{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T09:00:31Z","timestamp":1790326831624,"version":"4.1.0"},"reference-count":16,"publisher":"Wiley","issue":"9","license":[{"start":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T00:00:00Z","timestamp":1790121600000},"content-version":"vor","delay-in-days":22,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"},{"start":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T00:00:00Z","timestamp":1788220800000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Journal of Morphology"],"published-print":{"date-parts":[[2026,9]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    Accipitridae (eagles, hawks, and kites) are raptorial birds whose anisodactyl feet combine support, perching, and prey capture. In several Accipitridae, the proximal and intermediate phalanges of the inner toe (digit II; phalanges II\u20101 and II\u20102) are fused completely or partly into a single functional unit. The character occurs in a restricted but ecologically heterogeneous set of kites and sea eagles and is absent from many other raptorial taxa. Its distribution is therefore not explained adequately by body size, broad diet or predation in itself. This synthesis interprets the fused condition in relation to the organization of the accipitrid grasp, in which the hallux (digit I) and digit II form the principal opposed pair for fixing prey, whereas digits III and IV enlarge and stabilize the contact field. Fusion removes a mobile joint from the basal portion of digit II, stiffens the force\u2010transmitting chain and reduces deformation, hyperextension and shear during flexor loading. The same change necessarily reduces the capacity of digit II to conform to curved or irregular prey surfaces. The fused toe is consequently interpreted as a specialization for rapid and mechanically firm fixation rather than for maximizing congruence between the foot and the prey. This trade\u2010off reconciles the occurrence of fusion across taxa with different diets: the relevant common factor is not prey category, but the value of establishing an immediate, high\u2010force opposed grip before struggling prey can escape. The available distribution also retains systematic information, although variation in the Black\u2010collared Hawk,\n                    <jats:italic>Busarellus nigricollis<\/jats:italic>\n                    and the separation of fused taxa among modern lineages preclude treating the condition as a universally invariant synapomorphy. Fusion is best understood as a restricted osteological configuration that integrates phylogenetic history with a consistent functional bias towards speed and rigidity of fixation at the expense of contact conformity.\n                  <\/jats:p>","DOI":"10.1002\/jmor.70180","type":"journal-article","created":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T10:55:16Z","timestamp":1790160916000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Fusion of the Basal Phalanges of Digit II in Accipitridae (Aves: Eagles, Hawks, and Kites): A Functional Trade\u2010Off Between Rapid Force Transmission and Surface\u2010Conforming Grasp"],"prefix":"10.1002","volume":"287","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8074-615X","authenticated-orcid":false,"given":"Andrei V.","family":"Zinoviev","sequence":"first","affiliation":[{"name":"Department of Zoology and Physiology Tver State University Tver Tver Region Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,9,23]]},"reference":[{"key":"e_1_2_12_2_1","doi-asserted-by":"publisher","DOI":"10.1093\/zoolinnean\/zlag054"},{"key":"e_1_2_12_3_1","doi-asserted-by":"publisher","DOI":"10.1098\/rsos.140350"},{"key":"e_1_2_12_4_1","first-page":"143","article-title":"The Inner Toe of Megatriorchis, Erythrotriorchis and Harpyopsis","volume":"105","author":"Boles W. 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Evolutionary Theory"},{"key":"e_1_2_12_12_1","first-page":"1","article-title":"A Contribution to the Morphology and Phylogeny of the Falconiformes. Part IV","volume":"3","author":"Jollie M.","year":"1977","journal-title":"Evolutionary Theory"},{"key":"e_1_2_12_13_1","first-page":"8","article-title":"The Distribution of Fused Phalanges of the Inner Toe in the Accipitridae","volume":"102","author":"Olson S. 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