title: Mammalian evolution. Evolutionary development in basal mammaliaforms as revealed by a docodontan.
abstract: A new Late Jurassic docodontan shows specializations for a subterranean lifestyle. It is similar to extant subterranean golden moles in having reduced digit segments as compared to the ancestral phalangeal pattern of mammaliaforms and extant mammals. The reduction of digit segments can occur in mammals by fusion of the proximal and intermediate phalangeal precursors, a developmental process for which a gene and signaling network have been characterized in mouse and human. Docodontans show a positional shift of thoracolumbar ribs, a developmental variation that is controlled by Hox9 and Myf5 genes in extant mammals. We argue that these morphogenetic mechanisms of modern mammals were operating before the rise of modern mammals, driving the morphological disparity in the earliest mammaliaform diversification.
authors: Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA. zxluo@uchicago.edu mengqingjin@bmnh.org.cn.
authors: Zhe-Xi
authors: ZX
authors: Luo
authors: Beijing Museum of Natural History, Beijing 100050, China. zxluo@uchicago.edu mengqingjin@bmnh.org.cn.
authors: Qing-Jin
authors: QJ
authors: Meng
authors: Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China.
authors: Qiang
authors: Q
authors: Ji
authors: Beijing Museum of Natural History, Beijing 100050, China.
authors: Di
authors: D
authors: Liu
authors: Beijing Museum of Natural History, Beijing 100050, China.
authors: Yu-Guang
authors: YG
authors: Zhang
authors: Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL 60637, USA.
authors: April I
authors: AI
authors: Neander
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002681:China; D050278:Finger Phalanges / Q000033:anatomy & histology* / Q000254:growth & development*; D005528:Foot / Q000033:anatomy & histology / Q000254:growth & development; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology; D006801:Humans; D008322:Mammals / Q000033:anatomy & histology* / Q000235:genetics / Q000254:growth & development*; D051379:Mice; D009024:Morphogenesis / Q000235:genetics / Q000502:physiology*; D051787:Myogenic Regulatory Factor 5 / Q000235:genetics / Q000502:physiology
chemical_list: D018398:Homeodomain Proteins; D051787:Myogenic Regulatory Factor 5; C097899:homeobox protein HOXA9