Evolutionary development of the middle ear in Mesozoic therian mammals. Science (New York, N.Y.) [Science] Journal article

Title	Evolutionary development of the middle ear in Mesozoic therian mammals.
Author(s)	Ji Q, Luo ZX, Zhang X, Yuan CX, Xu L
Institution	Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China.
Source	Science 2009 Oct 9; 326(5950):278-81.
MeSH	Animals Cartilage Chondrogenesis Dentition Ear Ossicles Ear, Middle Embryo, Mammalian Evolution Fossils Gene Expression Regulation, Developmental Intercellular Signaling Peptides and Proteins Mammals Mandible Mice Mice, Mutant Strains Osteogenesis Phylogeny Signal Transduction
Abstract	The definitive mammalian middle ear (DMME) is defined by the loss of embryonic Meckel's cartilage and disconnection of the middle ear from the mandible in adults. It is a major feature distinguishing living mammals from nonmammalian vertebrates. We report a Cretaceous trechnotherian mammal with an ossified Meckel's cartilage in the adult, showing that homoplastic evolution of the DMME occurred in derived therian mammals, besides the known cases of eutriconodonts. The mandible with ossified Meckel's cartilage appears to be paedomorphic. Reabsorption of embryonic Meckel's cartilage to disconnect the ear ossicles from the mandible is patterned by a network of genes and signaling pathways. This fossil suggests that developmental heterochrony and gene patterning are major mechanisms in homplastic evolution of the DMME.
Language	eng
Pub Type(s)	Journal Article Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S.
PubMed ID	19815774

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