Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 9 October 2009:
Vol. 326. no. 5950, pp. 243 - 244
DOI: 10.1126/science.1181131
Prev | Table of Contents | Next

Perspectives

Paleontology:

On the Mammalian Ear

Thomas Martin and Irina Ruf

During their development, embryos of many species repeat evolutionary stages of their ancestors (1). For example, in human embryos gill pouches are formed during early developmental stages. Developmental heterochrony—that is, the differing timing of developmental processes during embryonic growth—can lead to a premature fixation of ancestral character states and the retention of embryonic patterns in the adult. This process is believed to be an important driving force for evolution (2, 3). One of the key innovations in mammalian history is the evolution of the mammalian ear, leading to the most efficient hearing among vertebrates. On page 278 of this issue, Ji et al. (4) use an analysis of the Early Cretaceous mammal Maotherium to show how heterochrony routed the evolution of the definitive mammalian middle ear (DMME).

Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Nussallee 8, 53115 Bonn, Germany.

E-mail: tmartin{at}uni-bonn.de

Read the Full Text

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)