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The Evolution of Mammals

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
Created by: LionsandGiants