The outermost layer of skin the epidermis produces a variety of growths in animal and bird species Because dinosaurs were reptiles and modern reptiles have scales and armor plates on their skin it was long assumed that dinosaurs had the same type of skin

The outermost layer of skin, the epidermis, produces a variety of growths in animal and bird species. Because dinosaurs were reptiles, and modern reptiles have scales and armor plates on their skin, it was long assumed that dinosaurs had the same type of skin coverings. However, dinosaurs had many traits that modern reptiles lack, and evidence gathered by paleontologists indicates that dinosaurs may have, in fact, possessed feathers like modern birds.

Descendants

One reason for believing that dinosaurs possessed feathers is that they are a defining trait of their descendants: modern birds. All modern birds have feathers that cover their bodies to some degree, and this is true of all birds in the fossil record as well. Therefore, it is reasonable to assume that they inherited this trait from their ancestors.

Fossil Feathers

There is physical evidence that some dinosaurs did certainly have feathers. Feathers are clearly visible on fossils ranging from the duck-sized Mei Long to the largest known feathered dinosaur, the Yutyrannus huali, a Tyrannosaurus cousin that weighed more than 3,000 pounds.The feathered fossils belong to species that are unrelated and include both predator and prey animals. This strongly suggests that feathers were common to all dinosaurs.

Need for Feathers

While feathers are most commonly associated with flight, they almost certainly evolved first as a way of regulating temperature. Many of the feathers that have left fossil imprints look more like the downy fluff of a modern chick or hatchling than the stiff plumes of adult birds. Such filament-like feathers would likely have been helpful in trapping body heat. Warm-blooded modern birds use feathers to insulate themselves in colder climates and it is reasonable to assume that dinosaurs would have put feathers to the same use.

Many scientists take issue with the arguments you read in the article. They don’t think those arguments prove that all dinosaurs had feathers.

Take the descendants argument. We know that birds evolved from theropod dinosaurs, which is a specific group of mostly predatory dinosaurs. Some theropods were feathered- so feathered that they might have looked more like turkeys than lizards. But not all dinosaurs have modern descendants we can look at. Many of the herbivorous, plant eating dinosaurs have no close living relatives. So, the presence of feathers in all extinct and modern birds indicates that they inherited them from theropods. It doesn’t prove that all dinosaurs had feathers, or even that all theropods had them, but some must have.

Well, what about the fossil specimens of some dinosaurs that had feathers? That also doesn’t necessarily mean that dinosaurs were gigantic chickens or pigeons. There are also fossil specimens of skin impressions from other dinosaur species that show no evidence of any kind of feathers. A number of prominent dinosaur lineages: Stegosaurs, Ankylosaurs,Triceratops, as well as the sauropods, show no record of feathers. The skin samples we can connect to those species show bumpy skin, scales, or armor plates.

Ok, so how about the need for feathers? Feathers do make great insulation, that's true, but larger dinosaur species could have relied on gigantothermy. Gigantothermy means that an animal can be so large that it takes a long time for its internal temperature to change significantly, which contributes to a consistent average temperature despite daily environmental temperature changes. There are animals, such as large sea turtles, which maintain their temperatures this way. Another relevant issue is that if dinosaurs had relied on heat from the sun to maintain their core temperatures, then feathers that block sunlight from reaching the skin would have been unhelpful.