Abstract: The rodent family Platacanthomyidae encompasses both the Malabar spiny tree mouse (genus Platacanthomys) and the soft-furred tree mice (genus Typhlomys). This family represents a typical relict group of ancient origin, and its evolutionary history and dynamics warrant further investigation. A critical scientific question concerns whether the evolutionary trajectory of this ancient taxon has been shaped by environmental perturbations, such as the periodic climatic oscillations of the Quaternary glacial periods. This study aims to elucidate the evolutionary trajectory of the Platacanthomyidae by examining fossil records alongside extant species. Molecular dating revealed that the most speciose genus Typhlomys within this family began diverging approximately 21.15 million years ago (Mya). The speciation rate and net diversification rate of the Platacanthomyidae was notably high around 20 Mya, but it has shown a continuous decline since then, while the extinction rate of this taxa has remained stable. The current dataset indicates that the evolutionary trajectory of this family appears to have remained unaffected by late Cenozoic climatic fluctuations and subsequent anthropogenic influences associated with societal development. The ancestral distribution reconstruction has not yielded conclusive evidence regarding the origin of this family, thereby positioning it among the most enigmatic taxa within Rodentia. Moreover, the evolutionary mechanisms underlying the divergence of these ancestral species and their subsequent ecological adaptations to paleoenvironmental changes require future studies.

Key words: fossil, molecular clock, Neocometes, Platacanthomyidae, Platacanthomys, Typhlomys