Cephalomys is the best-known cephalomyid, recorded in five localities in Argentina and known from well-preserved mandibles, fragments of skull, and a large number of isolated teeth, from both juveniles and adults. Despite this, a modern description is lacking and the validity of some species of Cephalomys has been questioned in the last few years. New material from the Deseadan locality of Cabeza Blanca (Chubut, Argentina), including skull fragments unknown for the species thus far, and well-preserved juvenile teeth, along with a large number of specimens from collections in Argentina, allow us to propose a more complete description of the genus and a new taxonomic arrangement for the Cephalomys species. We also analysed some dubious records of Cephalomys from Quebrada Honda and Pico Truncado and confirm that they are not part of this genus. We consider C. plexus to be a synonym of C. arcidens, we consider the combination previously proposed for C. bolivianus (as a species of Asteromys) to be valid, and we consider C. ceciae also to be a valid species. We performed a phylogenetic analysis including for the first time all cephalomyids (Cephalomys, Litodontomys, Cephalomyopsis, Soriamys and Banderomys) and possibly related genera (Perimys, Scotamys, Asteromys) to test the position of the family Cephalomyidae among the other caviomorph rodents, as well as its validity and internal relationships. The results recovered Cephalomyidae as a clade, including Cephalomys, Cephalomyopsis and Litodontomys. The monophyly of Cephalomys could not be confirmed. Soriamys and Banderomys were recovered within Cavioidea. Perimys, Scotamys and Asteromys were recovered within Chinchilloidea, and we analysed the implications of their positions within the group. The implications in terms of the biochron, distribution and evolutionary history of the Cephalomyidae, considering the new definition for the family proposed herein (including only Cephalomys, Cephalomyopsis and Litodontomys), are discussed, as well as inferences regarding caviomorph evolution at the scale of the entire group.

头颅病是最著名的头颅病，在阿根廷的五个地方都有记载，并从保存完好的下颌骨，头骨碎片和大量幼年和成年牙齿中获知。尽管如此，仍缺乏现代的描述，并且在过去几年中对某些头孢菌属物种的有效性提出了质疑。来自Cabeza Blanca（阿根廷丘布特）的Deseadan地区的新材料，包括迄今为止对该物种未知的头骨碎片，以及保存完好的幼齿，以及阿根廷收集的大量标本，使我们能够提出更多建议。属的完整描述和头孢菌属的新分类学安排。我们还分析了头颅切开术的一些可疑记录来自Quebrada Honda和Pico Truncado，并确认它们不属于该类。我们认为丛神经隐孢子虫是弓形隐孢子虫的同义词，我们认为先前为玻利维亚隐孢子虫（作为一种不育植物）提议的组合是有效的，并且我们认为cececee也为有效菌种。我们进行了系统发育分析，包括首次全部cephalomyids（Cephalomys，Litodontomys，Cephalomyopsis，Soriamys和Banderomys），并可能近缘属（Perimys，Scotamys，Asteromys），以测试头孢菌科在其他啮齿类啮齿动物中的位置，以及其有效性和内部关系。结果痊愈Cephalomyidae作为一个分支，包括Cephalomys，Cephalomyopsis和Litodontomys。头颅病的单眼病无法确定。Soriamys和Banderomys在Cavioidea内被发现。Perimys，Scotamys和Asteromys在金鸡革兰中被发现，我们分析了它们在小组中的地位。在Cephalomyidae的biochron，分布及进化历史方面的影响，考虑到这里提出的家庭（仅包括新定义Cephalomys，Cephalomyopsis和Litodontomys），进行了讨论，以及在的规模有关豚鼠小目演变推论整个小组。