{"id":14478,"date":"2022-06-30T21:33:53","date_gmt":"2022-06-30T21:33:53","guid":{"rendered":"https:\/\/www.lifescienceart.com\/?p=14478"},"modified":"2022-06-30T21:33:53","modified_gmt":"2022-06-30T21:33:53","slug":"dinosaur-extinction-theories-vitamin-d-uv-radiation","status":"publish","type":"post","link":"https:\/\/www.lifescienceart.com\/cs\/science\/paleontology\/dinosaur-extinction-theories-vitamin-d-uv-radiation\/","title":{"rendered":"Vym\u00edr\u00e1n\u00ed dinosaur\u016f: Nedostatek vitaminu D a UV z\u00e1\u0159en\u00ed jako mo\u017en\u00e9 p\u0159\u00ed\u010diny"},"content":{"rendered":"

Vym\u00edr\u00e1n\u00ed dinosaur\u016f: Role UV z\u00e1\u0159en\u00ed a nedostatku vitaminu D<\/h2>\n\n

Environment\u00e1ln\u00ed zm\u011bny a hromadn\u00e9 vym\u00edr\u00e1n\u00ed<\/h2>\n\n

Vym\u00edr\u00e1n\u00ed dinosaur\u016f, katastrofick\u00e1 ud\u00e1lost, ke kter\u00e9 do\u0161lo p\u0159ed 65 miliony let, uchv\u00e1tila v\u011bdce na cel\u00e9 v\u011bky. Mezi mnoha navrhovan\u00fdmi teoriemi z\u00edskala pozornost my\u0161lenka, \u017ee n\u00e1hl\u00e1 zm\u011bna \u017eivotn\u00edho prost\u0159ed\u00ed sehr\u00e1la v\u00fdznamnou roli.<\/p>\n\n

Harryho Marshallova hypot\u00e9za k\u0159ivice<\/h2>\n\n

V roce 1928 p\u0159edlo\u017eil patolog Harry T. Marshall zaj\u00edmavou hypot\u00e9zu, \u017ee dinosau\u0159i mohli podlehnout k\u0159ivici, co\u017e je stav zp\u016fsoben\u00fd nedostatkem vitaminu D. Marshall teoretizoval, \u017ee oblaka prachu zast\u00ednila slunce a od\u0159\u00edzla dinosaury od p\u0159\u00edsunu ultrafialov\u00e9ho (UV) z\u00e1\u0159en\u00ed, kter\u00e9 je nezbytn\u00e9 pro produkci vitaminu D.<\/p>\n\n

D\u016fkazy o nedostatku vitaminu D<\/h2>\n\n

Marshallova hypot\u00e9za z\u00edskala d\u016fv\u011bryhodnost o n\u011bkolik desetilet\u00ed pozd\u011bji, kdy\u017e ji Charles Cockell ze Stanfordovy univerzity znovu p\u0159ezkoumal v \u010dasopise Paleobiology. Cockell pouk\u00e1zal na to, \u017ee kapradiny a dal\u0161\u00ed vegetace, kter\u00e1 tvo\u0159ila v\u00fdznamnou \u010d\u00e1st j\u00eddeln\u00ed\u010dku dinosaur\u016f, postr\u00e1d\u00e1 slou\u010deniny pohlcuj\u00edc\u00ed UV z\u00e1\u0159en\u00ed. To nazna\u010duje, \u017ee dinosau\u0159i mohli m\u00edt pot\u00ed\u017ee se z\u00edsk\u00e1v\u00e1n\u00edm dostate\u010dn\u00e9ho mno\u017estv\u00ed vitaminu D ze sv\u00fdch potravinov\u00fdch zdroj\u016f.<\/p>\n\n

Vyvr\u00e1cen\u00ed hypot\u00e9zy o poj\u00edd\u00e1n\u00ed vajec<\/h2>\n\n

Jedna popul\u00e1rn\u00ed, ale chybn\u00e1 teorie vym\u00edr\u00e1n\u00ed tvrdila, \u017ee mal\u00ed savci po\u017e\u00edraj\u00ed vejce dinosaur\u016f, co\u017e vedlo k jejich z\u00e1niku. Tato teorie v\u0161ak nezohled\u0148uje obrovsk\u00fd po\u010det vajec, kter\u00fd by byl nezbytn\u00fd k udr\u017een\u00ed populace savc\u016f. Nav\u00edc paleontologov\u00e9 nena\u0161li \u017e\u00e1dn\u00e9 d\u016fkazy o roz\u0161\u00ed\u0159en\u00e9 predaci vajec.<\/p>\n\n

Vliv UV z\u00e1\u0159en\u00ed<\/h2>\n\n

Cockell posunul Marshallovu hypot\u00e9zu o krok d\u00e1le a navrhl, \u017ee nadm\u011brn\u00e9 UV z\u00e1\u0159en\u00ed zp\u016fsoben\u00e9 periodick\u00fdmi vy\u010derp\u00e1n\u00edmi ozonov\u00e9 vrstvy mohlo b\u00fdt zodpov\u011bdn\u00e9 za hromadn\u00e1 vym\u00edr\u00e1n\u00ed. UV z\u00e1\u0159en\u00ed m\u016f\u017ee po\u0161kodit DNA a potla\u010dit imunitn\u00ed syst\u00e9m, co\u017e \u010din\u00ed organismy zraniteln\u011bj\u0161\u00edmi v\u016f\u010di nemocem a environment\u00e1ln\u00edm stresor\u016fm.<\/p>\n\n

D\u016fkazy o \u00fabytku ozonu<\/h2>\n\n

P\u0159esto\u017ee hypot\u00e9za o \u00fabytku ozonu z\u016fst\u00e1v\u00e1 spekulativn\u00ed, existuj\u00ed d\u016fkazy, kter\u00e9 nazna\u010duj\u00ed, \u017ee mohla hr\u00e1t roli. Studie uk\u00e1zaly, \u017ee v k\u0159\u00eddov\u00e9m obdob\u00ed byla ozonov\u00e1 vrstva ten\u010d\u00ed, ne\u017e je dnes, co\u017e umo\u017enilo, aby se na zemsk\u00fd povrch dostalo v\u00edce UV z\u00e1\u0159en\u00ed.<\/p>\n\n

Prob\u00edhaj\u00edc\u00ed v\u00fdzkum a d\u016fsledky<\/h2>\n\n

Teorie o vym\u00edr\u00e1n\u00ed dinosaur\u016f v\u011bdci neust\u00e1le zp\u0159es\u0148uj\u00ed a diskutuj\u00ed o nich. Marshallova p\u016fvodn\u00ed hypot\u00e9za a Cockellovo n\u00e1sledn\u00e9 zkoum\u00e1n\u00ed UV z\u00e1\u0159en\u00ed poskytly cenn\u00e9 poznatky o potenci\u00e1ln\u00edch environment\u00e1ln\u00edch faktorech, kter\u00e9 mohly p\u0159isp\u011bt k t\u00e9to katastrofick\u00e9 ud\u00e1losti.<\/p>\n\n

V\u00fdznam vitaminu D<\/h2>\n\n

Nedostatek vitaminu D je spojen s \u0159adou zdravotn\u00edch probl\u00e9m\u016f u modern\u00edch zv\u00ed\u0159at, v\u010detn\u011b deformac\u00ed kost\u00ed, svalov\u00e9 slabosti a dysfunkce imunitn\u00edho syst\u00e9mu. Je pravd\u011bpodobn\u00e9, \u017ee podobn\u00e9 zdravotn\u00ed probl\u00e9my tr\u00e1pily dinosaury v obdob\u00edch omezen\u00e9ho vystaven\u00ed UV z\u00e1\u0159en\u00ed.<\/p>\n\n

Environment\u00e1ln\u00ed zm\u011bny a budouc\u00ed vym\u00edr\u00e1n\u00ed<\/h2>\n\n

Studium teori\u00ed vym\u00edr\u00e1n\u00ed dinosaur\u016f m\u00e1 d\u016fsledky pro pochopen\u00ed potenci\u00e1ln\u00edch dopad\u016f environment\u00e1ln\u00edch zm\u011bn na modern\u00ed druhy. Vzhledem k tomu, \u017ee lidsk\u00e9 \u010dinnosti neust\u00e1le m\u011bn\u00ed ekosyst\u00e9my planety, je nezbytn\u00e9 zv\u00e1\u017eit zp\u016fsoby, jak\u00fdmi mohou tyto zm\u011bny ovlivnit zdrav\u00ed a p\u0159e\u017eit\u00ed rostlin i \u017eivo\u010dich\u016f.<\/p>","protected":false},"excerpt":{"rendered":"

Vym\u00edr\u00e1n\u00ed dinosaur\u016f: Role UV z\u00e1\u0159en\u00ed a nedostatku vitaminu D Environment\u00e1ln\u00ed zm\u011bny a hromadn\u00e9 vym\u00edr\u00e1n\u00ed Vym\u00edr\u00e1n\u00ed dinosaur\u016f, katastrofick\u00e1 ud\u00e1lost, ke kter\u00e9 do\u0161lo p\u0159ed 65 miliony let, uchv\u00e1tila v\u011bdce na cel\u00e9 v\u011bky.…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[138],"tags":[134,137,19436,19435,400],"class_list":["post-14478","post","type-post","status-publish","format-standard","hentry","category-paleontology","tag-dinosaurs","tag-paleontology","tag-uv-radiation","tag-vitamin-d","tag-extinction"],"_links":{"self":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/14478","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=14478"}],"version-history":[{"count":1,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/14478\/revisions"}],"predecessor-version":[{"id":14479,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/posts\/14478\/revisions\/14479"}],"wp:attachment":[{"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/media?parent=14478"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/categories?post=14478"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lifescienceart.com\/cs\/wp-json\/wp\/v2\/tags?post=14478"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}