Platacanthomyidae is a small family of rodents. It contains just three species in two genera: Platacanthomys, the spiny dormouse, and Typhlomys, the pygmy dormice.
Platacanthomyids have a discontinuous Old World distribution. They are found in several regions of southern India, southern China, and northern Vietnam.
Biogeographic Regions: palearctic (Native ); oriental (Native )
Platacanthomyids are mouselike in overall appearance, with tail length ranging from 75 to 138 mm and total body length ranging from 70 to 212 mm. Long, stiff hairs form a brush on the tip of the tail. The feet are slim and small with medium long digits. Four of the digits on the front foot have claws, and the fifth is a rudimentary thumb with a nail. The soles of all four feet are naked and have six pads. Long vibrissae protrude from the relatively short muzzle. The ears are prominent and sparsely furred. Sexual dimorphism has not been described in this group.
The dental formula is 1/1, 0/0, 0/0, 3/3 = 16. The cheek teeth are high-crowned and parallel ridges of enamel run diagonally across the crowns. The enamel on the incisors is orange. The molars in the upper jaw each have three roots; those in the lower jaw have two. The first two molars are about the same size, and the third is about 2/3 the size of the other two.
The small, delicate dentary has a low, angular coronoid process that in most specimens is positioned just slightly higher than the condyloid process. The unperforated angular process is not inflected lingually. The wide hard palate terminates anterior to the rear margins of the molar rows. The interorbital region and the interparietal are both broad, the occiput is deep, and the infraorbital foramina are large and narrow. The lateral surface of the alisphenoid canal is formed by the alisphenoid bone. The pterygoid fossa, which may or may not be perforated with tiny holes, is broad, flat, and smoothly continuous with the sides of the braincase. The masticatory-buccinator formanina are coalesced into one opening. The complete, slightly enlarged mastoid is not perforated. The small squamosomastoid foramen is contained within the suture between the squamosal and the mastoid. The auditory bullae are relatively small and lack transbullar septae.
Other Physical Features: endothermic ; bilateral symmetry
Platycanthomyids live in moist, rocky, tropical and subtropical forests at elevations of 600 to 2100 meters. They inhabit burrows, tree cavities, and clefts between rocks, often near streams.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest
Platacanthomyids reportedly eat leaves, stems, fruit, seeds, and roots.
Primary Diet: herbivore (Folivore , Frugivore , Granivore )
Platacanthomyids are herbivores, meaning that they are at least primary consumers in their ecosystem.
There are no reports of predation on platacanthomyids, although it is likely that small to medium-sized predators, such as large snakes, raptors, and mammalian carnivores, will target these species. Native people of southern China and northern Vietnam claim that cats will not eat Typhlomys species.
Life History and Behavior
It is unknown how these rodents communicate. They do have the ability to perceive their world through visual, auditory, tactile, and chemical means, though it is not known how well-developed any of these senses are.
Perception Channels: visual ; tactile ; acoustic ; chemical
The lifespan of platacanthomyids has not been reported.
No information is available on the mating system of platacanthomyids.
No information is available on the reproduction of platacanthomyids, besides the fact that they are eutherian mammals and therefore reproduce sexually via internal fertilization and bear live young.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous
Female platacanthomyids nurse their young, being mammals, but no other information is available on the investment that they make in their offspring.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:1
Specimens with Barcodes:1
Species With Barcodes:1
One of the three species in this family, Typhlomys cinereus, the Chapa pygmy dormouse, is listed as critically endangered by the IUCN. This species is known only from a single locality and therefore is extremely vulnerable to habitat destruction.
Relevance to Humans and Ecosystems
In parts of India, Platacanthomys lasiurus are abundant and are referred to as "pepper rats", because they raid and destroy pepper crops.
Negative Impacts: crop pest
There are no known positive impacts of platacanthomyids on humans, except in their roles in the healthy ecosystems they inhabit.
The rodent family Platacanthomyidae, or Oriental dormice, includes the spiny dormice and the Chinese pygmy dormice. In spite of their appearance, these animals are not true dormice, but are part of the large and complex superfamily Muroidea. The platacanthomyids can be distinguished from the true dormice, because they have no premolars, giving them three cheek teeth, like their relatives, the Muroidea.
The evolutionary relationship of the Platacanthomyidae was uncertain until a molecular phylogenetic study found it to be the earliest extant lineage to branch within the superfamily Muroidea. They can be distinguished from both the family Spalacidae and the Eumuroida (all non-spalacid and non-platacanthomyid muroids), by the distinct shape of their infraorbital canal and by the presence of multiple openings in the palate of the skull. On the basis of these two characteristics, they have been considered to be distinct from all other muroids. More work is needed to determine the evolutionary position of this subfamily.
- Family Platacanthomyidae
- Genus †Neocometes
- Genus Platacanthomys (spiny dormouse)
- Genus Typhlomys (pygmy dormice)
- Lee and Jacobs, 2010.
- Jansa, Giarla, and Lim, 2009.
- Lee, Yuong-Nam and Louis L. Jacobs. 2010. The Platacanthomyine Rodent Neocometes from the Miocene of South Korea and Its Paleobiogeographical Implications. Acta Palaeontologica Polonica 55(4):581-586. doi:10.4202/app.2010.0013
- Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. Pp. 894-1531 in Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore.
- Norris, R. W., K. Y. Zhou, C. Q. Zhou, G. Yang, C. W. Kilpatrick, and R. L. Honeycutt. 2004. The phylogenetic position of the zokors (Myospalacinae) and comments on the families of muroids (Rodentia). Molecular Phylogenetics and Evolution, 31:972-978.
- Nowak, R. M. 1999. Walker's Mammals of the World, Vol. 2. Johns Hopkins University Press, London.
- Steppan, S. J., R. A. Adkins, and J. Anderson. 2004. Phylogeny and divergence date estimates of rapid radiations in muroid rodents based on multiple nuclear genes. Systematic Biology, 53:533-553.
- Jansa, S.A., T.C. Giarla, and B.K. Lim. 2009. The Phylogenetic Position of the Rodent Genus Typhlomys and the Geographic Origin of Muroidea. "Journal of Mammalogy": October 2009, Vol. 90, No. 5, pp. 1083-1094. doi:10.1644/08-MAMM-A-318.1
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