\u0130\u015f hayat a\u011fac\u0131n\u0131 olu\u015fturmaya geldi\u011finde, k\u00f6pekbal\u0131\u011f\u0131 ile insan aras\u0131ndaki en \u00f6nemli farkl\u0131l\u0131k ne uzuvlar ile y\u00fczge\u00e7ler, ne de akci\u011ferlerle solunga\u00e7lar aras\u0131ndaki. Farkl\u0131l\u0131klar\u0131n temeli iskeletlerimizde. K\u00f6pekbal\u0131klar\u0131n\u0131n iskeleti k\u0131k\u0131rdak yap\u0131l\u0131d\u0131r ve bu onlar\u0131 vatoz ailesi bal\u0131klar\u0131yla birlikte k\u0131k\u0131rdakl\u0131 bal\u0131klar s\u0131n\u0131f\u0131na sokar. \u0130nsanlar (modern omurgal\u0131lar\u0131n b\u00fcy\u00fck k\u0131sm\u0131 ile birlikte) kemikli bal\u0131klar grubundan gelmektedir. Bu iki grubun en az 420 milyon y\u0131l \u00f6nce birbirinden ayr\u0131ld\u0131\u011f\u0131 biliminsanlar\u0131 taraf\u0131ndan biliniyor olsa da, en eski ortak atalar\u0131n neye benzedi\u011fi h\u00e2l\u00e2 gizemini koruyan bir konudur. Sibirya\u2019da bulunan k\u00fc\u00e7\u00fck bir bal\u0131k fosilinin kafatas\u0131ndaki yeni bulgular, bu konuda ipu\u00e7lar\u0131 sa\u011flayabilir.<\/p>\n
S\u00f6zkonusu fosil en fazla 415 milyon y\u0131l \u00f6ncesine, erken devoniyen d\u00f6nemine ait bir bal\u0131k kafatas\u0131. 1992\u2019de yay\u0131mlanan k\u0131sa bir makalede bu fosile, kemikli bir bal\u0131k olan ve Yeni Sibirya Adalar\u0131\u2019nda ya\u015fam\u0131\u015f olan Dialipina<\/em>\u2019ya kafatas\u0131 ve pullar\u0131 bak\u0131m\u0131ndan benzerli\u011fiyle de\u011finilmi\u015f ve bu benzerlikler nedeniyle fosil kemikli bal\u0131k olarak s\u0131n\u0131fland\u0131r\u0131lm\u0131\u015ft\u0131r. Bu d\u00f6neme ait kemikli bal\u0131klara \u00e7ok nasir rastlan\u0131r, bu y\u00fczden Kraliyet Koleji\u2019nden paleontolog Martin Brazeau, internetten fosilin daha detayl\u0131 bir foto\u011fraf\u0131n\u0131 ula\u015ft\u0131\u011f\u0131nda Oxford \u00dcniversitesi\u2019nden meslekta\u015flar\u0131 Sam Giles ve Matt Friedman ile fosilin k\u00f6kenlerinin daha detayl\u0131 bir ara\u015ft\u0131rmaya de\u011fece\u011fine karar verdiler.<\/p>\n Bu bal\u0131\u011f\u0131n evrimsel s\u00fcre\u00e7te nereye denk geldi\u011fini anlayabilmek i\u00e7in ara\u015ft\u0131rmac\u0131lar, 1 cm uzunlu\u011fundaki kafatas\u0131na zarar vermeden i\u00e7indeki kemiklerin yap\u0131s\u0131n\u0131 micro-CT taramas\u0131ndan yararlanarak inceledi. Bu teknik hastanelerde kullan\u0131lan ve v\u00fccudun i\u00e7ini g\u00f6rmemize olanak sa\u011flayan CT-g\u00f6r\u00fcnt\u00fcleme tekni\u011fine benzer. Fosil, kafa kubbesinin \u015fekli ve pullar\u0131ndaki enamel yap\u0131s\u0131 gibi y\u00fczeysel \u00f6zelliklerine bak\u0131larak, ba\u015fta kemikli bal\u0131k olarak s\u0131n\u0131fland\u0131r\u0131lm\u0131\u015ft\u0131. Fakat CT taramas\u0131 hem kemikli hem de k\u0131k\u0131rdakl\u0131 bal\u0131klara \u00f6zg\u00fc b\u00f6l\u00fcmlere sahip oldu\u011funu ortaya koydu. \u00d6rnek vermek gerekirse fosil, bug\u00fcnk\u00fc kemikli bal\u0131klar\u0131nkine benzer kemikli plakalardan olu\u015furken ayn\u0131 zamanda sinirler ve beyin \u00e7evresindeki kan damarlar\u0131 a\u00e7\u0131s\u0131ndan k\u0131k\u0131rdakl\u0131 bal\u0131klara benziyor. Nature<\/em> dergisinin internet sitesinde yer alan habere g\u00f6re ara\u015ft\u0131rma grubu fosile, Roma Tanr\u0131s\u0131 Janus\u2019tan esinlenerek Janusiscus schultzei<\/em> ad\u0131n\u0131 verdi.<\/p>\n Ara\u015ft\u0131rmalara g\u00f6re \u00e7eneli omurgal\u0131lar\u0131n iki \u015fubesinde de, kafatas\u0131ndaki kemikli plakalar gibi yaln\u0131zca kemikli bal\u0131klara \u00f6zg\u00fc k\u0131s\u0131mlar mevcut; fakat bu k\u0131s\u0131mlar k\u0131k\u0131rdakl\u0131 bal\u0131klara giden dalda sonradan kayboluyor. 2013\u2019de yap\u0131lan ba\u015fka bir ara\u015ft\u0131rmada kemikli bal\u0131klara \u00f6zg\u00fc oldu\u011fu d\u00fc\u015f\u00fcn\u00fclen baz\u0131 \u00f6zelliklerin, k\u0131k\u0131rdakl\u0131 bal\u0131klarla olan ortak atalarla ilintili, soyu t\u00fckenmi\u015f bir t\u00fcr olan Placodeus<\/em>\u2019da g\u00f6r\u00fclmesi de bu bulgulara dayanmakta. 2014\u2019de yap\u0131lan bir \u00e7al\u0131\u015fmada da 325 milyon y\u0131ll\u0131k bir k\u00f6pekbal\u0131\u011f\u0131 fosilinden \u015fa\u015f\u0131lacak say\u0131da kemikli bal\u0131k \u00f6zelli\u011fi ortaya \u00e7\u0131kar\u0131ld\u0131. Ata t\u00fcrde ayn\u0131 \u00f6zellikler mevcutsa, k\u00f6pekbal\u0131klar\u0131 sand\u0131\u011f\u0131m\u0131zdan daha \u00f6zelle\u015fmi\u015f bir t\u00fcr olabilir. \u201cBu bulgular\u0131n tamam\u0131 k\u0131k\u0131rdakl\u0131 bal\u0131klar\u0131n kemiklilerden daha ilkel oldu\u011fu yan\u0131lg\u0131s\u0131n\u0131 d\u00fczeltebilir\u201d diyor ba\u015fyazar Giles.<\/p>\n Bir grubun di\u011ferinin \u00f6nc\u00fcl\u00fc olmas\u0131ndansa, iki grubun farkl\u0131 adaptasyonlarla ve ortak atalar\u0131ndan ald\u0131klar\u0131 farkl\u0131 \u00f6zellikleri koruyarak evrimle\u015fti\u011fini s\u00f6ylemek daha do\u011fru olur. Giles bu durumu \u201c\u0130ki grup denizde ya\u015faman\u0131n zorluklar\u0131na farkl\u0131 yakla\u015ft\u0131\u201d diye a\u00e7\u0131kl\u0131yor.<\/p>\n Avustralya, Adelaide\u2019deki Flinders \u00dcniversitesi\u2019nden paleontolog John Long, Janusiscus<\/em>\u2019un b\u00fcy\u00fcleyici bir ke\u015fif oldu\u011funu s\u00f6yl\u00fcyor ve \u015f\u00f6yle diyor: \u201cDetayl\u0131 CT taramas\u0131 kullan\u0131lmadan ara\u015ft\u0131rma ger\u00e7ekle\u015ftirilemezdi. Kritik ge\u00e7i\u015f fosillerinin modern teknolojinin bu \u015fekilde kullan\u0131m\u0131 ile incelenmesi yeni bilgiler a\u00e7\u0131\u011fa \u00e7\u0131kararak bizim yapt\u0131\u011f\u0131m\u0131z \u015fekliyle paleontolojiyi d\u00f6n\u00fc\u015ft\u00fcr\u00fcyor.\u201d<\/p>\n Kaynak<\/strong><\/p>\n http:\/\/news.sciencemag.org\/paleontology\/2015\/01\/ancient-fossil-may-rewrite-fish-family-tree<\/p>\n","protected":false},"excerpt":{"rendered":" \u0130\u015f hayat a\u011fac\u0131n\u0131 olu\u015fturmaya geldi\u011finde, k\u00f6pekbal\u0131\u011f\u0131 ile insan aras\u0131ndaki en \u00f6nemli farkl\u0131l\u0131k ne uzuvlar ile y\u00fczge\u00e7ler, ne de akci\u011ferlerle solunga\u00e7lar aras\u0131ndaki. Farkl\u0131l\u0131klar\u0131n temeli iskeletlerimizde. K\u00f6pekbal\u0131klar\u0131n\u0131n iskeleti k\u0131k\u0131rdak yap\u0131l\u0131d\u0131r ve bu onlar\u0131 vatoz ailesi bal\u0131klar\u0131yla birlikte k\u0131k\u0131rdakl\u0131 bal\u0131klar s\u0131n\u0131f\u0131na sokar. \u0130nsanlar (modern omurgal\u0131lar\u0131n b\u00fcy\u00fck k\u0131sm\u0131 ile birlikte) kemikli bal\u0131klar grubundan gelmektedir. Bu iki grubun en az […]<\/p>\n","protected":false},"author":899,"featured_media":24459,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[169,19,21,38],"tags":[3092,1138,200,3093],"class_list":["post-24458","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-132-sayi","category-bilim-gundemi","category-biyoloji","category-dergi-sayilari","tag-antik-fosil","tag-balik","tag-evrim","tag-soyagaci"],"acf":[],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts\/24458","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/users\/899"}],"replies":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/comments?post=24458"}],"version-history":[{"count":0,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/posts\/24458\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/media\/24459"}],"wp:attachment":[{"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/media?parent=24458"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/categories?post=24458"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bilimvegelecek.com.tr\/index.php\/wp-json\/wp\/v2\/tags?post=24458"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}