パレオゾーイクアモノイド縫合物の複雑性の進化
1Department of Geology, Bryn Mawr College, Bryn Mawr, PA 19010, USA. Cincinnati Museum Center, Geier Collections and Research Center, Cincinnati, OH 45202, USA. Paleontological Research Institute, Russian Academy of Sciences, Profsoyuznaya 123, 117647 Moscow, Russia.
Science (New York, N.Y.)
|October 26, 1999
まとめ
パレオゾーイクアモノイドは,1億4000万年以上にわたってセプト縫合の複雑性が著しく増加した. 大量絶滅にもかかわらず,長期的な進化的傾向は,これらの海洋無脊椎動物におけるより大きな複雑性を好む.
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
- マリン・バイオロジー マリン・バイオロジー
背景:
- アムノイドは,絶滅した海洋頭足類の一種で,古生代と中生代における重要なインデックス化石である.
- 彼らの複雑な殻構造,特に隔膜縫合は,進化的変化の記録を提供します.
- アムモノイドの進化の傾向を理解することで,より広範な進化パターンの洞察が得られます.
研究 の 目的:
- パレオゾイクアモノイドにおけるセプト縫合の複雑性の長期的な傾向を定量化するために.
- 進化の複雑さを形作る上で祖先と絶滅の出来事の役割を調査する.
- アムモノイドの進化における複雑性の増大に固有のバイアスが存在するかどうかを判断する.
主な方法:
- パレオゾーイクアモノイドの588の属で1億4000万年を網羅したセプト縫合の複雑性の分析.
- 475組の祖先と子孫の複合性の比較.
- 12の特定のサブクラード (373の属) 内の複雑性傾向の検討.
主要な成果:
- 14000万年以上に渡って,平均セプト縫合の複雑性が1600%増加することが観察されました.
- 子孫は,祖先よりも複雑になる可能性が2倍以上あった.
- 12のサブクラードは,平均34%の複雑度上昇を示した.
結論:
- このデータは,アンモノイドの進化における複雑性の増加を好む長期的なバイアスまたは駆動システムを示唆しています.
- 大量絶滅は,この傾向に反して行動し,しばしばより複雑な形態を排除し,進化の軌道をリセットしました.
- 進化の傾向は,内在的なバイアスと,絶滅の出来事のような外在的な要因の両方によって影響を受けることがあります.
関連する概念動画
01:26Joints
Joints, also called articulations or articular surfaces, are points at which ligaments or other tissues connect adjacent bones. Joints permit movement and stability, and can be classified based on their structure or function.
Structural joint classifications are based on the material that makes up the joint as well as whether or not the joint contains a space between the bones. Joints are structurally classified as fibrous, cartilaginous, or synovial.
Fibrous Joints Are Immovable
The bones of a...
Structural joint classifications are based on the material that makes up the joint as well as whether or not the joint contains a space between the bones. Joints are structurally classified as fibrous, cartilaginous, or synovial.
Fibrous Joints Are Immovable
The bones of a...
02:06Conditions on Early Earth
Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen into the primordial atmosphere. However, organisms with the characteristics of life were not initially present on earth. Scientists have used experimentation to determine how organisms evolved that could grow, reproduce, and maintain an internal environment.
01:22Sutures of the Skull
The human skull is composed of several bones that come together to protect the brain and support the structures of the face. The junctions where these bones meet are called sutures.
Sutures are immobile joints between adjacent bones of the skull. The narrow gap between the bones is filled with dense, fibrous connective tissue that unites the bones. The long sutures located between the skull bones are not straight but instead follow irregular, tightly twisting paths. These twisting lines tightly...
Sutures are immobile joints between adjacent bones of the skull. The narrow gap between the bones is filled with dense, fibrous connective tissue that unites the bones. The long sutures located between the skull bones are not straight but instead follow irregular, tightly twisting paths. These twisting lines tightly...
01:03Structural Joints: Fibrous Joints
Fibrous joints are a type of joint where the bones are connected by fibrous connective tissue. These joints provide stability and minimal to no movement between the articulating bones. There are three types of fibrous joints.
Suture
All the bones of the skull, except for the mandible, are joined to each other by a fibrous joint called a suture. The fibrous connective tissue found at a suture strongly unites the adjacent skull bones and thus helps to protect the brain and form the face. In...
Suture
All the bones of the skull, except for the mandible, are joined to each other by a fibrous joint called a suture. The fibrous connective tissue found at a suture strongly unites the adjacent skull bones and thus helps to protect the brain and form the face. In...
01:17Structural Joints: Cartilaginous Joints
As the name indicates, at a cartilaginous joint, the adjacent bones are united by cartilage, a tough but flexible type of connective tissue. Unlike synovial joints, these types of joints lack a joint cavity and involve bones joined together by either hyaline cartilage or fibrocartilage.
There are two types of cartilaginous joints:
Synchondrosis
A synchondrosis ("joined by cartilage") is a cartilaginous joint where bones are connected by hyaline cartilage. Synchondrosis may be temporary or...
There are two types of cartilaginous joints:
Synchondrosis
A synchondrosis ("joined by cartilage") is a cartilaginous joint where bones are connected by hyaline cartilage. Synchondrosis may be temporary or...
01:20Structural Classification of Joints
Joints, also known as articulations, are classified based on their structural characteristics, i.e., based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage, or whether the articulating surfaces contact each other within a fluid-filled joint cavity. These differences serve to divide the joints of the body into three structural classifications.
A fibrous joint is where the adjacent bones are united by fibrous connective...
A fibrous joint is where the adjacent bones are united by fibrous connective...