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The evolution of the digestive system has formed a significant influence in mammal evolution. With the emergence of mammals, the digestive system was modified in a variety of ways depending on the animal's diet. For example, cats and most carnivores have simple large intestines, while the horse as a herbivore has a voluminous large intestine. [127]
Ceratopsian dinosaurs appear in the fossil record and the oldest known eutherian mammal: Juramaia. 160 Ma Multituberculate mammals (genus Rugosodon) appear in eastern China. 155 Ma First blood-sucking insects (ceratopogonids), rudist bivalves, and cheilostome bryozoans.
Comparing this to other mammals, it can be inferred that the first mammals to gain sexual differentiation through the existence or lack of SRY gene (found in the y-Chromosome) evolved only in the therians. Early mammals and possibly their eucynodontian ancestors had epipubic bones, which serve to hold the pouch in modern marsupials (in both sexes).
“Some of the earliest mammals were forced to live toward the bottom of the food chain and have likely spent 100 million years during the age of the dinosaurs evolving to survive through rapid ...
Dinosaurs evolved from more primitive reptiles in the aftermath of Earth's biggest mass-extinction event caused by extreme volcanism at the end of the Permian Period about 252 million years ago.
A microbiologist is proposing the idea that the reign of dinosaurs forced mammals to speed up their reproductive cycle, eliminating key longevity genes. Historic Dinosaur Dominance May Cause ...
Each order of dinosaur has slightly differing pelvis bones providing evidence of common descent. Additionally, modern birds show a similarity to ancient saurischian pelvic structures indicating the evolution of birds from dinosaurs. This can also be seen in Figure 5c as the Aves branch off the Theropoda suborder.
The most striking feature of evolution of the pelvis in primates is the widening and the shortening of the blade called the ilium. Because of the stresses involved in bipedal locomotion, the muscles of the thigh move the thigh forward and backward, providing the power for bi-pedal and quadrupedal locomotion.