anapsida
Noun A subclass of reptiles characterized by a skull that lacks temporal openings (fenestrae) behind the eye sockets. This group is considered the most primitive among amniotes and traditionally includes turtles, tortoises, and their extinct relatives from the Permian period.
The term is used in scientific, particularly paleontological and zoological, contexts to classify a specific group of reptiles based on skull morphology. * Modern phylogenetic studies often reclassify turtles within a different clade, but the term "Anapsida" remains useful for describing the ancestral skull condition. * The fossil record of the Anapsida provides crucial evidence for understanding early reptile evolution.
- "The Anapsida are distinguished from other reptiles by their solid skull roof."
- "Turtles were long considered the sole surviving members of the subclass Anapsida."
- "Paleontologists study Permian Anapsida to learn about prehistoric ecosystems."
- Phylogenetic Context: In modern cladistics, the grouping "Anapsida" is often considered paraphyletic. The term is frequently used to describe an anatomical condition (anapsid skull) rather than a strict monophyletic taxon.
- Contrast with Other Groups: The anapsid skull structure contrasts with the diapsid skull (two openings) found in lizards, snakes, crocodilians, and birds, and the synapsid skull (one opening) found in mammals and their ancestors.
- Anapsid (adjective/noun): Describing the skull condition or a member of the Anapsida.
- Example: "The anapsid skull is a primitive characteristic."
- Anapsid Reptile: Another term for a member of this group.
- Anapsid Reptiles (descriptive synonym)
This word has a single, specific meaning within zoological and paleontological classification. It does not have general or figurative meanings.
Not applicable. This is a scientific term and is not used in idiomatic expressions or phrasal verbs.
- oldest known reptiles; turtles and extinct Permian forms