Dinosaurs-on-Stamps . info
What is a Dinosaur?
Lets start with some published definitions.
According to "Encyclopedia Britannica":
"dinosaur, a term popularly used for the members of a great series of reptiles that were the dominant land animals during most of the Mesozoic Era (from 225,000,000 to 65,000,000 years ago), the age of reptiles, but became extinct at its close."
According to "Webster's New Collegiate Dictionary":
"dinosaur, any of a group (Dinosauria) of extinct terrestrial carnivorous or herbivorous reptiles."
According to "Microsoft's Encarta Encyclopedia":
"A dinosaur one of a group of extinct reptiles that lived from about 230 million to about 65 million years ago ..... dinosaurs [are distinguished] from other prehistoric reptiles by their upright rather than sprawling legs and by the presence of three or more vertebrae supporting the pelvis, or hipbone ..... Dinosaur bones occur in sediments that were deposited during the Mesozoic Era, the so-called era of middle animals, also known as the age of reptiles. This era is divided into three periods: the Triassic (dating from 245 million to 208 million years ago), the Jurassic (208 million to 144 million years ago), and the Cretaceous (144 million to 65 million years ago)."
According to the "International Chronostratigraphic Chart 2015" (ICS):
"The Mesozoic Era (also known as the age of reptiles) is divided into three periods: the Triassic (dating from 252 million to 201 million years ago), the Jurassic (201 million to 145 million years ago), and the Cretaceous (145 million to 66 million years ago)."
So far, the only real problem that we have is the beginning of the Triassic Age (252 or 245 million years ago).
Considering that the earth is 4.5 billion years old, this discrepancy is less than half of one percent.
Minor, but I would use the ICS reference.
According to these definitions:
A dinosaur was a reptile.
There were mammals, fish, birds and other animals during the Mesozoic Era which also left fossils.
A dinosaur was terrestrial.
That is, it was a land animal.
A dinosaur did not inhabit the oceans or the seas.
Nor did it fly.
There were marine reptiles and flying reptiles that also lived during the Mesozoic Era, along with the dinosaurs; but they were not dinosaurs.
A dinosaur lived during the Mesozoic Era.
A Dimetrodon (a carnivore) or an Edaphosaurus (a herbivore) are two sail-backed Permian reptiles.
The Permian Age lasted from 299 million years ago until 252 million years ago; before the Mesozoic Era.
These two reptiles existed before the dinosaurs; they are not dinosaurs as is often depicted.
A dinosaur had upright rather than sprawling legs, which eliminates many of the other amphibious reptiles that lived with the dinosaurs.
I know these definitions may be simplistic, but to maintain a thematic collection of 'Dinosaurs on Stamps', I have had to define exactly what is a dinosaur.
It presently includes over two-hundred countries, hundreds of stamp issues and over two-hundred sixty genera represented.
Maintained by Robert Margulski;
E-Mail your comments to: RLM07@Margulski.name