SynapsidPermian
Dimetrodon
Many of its fossils come from the Red Beds of Texas and Oklahoma.
Meet DimetrodonExplore the prehistoric world
Synapsids
Sails, tusks and a place on the mammal side of the family tree. Explore the extinct synapsids in Dinosgacha.
9creatures in this group
3 game stages each
3 game stages each
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Meet the collection
Showing 1–9 of 9 creatures
Synapsid
SynapsidCarboniferous / Permian
Edaphosaurus
It ate plants, unlike its fellow sail-backed synapsid Dimetrodon.
Meet Edaphosaurus
SynapsidPermian
Cotylorhynchus
It was one of the large land vertebrates of its time.
Meet Cotylorhynchus
SynapsidPermian
Inostrancevia
It is known from several skulls and two nearly complete skeletons.
Meet Inostrancevia
SynapsidPermian
Estemmenosuchus
Its striking cranial protuberances could have been used for display between individuals.
Meet Estemmenosuchus
SynapsidPermian / Triassic
Lystrosaurus
It had two tusks and a tough, horn-covered beak suited to cutting plants.
Meet Lystrosaurus
SynapsidPermian
Dicynodon
It had a tough, horn-covered beak and two tusks, which may have helped it dig up food.
Meet Dicynodon
SynapsidPermian
Tiarajudens
Tiarajudens was a synapsid with conspicuous saber-like canines despite evidence for plant processing.
Meet Tiarajudens
SynapsidLate Permian
Suminia
Suminia was a small synapsid with grasping adaptations in its limbs.
Meet SuminiaA closer look at synapsids
Dimetrodon is often mistaken for a dinosaur, but it belongs to the synapsid branch that also includes mammals. Its sail and sprawling shape do not make it a reptile ancestor. The familiar phrase “mammal-like reptile” reflects an older way of classifying these animals.
This page follows the catalogue’s synapsid category; mammals have their own browsing group even though they are also synapsids. Explore each animal’s skull, teeth and geological period. Their evolution was a branching history, not a single ladder leading from every fossil directly to modern mammals.
Is Dimetrodon a dinosaur or a mammal?
Neither. Dimetrodon was a non-mammalian synapsid: an extinct relative on the broader branch containing mammals. It was more closely related to mammals than to dinosaurs, but that does not make it a modern mammal.
Further reading: Harvard Museum of Natural History: Dimetrodon · Angielczyk: Synapsids and the ancient relatives of mammals
AI-generated, stylized game illustrations. These designs and growth stages are imaginative, not scientific reconstructions. Open a profile for its fossil information and sources.