Evolution Of Dinosaurs Essay

Dinosaurs are the most successful of all terrestrial vertebrates. They dominated life on land for about 150 million years, which is the longest for any animal on Earth till date. Humans in comparison have been on earth for nearly, only 1 million years. Dinosaurs, owing to their gigantic size and uniqueness, have remained in the limelight since the discovery of it’s fossils. Scientists have studied and debated over it’s various characters. Since these animals are extinct and can be studied only by their fossil records, a lot of speculations have risen about their traits, one such area is the question about their mechanism of thermoregulation – whether dinosaurs were cold or warm blooded animals. Dinosaurs are “reptiles”, which are characteristically ectothermic animals hence

The fossils from Cretacean Ornithopod Thescelosaurus reveal that it had a four-chambered heart and a single aorta.
6. Warm blooded birds have supposedly evolved from dinosaurs.

(I) Conclusion from Type I evidences :

The Type I evidences point out to the fact that dinosaurs exhibiting them were ectotherms or cold-blooded. Ectotherms, cannot produce heat by their own metabolism and depend on an external source to heat their bodies. The external sources are the sun and the air around the ectotherm’s body. Dinosaurs lived at an age when the climate was much warmer. Hence, it must have been more natural for these organisms to be ectothermal as they could easily warm their bodies from the sun and their environment.

1. Since dinosaurs had evolved from a reptilian ancestor, it’s more likely that they were cold blooded just like the reptiles.
2. (a) Slow and sluggish behaviour in Sauropods and Stegosaurs points out that they lacked endothermy, as with endothermy, a high metabolic rate is associated which makes endotherms more active and agile.
(b) Daytime activity also suggests that they were