| Term | Definition |
| Plecosauria | - Early Permian.
- Varied diet and activity.
- Large Dorsal Sail.
- 3 meters long. |
| Ancestral Characteristics of: Plecosauria | - Weakly heterodont.
- Angular/articular in mandible.
- Single occipital condyle.
- No secondary palate. |
| Early Therapsida | - Middle Permian.
- Active and diverse.
- Some dominant herbivores for 60 million years.
- Extinct after Permian-Triassic Event. |
| Derived Characteristics of: Early Therapsida | - Enlarged temporal opening.
- Partial secondary palate.
- Major skull and jaw changes. |
| Advanced Therapsida | - Includes Cynodonts.
- Triassic to mid-Jurassic.
- Diverse herbivores and carnivores.
- Conflict over rather one or more than one line gave rise to modern mammals. |
| Mammalian Characteristics of: Advanced Therapsida | - Double occipital condyle.
- Complete secondary palate.
- Expansion of temporal opening and brain case.
- Strongly heterodont dentition. |
| Early Mammals | - 250 million years ago.
- Overlapped with Cyodonts and dinosaurs.
- Small and nocturnal. |
| Early Prototherians Include... | - Morganucodontids.
- Triconodonts.
- Docodonta.
- Multituberculata. |
| Morganucodontids | - Early Prototherian
- Small (10 cm).
- Good hearing.
- Probably nocturnal.
- Expanded dentary bone with dentary-squamosal articulation.
- Mammalian posture. |
| Triconodonts Include... | - Jeholodens.
- Repenomamus giganticus. |
| Jeholodens | - Triconodont
- Derived pectoral girdle.
- Ancestral pelvic girdle. |
| Repenomamus giganticus | - Triconodont
- Largest mammal of Cretaceous period
- 1 m long and 12-14 Kg
- Fed on young dinosaurs |
| Docodonta | - Early Prototherian
- Late Jurassic period.
- Complex teeth, omnivores.
- Primitive jaw articulation. |
| Multituberculata | - Early Prototherian.
- Diverse and persistent (lasted 120 million years starting in Jurassic).
- Mouse to marmot size.
- Overlap with modern mammals.
- Unique dentition with chisel like incisors and 8 grinding molars.
- Exploitation of niches. |
| Early Therians Include... | - Symmetrodonta (Insectivores).
- Eupantotheria.
- Tribosphenic molars, basic for later mammals, for shearing and grinding |
