A new developmental mechanism for the separation of the mammalian middle ear ossicles from the jaw

Daniel J. Urban, Neal Anthwal, Zhe Xi Luo, Jennifer A. Maier, Alexa Sadier, Abigail S. Tucker, Karen E. Sears

Research output: Contribution to journalArticlepeer-review


Multiple mammalian lineages independently evolved a definitive mammalian middle ear (DMME) through breakdown of Meckel’s cartilage (MC). However, the cellular and molecular drivers of this evolutionary transition remain unknown for most mammal groups. Here, we identify such drivers in the living marsupial opossum Monodelphis domestica, whose MC transformation during development anatomically mirrors the evolutionary transformation observed in fossils. Specifically, we link increases in cellular apoptosis and TGF-BR2 signalling to MC breakdown in opossums. We demonstrate that a simple change in TGF-b signalling is sufficient to inhibit MC breakdown during opossum development, indicating that changes in TGF-b signalling might be key during mammalian evolution. Furthermore, the apoptosis that we observe during opossum MC breakdown does not seemingly occur in mouse, consistent with homoplastic DMME evolution in the marsupial and placental lineages.

Original languageEnglish (US)
Article number20162416
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1848
StatePublished - Feb 8 2017


  • Apoptosis
  • Marsupial
  • Meckel’s cartilage
  • Origin of mammals
  • TGFB signalling

ASJC Scopus subject areas

  • General Immunology and Microbiology
  • General Biochemistry, Genetics and Molecular Biology
  • General Environmental Science
  • General Agricultural and Biological Sciences


Dive into the research topics of 'A new developmental mechanism for the separation of the mammalian middle ear ossicles from the jaw'. Together they form a unique fingerprint.

Cite this