Search Dictionary
Definition of pelycosaur
pelycosaur
/ˈpɛl.ɪ.kəˌsɔːr/
pel · y · co · saur
Plural:pelycosaurs
•Adjective:pelycosaurian
pelycosaur Lexical Profile
CEFR
C2
Grade
11
Tier
3
Usage
Rare
pelycosaur Game Scores & Validity
Scrabble US
Scrabble UK
WWF
Wordle Guess
• noun
1
Any member of an informal group of primitive, Late Paleozoic synapsids that are closely related to the ancestors of mammals, famously represented by the sail-backed Dimetrodon.
Example
"Often mistaken for a dinosaur, the sail-backed Dimetrodon was actually a pelycosaur that roamed the Earth millions of years before the first true dinosaurs appeared."
Synonyms
View all synonyms for pelycosaurWord Nuance & Usage
Pelycosaurs are frequently, yet incorrectly, identified as dinosaurs; they actually lived tens of millions of years earlier during the Paleozoic era and are more closely related to the ancestors of mammals.
Word Origin & Etymology
Coined in the late 19th century from the Greek words 'pelyx' (basin or bowl) and 'sauros' (lizard), referring to the basin-like shape of their pelvic girdles.
Cite this Entry
Wordmom. (2026). Definition of Pelycosaur. In Wordmom Dictionary. Retrieved Oct 15, 2026, from https://wordmom.com/dictionary/pelycosaur