Tsaganomyidae is an extinct family of rodent

Rodent

Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

s from Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

. It contains three genera. Tsaganomyids are generally considered to be related to the Hystricognathi

Hystricognathi

Hystricognathi is an infraorder of rodents. Hystricognaths are distinguished from other rodents by the bone structure of their skulls. The masseter medialis passes partially through the infraorbital foramen and connects to the bone on the opposite side...

 (porcupine

Porcupine

Porcupines are rodents with a coat of sharp spines, or quills, that defend or camouflage them from predators. They are indigenous to the Americas, southern Asia, and Africa. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about long, with...

s and relatives). Members of Tsaganomyidae were fossorial

Fossorial

A fossorial organism is one that is adapted to digging and life underground such as the badger, the naked mole rat, and the mole salamanders Ambystomatidae...

 (digging) rodents that probably used their incisor

Incisor

Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...

 teeth to dig like some living mole rats

Blesmol

The blesmols, also known as mole rats, or African mole-rats, are burrowing rodents of the family Bathyergidae. They represent a distinct evolution of a subterranean life among rodents much like the pocket gophers of North America, the tuco-tucos in South America, or the Spalacidae.- Distribution...

.

Characteristics

Tsaganomyids had a protrogomorphous zygomasseteric system

Zygomasseteric system

The zygomasseteric system in rodents is the anatomical arrangement of the masseter muscle of the jaw and the zygomatic arch of the skull...

, a hystricognathous lower jaw, and multiserial enamel

Tooth enamel

Tooth enamel, along with dentin, cementum, and dental pulp is one of the four major tissues that make up the tooth in vertebrates. It is the hardest and most highly mineralized substance in the human body. Tooth enamel is also found in the dermal denticles of sharks...

in their incisor teeth.