{"id":10622,"date":"2010-03-01T12:52:31","date_gmt":"2010-03-01T10:52:31","guid":{"rendered":"http:\/\/109.232.216.219\/~bilimvegelecek\/?p=10622"},"modified":"2017-05-29T12:55:05","modified_gmt":"2017-05-29T09:55:05","slug":"yoksa-sanilanin-tam-tersine-kuslar-mi-dinozorlarin-atasi","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2010\/03\/01\/yoksa-sanilanin-tam-tersine-kuslar-mi-dinozorlarin-atasi","title":{"rendered":"Yoksa san\u0131lan\u0131n tam tersine, ku\u015flar m\u0131 dinozorlar\u0131n atas\u0131?"},"content":{"rendered":"

ABD k\u00f6kenli Ulusal Bilimler Akademisi\u2019ndeki \u0130lerlemeler<\/em> (PNAS<\/em>) adl\u0131 derginin, 16 \u015eubat 2010 tarihli say\u0131s\u0131nda yay\u0131nlanan, biri ara\u015ft\u0131rma (1) di\u011feri derleme (2) olan iki adet makale, ku\u015flar\u0131n karada ya\u015fayan theropodlardan (Jurassic Park ve AROG gibi filmlerde s\u0131k\u00e7a g\u00f6rd\u00fc\u011f\u00fcm\u00fcz nam-\u0131 di\u011fer Trex –Tyrannosaurus rex<\/em>– gibi arka iki ekstrimiteleri -ayaklar\u0131- \u00fczerinde hareket eden dinozorlar\u0131n ve g\u00fcn\u00fcm\u00fczdeki ku\u015flar\u0131n da dahil oldu\u011fu biyolojik sistematikte bir grup) t\u00fcremedi\u011fine dair var olanlar\u0131n \u00fczerine yeni bulgular koyarak, u\u00e7u\u015fun evrimi hakk\u0131nda y\u0131llard\u0131r kabul edilen teorileri sorguluyor.<\/p>\n

2003\u2019te ke\u015ffedilen ve \u201cMicroraptor\u201d ad\u0131 verilen fosil \u00fczerinde, u\u00e7u\u015fa uygun olup olmad\u0131\u011f\u0131 hakk\u0131nda fikir sahibi olabilmek i\u00e7in, \u00fc\u00e7 boyutlu modeller olu\u015fturularak yap\u0131lan ara\u015ft\u0131rmaya g\u00f6re, Microraptor yerden havalanacak bir yap\u0131ya sahip olmasa da a\u011fa\u00e7lar\u0131n tepesinden s\u00fcz\u00fclerek u\u00e7abilen, k\u00fc\u00e7\u00fck ve t\u00fcyl\u00fc bir hayvand\u0131. PNAS<\/em>\u2019daki derleme makalenin (1) yazar\u0131, ABD\u2019nin Oregon eyaletindeki Oregon Devlet \u00dcniversitesi\u2019nde (OSU) zooloji profes\u00f6r\u00fc olan John Ruben derlemesinde, bir \u00f6nceki paragrafta s\u00f6z etti\u011fimiz ara\u015ft\u0131rma makalesinin (2) son derece iyi yap\u0131lm\u0131\u015f bir \u00e7al\u0131\u015fma oldu\u011funu ve yak\u0131n zamanda yay\u0131nlanan ve ku\u015flar\u0131n dinozorlardan t\u00fcredi\u011fini sorgulayan benzer makaleler ile tutarl\u0131 oldu\u011funu vurgulamaktad\u0131r.<\/p>\n

Ruben, kan\u0131tlar\u0131n giderek artmas\u0131na dayanarak, sadece, san\u0131lan\u0131n tam aksine ku\u015flar\u0131n dinozorlardan t\u00fcremedi\u011fi, baz\u0131 dinozor t\u00fcrlerinin de ku\u015flardan t\u00fcremi\u015f olabilece\u011fi yorumunu yap\u0131yor.<\/p>\n

Ruben bu son \u00e7al\u0131\u015fman\u0131n da (1) deste\u011fiyle, kan\u0131tlardan o kadar emin ki, son 20 y\u0131ld\u0131r kabul edilen ku\u015flar\u0131n dinozorlardan t\u00fcredi\u011fi konusundaki b\u00fcy\u00fcn\u00fcn bozuldu\u011funu ve tart\u0131\u015fmalar\u0131n bu son \u00e7al\u0131\u015fma ile bitti\u011fini belirtiyor. Ruben ku\u015flar\u0131n dinozorlardan geldi\u011fi konusundaki tart\u0131\u015fmalar\u0131n, asl\u0131nda dinozorlar\u0131n ku\u015flardan t\u00fcremi\u015f olabilece\u011fi \u015feklinde sonu\u00e7land\u0131\u011f\u0131n\u0131 belirtse de, bu son \u00e7al\u0131\u015fman\u0131n daha hen\u00fcz her \u015feyi \u00e7\u00f6zmedi\u011fini, ku\u015flar\u0131n dinozorlardan t\u00fcredi\u011fi konusundaki daha bir\u00e7ok tutars\u0131z nokta oldu\u011funu, bu son \u00e7al\u0131\u015fman\u0131n ise bu tutars\u0131zl\u0131klara bir yenisini ekledi\u011fini s\u00f6yl\u00fcyor.<\/p>\n

Ruben derlemesinde (2) dinozorlar\u0131n ku\u015flardan gelmi\u015f olabilece\u011fi tezi konusuna ise \u015fu \u015fekilde a\u00e7\u0131kl\u0131k getiriyor:<\/p>\n

\u201cOSU\u2019daki yakla\u015f\u0131k 20 y\u0131ll\u0131k ku\u015f ve dinozor morfolojisi \u00fczerine yapt\u0131\u011f\u0131m ara\u015ft\u0131rmalar ve di\u011fer makalelerin yan\u0131nda PNAS<\/em>\u2019da yay\u0131nlanan son ara\u015ft\u0131rma makalesi \u0131\u015f\u0131\u011f\u0131nda s\u00f6yleyebilirim ki; ku\u015flar\u0131n dinozorlardan geldi\u011fi tezinin \u00e7\u00fcr\u00fcmesinden \u00f6teye, sonu\u00e7lar \u00e7ok daha farkl\u0131 bir \u015feyi vaat etmektedir. O da ku\u015flar ile dinozorlar\u0131n ortak bir atadan t\u00fcredikleri ve ayr\u0131 bir \u015fekilde kendi yollar\u0131nda ilerledikleri, milyonlarca y\u0131ll\u0131k ayr\u0131 devam eden evrim ser\u00fcvenleri sonras\u0131nda ise baz\u0131 ku\u015flar\u0131n Raptor\u2019lara (Velocirapotor<\/em> cinsi dinozorun pop\u00fcler s\u00f6yleni\u015f \u015fekli) evrimle\u015fti\u011fidir. Bence dinozor olarak kabul edilen Velociraptor gibi k\u00fc\u00e7\u00fck canl\u0131lar u\u00e7amayan ku\u015flard\u0131r.<\/p>\n

\"\"
1915\u2019te do\u011fa bilimcisi William Beebe taraf\u0131ndan, ilk ku\u015flar\u0131n nas\u0131l g\u00f6r\u00fcnd\u00fc\u011f\u00fcn\u00fc, a\u011fa\u00e7lardan s\u00fcz\u00fcl\u00fcrken g\u00f6steren hipotetik resim. 2003\u2019te bulunan, ku\u015flar\u0131n karada ya\u015fayan Theropod\u2019lardan t\u00fcredi\u011fi teorisine dair \u015f\u00fcphelerin artmas\u0131na neden olan, en nadir fosillerden biri olan Microraptor\u2019a \u00e7arp\u0131c\u0131 \u015fekilde benzedi\u011fi g\u00f6r\u00fclmektedir.<\/figcaption><\/figure>\n

\u201cRaptor\u2019lar az \u00e7ok dinozorlara benzese de, Tyrannosaurus<\/em> gibi di\u011fer Theropod dinozorlardan \u00e7ok ku\u015flarla daha fazla ortak noktas\u0131 var. PNAS<\/em> makalesindeki son kan\u0131t da, art\u0131k en sonunda dinozor olarak kabul edilen bu hayvanlar\u0131n -Raptor- ku\u015flardan t\u00fcredi\u011fini g\u00f6stermektedir.<\/p>\n

\u201cGe\u00e7en sene ADB\u2019nin Florida eyaletindeki Florida Devlet \u00dcniversitesi\u2019nde de benzer \u015f\u00fcpheler uyand\u0131ran bir \u00e7al\u0131\u015fma yap\u0131lm\u0131\u015ft\u0131. Bu PNAS<\/em>\u2019daki en son \u00e7al\u0131\u015fmada da, ara\u015ft\u0131rmac\u0131lar d\u00f6rt ekleminde de t\u00fcyleri h\u00e2l\u00e2 duran, iki kanatl\u0131 bir yap\u0131ya sahip \u00e7ok de\u011ferli bir fosil incelediler. Modeli \u00fczerinde yap\u0131lan s\u00fcz\u00fclme testleri, bu yap\u0131n\u0131n karadan havaya de\u011fil de, g\u00fcn\u00fcm\u00fczdeki u\u00e7an sincaplar gibi a\u011fa\u00e7lar\u0131n tepesinden a\u015fa\u011f\u0131ya s\u00fcz\u00fclmeye yarad\u0131\u011f\u0131n\u0131 g\u00f6sterdi. Uzun s\u00fcredir bir\u00e7ok ara\u015ft\u0131r\u0131c\u0131 da a\u011fa\u00e7lar\u0131n tepesinden a\u015fa\u011f\u0131ya s\u00fcz\u00fclebilen hayvanlar\u0131n modern ku\u015flar\u0131n atas\u0131 oldu\u011funa inanmaktayd\u0131 zaten.<\/p>\n

Bu Microraptor modeli yerden havalanmak i\u00e7in uygun g\u00f6r\u00fcnm\u00fcyor ve karada ya\u015fayan Theropod tipi dinozorlar\u0131n kanatlar geli\u015ftirerek u\u00e7mas\u0131 olas\u0131l\u0131\u011f\u0131n\u0131 da son derece zor k\u0131l\u0131yor. Di\u011fer yandan baz\u0131 ku\u015f t\u00fcrlerinin evrimle\u015ferek, evrim basamaklar\u0131n\u0131n ilerisinde bir noktada, u\u00e7ma yeteneklerini kaybederek, karada ya\u015fayan, u\u00e7amayan Raptor gibi hayvanlara d\u00f6n\u00fc\u015fmesi \u00e7ok daha olas\u0131. Bu bir\u00e7ok insan\u0131 k\u0131zd\u0131rabilir, fakat bu senaryo \u00e7ok daha mant\u0131kl\u0131 geliyor bana.\u201d<\/p>\n

OSU\u2019deki ara\u015ft\u0131rmac\u0131lar ge\u00e7en sene Journal of Morphology<\/em>\u2019de kendi yapt\u0131klar\u0131 \u00e7al\u0131\u015fmada, ku\u015flardaki g\u00f6\u011f\u00fcs kemi\u011finin ve g\u00f6\u011f\u00fcs kaslar\u0131n\u0131n konumunun uzun soluklu ve uzun mesafeli u\u00e7u\u015flar i\u00e7in yeterli akci\u011fer kapasitesine sahip olmas\u0131n\u0131 sa\u011flamas\u0131 a\u00e7\u0131s\u0131ndan, ku\u015f biyolojisinin temel belirleyici noktalar\u0131ndan biri oldu\u011funu bulmu\u015flard\u0131. Bununla birlikte Theropod\u2019larda bu \u00f6zellik bulunmuyor. Di\u011fer belirlenen morfolojik \u00f6zellikler de ku\u015flar\u0131n dinozorlardan t\u00fcredi\u011fi teorisi konusunda tutars\u0131zl\u0131k ortaya koymaktad\u0131r. Ve belki de en \u00f6nemlisi ku\u015f fosillerinin, ku\u015flar\u0131n atas\u0131 say\u0131lan dinozorlar\u0131n ke\u015ffinden \u00e7ok daha \u00f6nce bulunmas\u0131d\u0131r. Bu bilgilerin \u0131\u015f\u0131\u011f\u0131nda yine Ruben\u2019in dedi\u011fi gibi tersine k\u0131yasla, Raptor\u2019lar\u0131n ku\u015flardan t\u00fcremi\u015f olmas\u0131 \u00e7ok daha tutarl\u0131 bir teori.<\/p>\n

Ruben PNAS<\/em>\u2019daki derlemesini \u015f\u00f6yle toparl\u0131yor:<\/p>\n

\u201cOSU\u2019da ku\u015f biyolojisi ve fizyolojisi \u00fczerine yap\u0131lan ara\u015ft\u0131rmalar 1990\u2019lardan beri konunun sorgulanmas\u0131na neden oluyordu. Art\u0131k daha fazla \u00e7al\u0131\u015fma ve ara\u015ft\u0131rmac\u0131 bu konu ve getirece\u011fi yenilikler \u00fczerine \u00e7al\u0131\u015f\u0131yor. Eski teoriler daha pop\u00fclerdi, insanlar\u0131n ilgisini \u00e7ekmi\u015fti ve \u00e7o\u011fu insan bilgileri do\u011fru yorumlamak yerine g\u00f6rmek istedi\u011fini g\u00f6rd\u00fc. Can s\u0131k\u0131c\u0131 yeni fosiller daha \u00f6nce pop\u00fclaritesini hi\u00e7 yitirmeyen, ku\u015flar\u0131n dinozorlardan geldi\u011fi b\u00fcy\u00fcs\u00fcne art\u0131k \u00e7omak soktu. Fosil kay\u0131tlar\u0131n\u0131n bu kadar kaprisli olmas\u0131, uzun s\u00fcre \u00f6nce nesli t\u00fckenmi\u015f bir\u00e7ok ya\u015fam formu hakk\u0131ndaki \u00e7\u00f6z\u00fcme yak\u0131n en temel sorulara daha dikkatli yakla\u015f\u0131lmas\u0131 gereklili\u011fini ortaya koymaktad\u0131r.\u201d (3)<\/p>\n

 <\/p>\n

KAYNAKLAR<\/strong><\/p>\n

1) David E. Alexander, Enpu Gong, Larry D. Martin, David A. Burnham, and Amanda R. Falk, Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui<\/em>, PNAS, 16 \u015eubat 2010, 107, 7, 2972-2976. Bas\u0131mdan \u00f6nce online yay\u0131n, 9 \u015eubat, 2010, doi: 10.1073\/pnas.0911852107<\/p>\n

2) John Ruben, Paleobiology and the origins of avian flight, PNAS, 16 \u015eubat 2010, 107, 7, 2733-2734. Bas\u0131mdan \u00f6nce online yay\u0131n, 9 \u015eubat, 2010, doi: 10.1073\/pnas.0915099107<\/p>\n

3) Oregon State University (2010, February 10). Bird-from-dinosaur theory of evolution challenged: Was it the other way around?. ScienceDaily<\/em>. 21 \u015eubat, 2010\u2019da http:\/\/www.sciencedaily.com\/releases\/2010\/02\/100209183335.htm adresinden al\u0131nm\u0131\u015ft\u0131r.<\/p>\n","protected":false},"excerpt":{"rendered":"

ABD k\u00f6kenli Ulusal Bilimler Akademisi\u2019ndeki \u0130lerlemeler (PNAS) adl\u0131 derginin, 16 \u015eubat 2010 tarihli say\u0131s\u0131nda yay\u0131nlanan, biri ara\u015ft\u0131rma (1) di\u011feri derleme (2) olan iki adet makale, ku\u015flar\u0131n karada ya\u015fayan theropodlardan (Jurassic Park ve AROG gibi filmlerde s\u0131k\u00e7a g\u00f6rd\u00fc\u011f\u00fcm\u00fcz nam-\u0131 di\u011fer Trex –Tyrannosaurus rex– gibi arka iki ekstrimiteleri -ayaklar\u0131- \u00fczerinde hareket eden dinozorlar\u0131n ve g\u00fcn\u00fcm\u00fczdeki ku\u015flar\u0131n da […]<\/p>\n","protected":false},"author":778,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[110,19],"tags":[],"class_list":["post-10622","post","type-post","status-publish","format-standard","hentry","category-73-sayi","category-bilim-gundemi"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t