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02:56The Fossil Record
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...
01:12Carbon Skeletons
Life on Earth is carbon-based, as all macromolecules that make up living organisms contain carbon atoms. All organic compounds have a carbon backbone. Each carbon atom is tetravalent and can bond with four other atoms, making it an extraordinarily flexible component of biological molecules. Because carbon’s valence electrons are stable, it rarely becomes an ion. As the carbon chain increases in length, structural modifications such as ring structures, double bonds, and branching side chains...
01:26Bone Markings
Bones have various surface features that help form joints and attach to other soft tissues. Depending on the function, bone markings are categorized into articulating projections, processes for attachment, depressions, and openings.
Articulating Projections
Articulating projections are found where two bones meet to form a joint. These structures are usually found at the ends of bones. The largest articulation is a rounded projection called the head, supported by a narrow neck at the ends of...
Articulating Projections
Articulating projections are found where two bones meet to form a joint. These structures are usually found at the ends of bones. The largest articulation is a rounded projection called the head, supported by a narrow neck at the ends of...
01:21Tooth Anatomy
The human tooth enables us to eat a variety of foods, speak clearly, and even aid in shaping our faces. Teeth are composed of various elements that work together. Here's a detailed look at the anatomy of a human tooth.
The Crown, Neck, and Root
The visible part of the tooth is referred to as the crown. It's covered by enamel, the hardest substance in the human body. The crown is uniquely shaped for each type of tooth, allowing for different functions such as cutting, tearing, or grinding food.
The Crown, Neck, and Root
The visible part of the tooth is referred to as the crown. It's covered by enamel, the hardest substance in the human body. The crown is uniquely shaped for each type of tooth, allowing for different functions such as cutting, tearing, or grinding food.
01:12The Hyoid Bone
The hyoid bone is a small U-shaped bone located in the upper neck at the level of the inferior mandible, with its tips pointing posteriorly. It does not directly articulate with any other bone in the body. The hyoid acts as the attachment site for the tongue, the larynx, and the pharynx. It is held in position by a series of small muscles attached from above or below. These muscles help to move the hyoid up/down or forward/back in coordination with movements of the tongue, larynx, and pharynx...
01:19Bones of the Upper Limb: Humerus
The upper limb consists of the arm, forearm, wrist, and hand bones. The humerus is the single bone of the upper arm region. Proximally, it has a large, spherical, smooth head that articulates with the glenoid cavity of the scapula to form the glenohumeral or shoulder joint. The margin of the head is the anatomical neck, a residual epiphyseal plate. Laterally it extends to form bony projections called the greater tubercle and the lesser tubercle. Next to the tubercles is the surgical neck, a...
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並び替え
Same author
Paleotribological models using preserved fossil tissue properties reveal functional significance of Eurasian mammoth dental evolution.
Acta biomaterialia·2026
恐竜のヴェロシラプター (Velociraptor) の羽毛羽根のノブ.
Alan H Turner1, Peter J Makovicky, Mark A Norell
1Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024-5192, USA. turner@amnh.org
Science (New York, N.Y.)
|September 22, 2007
まとめ
Velociraptor mongoliensisのような羽ばたき恐竜は知られているが,より大きな種の証拠は稀である. 新しい発見は,ベロシラプトルの前腕に羽根のノブを明らかにし,このより大きく,飛べないセロポッド恐竜に羽根があることを確認しています.
科学分野:
- パレオントロジー・パレオントロジー
- 進化生物学の進化生物学について
- 恐竜の古生物学について
背景:
- 羽毛のある非鳥類のセロポッド恐竜は知られているが,化石の証拠は,特定の化石 lagerstätten で保存された小型の体を持つ種に偏っている.
- より大きなセロポッド恐竜の羽の分布を理解することは,保存バイアスのために制限されています.
研究 の 目的:
- 羽毛の存在の直接的な証拠を提供するために,より大きな体を持つ,派生した,そして飛べないセロポッド恐竜のヴェロシラプター・モンゴリーエンシス.
- 非鳥類のセロポッド群の羽の分布と進化に関する知識を広げる.
主な方法:
- Velociraptor mongoliensisの標本の前腕の後部の検査.
- 大きな羽根の固定点を示す羽根ノブの識別.
主要な成果:
- 羽毛の直接的な証拠は,ベロシラプトル・モンゴリエンシス (Velociraptor mongoliensis) で発見された.
- 前腕の後部にペンキのノブが確認され,二次羽の存在を示した.
結論:
- この発見は,より大きく,飛べないセロポッド族の属に羽がいたことを確認した.
