Platacanthomyidae

Südindischer Stachelbilch ( Platacanthomys Lasiurus )

The Stachelbilche ( Platacanthomyidae ), also known as "thorn Hyraxes " are a associated with the mouse -like family of rodents. With the South Indian and the Chinese Stachelbilch Zwergbilch they are widespread in the southern and southeastern Asia. Because of dental features were formerly often associated with the Bilchen, where the two are very different, tree-dwelling species also resemble externally especially because of its bushy tail.

Characteristic within the mice -like the brush-like ending tail, the notches on the upper incisors, the flat chewing surfaces of molars, the melting pattern is formed by mutually parallel, oblique rows of elongated ridges and valleys, the small muscular process of the lower jaw, the enlarged foramen palatine posteriorly between the first upper molars, the fusion of the palatine foramen dorsal to the foramen sphenopalatine, the absence of the accessory foramen ovale and the large maxillary posterior foramen.

• 4.1 Outer systematics
• 4.2 Internal systematics
• 4.3 nomenclature

Physique

Appearance

Stachelbilche are relatively small mouse -like with bilchartigem physique. Your head-body length is 118-140 mm in the South Indian Stachelbilch and 70 to 89 millimeters at the Chinese Zwergbilch. The slightly bushy tail is the South Indian Stachelbilch shorter than the head -body length, the Chinese Zwergbilch he is against it longer. The rear two-thirds of the tail resemble a bottle brush. The coat is in the South Indian Stachelbilch prickly, the Chinese Zwergbilch however, it is dense and soft. The whiskers on the muzzle are long. The paws are small and slender, and the toes are moderately long. Are located on the front feet four toes with claws and a rudimentary thumb nail and on the hind paws are five toes. The soles of the front and hind feet are naked and have six bales. The females of the South Indian Stachelbilchs have two teats and the Chinese Zwergbilchs four.

Skull and teeth

The skull of Stachelbilche has a short in comparison to the skull snout. The zygomatic arches are moderately strong, or thin and delicate. The Jochbogenplatten are narrow to moderately broad, and its front edge is curved inward. The infraorbital foramen is large and narrow and the posterior maxillary foramen is also large. The interorbital region and the intermediate parietal bones are broad and the occipital bone is deep. In relation to the skull, the bullae are small and they have no continuous septa (septum ) on. The mastoid of the temporal bone is slightly bloated and did not break the window. The foramen squamosomastoideum is small and limited to the suture between squamosal and mastoid. The foramen stapediale is small or missing. The bony palate is broad and ends in front of the rear edge of the back teeth. The incisive foramina are short and between the first upper molars is the bony palate by two enlarged palatine foramina broken posterior. The posterior palatal foramen is fused to the sphenopalatine foramen. The fossa mesopterygoidea wide. The fossae pterygoideae are also wide, flat, merging smoothly with the sides of the skull and are intact or have small holes. The foramen buccinatorium and the Forum masticatorium are fused together and a patent foramen ovale accessorium missing. The foramen lacerum medium is small and fused postglenoidale with the excessively large foramen or it is tiny and postglenoidale separated from the small foramen. Alisphenoid forms the lateral surface of the canal alisphenoideus. The lower jaw is small and dainty. Its low and edged muscle extension is usually only slightly higher than the condylar process. The angle of projection is bent or broken inside.

The dentition of Stachelbilche has a designed as incisor tooth incisor and three niederkronige, jochzähnige molars in each jaw half. The upper incisors are at right angles to the skull. They have no groove, but are notched. The enamel of the incisors is orange. In the South Indian Stachelbilch the upper molar tooth rows running along the front light and the Chinese Zwergbilch parallel to each other. The second upper and lower molars is about as large as the first or slightly less and the third is about a third smaller than the other two. The upper molars have three roots and the lower two. Your occlusal surface is flat and the melting pattern is formed by mutually parallel, oblique rows of elongated ridges and valleys. The ridges and valleys of the third molar tooth run almost horizontally instead of diagonally.

Internal organs

An appendix is missing from the South Indian and the Chinese Stachelbilch Zwergbilch he is small.

Habitat and Distribution

The habitat of the arboreal Stachelbilche are rocky mountain gorges up to a height of 900 meters above sea level in the South Indian Stachelbilch and mountain forests up to an altitude of 1200 meters or higher in the Chinese Zwergbilch. Its distribution area covers the southwestern India and the southeastern China and northern Vietnam.

Phylogeny

Although today is characterized by many features derived, Stachelbilche from the lower Miocene are recognizable as such. Since they differ in their dental features strikingly cricetiden of mice -like the Miocene, they have probably already been cleaved during the Eocene or Oligocene. The melting patterns of their molars and their relative size to each other could be similar to that derived from a basic plan of Eucricetodon. They probably originated in Asia and arrived in the Miocene as a species Neocometes to Europe and to Spain. Fossil species of the genera Platacanthomys and Typhlomys are known from the Miocene of China. Whether a 17 million year old find from the Siwaliks of northern Pakistan is attributable to Stachelbilchen, however, is doubtful.

Systematics and Nomenclature

Outer systematics

According to molecular genetic studies of the nuclear IRBP and GHR genes Stachelbilche are the sister group of all other extant mice -like and not closely related to the Bilchen. On one belonging to the mouse -like point and morphological characteristics, including the only three molars in each half of the jaw, the small bullae without continuous partitions and the bent neither in nor perforated angle extension of the mandible. Also the melting pattern of the molars differs in important details from that of the dormouse and were more similar to the Malagasy Voalavoanala. Thus, the melting bars are oblique and not transverse as in the Bilchen at the Stachelbilchen.

Superficially, the melting patterns are similar, however, and so the Stachelbilche were often associated with the Bilchen since the first description of South Indian Stachelbilchs in 1859 by Edward Blyth or placed near them. Wilhelm Peters brought against it in 1865 with the mice -like connected. Samuel Schaub and Helmut Zapfe showed in 1951 that the valleys do not correspond to those of dormice in the melting pattern, but that the melting pattern can be derived from cricetiden basic plan. They arranged the Stachelbilche 1953 agitators to.

Inside systematics

A fossil and two extant genera of the Stachelbilche with several fossil and two extant species can be distinguished:

• † Neocometes Schaub & Zapfe, 1953 † Neocometes My orientalis, Ginsburg & Ratanasthien, 1990 from the Miocene of Thailand
• † Neocometes similis Fahlbusch, 1966 from the Miocene of Europe
• † Neocometes brunonis Schaub & Zapfe, 1953 from the Miocene of Europe

• † Typhlomys Primitivus Qiu, 1989 from the Miocene of China
• † Typhlomys intermedius Zheng, 1993 from the Pliocene of China
• Chinese Zwergbilch, Typhlomys cinereus Milne -Edwards, 1877 in southeastern China and northern Vietnam
• † Typhlomys hipparionium Qiu, 1989 from the Miocene of China
• † Typhlomys macrourus Zheng, 1993 from the Pliocene of China

• † Platacanthomys dianensis Qiu, 1989 from the Miocene of China
• Südindischer Stachelbilch, Platacanthomys Lasiurus Blyth, 1859 in southwest India

The genera Neocometes and Typhlomys are morphologically similar. Contrast Platacanthomys has more derived dental features and represents a separate development branch represents the differences between Typhlomys and Platacanthomys are so large that Sergei Ivanovich Ognew led them into separate subfamilies of dormice 1947.

Nomenclature

The subfamily Platacanthomyinae with the type genus Platacanthomys was erected in 1876 by Edward Richard Alston. Gerrit Smith Miller and James Williams Gidley led 1918 the family Platacanthomyidae and Sergei Ivanovich Ognew 1947, the tribe Platacanthomyini. The subfamily Typhlomyinae with the type genus Typhlomys presented Ognew 1947.