therapsid
Noun A member of the extinct order Therapsida, a group of advanced synapsid reptiles that lived from the Middle Permian to the Early Jurassic periods. Therapsids are characterized by more mammal-like skeletal features, such as differentiated teeth and limbs positioned more directly under the body, and are considered the direct ancestors of mammals.
The word "therapsid" is used as a singular noun to refer to an individual animal belonging to this order, or as a plural noun ("therapsids") to refer to the group collectively. It is a scientific term used primarily in paleontology and evolutionary biology.
- The fossil record shows that therapsids diversified into herbivorous and carnivorous forms.
- A key therapsid characteristic is the presence of a single opening in the skull behind each eye, a trait shared with mammals.
- Scientists study therapsid anatomy to understand the evolutionary transition from reptiles to mammals.
- The term is often used in discussions about the origin of mammalian traits such as endothermy (warm-bloodedness), specialized dentition, and jaw structure.
- It can be used attributively (like an adjective) in compound scientific terms, such as "therapsid fauna" or "therapsid evolution."
- Therapsida: The scientific order name.
- Synapsid: The larger clade or subclass that includes both early "pelycosaurs" (like Dimetrodon) and the more advanced therapsids. All therapsids are synapsids, but not all synapsids are therapsids.
- Cynodont: A specific, highly advanced subgroup of therapsids that are the most direct ancestors of mammals.
- Mammal-like reptile (This is a common, less technical descriptive synonym, though modern cladistics classifies them as synapsids, not true reptiles).
- Proto-mammal (A descriptive term emphasizing their ancestral relationship to mammals).
The word "therapsid" has a single, specific meaning in scientific terminology. It does not have common idiomatic or figurative uses outside of paleontology.
- probably warm-blooded; considered direct ancestor of mammals