{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,28]],"date-time":"2026-10-28T03:10:59Z","timestamp":1793157059079,"version":"4.5.0"},"reference-count":54,"publisher":"National Academy of Sciences","issue":"5","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2010,2,2]]},"abstract":"<jats:p>\n                    The development of distinct regions in the amniote vertebral column results from somite formation and\n                    <jats:italic>Hox<\/jats:italic>\n                    gene expression, with the adult morphology displaying remarkable variation among lineages. Mammalian regionalization is reportedly very conservative or even constrained, but there has been no study investigating vertebral count variation across Amniota as a whole, undermining attempts to understand the phylogenetic, ecological, and developmental factors affecting vertebral column variation. Here, we show that the mammalian (synapsid) and reptilian lineages show early in their evolutionary histories clear divergences in axial developmental plasticity, in terms of both regionalization and meristic change, with basal synapsids sharing the conserved axial configuration of crown mammals, and basal reptiles demonstrating the plasticity of extant taxa. We conducted a comprehensive survey of presacral vertebral counts across 436 recent and extinct amniote taxa. Vertebral counts were mapped onto a generalized amniote phylogeny as well as individual ingroup trees, and ancestral states were reconstructed by using squared-change parsimony. We also calculated the relationship between presacral and cervical numbers to infer the relative influence of homeotic effects and meristic changes and found no correlation between somitogenesis and\n                    <jats:italic>Hox<\/jats:italic>\n                    -mediated regionalization. Although conservatism in presacral numbers characterized early synapsid lineages, in some cases reptiles and synapsids exhibit the same developmental innovations in response to similar selective pressures. Conversely, increases in body mass are not coupled with meristic or homeotic changes, but mostly occur in concert with postembryonic somatic growth. Our study highlights the importance of fossils in large-scale investigations of evolutionary developmental processes.\n                  <\/jats:p>","DOI":"10.1073\/pnas.0912622107","type":"journal-article","created":{"date-parts":[[2010,1,11]],"date-time":"2010-01-11T22:29:07Z","timestamp":1263248947000},"page":"2118-2123","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":189,"title":["Homeotic effects, somitogenesis and the evolution of vertebral numbers in recent and fossil amniotes"],"prefix":"10.1073","volume":"107","author":[{"given":"Johannes","family":"M\u00fcller","sequence":"first","affiliation":[{"name":"Museum f\u00fcr Naturkunde \u2013 Leibniz-Institut f\u00fcr Evolutions- und Biodiversit\u00e4tsforschung an der Humboldt-Universit\u00e4t zu Berlin, D-10115 Berlin, Germany;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Torsten M.","family":"Scheyer","sequence":"additional","affiliation":[{"name":"Pal\u00e4ontologisches Institut und Museum, Universit\u00e4t Z\u00fcrich, CH-8006 Z\u00fcrich, Switzerland;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jason J.","family":"Head","sequence":"additional","affiliation":[{"name":"Department of Biology, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Paul M.","family":"Barrett","sequence":"additional","affiliation":[{"name":"Department of Palaeontology, Natural History Museum, London SW7 5BD, United Kingdom;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ingmar","family":"Werneburg","sequence":"additional","affiliation":[{"name":"Pal\u00e4ontologisches Institut und Museum, Universit\u00e4t Z\u00fcrich, CH-8006 Z\u00fcrich, Switzerland;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Per G. P.","family":"Ericson","sequence":"additional","affiliation":[{"name":"Department of Vertebrate Zoology, Swedish Museum of Natural History, SE-10405 Stockholm, Sweden; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Diego","family":"Pol","sequence":"additional","affiliation":[{"name":"Consejo Nacional de Investigaciones Cient\u00edficas y T\u00e9cnicas, Museo Paleontol\u00f3gico Egidio Feruglio, Trelew CP 9100, Argentina"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marcelo R.","family":"S\u00e1nchez-Villagra","sequence":"additional","affiliation":[{"name":"Pal\u00e4ontologisches Institut und Museum, Universit\u00e4t Z\u00fcrich, CH-8006 Z\u00fcrich, Switzerland;"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"341","published-online":{"date-parts":[[2010,1,11]]},"reference":[{"key":"e_1_3_3_1_2","doi-asserted-by":"publisher","DOI":"10.1242\/dev.125.2.151"},{"key":"e_1_3_3_2_2","volume-title":"Endless Forms Most Beautiful","author":"Carroll SB","year":"2005","unstructured":"SB Carroll Endless Forms Most Beautiful (Norton, New York, 2005)."},{"key":"e_1_3_3_3_2","doi-asserted-by":"publisher","DOI":"10.1038\/nature07020"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1038\/nrg2320"},{"key":"e_1_3_3_5_2","doi-asserted-by":"publisher","DOI":"10.1098\/rsbl.2007.0069"},{"key":"e_1_3_3_6_2","volume-title":"Developmental Biology","author":"Gilbert SF","year":"2008","unstructured":"SF Gilbert Developmental Biology (Sinauer, 8th Ed, New York, 2008).","edition":"8"},{"key":"e_1_3_3_7_2","doi-asserted-by":"publisher","DOI":"10.1242\/dev.121.2.333"},{"key":"e_1_3_3_8_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.1085672"},{"key":"e_1_3_3_9_2","first-page":"305","volume-title":"Beyond Heterochrony: The Evolution of Development","author":"Polly PD","year":"2001","unstructured":"PD Polly, JJ Head, MJ Cohn Beyond Heterochrony: The Evolution of Development, ed ML Zelditch (Wiley, New York), pp. 305\u2013335 (2001)."},{"key":"e_1_3_3_10_2","doi-asserted-by":"crossref","first-page":"33","DOI":"10.7551\/mitpress\/4734.003.0009","volume-title":"Modularity. Understanding the Development and Evolution of Complex Natural Systems","author":"Wagner GP","year":"2005","unstructured":"GP Wagner, J Mezey, R Calabretta Modularity. Understanding the Development and Evolution of Complex Natural Systems, eds W Callebaut, D Rasskin-Gutman (MIT Press, Cambridge, MA), pp. 33\u201350 (2005)."},{"key":"e_1_3_3_11_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0070-2153(09)88007-1"},{"key":"e_1_3_3_12_2","doi-asserted-by":"publisher","DOI":"10.1002\/jez.b.21305"},{"key":"e_1_3_3_13_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0092-8674(01)00436-6"},{"key":"e_1_3_3_14_2","doi-asserted-by":"publisher","DOI":"10.1242\/dev.129.16.3851"},{"key":"e_1_3_3_15_2","doi-asserted-by":"publisher","DOI":"10.1002\/jez.b.21029"},{"key":"e_1_3_3_16_2","first-page":"206","article-title":"Morphologic and ontogenetic patterns in elasmosaur neck length, with comments on the taxonomic utility of neck length variables","volume":"5","author":"O\u2019Keefe FR","year":"2006","unstructured":"FR O\u2019Keefe, N Hiller, Morphologic and ontogenetic patterns in elasmosaur neck length, with comments on the taxonomic utility of neck length variables. Paludicola 5, 206\u2013229 (2006).","journal-title":"Paludicola"},{"key":"e_1_3_3_17_2","doi-asserted-by":"publisher","DOI":"10.1002\/ar.20534"},{"key":"e_1_3_3_18_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1095-8312.2007.00714.x"},{"key":"e_1_3_3_19_2","doi-asserted-by":"publisher","DOI":"10.1186\/1741-7007-6-14"},{"key":"e_1_3_3_20_2","doi-asserted-by":"publisher","DOI":"10.1002\/jez.b.21238"},{"key":"e_1_3_3_21_2","doi-asserted-by":"publisher","DOI":"10.2307\/2390230"},{"key":"e_1_3_3_22_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1096-0031.1988.tb00514.x"},{"key":"e_1_3_3_23_2","first-page":"472","volume-title":"Pal\u00e4ontologie der Wirbeltiere","author":"Benton MJ","year":"2007","unstructured":"MJ Benton Pal\u00e4ontologie der Wirbeltiere (Dr. Friedrich Pfeil, Munich), pp. 472, [German translation of Vertebrate Paleontology, 3rd Ed]. (2007)."},{"key":"e_1_3_3_24_2","doi-asserted-by":"publisher","DOI":"10.1006\/scdb.1996.0022"},{"key":"e_1_3_3_25_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1525-142X.2008.00303.x"},{"key":"e_1_3_3_26_2","doi-asserted-by":"publisher","DOI":"10.1086\/284325"},{"key":"e_1_3_3_27_2","volume-title":"COMPARE, Computer programs for the statistical analysis of comparative data","author":"Martins EP","year":"2004","unstructured":"EP Martins COMPARE, Computer programs for the statistical analysis of comparative data (Indiana Univ, Bloomington, Ver 4.6b. (2004)."},{"key":"e_1_3_3_28_2","doi-asserted-by":"publisher","DOI":"10.1002\/dvdy.21286"},{"key":"e_1_3_3_29_2","first-page":"175","volume-title":"Ichthyopterygia. Handbuch der Pal\u00e4oherpetologie Part 8","author":"McGowan C","year":"2003","unstructured":"C McGowan, R Motani Ichthyopterygia. Handbuch der Pal\u00e4oherpetologie Part 8 (Dr. Friedrich Pfeil, Munich), pp. 175 (2003)."},{"key":"e_1_3_3_30_2","doi-asserted-by":"publisher","DOI":"10.1038\/20944"},{"key":"e_1_3_3_31_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.ydbio.2009.04.031"},{"key":"e_1_3_3_32_2","first-page":"52","volume-title":"Key Words and Concepts in Evolutionary Developmental Biology","author":"Schwenk K","year":"2003","unstructured":"K Schwenk, GP Wagner Key Words and Concepts in Evolutionary Developmental Biology, eds BK Hall, WM Olson (Harvard Univ Press, Cambridge, MA), pp. 52\u201361 (2003)."},{"key":"e_1_3_3_33_2","first-page":"379","volume-title":"Recent Advances in the Origin and Early Radiation of Vertebrates","author":"M\u00fcller J","year":"2004","unstructured":"J M\u00fcller Recent Advances in the Origin and Early Radiation of Vertebrates, eds G Arratia, R Cloutier, VH Wilson (Dr. Friedrich Pfeil, Munich), pp. 379\u2013408 (2004)."},{"key":"e_1_3_3_34_2","doi-asserted-by":"publisher","DOI":"10.1017\/S0022336000017236"},{"key":"e_1_3_3_35_2","doi-asserted-by":"publisher","DOI":"10.1038\/nature06277"},{"key":"e_1_3_3_36_2","volume-title":"The Origin and Evolution of Mammals","author":"Kemp T","year":"2005","unstructured":"T Kemp The Origin and Evolution of Mammals (Oxford Univ Press, Oxford, 2005)."},{"key":"e_1_3_3_37_2","first-page":"77","article-title":"The second thalattosaur from the Triassic of. Guizhou, China","volume":"39","author":"Liu J","year":"2001","unstructured":"J Liu, O Rieppel, The second thalattosaur from the Triassic of. Guizhou, China. Vertebrata Palasiatica 39, 77\u201387 (2001).","journal-title":"Vertebrata Palasiatica"},{"key":"e_1_3_3_38_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.1117241"},{"key":"e_1_3_3_39_2","volume-title":"Mammals of the USSR and Adjacent Countries, Volume IX: Cetacea","author":"Tomilin AG","year":"1957","unstructured":"AG Tomilin Mammals of the USSR and Adjacent Countries, Volume IX: Cetacea (Acad Sci Publ House, Moscow, [in Russian]. (1957)."},{"key":"e_1_3_3_40_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.0014-3820.2006.tb01896.x"},{"key":"e_1_3_3_41_2","doi-asserted-by":"publisher","DOI":"10.1017\/S1477200006002258"},{"key":"e_1_3_3_42_2","article-title":"Evolution of the axial skeleton in armadillos (Mammalia, Dasypodidae)","author":"Galliari FC","year":"2009","unstructured":"FC Galliari, AC Carlini, MR S\u00e1nchez-Villagra, Evolution of the axial skeleton in armadillos (Mammalia, Dasypodidae). Mamm Biol, doi:10.1016\/j.mambio.2009.03.014. (2009).","journal-title":"Mamm Biol"},{"key":"e_1_3_3_43_2","doi-asserted-by":"publisher","DOI":"10.1038\/nature07533"},{"key":"e_1_3_3_44_2","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2148-9-82"},{"key":"e_1_3_3_45_2","doi-asserted-by":"publisher","DOI":"10.1046\/j.1096-3642.2002.00029.x"},{"key":"e_1_3_3_46_2","first-page":"201","volume-title":"in Biology of the Reptilia, Volume 1: Morphology","author":"Hoffstetter R","year":"1969","unstructured":"R Hoffstetter, J-P Gasc in Biology of the Reptilia, Volume 1: Morphology, ed C Gans (Academic, London), pp. 201\u2013310 (1969)."},{"key":"e_1_3_3_47_2","doi-asserted-by":"publisher","DOI":"10.11646\/zootaxa.1841.1.1"},{"key":"e_1_3_3_48_2","volume-title":"From Embryology to Evo-Devo: A History of Developmental Evolution","author":"Wagner G","year":"2007","unstructured":"G Wagner From Embryology to Evo-Devo: A History of Developmental Evolution, eds MD Laubichler, J Maienschein (MIT Press, Cambridge, MA, 2007)."},{"key":"e_1_3_3_49_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.0606028103"},{"key":"e_1_3_3_50_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev.ecolsys.34.011802.132351"},{"key":"e_1_3_3_51_2","doi-asserted-by":"publisher","DOI":"10.1093\/molbev\/msi075"},{"key":"e_1_3_3_52_2","volume-title":"Mesquite: A Modular System for Evolutionary Analysis","author":"Maddison WP","year":"2004","unstructured":"WP Maddison, DR Maddison Mesquite: A Modular System for Evolutionary Analysis (Univ of Arizona, Tucson, Ver 2.6. (2004)."},{"key":"e_1_3_3_53_2","doi-asserted-by":"publisher","DOI":"10.1080\/10635150600755396"},{"key":"e_1_3_3_54_2","doi-asserted-by":"publisher","DOI":"10.1002\/mmng.200800011"}],"container-title":["Proceedings of the National Academy of Sciences"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pnas.org\/doi\/pdf\/10.1073\/pnas.0912622107","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,5,29]],"date-time":"2023-05-29T09:21:37Z","timestamp":1685352097000},"score":1,"resource":{"primary":{"URL":"https:\/\/pnas.org\/doi\/full\/10.1073\/pnas.0912622107"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2010,1,11]]},"references-count":54,"journal-issue":{"issue":"5","published-print":{"date-parts":[[2010,2,2]]}},"alternative-id":["10.1073\/pnas.0912622107"],"URL":"https:\/\/doi.org\/10.1073\/pnas.0912622107","relation":{},"ISSN":["0027-8424","1091-6490"],"issn-type":[{"value":"0027-8424","type":"print"},{"value":"1091-6490","type":"electronic"}],"subject":[],"published":{"date-parts":[[2010,1,11]]},"assertion":[{"value":"2010-01-11","order":2,"name":"published","label":"Published","group":{"name":"publication_history","label":"Publication History"}}]}}