Paramys is an extinct genus of rodents from North America, Europe, and Asia. It is one of the oldest genera of rodents known and probably lived in trees. While the genus name literally means "near a mouse", it coexisted with Thisbemys, a similar rodent, thus yielding a reference to Pyramus and Thisbe.
Description The brain of both the Early Eocene P. copei and the Middle Eocene P. delicatus was characterised by a lower neocortical surface area, smaller paraflocculi, and larger olfactory bulbs relative to total endocranial volume of later rodents, and they both possessed encephalisation quotients higher than that of Ischyromys typus. The enamel in Paramys incisors was about 50 µm thick. Paramys incisor enamel had pauciserial Hunter-Schreger bands (HSBs) with about 2-3 enamel prisms per band. The interprismatic matrix ran parallel to enamel prisms.
Palaeobiology
Locomotion P. delicatus possessed more robust limbs and could apply a greater mechanical advantage using its limbs relative to most living squirrels, including living semi-fossorial squirrels. This suggests that it was a semi-fossorial animal that was adapted for scratch-digging.
References
Further reading Matthew, W. D. 1910. On the osteology and relationships of Paramys and the affinities of the Ischyromyidae. Bulletin of the American Museum of Natural History, 28:43–72. Kenneth D. Rose, 2006. The Beginning of the Age of Mammals. The Johns Hopkins University Press. Baltimore MD. pp. 306–335 Kenneth D. Rose and Brenda J. Chinnery. The Postcranial Skeleton of Early Eocene Rodents. Bulletin of Carnegie Museum of Natural History. Volume 36, Issue 1 (December 2004): pp. 211–244 Tullberg, T. 1899. Ueber das System der Nagethiere. Eine Phylogenetische Studie. Nova Acta Regiae Soc. Scient Upsala, ser. 3, vol. 18: v + 514 pp., 57 pls Wodd A. E. 1962. The Early Tertiary rodents of the family Paramyidae. Transactions of the American Philosophical Society. new series 52(1): 1–261.