Fossil evidence on evolution of inner ear cochlea in Jurassic mammals
- 28 July 2010
- journal article
- research article
- Published by The Royal Society in Proceedings. Biological sciences
- Vol. 278 (1702), 28-34
- https://doi.org/10.1098/rspb.2010.1148
Abstract
The coiled cochlea is a key evolutionary innovation of modern therian mammals. We report that the Late Jurassic mammal Dryolestes, a relative to modern therians, has derived bony characteristics of therian-like innervation, but its uncoiled cochlear canal is less derived than the coiled cochlea of modern therians. This suggests a therian-like innervation evolved before the fully coiled cochlea in phylogeny. The embryogenesis of the cochlear nerve and ganglion in the inner ear of mice is now known to be patterned by neurogenic genes, which we hypothesize to have influenced the formation of the auditory nerve and its ganglion in Jurassic therian evolution, as shown by their osteological correlates in Dryolestes, and by the similar base-to-apex progression in morphogenesis of the ganglion in mice, and in transformation of its canal in phylogeny. The cochlear innervation in Dryolestes is the precursory condition in the curve-to-coil transformation of the cochlea in mammalian phylogeny. This provides the timing of the evolution, and where along the phylogeny the morphogenetic genes were co-opted into patterning the cochlear innervation, and the full coiling of the cochlea in modern therians.This publication has 30 references indexed in Scilit:
- Inner ear of a notoungulate placental mammal: anatomical description and examination of potentially phylogenetically informative charactersJournal of Anatomy, 2010
- The Eutherian Mammal Maelestes gobiensis from the Late Cretaceous of Mongolia and the phylogeny of cretaceous eutheriaBulletin of the American Museum of Natural History, 2009
- Petrosal anatomy and inner ear structures of the Late Jurassic Henkelotherium (Mammalia, Cladotheria, Dryolestoidea): insight into the early evolution of the ear region in cladotherian mammalsJournal of Anatomy, 2009
- Petrosal anatomy in the fossil mammal Necrolestes: evidence for metatherian affinities and comparisons with the extant marsupial moleJournal of Anatomy, 2008
- Sox2 signaling in prosensory domain specification and subsequent hair cell differentiation in the developing cochleaProceedings of the National Academy of Sciences of the United States of America, 2008
- The influence of cochlear shape on low-frequency hearingProceedings of the National Academy of Sciences of the United States of America, 2008
- The primate semicircular canal system and locomotionProceedings of the National Academy of Sciences of the United States of America, 2007
- Earliest Eutherian Ear Region: A Petrosal Referred to Prokennalestes from the Early Cretaceous of MongoliaAmerican Museum Novitates, 2001
- An X-radiographic and SEM study of the osseous inner ear of multituberculates and monotremes (Mammalia): implications for mammalian phylogeny and evolution of hearingZoological Journal of the Linnean Society, 1997
- Osseous inner ear structures and hearing in early marsupials and placentalsZoological Journal of the Linnean Society, 1995