Ve sv\u011bt\u011b dinosaur\u016f bizarn\u00ed struktury jako jsou plachty a rohy \u010dasto p\u0159itahuj\u00ed pozornost. Nicm\u00e9n\u011b objev nov\u00e9ho druhu hadrosaurida, Acristavus gagslarsoni, vrhl sv\u011btlo na jin\u00fd aspekt t\u011bchto prav\u011bk\u00fdch b\u00fdlo\u017eravc\u016f: jejich nezdobnost.<\/p>\n\n
Acristavus \u017eil p\u0159ibli\u017en\u011b p\u0159ed 79 miliony let v z\u00e1padn\u00ed \u010d\u00e1sti Severn\u00ed Ameriky. Jeho poz\u016fstatky byly nalezeny ve formaci Two Medicine v Montan\u011b a ve formaci Wahweap v Utahu, reprezentovan\u00e9 t\u00e9m\u011b\u0159 kompletn\u00edmi lebkami a dal\u0161\u00edmi skelet\u00e1ln\u00edmi prvky.<\/p>\n\n
Na rozd\u00edl od mnoha jin\u00fdch hadrosaurid\u016f, Acristavus postr\u00e1dal propracovan\u00e9 lebkov\u00e9 ozdoby, kter\u00e9 charakterizovaly jeho p\u0159\u00edbuzn\u00e9. Tento \u201eneozdobn\u00fd\u201c vzhled jej odli\u0161uje a poskytuje cenn\u00e9 poznatky o evolu\u010dn\u00ed historii hadrosaurid\u016f.<\/p>\n\n
Hadrosau\u0159i jsou r\u016fznorod\u00e1 skupina dinosaur\u016f, kte\u0159\u00ed se vyvinuli z \u010dasn\u011bj\u0161\u00edch p\u0159\u00edbuzn\u00fdch zn\u00e1m\u00fdch jako iguanodonti. Jedn\u00edm z ur\u010duj\u00edc\u00edch znak\u016f hadrosaurid\u016f je jejich mno\u017estv\u00ed hlavov\u00fdch ozdob, v\u010detn\u011b \u010denic s v\u00fd\u010dn\u011blky, p\u00e1del a l\u017eic. Nicm\u00e9n\u011b hladk\u00e1 lebka Acristavuse nazna\u010duje, \u017ee zdobnost nebyla univerz\u00e1ln\u00edm znakem mezi hadrosauridy.<\/p>\n\n
Objev Acristavuse podporuje hypot\u00e9zu, \u017ee dv\u011b hlavn\u00ed podskupiny hadrosaurid\u016f, lambeosaurini a hadrosaurini, nez\u00e1visle vyvinuly r\u016fzn\u00e9 zp\u016fsoby zdoben\u00ed. Lambeosaurini, jako nap\u0159\u00edklad Parasaurolophus, m\u011bli dlouh\u00e9, h\u0159ebenat\u00e9 lebky, zat\u00edmco hadrosaurini, jako nap\u0159\u00edklad Maiasaura, m\u011bli jemn\u011bj\u0161\u00ed lebe\u010dn\u00ed modifikace.<\/p>\n\n
Evolu\u010dn\u00ed pozice Acristavuse nazna\u010duje, \u017ee nejran\u011bj\u0161\u00ed hadrosauridn\u00ed dinosau\u0159i nem\u011bli na lebk\u00e1ch \u017e\u00e1dn\u00e9 ozdoby. To nazna\u010duje, \u017ee zdobnost se vyvinula nez\u00e1visle v ka\u017ed\u00e9 ze dvou hlavn\u00edch podskupin. Nicm\u00e9n\u011b z\u016fst\u00e1v\u00e1 mo\u017en\u00e9, \u017ee Acristavus druhotn\u011b ztratil ozdoby, kter\u00e9 byly p\u0159\u00edtomny u jeho p\u0159edka, jak je vid\u011bt u pozd\u011bj\u0161\u00edho hadrosaurida Edmontosaura.<\/p>\n\n
Acristavus je pouze jeden objev a je pot\u0159eba dal\u0161\u00edho v\u00fdzkumu, abychom pln\u011b pochopili evolu\u010dn\u00ed historii ozdob hadrosaurid\u016f. Nicm\u00e9n\u011b jeho jedine\u010dn\u00e9 rysy a evolu\u010dn\u00ed pozice poskytuj\u00ed cenn\u00e9 informace.<\/p>\n\n
Acristavus pat\u0159il do zvl\u00e1\u0161tn\u00ed podskupiny hadrosaurid\u016f zn\u00e1m\u00e9 jako Brachylophosaurini, kter\u00e1 zahrnuje tak\u00e9 Maiasauru a Brachylophosaura. Zat\u00edmco Maiasaura a Brachylophosaurus vykazovali modifikovan\u00e9, zdoben\u00e9 \u010denichy, Acristavus si zachoval lebku s archai\u010dt\u011bj\u0161\u00edm vzhledem.<\/p>\n\n
Objev Acristavuse otev\u0159el nov\u00e9 cesty v\u00fdzkumu evoluce hadrosaurid\u016f. S trochou \u0161t\u011bst\u00ed pomohou budouc\u00ed objevy paleontolog\u016fm l\u00e9pe pochopit, jak tito prav\u011bc\u00ed ob\u0159i z\u00edskali sv\u00e9 v\u00fdrazn\u00e9 lebkov\u00e9 ozdoby.<\/p>","protected":false},"excerpt":{"rendered":"
Acristavus: Nov\u00fd hadrosaurid z \u00fazem\u00ed Severn\u00ed Ameriky Objev Acristavuse Ve sv\u011bt\u011b dinosaur\u016f bizarn\u00ed struktury jako jsou plachty a rohy \u010dasto p\u0159itahuj\u00ed pozornost. Nicm\u00e9n\u011b objev nov\u00e9ho druhu hadrosaurida, Acristavus gagslarsoni, vrhl…<\/p>\n","protected":false},"author":1,"featured_media":24106,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[138],"tags":[18121,18123,512,16776,137,18122],"class_list":["post-13436","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-paleontology","tag-acristavus","tag-brachylophosaurini","tag-dinosaur-evolution","tag-hadrosaur","tag-paleontology","tag-unornamented-hadrosaurs"],"_links":{"self":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/13436","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/comments?post=13436"}],"version-history":[{"count":2,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/13436\/revisions"}],"predecessor-version":[{"id":24241,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/13436\/revisions\/24241"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/media\/24106"}],"wp:attachment":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/media?parent=13436"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/categories?post=13436"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/tags?post=13436"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}