评论"超结构揭示了原始脊椎动物的喉骨"
Kaiyue He1, Jianni Liu1, Jian Han1
1Shaanxi Key Laboratory of Early Life and Environments, State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University (NWU), Xi'an 710069, P. R. China.
Science (New York, N.Y.)
|July 27, 2023
概括
云纳动物不是干群的脊椎动物. 超过8000个标本的超结构和形态分析驳斥了关键脊椎动物特征的存在,挑战了以前的遗传学建议.
科学领域:
- 古生物学
- 发育生物学
- 进化生物学
背景情况:
- 根据特定的解剖学特征,先前的研究提出了yunnanozoans作为干群脊椎动物.
- 这些特征包括所谓的细胞软骨,纤维素微纤维和分支弧中的下弦棒.
研究的目的:
- 重新评估云纳动物的遗传位置.
- 研究云纳动物的超级结构和形态,以证实或驳斥脊椎动物的亲缘关系.
主要方法:
- 详细的超结构分析的yunnanozoan标本.
- 对超过8000个云纳动物标本进行了全面的形态检查.
- 与已知的脊椎动物和无脊椎动物类型进行比较分析.
主要成果:
- 证实了云纳动物细胞软骨的缺失.
- 证明没有纤维素微纤维.
- 皮带下棒结构没有被确定为脊椎动物结构的同类.
- 形态和超结构证据不支持脊椎动物的亲缘关系.
结论:
- 云纳动物不是干群的脊椎动物.
- 根据新的证据,此前提出的基因分类被拒绝.
- 需要进一步的研究来确定云纳动物在甲基动物中的精确基因位置.
相关概念视频
01:23Phylogeny
44.5K
Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon (singular). Taxa (plural) can span different levels of the evolutionary hierarchy. For instance, the group containing all birds is a taxon (comprising the class Aves), and the group of all species of daisies (the genus Bellis) is a taxon. Phylogenies can likewise include just one genus (i.e., depict species relationships) or span an entire kingdom.
44.5K
02:56The Fossil Record
25.3K
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
25.3K
01:55Bone Structure
48.7K
Within the skeletal system, the structure of a bone, or osseous tissue, can be exemplified in a long bone, like the femur, where there are two types of osseous tissue: cortical and cancellous.
48.7K
01:09Changes in the Appendicular Skeleton with Age
2.1K
The upper and lower limb initially develops as a small bulge called a limb bud, which appears on the lateral side of the early embryo. The upper limb bud appears near the end of the fourth week of development, with the lower limb bud appearing shortly after.
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
2.1K
02:40The Tree of Life - Bacteria, Archaea, Eukaryotes
32.6K
The “tree of life” describes the evolution of life and the evolutionary relationships between organisms. The root of the tree is the common ancestor to all life on Earth. All other species radiate from this point, much like the branches of a tree. The numerous tips of these branches on the tree of life represent every living, or extant, species. Extinct species, which are species that no longer exist, can be found towards the center of the tree. Currently, these organisms, both...
32.6K
01:15Bones of the Upper Limb: Ulna
2.2K
The ulna and radius are parallel bones of the antebrachium or the forearm. The ulna lies medially and consists of a bony tip called the olecranon process at its proximal end. This hook-like projection articulates with the olecranon fossa of the humerus and forms the "hinged" ulnohumeral part of the elbow joint. This joint facilitates forearm extension and flexion while preventing its hyperextension. Similarly, the coronoid process, another bony projection on the proximal/anterior side...
2.2K