2005年にMary Schweitzer準教授はティラノサウルスの化石に残された血管と血球を発見したという論文を発表した:
[Schweitzer et al.: Soft-Tissue Vessels and Cellular Preservation in Tyrannosaurus rex , Science, 307, 1952-1955, 2005]

Soft tissues are preserved within hindlimb elements of Tyrannosaurus rex (Museum of the Rockies specimen 1125). Removal of the mineral phase reveals transparent, flexible, hollow blood vessels containing small round microstructures that can be expressed from the vessels into solution. Some regions of the demineralized bone matrix are highly fibrous, and the matrix possesses elasticity and resilience. Three populations of microstructures have cell-like morphology. Thus, some dinosaurian soft tissues may retain some of their original flexibility, elasticity, and resilience.

軟組織がMuseum of the Rockes標本1125のティラノサウルス・レックスの後肢要素内に保存されていた。鉱物相の除去によって、血管から溶液に発現可能な球体の微細構造を含む、透明で柔軟で中空の血管が顕わになった。鉱質除去した骨基質は高度に繊維で、基質は弾性体である。これらの微細構造の集団は細胞のような形状をしている。この微細構造の集団によって細胞のような構造を形作っている。したがって、恐竜の軟組織の中には元々の弾力性や弾性を残していると思われる。

これについて、毎度おなじみの"創造論者の主張 by Mark Isaak"で反論されている:
The reports of the soft tissue, though remarkable, have been sensationalized further. The tissues were not soft and pliable originally. The tissues were rehydrated in the process of removing the surrounding mineral components of the bone (Schweitzer et al. 2005). Moreover, it is unknown whether the soft tissues are original tissues. Fossil flexible tissues and nucleated cells have been found before in which the original material was not preserved (Stokstad 2005).

軟組織の発見は注目に値するが、センセーショナルに扱われすぎた。軟組織は発見時はやわらかくなかった。軟組織は周辺の鉱物成分の除去のプロセスにおいて、水を注入された[Schweitzer et al. 2005]。さらに、軟組織がもともとの恐竜の組織かどうかはわかっていない。化石のやわらかな組織と核とされた細胞は、元の物質が保存されていないところから、発見された[Stokstad 2005]。

[Claim CC371.1]
[Kaye TG, Gaugler G, Sawlowicz Z (2008) Dinosaurian Soft Tissues Interpreted as Bacterial Biofilms. PLoS ONE 3(7): e2808. doi:10.1371/journal.pone.0002808]

A scanning electron microscope survey was initiated to determine if the previously reported findings of “dinosaurian soft tissues” could be identified in situ within the bones. The results obtained allowed a reinterpretation of the formation and preservation of several types of these “tissues” and their content. Mineralized and non-mineralized coatings were found extensively in the porous trabecular bone of a variety of dinosaur and mammal species across time. They represent bacterial biofilms common throughout nature. Biofilms form endocasts and once dissolved out of the bone, mimic real blood vessels and osteocytes. Bridged trails observed in biofilms indicate that a previously viscous film was populated with swimming bacteria. Carbon dating of the film points to its relatively modern origin. A comparison of infrared spectra of modern biofilms with modern collagen and fossil bone coatings suggests that modern biofilms share a closer molecular make-up than modern collagen to the coatings from fossil bones. Blood cell size iron-oxygen spheres found in the vessels were identified as an oxidized form of formerly pyritic framboids. Our observations appeal to a more conservative explanation for the structures found preserved in fossil bone.


Scienceblog.comにブログを持つGrrlScientist Tara C SmithGreg Ladenが早速レビューしているとおりで:
[Tara C Smith: "Dinosaur soft tissue--just bacterial biofilm?" (2008/07/30)]

This paper seems to deal a pretty convincing blow to the "dino blood" theory, but I'm anxious to see what the dino experts have to say about it, including the original proponents of the hypothesis.

posted by Kumicit at 2008/08/02 00:00 | Comment(0) | TrackBack(0) | News | このブログの読者になる | 更新情報をチェックする



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