Somali gerbil , the bony components of the chewing apparatus are not that specialized in most “typical gerbils”. The keel of the zygomatic plate is not really elongated. Rather, in some “higher gerbils”, the vertical expansion of the plate leads to an increase in the original surface of the masticatory muscle . An orbital shield is not very developed.
The main derived common feature of the "typical gerbils" is the way in which the wart part of the tympanic bladder is inflated. The inflation results from the penetration of the tympanic cavity into the wart part, mainly from below . It begins with a reduction in size of the parasubarceal fossa due to penetration of the tympanic cavity from both below and in front. Both penetration paths meet in the middle of the wart part and a diagonally lying septum ( septum mastoideum ) is formed, which separates the anterior atrium ( antrum epimastoideum ) and the lower atrium ( antrum tympano-mastoideum ). This expression can be found in the genus Dipodillus .
In contrast to the advanced representatives of the taterillins, the subsequent inflation only involves the lower atrium. The septum of the mastoid cavity is thus moved forward into a vertical position and the antrum tympano-mastoideum fills almost the entire wart part. At the same time, the lower septum ( septum tympano-mastoideum ) moves upwards in relation to the suture between the tympanic bone and the wart and an additional lower septum ( septum mastoideum ventralis ) is created at the suture . This forms the lower limit of the mastoid cavity to the tympanic cavity and delimits the additionally forming lower atrium ( antrum mastoideum ventralis ).
Finally, the expansion of the mastoid wall to the rear leads to the formation of a septum arch, which connects the posterior semicircular canal ( canalis semicircularis posterior ) with the mastoid wall and the opening of an additional posterior cell ( cellula mastoidea posterior ) of the mastoid process into the antrum tympano-mastoideum limited. With the antrum tympano-mastoideum , the fairly large antrum mastoideum ventralis and the cellula mastoidea posterior , the wart part of most representatives of the "typical gerbils" with completely inflated tympanic bladders is the most complicated of all gerbils.
denture
| 1 | · | 0 | · | 0 | · | 3 | = 16 |
| 1 | · | 0 | · | 0 | · | 3 |
The transformation of the dentition of the “typical gerbils” generally follows the development from the original, relatively low-crowned and blunt-humped type of molars to the advanced, high-crowned , prismatic type. From the latter, the rootless molars of the gerbil, unique within the gerbil, developed .
Apart from small outgrowths of the tooth cusps , which appear as the attachment of minor humps in some "lower gerbils" with blunt-humped molars, no minor humps have been preserved. The original, blunt-humped type is characterized by main bumps, which remain clearly separated from each other for quite a long time, as well as by an original asymmetry. Both the size of the main bumps and the side indentations are very different. The metaconus is the smallest main cusp and the paraflexus and hypoflexus of the first maxillary molar are the widest indentations. This original asymmetry is passed on to the semi-prismatic type, which differs from the actual prismatic type of the "higher gerbils". This is the simplest type, especially the Przewalski gerbil . The anteroconid of the mandibular first molar is of the simple, diamond-shaped type. However, according to Petter (1973) and Pawlinow (1984), a horseshoe type occurs in some specimens of Dipodillus and gerbils in rare cases. This can be interpreted as a retrograde morphotype and thus indicates that the diamond-shaped type in the gerbils probably evolved from the horseshoe type.
The tooth roots , like the molar crowns, are simplified and the middle root is reduced in size.
Systematics
Internal system
The "typical gerbils" are listed here as the Gerbillini tribe with the following subgroups:
- the "lower gerbils" (Gerbillina) in Africa and Asia,
- the "higher gerbils" (Rhombomyina) also in Africa and Asia as well
- the bush-tailed gerbil ( Sekeetamys calurus ) in Egypt and neighboring Asia.
Very varied in appearance , they look like an artificial grouping. However, their tribal history is well supported by morphological and molecular genetic characteristics. Only the affiliation of a few genres is uncertain and their systematic assignment is therefore handled differently. There is also some disagreement about the number and composition of the subgroups.
Today's phylogenetically oriented systematists distinguish between two subgroups, the "lower gerbils" with the actual gerbils and other representatives, and the "higher gerbils" with the racing rats and related species. The “lower gerbils”, which are generally very similar to one another, are grouped together on the basis of original similarities , while the “higher gerbils” are based on derived similarities between the molar crowns and the sound conduction apparatus. The assignment of the bush-tailed gerbil within the "typical gerbil" is uncertain. It is viewed either as a specialized "lower gerbil" or as a generalized "higher gerbil".
The fat-tailed gerbil may have been assigned to the "higher gerbils" due to an error. Derived peculiarities justify their special position and that of the brewer gerbil within the "typical gerbil ". Molecular genetic studies even suggest a common basal position of the two morphologically very peculiar species within the gerbil. The same studies see the little bare-soled gerbils , which, based on morphological investigations , were placed with the gerbil urines without exception , as a sister group of the “typical gerbils”. The Cape short-tailed gerbil was also placed on the basis of the "typical gerbils" because of a possibly incorrectly assumed correspondence in the wart part.
History of the system
Based on the construction of the molars, Vladimir Georgievich Geptner divided the gerbil family into three subfamilies in 1933 . However, he did not yet recognize the commonality of the “typical gerbils” and distributed them to all three subfamilies. Even from Francis Petter's genealogical scheme from 1975, which is also based on the construction of the molars, it is not yet possible to deduce any togetherness.
They were first recognized as belonging together in 1977 by Jean Chaline . Based on the degree of inflation of the wart part, this divided the non-extinct gerbils into two subfamilies and assigned all "typical gerbils" to the subfamily Gerbillinae. Igor Jakowlewitsch Pavlinow came to a similar conclusion in 1982 based on the type of distension of the wart part and, to a lesser extent, on the structure of the molars and other morphological features. He ordered as "typical" ( english typical ) Gerbils designated including the Brewers gerbil and pachyuromys the Gerbillinae, informing them on to four tribes. He presented the ancestral relationships as follows:
| Gerbils (Gerbillidae) |
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In 1989 Haiyan Tong assigned the fat-tailed gerbil to the “higher gerbils” and the brewer gerbil and the Cape short-tailed gerbil in descending basal order within the “typical gerbils”. He presented the phylogenetic relationships based on the bloating of the wart part as follows:
| Gerbils (Gerbillidae) |
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Cytogenetic investigations of the chromosomes as well as allozyme analyzes (Benazzou, 1984) and molecular genetic investigations using DNA / DNA hybridization (Chevret, 1994) provided only moderate support for the "typical gerbils" as a family group.
Molecular genetic studies of mitochondrial cytochrome - b - and 12S - rRNA genes by Pascale Chevret and Gauthier Dobigny 2005 confirmed they clearly against it. Chevret and Dobigny also found that the brewer gerbil and the fat-tailed gerbil had a common sister group relationship to all other gerbils, as well as a sister group relationship between the bare-sole gerbils and the "typical gerbils" supported with a bootstrap value of more than 90 percent. Chevret and Dobigny gave the ancestral history as follows:
| Gerbils (Gerbillidae) |
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Tribal history
According to the investigations by Chevret and Dobigny (2005) using a relaxed molecular clock , the “typical gerbils” split from the bare-sole gerbils about 8.52 million years ago, i.e. in the Upper Miocene, and into about 7.57 million years ago the "lower" and the "higher gerbils". The bush-tailed gerbil and the real gerbil separated from each other about 5.97 million years ago. The split between house mouse and brown rat , which was set at an age of 12.84 million years, served as calibration . A relationship of the fossil genera Pseudomeriones , Epimeriones and Mascaramys to the “typical gerbils”, especially the “higher reindeer mice”, was discussed. They were also assigned the fossil genus Abudhabia .
Africa is assumed to be the original range of the "typical gerbils" and the individual groups may have spread to Asia separately from one another.
literature
Used literature:
- Pascale Chevret, Gauthier Dobigny: Systematics and evolution of the subfamily Gerbillinae (Mammalia, Rodentia, Muridae) . In: Molecular Phylogenetics and Evolution . tape 35 , no. 3 , 2005, ISSN 1055-7903 , p. 674-688 , doi : 10.1016 / j.ympev.2005.01.001 .
- Malcolm C. McKenna, Susan K. Bell: Classification of Mammals Above the Species Level . Columbia University Press, New York 1997, ISBN 0-231-11012-X (631 pages).
- Pawel Alexandrovich Panteleev: The Rodents of the Palaearctic: Composition and Areas . Russian Academy of Sciences, Moscow 1998, ISBN 5-86695-002-2 (116 pages, Russian title: Грызуны Палеарктики: состав и ареалы; pp. 98-101).
- Igor Jakowlewitsch Pawlinow: A review of phylogeny and classification of Gerbillinae (Mammalia: Rodentia) . In: Soologicheskie issledovanija . No. 9 , 2008, ISSN 1025-532X , p. 1-68 .
Literature used indirectly:
- Touria Benazzou: Contribution à l'étude de l'évolution chromosomique et de la diversification biochimique des Gerbillidés (Rongeurs) . University of Paris 11 1984 (doctoral thesis).
- Jean Chaline, Pierre Mein, Francis Petter: Les grandes lignes d'une classification evolutive des Muroidea . In: Mammalia . tape 41 , no. 3 , 1977, ISSN 0025-1461 , pp. 245-252 .
- Pascale Chevret: Etude évolutive des Murinae (Rongeurs: Mammifères) africains par hybridation ADN / ADN. Comparaison with the approches morphologiques et paleontologiques . University of Montpellier 2 1994 (doctoral thesis).
- Wladimir Georgijewitsch Geptner: Notes on the Gerbillidae (Mammalia, Rodentia). V. On the classification of the Gerbillidae . In: Zoologischer Anzeiger . tape 102 , no. 3/4 , 1933, ISSN 0044-5231 , p. 107-112 .
- Igor Jakowlewitsch Pawlinow: [Phylogeny and classification of the subfamily Gerbillinae] . In: Bjulleten Moskowskowo obschtschestwa ispytatelei prirody. Otdel biologically . tape 87 , no. 2 , 1982, ISSN 0027-1403 , pp. 19–31 (Russian with English summary).
- Igor Jakowlewitsch Pawlinow: [Evolution of the dental crown pattern in Gerbillidae] . In: Sbornik trudow Soologitscheskowo museia MGU . tape 22 , 1984, ISSN 0134-8647 , pp. 93–134 (Russian with English summary).
- Igor Jakowlewitsch Pavlinow, Ju. A. Dubrowski, Olga Leonidowna Rossolimo, Je. G. Potapova: [Gerbils of the World] . 1990, ISBN 5-02-005350-3 (364 pages; original Russian title: Песчанки мировой фауны).
- Francis Petter: Tendances evolutive dans le genre Gerbillus (Rongeurs, Gerbillides) . In: Mammalia . tape 37 , no. 4 , 1973, ISSN 0025-1461 , pp. 631-636 .
- Francis Petter: La diversite des Gerbillides . In: Monogr. Biol . No. 28 , 1975, p. 177-183 .
- Haiyan Tong: Origine et évolution des Gerbillidae (Mammalia, Rodentia) en Afrique du Nord . In: Mémoires de la Société géologique de France, nouvelle série . No. 155 , 1989, ISBN 2-85363-050-1 , ISSN 0249-7549 , pp. 1-120 .
Individual evidence
- ^ Pavlinow, 2008 (pp. 56-58).
- ↑ Panteleev, 1998 (pp. 95-101).
- ↑ a b McKenna and Bell, 1997 (p. 158).
- ↑ a b c d e Pawlinow, 2008 (p. 42).
- ↑ Pawlinow, 2008 (p. 42, Fig. 1c).
- ↑ a b c Pawlinow, 2008 (p. 42, fig. 7e – f).
- ↑ Pawlinow, 2008 (p. 42, Fig. 4a, Fig. 4f – j).
- ↑ Pawlinow, 2008 (p. 42, Fig. 5e – f).
- ↑ a b c Pawlinow, 2008 (p. 43).
- ↑ Pavlinow, 2008 (p. 52).
- ↑ Geptner, 1933. → Quoted in: Pawlinow, 2008 (p. 31).
- ↑ Petter, 1975. → Quoted in: Pawlinow, 2008 (p. 28, Fig. 10a).
- ↑ Chaline and colleagues, 1977. → Quoted in: Pawlinow, 2008 (p. 31).
- ^ Pawlinow, 1982. → Quoted in: Pawlinow, 2008 (p. 31).
- ↑ Pawlinow and colleagues, 1990. → Quoted in: Pawlinow, 2008 (pp. 31–32, Fig. 10b).
- ^ Tong, 1989. → Quoted in: Pawlinow, 2008 (p. 43).
- ↑ Tong, 1989. → Quoted in: Pawlinow, 2008 (p. 32, Fig. 10c).
- ↑ Benazzou, 1984. → Quoted in: Chevret and Dobigny, 2005 (Fig. 1C – D)
- ↑ Chevret, 1994. → Quoted in: Chevret and Dobigny, 2005 (Fig. 1E).
- ↑ Chevret and Dobigny, 2005 (Fig. 3).
- ↑ Chevret and Dobigny, 2005 (Table 5).
- ↑ Chevret and Dobigny, 2005 (p. 686, fig. 4).