Traditionally, Sarcomastigophora was part of the kingdom Protista, which included a wide range of eukaryotic organisms. However, subsequent molecular phylogenetic studies have shown that Protista is polyphyletic, meaning that it did not share a common ancestor. As a result, Sarcomastigophora and other traditional protist groups have been reorganized based on their evolutionary relationships.
Here are some key points about Sarcomastigina:
1. Obsolete Classification: Sarcomastigina, as a single taxonomic group, is now considered obsolete based on modern molecular evidence. It is not recognized in modern classification systems.
2. Amoeboid and Flagellated Organisms: Sarcomastigina encompassed both amoeboid and flagellated organisms, which were grouped together based on shared similarities in cellular structure and locomotion. Amoeboid organisms use pseudopodia for movement and capturing prey, while flagellated organisms use whip-like structures called flagella for locomotion.
3. Examples: Some well-known examples of organisms traditionally classified within Sarcomastigina include:
- Amoebas: Amoeboid organisms found in diverse environments, known for their ability to change shape by extending pseudopodia.
- Euglena: A flagellated organism that possesses both plant-like and animal-like characteristics.
- Giardia: A flagellated parasite that causes giardiasis, a common diarrheal disease.
- Trypanosoma: A flagellated parasite responsible for causing African sleeping sickness and Chagas disease.
4. Polyphyletic Group: Molecular phylogenetic studies have revealed that Sarcomastigina is a polyphyletic group. This means that the organisms traditionally classified under Sarcomastigina do not share a recent common ancestor and have different evolutionary origins.
5. Reorganization: As a result of these findings, organisms that were previously classified under Sarcomastigina have been assigned to various eukaryotic supergroups based on their true evolutionary relationships. These supergroups include Excavata, Amoebozoa, Opisthokonta, and others.
In summary, Sarcomastigina is no longer considered a valid taxonomic group. Modern classifications use molecular data to assign organisms to monophyletic groups based on their evolutionary relationships, resulting in a more accurate understanding of eukaryotic diversity.