圖片說明:新研究確證了恐龍與鳥類、乳齒象與現(xiàn)代大象的親緣關(guān)系,。
(圖片來源:Zina Deretsky, National Science Foundation)
美國科學(xué)家近日在分子水平上分析了6800萬年前的暴龍(Tyrannosaurus rex)的蛋白質(zhì)片斷,,并與21種現(xiàn)代物種的蛋白質(zhì)序列進(jìn)行了比較,,結(jié)果確證,,恐龍與鳥類具有共同祖先,。研究文章發(fā)表在4月25日的《科學(xué)》(Science)雜志上。
領(lǐng)導(dǎo)此次研究的是美國哈佛醫(yī)學(xué)院的John M. Asara,。研究所用的膠原蛋白(collagen protein)取自2003年發(fā)現(xiàn)的一段暴龍腿骨化石,,Asara和同事曾于去年對(duì)這段蛋白質(zhì)進(jìn)行了測(cè)序。
在最新的研究中,,Asara和同事將這段蛋白質(zhì)與其它21種物種的相關(guān)蛋白質(zhì)進(jìn)行了比較,,目的在于利用分子證據(jù)將暴龍置于動(dòng)物界進(jìn)化樹的適當(dāng)位置。
Asara說:“我們確定了,與其它我們研究的物種相比,,包括美洲鱷和綠變色龍等現(xiàn)代爬行動(dòng)物,,暴龍與鳥類(鴕鳥和雞)具有更近的親緣關(guān)系。
科學(xué)家之前一直懷疑鳥類是恐龍現(xiàn)存最近的親屬,,這一假設(shè)很大程度上依賴于鳥類和恐龍骨骼形態(tài)上的相似性,。此次研究則是從分子水平上確證了二者之間的親緣關(guān)系。另外,,此次研究還同時(shí)得出結(jié)論認(rèn)為,,16萬至60萬年前的乳齒象(mastodon)與現(xiàn)代大象之間存在緊密的系統(tǒng)發(fā)生聯(lián)系。(科學(xué)網(wǎng) 梅進(jìn)/編譯)
生物谷推薦原始出處:
(Science),,Vol. 320. no. 5875, p. 499,,Chris L. Organ,John M. Asara
Molecular Phylogenetics of Mastodon and Tyrannosaurus rex
Chris L. Organ,1,2 Mary H. Schweitzer,3,4 Wenxia Zheng,3 Lisa M. Freimark,5 Lewis C. Cantley,5,6 John M. Asara5,6*
We report a molecular phylogeny for a nonavian dinosaur, extending our knowledge of trait evolution within nonavian dinosaurs into the macromolecular level of biological organization. Fragments of collagen 1(I) and 2(I) proteins extracted from fossil bones of Tyrannosaurus rex and Mammut americanum (mastodon) were analyzed with a variety of phylogenetic methods. Despite missing sequence data, the mastodon groups with elephant and the T. rex groups with birds, consistent with predictions based on genetic and morphological data for mastodon and on morphological data for T. rex. Our findings suggest that molecular data from long-extinct organisms may have the potential for resolving relationships at critical areas in the vertebrate evolutionary tree that have, so far, been phylogenetically intractable.
1 Harvard University, Cambridge, MA 02138, USA.
2 Museum of Comparative Zoology, Cambridge, MA 02138, USA.
3 North Carolina State University, Raleigh, NC 27695, USA.
4 North Carolina Museum of Natural Sciences, Raleigh, NC 27601, USA.
5 Beth Israel Deaconess Medical Center, Boston, MA 02115, USA.
6 Harvard Medical School, Boston, MA 02115, USA.