{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T16:04:44Z","timestamp":1784822684302,"version":"3.55.0"},"reference-count":109,"publisher":"Oxford University Press (OUP)","license":[{"start":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T00:00:00Z","timestamp":1782950400000},"content-version":"vor","delay-in-days":182,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100014013","name":"UK Research and Innovation","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100014013","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,1,12]]},"abstract":"<jats:title>Synopsis<\/jats:title>\n                  <jats:p>Testing hypotheses of phenotypic modularity involves assessing whether groups of traits covary more strongly with each other than with parts outside the group. Structural equation modeling (SEM) is a flexible statistical framework for interrogating complex relationships between sets of variables, making it ideally suited to studies of hierarchical modularity and integration. However, quantifying the modular organization of high-dimensional traits using SEM in a phylogenic context has only recently become possible through new methodological advances. Here, we applied SEM to investigate patterns and correlates of phenotypic modularity in the skull and brain of birds. Birds independently evolved relatively large brains multiple times, as well as a wide range of different skull and brain morphologies. While some have proposed the bird skull is composed of several functional or developmental modules, others have suggested the skull is highly integrated, with allometric scaling structuring trait correlations. The data best supported a model in which brain shape is influenced by a hard tissue module consisting of neurocranium and rostrum (RS) shape, as well as the jaw musculature. RS itself does not strongly covary with other aspects of the skull and brain however, suggesting decoupling of beak morphology from the rest of the avian cranium. All variables, with the exception of RS, are strongly influenced by size, supporting the idea that allometry is a major influence on craniofacial integration in birds. These results provide new insights into likely drivers shaping the evolution of the skull in birds and highlight the usefulness of\u00a0phyloSEM testing hypotheses of evolutionary modularity and integration.<\/jats:p>","DOI":"10.1093\/icb\/icag106","type":"journal-article","created":{"date-parts":[[2026,7,2]],"date-time":"2026-07-02T11:48:50Z","timestamp":1782992930000},"source":"Crossref","is-referenced-by-count":0,"title":["Structural Equation Modeling Reveals How Allometry Shapes Integration in Avian Cranial Evolution"],"prefix":"10.1093","volume":"66","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8291-7271","authenticated-orcid":false,"given":"J W","family":"Oyston","sequence":"first","affiliation":[{"name":"Division of Cell and Developmental Biology, Centre for Integrative Anatomy, University College London , Gower Street, WC1E 6BT, London ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7415-1010","authenticated-orcid":false,"given":"J T","family":"Thorson","sequence":"additional","affiliation":[{"name":"Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center , 7600 Sand Point Way N.E., WA 98115, Seattle ,","place":["USA"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A","family":"Knapp","sequence":"additional","affiliation":[{"name":"Division of Cell and Developmental Biology, Centre for Integrative Anatomy, University College London , Gower Street, WC1E 6BT, London ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R D","family":"Marek","sequence":"additional","affiliation":[{"name":"Division of Cell and Developmental Biology, Centre for Integrative Anatomy, University College London , Gower Street, WC1E 6BT, London ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9201-9213","authenticated-orcid":false,"given":"R N","family":"Felice","sequence":"additional","affiliation":[{"name":"Division of Cell and Developmental Biology, Centre for Integrative Anatomy, University College London , Gower Street, WC1E 6BT, London ,","place":["UK"]},{"name":"Science Group, Natural History Museum , Cromwell Road, SW7 5BD, London ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2026,7,2]]},"reference":[{"key":"2026072311172415300_bib1","volume-title":"Geomorph: Software for geometric morphometric analyses","author":"Adams","year":"2025"},{"key":"2026072311172415300_bib2","doi-asserted-by":"publisher","first-page":"e70024","DOI":"10.1111\/ede.70024","article-title":"Early ontogenetic allometry and shifting modularity in skull development of the Red Sea anemonefish, Amphiprion bicinctus","volume":"27","author":"Arnold","year":"2025","journal-title":"Evol Dev"},{"key":"2026072311172415300_bib3","doi-asserted-by":"publisher","first-page":"1111","DOI":"10.1098\/rstb.2009.0285","article-title":"The beak of the other finch: coevolution of genetic covariance structure and developmental modularity during adaptive evolution","volume":"365","author":"Badyaev","year":"2010","journal-title":"Philos Trans R Soc B Biol Sci"},{"key":"2026072311172415300_bib4","doi-asserted-by":"publisher","first-page":"2355","DOI":"10.1111\/2041-210X.13723","article-title":"geomorph v4.0 and gmShiny: enhanced analytics and a new graphical interface for a comprehensive morphometric experience","volume":"12","author":"Baken","year":"2021","journal-title":"Methods Ecol Evol"},{"key":"2026072311172415300_bib5","doi-asserted-by":"publisher","first-page":"204","DOI":"10.1111\/joa.12403","article-title":"Brain modularity across the theropod\u2013bird transition: testing the influence of flight on neuroanatomical variation","volume":"229","author":"Balanoff","year":"2016","journal-title":"J Anat"},{"key":"2026072311172415300_bib6","doi-asserted-by":"publisher","first-page":"1507","DOI":"10.1111\/2041-210X.14376","article-title":"Fast mvSLOUCH: multivariate Ornstein\u2013Uhlenbeck-based models of trait evolution on large phylogenies","volume":"15","author":"Bartoszek","year":"2024","journal-title":"Methods Ecol Evol"},{"key":"2026072311172415300_bib7","doi-asserted-by":"publisher","first-page":"637","DOI":"10.1111\/j.1469-7580.2006.00644.x","article-title":"Craniofacial levels and the morphological maturation of the human skull","volume":"209","author":"Bastir","year":"2006","journal-title":"J Anat"},{"key":"2026072311172415300_bib8","doi-asserted-by":"publisher","first-page":"424","DOI":"10.1016\/j.jhevol.2010.03.001","article-title":"Effects of brain and facial size on basicranial form in human and primate evolution","volume":"58","author":"Bastir","year":"2010","journal-title":"J Hum Evol"},{"key":"2026072311172415300_bib9","first-page":"389","article-title":"How to make a bird skull: major transitions in the evolution of the avian cranium, paedomorphosis, and the beak as a surrogate hand","volume-title":"Integrative and comparative biology","author":"Bhullar","year":"2016"},{"key":"2026072311172415300_bib10","doi-asserted-by":"publisher","first-page":"223","DOI":"10.1038\/nature11146","article-title":"Birds have paedomorphic dinosaur skulls","volume":"487","author":"Bhullar","year":"2012","journal-title":"Nature"},{"key":"2026072311172415300_bib11","doi-asserted-by":"publisher","first-page":"20180277","DOI":"10.1098\/rsif.2018.0277","article-title":"Analysis of modularity and integration suggests evolution of dragonfly wing venation mainly in response to functional demands","volume":"15","author":"Blanke","year":"2018","journal-title":"J R Soc Interface."},{"key":"2026072311172415300_bib12","doi-asserted-by":"publisher","first-page":"342","DOI":"10.1007\/s11692-022-09574-0","article-title":"Dimensions of morphological integration","volume":"49","author":"Bookstein","year":"2022","journal-title":"Evol Biol"},{"key":"2026072311172415300_bib13","doi-asserted-by":"publisher","first-page":"5352","DOI":"10.1073\/pnas.1602683113","article-title":"The shapes of bird beaks are highly controlled by nondietary factors","volume":"113","author":"Bright","year":"2016","journal-title":"Proc Natl Acad Sci USA"},{"key":"2026072311172415300_bib14","doi-asserted-by":"publisher","first-page":"104","DOI":"10.1186\/s12862-019-1432-1","article-title":"The multifactorial nature of beak and skull shape evolution in parrots and cockatoos (Psittaciformes)","volume":"19","author":"Bright","year":"2019","journal-title":"BMC Evol Biol"},{"key":"2026072311172415300_bib15","doi-asserted-by":"publisher","first-page":"746","DOI":"10.1093\/evolut\/qpac070","article-title":"Simultaneous integration and modularity underlie the exceptional body shape diversification of characiform fishes","volume":"77","author":"Burns","year":"2023","journal-title":"Evolution (NY)"},{"key":"2026072311172415300_bib16","doi-asserted-by":"publisher","first-page":"2345","DOI":"10.1016\/j.visres.2008.08.001","article-title":"The scaling of eye size in adult birds: relationship to brain, head and body sizes","volume":"48","author":"Burton","year":"2008","journal-title":"Vision Res"},{"key":"2026072311172415300_bib17","doi-asserted-by":"publisher","first-page":"90","DOI":"10.1007\/s11692-018-9463-x","article-title":"Integration and modularity in Procrustes shape data: is there a risk of spurious results?","volume":"46","author":"Cardini","year":"2019","journal-title":"Evol Biol"},{"key":"2026072311172415300_bib18","doi-asserted-by":"publisher","first-page":"e21622","DOI":"10.1002\/jmor.21622","article-title":"Differential growth of the adductor muscles, eyeball, and brain in the chick Gallus gallus with comments on the fossil record of stem-group birds","volume":"284","author":"Cerio","year":"2023","journal-title":"J Morphol"},{"key":"2026072311172415300_bib19","doi-asserted-by":"publisher","first-page":"3421","DOI":"10.1098\/rspb.2009.0888","article-title":"Developmental basis for telencephalon expansion in waterfowl: enlargement prior to neurogenesis","volume":"276","author":"Charvet","year":"2009","journal-title":"Proc R Soc B Biol Sci"},{"key":"2026072311172415300_bib20","doi-asserted-by":"publisher","first-page":"e2405887121","DOI":"10.1073\/pnas.2405887121","article-title":"Calibrating the genomic clock of modern birds using fossils","volume":"121","author":"Claramunt","year":"2024","journal-title":"Proc Natl Acad Sci USA"},{"key":"2026072311172415300_bib21","doi-asserted-by":"publisher","first-page":"1311","DOI":"10.1111\/2041-210X.12420","article-title":"mvMORPH: an R package for fitting multivariate evolutionary models to morphometric data","volume":"6","author":"Clavel","year":"2015","journal-title":"Methods Ecol Evol"},{"key":"2026072311172415300_bib22","doi-asserted-by":"publisher","first-page":"85","DOI":"10.1111\/ede.12421","article-title":"Covariation of brain and skull shapes as a model to understand the role of crosstalk in development and evolution","volume":"25","author":"Conith","year":"2023","journal-title":"Evol Dev"},{"key":"2026072311172415300_bib23","doi-asserted-by":"publisher","first-page":"33","DOI":"10.4404\/hystrix-24.1-6383","article-title":"Phylogenetic principal components analysis and geometric morphometrics","volume":"24","author":"David\u00a0Polly","year":"2013","journal-title":"Hystrix"},{"key":"2026072311172415300_bib24","doi-asserted-by":"publisher","first-page":"453","DOI":"10.1038\/s42003-019-0697-7","article-title":"Modularity increases rate of floral evolution and adaptive success for functionally specialized pollination systems","volume":"2","author":"Dellinger","year":"2019","journal-title":"Commun Biol"},{"key":"2026072311172415300_bib25","doi-asserted-by":"publisher","first-page":"e2101330118","DOI":"10.1073\/pnas.2101330118","article-title":"Integration drives rapid phenotypic evolution in flatfishes","volume":"118","author":"Evans","year":"2021","journal-title":"Proc Natl Acad Sci USA"},{"key":"2026072311172415300_bib26","doi-asserted-by":"publisher","first-page":"1543","DOI":"10.1038\/s41559-017-0288-2","article-title":"The skull roof tracks the brain during the evolution and development of reptiles including birds","volume":"1","author":"Fabbri","year":"2017","journal-title":"Nat Ecol Evol"},{"key":"2026072311172415300_bib27","doi-asserted-by":"publisher","first-page":"1129","DOI":"10.1038\/s41559-020-1225-3","article-title":"Metamorphosis shapes cranial diversity and rate of evolution in salamanders","volume":"4","author":"Fabre","year":"2020","journal-title":"Nat Ecol Evol"},{"key":"2026072311172415300_bib28","doi-asserted-by":"publisher","first-page":"555","DOI":"10.1073\/pnas.1716437115","article-title":"Developmental origins of mosaic evolution in the avian cranium","volume":"115","author":"Felice","year":"2018","journal-title":"Proc Natl Acad Sci USA"},{"key":"2026072311172415300_bib29","doi-asserted-by":"publisher","first-page":"371","DOI":"10.1093\/icb\/icz052","article-title":"Evolutionary integration and modularity in the archosaur cranium","volume":"59","author":"Felice","year":"2019","journal-title":"Integr Comp Biol"},{"key":"2026072311172415300_bib30","doi-asserted-by":"crossref","first-page":"445","DOI":"10.1146\/annurev.es.19.110188.002305","article-title":"Phylogenies and quantitative characters","volume":"19","author":"Felsenstein","year":"1988","journal-title":"Annu Rev Ecol Syst"},{"key":"2026072311172415300_bib31","doi-asserted-by":"publisher","first-page":"e82000","DOI":"10.1371\/journal.pone.0082000","article-title":"Skeletal correlates for body mass estimation in modern and fossil flying birds","volume":"8","author":"Field","year":"2013","journal-title":"PLoS One"},{"key":"2026072311172415300_bib32","volume-title":"sem: Structural equation models","author":"Fox","year":"2013"},{"key":"2026072311172415300_bib33","doi-asserted-by":"publisher","first-page":"20192474","DOI":"10.1098\/rspb.2019.2474","article-title":"Evolution of a multifunctional trait: shared effects of foraging ecology and thermoregulation on beak morphology, with consequences for song evolution","volume":"286","author":"Friedman","year":"2019","journal-title":"Proc R Soc B Biol Sci"},{"key":"2026072311172415300_bib34","doi-asserted-by":"publisher","first-page":"8582","DOI":"10.1073\/pnas.0701035104","article-title":"The theory of facilitated variation","volume-title":"PNAS","author":"Gerhart","year":"2007"},{"key":"2026072311172415300_bib35","author":"Gill","year":"2024"},{"key":"2026072311172415300_bib36","doi-asserted-by":"publisher","first-page":"270","DOI":"10.1086\/505758","article-title":"Cranial modularity shifts during mammalian evolution","volume":"168","author":"Goswami","year":"2006","journal-title":"Am Nat"},{"key":"2026072311172415300_bib37","doi-asserted-by":"publisher","first-page":"20220083","DOI":"10.1098\/rstb.2022.0083","article-title":"Developmental origin underlies evolutionary rate variation across the placental skull","volume":"378","author":"Goswami","year":"2023","journal-title":"Philosophical Trans R Soc B Biol Sci"},{"key":"2026072311172415300_bib38","doi-asserted-by":"publisher","first-page":"e9517","DOI":"10.1371\/journal.pone.0009517","article-title":"The influence of modularity on cranial morphological disparity in Carnivora and Primates (Mammalia)","volume":"5","author":"Goswami","year":"2010","journal-title":"PLoS One"},{"key":"2026072311172415300_bib39","doi-asserted-by":"publisher","first-page":"862","DOI":"10.1111\/j.1420-9101.2012.02477.x","article-title":"Shape, variance and integration during craniogenesis: contrasting marsupial and placental mammals","volume":"25","author":"Goswami","year":"2012","journal-title":"J Evol Biol"},{"key":"2026072311172415300_bib40","doi-asserted-by":"publisher","first-page":"669","DOI":"10.1093\/icb\/icz120","article-title":"High-density morphometric analysis of shape and integration: the good, the bad, and the not-really-a-problem","volume":"59","author":"Goswami","year":"2019","journal-title":"Integr Comp Biol"},{"key":"2026072311172415300_bib41","doi-asserted-by":"publisher","first-page":"101","DOI":"10.1038\/s43586-022-00184-w","article-title":"Principal component analysis","volume":"2","author":"Greenacre","year":"2022","journal-title":"Nat Rev Methods Primers"},{"key":"2026072311172415300_bib42","doi-asserted-by":"publisher","first-page":"1369","DOI":"10.1093\/icb\/icz105","article-title":"Integration and the developmental genetics of allometry","volume":"59","author":"Hallgr\u00edmsson","year":"2019","journal-title":"Integr Comp Biol"},{"key":"2026072311172415300_bib43","doi-asserted-by":"crossref","first-page":"183","DOI":"10.4324\/9780429269103-14","article-title":"Structural equation modeling","volume-title":"The essence of multivariate thinking: basic themes and methods","author":"Harlow","year":"2023"},{"key":"2026072311172415300_bib44","doi-asserted-by":"publisher","first-page":"1720","DOI":"10.1093\/evolut\/qpad079","article-title":"Ecological and life-history drivers of avian skull evolution","volume":"77","author":"Hunt","year":"2023","journal-title":"Evolution (NY)"},{"key":"2026072311172415300_bib45","doi-asserted-by":"publisher","first-page":"21","DOI":"10.1186\/s12983-021-00406-z","article-title":"Evolution and development of the bird chondrocranium","volume":"18","author":"H\u00fcppi","year":"2021","journal-title":"Front Zool"},{"key":"2026072311172415300_bib46","doi-asserted-by":"publisher","first-page":"103","DOI":"10.1111\/ede.12313","article-title":"Developmental bias, macroevolution, and the fossil record","volume":"22","author":"Jablonski","year":"2020","journal-title":"Evol Dev"},{"key":"2026072311172415300_bib47","doi-asserted-by":"publisher","first-page":"140187","DOI":"10.1098\/rsos.140187","article-title":"Endocranial and masticatory muscle volumes in myostatin-deficient mice","volume":"1","author":"Jeffery","year":"2014","journal-title":"R Soc Open Sci"},{"key":"2026072311172415300_bib48","doi-asserted-by":"publisher","first-page":"1284","DOI":"10.1111\/joa.13393","article-title":"Ontogenetic and in silico models of spatial-packing in the hypermuscular mouse skull","volume":"238","author":"Jeffery","year":"2021","journal-title":"J Anat"},{"key":"2026072311172415300_bib49","doi-asserted-by":"publisher","first-page":"495","DOI":"10.1111\/joa.12109","article-title":"Variation in avian brain shape: relationship with size and orbital shape","volume":"223","author":"Kawabe","year":"2013","journal-title":"J Anat"},{"key":"2026072311172415300_bib50","doi-asserted-by":"publisher","first-page":"1241","DOI":"10.1242\/dev.125.7.1241","article-title":"FGF-, BMP- and Shh-mediated signalling pathways in the regulation of cranial suture morphogenesis and calvarial bone development","volume":"7","author":"Kim","year":"1998","journal-title":"Development"},{"key":"2026072311172415300_bib51","volume-title":"Principles and practice of structural equation modeling","author":"Kline","year":"2023"},{"key":"2026072311172415300_bib52","doi-asserted-by":"publisher","first-page":"115","DOI":"10.1146\/annurev.ecolsys.37.091305.110054","article-title":"Morphological integration and developmental modularity","volume":"39","author":"Klingenberg","year":"2008","journal-title":"Annu Rev Ecol Evol Syst"},{"key":"2026072311172415300_bib53","doi-asserted-by":"publisher","first-page":"43","DOI":"10.4404\/hystrix-24.1-6367","article-title":"Cranial integration and modularity: insights into evolution and development from morphometric data","volume":"24","author":"Klingenberg","year":"2013","journal-title":"Hystrix"},{"key":"2026072311172415300_bib54","doi-asserted-by":"publisher","first-page":"591","DOI":"10.1093\/sysbio\/syt025","article-title":"Evolutionary covariation in geometric morphometric data: analyzing integration, modularity, and allometry in a phylogenetic context","volume":"62","author":"Klingenberg","year":"2013","journal-title":"Syst Biol"},{"key":"2026072311172415300_bib55","doi-asserted-by":"publisher","DOI":"10.1098\/rspb.2025.0848","article-title":"Avian cranial evolution is influenced by shape interactions between hard and soft tissue traits","volume":"292","author":"Knapp","year":"2025","journal-title":"Proc R Soc B Biol Sci"},{"key":"2026072311172415300_bib56","doi-asserted-by":"publisher","first-page":"1","DOI":"10.33988\/auvfd.1454398","article-title":"Exploring skull shape variation and allometry across different chicken breeds","volume":"72","author":"Korkmazcan","year":"2025","journal-title":"Ankara \u00dcniversitesi Veteriner Fak\u00fcltesi Dergisi"},{"key":"2026072311172415300_bib57","doi-asserted-by":"publisher","first-page":"20220080","DOI":"10.1098\/rstb.2022.0080","article-title":"Evolutionary mechanisms modulating the mammalian skull development","volume":"378","author":"Kyomen","year":"2023","journal-title":"Philos Trans R Soc B Biol Sci"},{"key":"2026072311172415300_bib58","doi-asserted-by":"publisher","first-page":"61","DOI":"10.3389\/fncom.2013.00061","article-title":"Evolutionary and developmental modules","volume":"7","author":"Lacquaniti","year":"2013","journal-title":"Front Comput Neurosci"},{"key":"2026072311172415300_bib59","doi-asserted-by":"publisher","first-page":"209","DOI":"10.2307\/2986915","article-title":"Factor analysis as a statistical method","volume":"12","author":"Lawley","year":"1962","journal-title":"J R Stat Soc Ser D Stat"},{"key":"2026072311172415300_bib60","doi-asserted-by":"publisher","first-page":"423","DOI":"10.1093\/evolut\/qpad214","article-title":"Pervasive cranial allometry at different anatomical scales and variational levels in extant armadillos","volume":"78","author":"Le\u00a0Verger","year":"2024","journal-title":"Evolution (NY)"},{"key":"2026072311172415300_bib61","doi-asserted-by":"publisher","first-page":"720","DOI":"10.1111\/j.1469-7580.2008.00900.x","article-title":"Spatial packing, cranial base angulation, and craniofacial shape variation in the mammalian skull: testing a new model using mice","volume":"212","author":"Lieberman","year":"2008","journal-title":"J Anat"},{"key":"2026072311172415300_bib62","doi-asserted-by":"publisher","first-page":"117","DOI":"10.1002\/1096-8644(2000)43:31+&lt;117::aid-ajpa5&gt;3.0.co;2-i","article-title":"The primate cranial base: ontogeny, function, and integration","volume":"113","author":"Lieberman","year":"2000","journal-title":"Am J Phys Anthropol"},{"key":"2026072311172415300_bib63","doi-asserted-by":"publisher","first-page":"16222","DOI":"10.1073\/pnas.1206205109","article-title":"Closely related bird species demonstrate flexibility between beak morphology and underlying developmental programs","volume":"109","author":"Mallarino","year":"2012","journal-title":"Proc Natl Acad Sci USA"},{"key":"2026072311172415300_bib64","doi-asserted-by":"publisher","first-page":"644099","DOI":"10.3389\/fcell.2021.644099","article-title":"Wnt signaling drives correlated changes in facial morphology and brain shape","volume":"9","author":"Marchini","year":"2021","journal-title":"Front Cell Dev Biol"},{"key":"2026072311172415300_bib65","doi-asserted-by":"publisher","first-page":"177","DOI":"10.1002\/dvg.20710","article-title":"Mechanisms that underlie co-variation of the brain and face","volume":"49","author":"Marcucio","year":"2011","journal-title":"Genesis"},{"key":"2026072311172415300_bib66","doi-asserted-by":"publisher","first-page":"216","DOI":"10.1186\/s12915-023-01715-x","article-title":"The neck as a keystone structure in avian macroevolution and mosaicism","volume":"21","author":"Marek","year":"2023","journal-title":"BMC Biol"},{"key":"2026072311172415300_bib67","doi-asserted-by":"publisher","first-page":"77","DOI":"10.1016\/j.geobios.2024.11.007","article-title":"Craniocervical morphological integration in birds","volume":"90","author":"Marug\u00e1n-Lob\u00f3n","year":"2025","journal-title":"Geobios"},{"key":"2026072311172415300_bib68","doi-asserted-by":"publisher","first-page":"197","DOI":"10.1111\/joa.13555","article-title":"Beyond the beak: brain size and allometry in avian craniofacial evolution","volume":"240","author":"Marug\u00e1n-Lob\u00f3n","year":"2022","journal-title":"J Anat"},{"key":"2026072311172415300_bib69","doi-asserted-by":"publisher","first-page":"1492","DOI":"10.1177\/00220345710500062301","article-title":"Neurotrophic processes in orofacial growth","volume":"50","author":"Moss","year":"1971","journal-title":"J Dent Res"},{"key":"2026072311172415300_bib70","doi-asserted-by":"publisher","first-page":"281","DOI":"10.1002\/ajpa.1330180406","article-title":"A functional approach to craniology","volume":"18","author":"Moss","year":"1960","journal-title":"Am J Phys Anthropol"},{"key":"2026072311172415300_bib71","doi-asserted-by":"publisher","first-page":"E174","DOI":"10.1086\/720745","article-title":"The effects of foraging ecology and allometry on avian skull shape vary across levels of phylogeny","volume":"200","author":"Natale","year":"2022","journal-title":"Am Nat"},{"key":"2026072311172415300_bib72","volume-title":"Morphological integration","author":"Olson","year":"1958"},{"key":"2026072311172415300_bib73","doi-asserted-by":"publisher","first-page":"249","DOI":"10.1111\/j.1461-0248.2009.01281.x","article-title":"Global biogeography and ecology of body size in birds","volume":"12","author":"Olson","year":"2009","journal-title":"Ecol Lett"},{"key":"2026072311172415300_bib74","doi-asserted-by":"publisher","first-page":"2025","DOI":"10.1101\/2025.02.04.634049","article-title":"Brain size dependent speciation and extinction rates in birds and the cognitive buffer hypothesis","volume":"2025","author":"Oyston","year":"2025","journal-title":"Biorxiv"},{"key":"2026072311172415300_bib75","doi-asserted-by":"publisher","first-page":"61","DOI":"10.3389\/fphys.2013.00061","article-title":"A review of hedgehog signaling in cranial bone development","volume":"4","author":"Pan","year":"2013","journal-title":"Front Physiol"},{"key":"2026072311172415300_bib76","doi-asserted-by":"publisher","first-page":"195","DOI":"10.1038\/s42003-020-0914-4","article-title":"Birds have peramorphic skulls, too: anatomical network analyses reveal oppositional heterochronies in avian skull evolution","volume":"3","author":"Plateau","year":"2020","journal-title":"Commun Biol"},{"key":"2026072311172415300_bib77","doi-asserted-by":"publisher","first-page":"118","DOI":"10.1007\/s11692-008-9038-3","article-title":"The evolution of modularity in the mammalian skull I: morphological integration patterns and magnitudes","volume":"36","author":"Porto","year":"2009","journal-title":"Evol Biol"},{"key":"2026072311172415300_bib78","doi-asserted-by":"publisher","first-page":"144","DOI":"10.1002\/ajpa.24340","article-title":"Arothron: an R package for geometric morphometric methods and virtual anthropology applications","volume":"176","author":"Profico","year":"2021","journal-title":"Am J Phys Anthropol"},{"key":"2026072311172415300_bib79","first-page":"311","article-title":"Testing quantitative genetic hypotheses about the evolutionary rate matrix for continuous characters","volume":"10","author":"Revell","year":"2008","journal-title":"Evol Ecol Res"},{"key":"2026072311172415300_bib80","doi-asserted-by":"publisher","first-page":"360","DOI":"10.1002\/jez.b.21092","article-title":"Phenotypic integration of neurocranium and brain","volume":"306","author":"Richtsmeier","year":"2006","journal-title":"J Exp Zool B Mol Dev Evol"},{"key":"2026072311172415300_bib81","doi-asserted-by":"publisher","first-page":"469","DOI":"10.1007\/s00401-013-1104-y","article-title":"Hand in glove: brain and skull in development and dysmorphogenesis","volume":"125","author":"Richtsmeier","year":"2013","journal-title":"Acta Neuropathol"},{"key":"2026072311172415300_bib82","doi-asserted-by":"publisher","first-page":"433","DOI":"10.1146\/annurev-genet-111523","article-title":"Cellular, molecular, and genetic mechanisms of avian beak development and evolution","volume":"58","author":"Schneider","year":"2026","journal-title":"Annu Rev Genet"},{"key":"2026072311172415300_bib83","doi-asserted-by":"publisher","first-page":"319","DOI":"10.1002\/ajpa.1330160305","article-title":"The cranial base","volume":"16","author":"Scott","year":"1958","journal-title":"Am J Phys Anthropol"},{"key":"2026072311172415300_bib84","doi-asserted-by":"crossref","DOI":"10.1017\/CBO9781139979573","volume-title":"Cause and correlation in biology: A user\u2019s guide to path analysis, structural equations and causal inference with R","author":"Shipley","year":"2016"},{"key":"2026072311172415300_bib85","doi-asserted-by":"publisher","first-page":"eabe2101","DOI":"10.1126\/sciadv.abe2101","article-title":"The evolution of mammalian brain size","volume":"7","author":"Smaers","year":"2021","journal-title":"Sci Adv"},{"key":"2026072311172415300_bib86","doi-asserted-by":"publisher","first-page":"20150187","DOI":"10.1098\/rstb.2015.0187","article-title":"The life-history basis of behavioural innovations","volume":"371","author":"Sol","year":"2016","journal-title":"Phil Trans R Soc B"},{"key":"2026072311172415300_bib87","doi-asserted-by":"publisher","first-page":"851","DOI":"10.1038\/s41586-024-07323-1","article-title":"Complexity of avian evolution revealed by family-level genomes","volume":"629","author":"Stiller","year":"2024","journal-title":"Nature"},{"key":"2026072311172415300_bib88","doi-asserted-by":"publisher","first-page":"1357","DOI":"10.1111\/jeb.14234","article-title":"phylosem: a fast and simple R package for phylogenetic inference and trait imputation using phylogenetic structural equation models","volume":"36","author":"Thorson","year":"2023","journal-title":"J Evol Biol"},{"key":"2026072311172415300_bib89","doi-asserted-by":"publisher","first-page":"581","DOI":"10.1111\/ele.13898","article-title":"AVONET: morphological, ecological and geographical data for all birds","volume":"25","author":"Tobias","year":"2022","journal-title":"Ecol Lett"},{"key":"2026072311172415300_bib90","doi-asserted-by":"publisher","first-page":"20150481","DOI":"10.1098\/rstb.2015.0481","article-title":"Cranial shape evolution in adaptive radiations of birds: comparative morphometrics of Darwin\u2019s finches and Hawaiian honeycreepers","volume":"372","author":"Tokita","year":"2017","journal-title":"Philos Trans R Soc B Biol Sci"},{"key":"2026072311172415300_bib91","doi-asserted-by":"publisher","first-page":"111828","DOI":"10.1016\/j.isci.2025.111828","article-title":"Emergent network properties link phenotypic modules to ecomorphological divergence in carnivoran mammals","volume":"28","author":"Tseng","year":"2025","journal-title":"iScience"},{"key":"2026072311172415300_bib92","doi-asserted-by":"publisher","first-page":"1668","DOI":"10.1242\/jeb.015289","article-title":"The relationship between shape of the skull and bite force in finches","volume":"211","author":"Van\u00a0Der\u00a0Meij","year":"2008","journal-title":"J Exp Biol"},{"key":"2026072311172415300_bib93","doi-asserted-by":"publisher","first-page":"161","DOI":"10.1007\/s10709-022-00158-6","article-title":"Solving the grand challenge of phenotypic integration: allometry across scales","volume":"150","author":"Vasseur","year":"2022","journal-title":"Genetica"},{"key":"2026072311172415300_bib94","doi-asserted-by":"publisher","first-page":"e391","DOI":"10.1002\/wdev.391","article-title":"Network-regulated organ allometry: the developmental regulation of morphological scaling","volume":"10","author":"Vea","year":"2021","journal-title":"Wiley Interdiscip Rev Dev Biol"},{"key":"2026072311172415300_bib95","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1007\/978-3-662-43550-2_8","article-title":"An introduction to phylogenetic path analysis","volume-title":"Modern phylogenetic comparative methods and their application in evolutionary biology","author":"Voyer","year":"2014"},{"key":"2026072311172415300_bib96","doi-asserted-by":"publisher","first-page":"20160214","DOI":"10.1098\/rspb.2016.0214","article-title":"Rates of morphological evolution are heterogeneous in early cretaceous birds","volume":"283","author":"Wang","year":"2016","journal-title":"Proc R Soc B"},{"key":"2026072311172415300_bib97","doi-asserted-by":"publisher","first-page":"e68809","DOI":"10.7554\/eLife.68809","article-title":"Novel neuroanatomical integration and scaling define avian brain shape evolution and development","volume":"10","author":"Watanabe","year":"2021","journal-title":"eLife"},{"key":"2026072311172415300_bib98","doi-asserted-by":"publisher","first-page":"14688","DOI":"10.1073\/pnas.1820967116","article-title":"Ecomorphological diversification in squamates from conserved pattern of cranial integration","volume":"116","author":"Watanabe","year":"2019","journal-title":"Proc Natl Acad Sci USA"},{"key":"2026072311172415300_bib99","doi-asserted-by":"publisher","first-page":"241","DOI":"10.1002\/jez.1101","article-title":"Developmental modularity and the evolutionary diversification of arthropod limbs","volume":"291","author":"Williams","year":"2001","journal-title":"J Exp Zool"},{"key":"2026072311172415300_bib100","first-page":"557","article-title":"Correlation and causation","volume":"20","author":"Wright","year":"1921","journal-title":"J Agric Res"},{"key":"2026072311172415300_bib101","doi-asserted-by":"publisher","first-page":"1059","DOI":"10.1242\/dev.099994","article-title":"Embryonic bauplans and the developmental origins of facial diversity and constraint","volume":"141","author":"Young","year":"2014","journal-title":"Development (Cambridge)"},{"key":"2026072311172415300_bib102","volume-title":"Geometric morphometrics for biologists: a primer","author":"Zelditch","year":"2012"},{"key":"2026072311172415300_bib103","doi-asserted-by":"publisher","first-page":"368","DOI":"10.2307\/2413401","article-title":"Evaluating models of developmental integration in the laboratory rat using confirmatory factor analysis","volume":"36","author":"Zelditch","year":"1987","journal-title":"Syst Zool"},{"key":"2026072311172415300_bib104","doi-asserted-by":"publisher","first-page":"377","DOI":"10.1111\/ede.12390","article-title":"What does modularity mean?","volume":"23","author":"Zelditch","year":"2021","journal-title":"Evol Dev"},{"key":"2026072311172415300_bib105","doi-asserted-by":"publisher","first-page":"56","DOI":"10.1007\/s11692-022-09581-1","article-title":"The predictable complexity of evolutionary allometry","volume":"50","author":"Zelditch","year":"2023","journal-title":"Evol Biol"},{"key":"2026072311172415300_bib106","doi-asserted-by":"publisher","first-page":"147","DOI":"10.1007\/s11692-023-09600-9","article-title":"Effects of Procrustes superimposition and semilandmark sliding on modularity and integration: an investigation using simulations of biological data","volume":"50","author":"Zelditch","year":"2023","journal-title":"Evol Biol"},{"key":"2026072311172415300_bib107","doi-asserted-by":"publisher","first-page":"756","DOI":"10.1111\/j.1525-142X.2008.00290.x","article-title":"Modularity of the rodent mandible: integrating bones, muscles, and teeth","volume":"10","author":"Zelditch","year":"2008","journal-title":"Evol Dev"},{"key":"2026072311172415300_bib108","article-title":"A note on numerical evaluation of conditional Akaike information for nonlinear mixed-effects models","author":"Zheng","year":"2024"},{"key":"2026072311172415300_bib109","first-page":"391","article-title":"Patterns of diversity in the avian skull","volume-title":"The Skull, Volume 2: Patterns of Structural and Systematic Diversity","author":"Zusi","year":"1993"}],"container-title":["Integrative And Comparative Biology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/academic.oup.com\/icb\/advance-article-pdf\/doi\/10.1093\/icb\/icag106\/68685321\/icag106.pdf","content-type":"application\/pdf","content-version":"am","intended-application":"syndication"},{"URL":"https:\/\/academic.oup.com\/icb\/article-pdf\/doi\/10.1093\/icb\/icag106\/68685321\/icag106.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/academic.oup.com\/icb\/article-pdf\/doi\/10.1093\/icb\/icag106\/68685321\/icag106.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T15:17:36Z","timestamp":1784819856000},"score":1,"resource":{"primary":{"URL":"https:\/\/academic.oup.com\/icb\/article\/doi\/10.1093\/icb\/icag106\/8723922"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026]]},"references-count":109,"URL":"https:\/\/doi.org\/10.1093\/icb\/icag106","relation":{},"ISSN":["1557-7023"],"issn-type":[{"value":"1557-7023","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[2026]]},"published":{"date-parts":[[2026]]},"article-number":"icag106"}}