Pelycosaurus

Pelycosaurus is an old term for a group of primitive synapsids that lived in the Late Paleozoic era, about 308 to 260 million years ago.
They are sometimes called "mammal-like reptiles" because they had some features that are similar to mammals, such as differentiated teeth and a developing hard palate.
However, they are not true reptiles, nor are they direct ancestors of mammals.
They are part of a larger group of synapsids that includes therapsids and mammals, but they are paraphyletic, meaning that they do not include all the descendants of their common ancestor.

Pelycosaurs are known for their diversity of forms and adaptations.
Some of them had large sails on their backs, such as Dimetrodon and Edaphosaurus, which may have helped them regulate their body temperature or display to mates or rivals.
Some of them were herbivorous, such as Casea and Eothyris, which had barrel-shaped bodies and small heads.
Some of them were carnivorous, such as Ophiacodon and Sphenacodon, which had long jaws and sharp teeth.

Pelycosaur fossils have been found mainly in Europe and North America, although some small, late-surviving forms are known from Russia and South Africa.
They were the dominant land animals for about 40 million years, until they were replaced by more advanced synapsids, the therapsids, in the middle of the Permian period.
Pelycosaurs show a remarkable transition in skeletal features from typical early reptiles to more mammal-like forms, such as the development of a secondary palate, the reduction of the number of bones in the lower jaw, and the enlargement of the temporal opening in the skull.

Pelycosaurs are an important group of animals that reveal the evolutionary history of synapsids and mammals.
They are also fascinating creatures that had a variety of shapes and lifestyles.
They are not well-known to the general public, but they deserve more attention and appreciation.

Pelycosaurus is an informal name for a group of primitive synapsids that lived during the Late Paleozoic era, about 308 to 260 million years ago.

Pelycosaurus fossils have been found mainly in Europe and North America, although some small, late-surviving forms are known from Russia and South Africa.

Some of the well-known pelycosaurs include Dimetrodon, Sphenacodon, Edaphosaurus, and Ophiacodon.

• A single hole in the skull behind each eye, where muscles attached to the jaw.

• Differentiated teeth, such as sharp canines and flat molars, for different functions.

• A bony spine or sail on the back, supported by long neural spines, which may have helped with thermoregulation or display.

• A sprawling posture, with legs positioned on the sides of the body, rather than underneath.