Brain virtual endocast inside the translucent skull (left), skull reconstruction (middle) and life reconstruction (right) of the late Oligocene Incamys bolivianus (YPM VPPU 21945) from the Salla-Luribay Basin in Bolivia. Credit: Jesús Gamarra González / Institut Català de Paleontologia Miquel Crusafont.
Phys.org has a story about a 30 million year old cousin of chinchillas. A study published in the journal Papers in Palaeontology found endocranial brain features that suggest Incamys bolivianus might have had enhanced auditory acuity and vocalization processing. Like modern chinchillas, this 30 million-year-old rodent may have been living in groups and using calls to communicate. The fossil specimens used in the study reside at the Yale Peabody Museum and were dated to the late Oligocene. The fossils were collected from the Salla-Luribay Basin in Bolivia.
A relevant and fascinating behavior of chinchillid rodents is that they produce a wide range of vocalization to communicate with other members of their group or colony. Different calls also known as whistles may correspond to different predators.
For this project, researchers created virtual brain endocasts for the fossil Incamys and for the three living Chinchillidae: chinchilla, plains viscacha, and mountain viscacha to uncover how the brain of the ancestor of Chinchillidae may have looked like.
They found that Incamys displayed an expansion of the temporal lobes of the cerebrum. This region of the brain and more specifically of the neocortex includes the auditory cortex responsible for processing sounds from our surroundings.