Paleontologists (scientists who study
ancient life) do find dinosaurs all over the
world. In fact, they have been found on every
major continent, including Antarctica, Australia,
India, and in the far north of Canada. Dinosaur
fossils are even known from Madagascar, Japan, and
Greenland! One of the reasons they are so widely
distributed is that they evolved during the Late
Triassic Period (beginning about 230 million
years ago) when the continents we recognize
today were still connected to each other.
Early dinosaurs really spread out over the
entire large continent known as "Gondwana".
During the Jurassic Period (from about 200-145
million years ago), Gondwana started to break
up into separate smaller continents. As those
continents moved away from one another, they
carried the early dinosaur ancestors with
them. Over time those dinosaurs gave rise to
many different kinds of dinosaurs-- Voila!
Dinosaur fossils all over the world!
Interestingly, fossils can tell us a lot about
paleogeography (ancient geography).
Paleontologists haven't found even one marine
dinosaur- NOT ONE! Animals like Mosasaurus were
marine lizards, not dinosaurs. The absence of
dinosaur fossils in marine sediments is good
evidence that dinosaurs were strictly
land-dwellers. Paleontologists haven't found
any fish- or dolphin-shaped dinosaurs with fins or
paddles either; they just didn't have the right
equipment to swim across large bodies of water.
The worldwide distribution of those land-bound
dinosaurs on continents that are now widely
separated by oceans provides evidence that the
continents were once together. Cool! There are
lots of fossil dinosaur eggs from many
different places. Based on what you now know about
how widespread dinosaurs were, this probably isn't
too surprising. Almost 50 egg species, or
"oospecies", are known mostly from central
Asia (China, Mongolia, Kyrgyzstan, eastern
Kazakhstan, and eastern Uzbekistan), southern
Europe, India, South America (Brazil, Argentina),
North America (Canada and United States), and
South Africa. Many of these are found in sediments
of Cretaceous age (deposited from about 145-65
million years ago). There are also earlier
dinosaur eggs from several places in North
America, including Mexico.
For dinosaurs and their relatives there are
six basic eggshell types based on
things like surface ornamentation, egg shape,
eggshell thickness, etc. Of these six eggshell
types, turtles, geckos, and crocodiles have three
specific types of eggshell; the other three
eggshell types characterize three dinosaur groups,
one of which includes birds. So technically, while
most dinosaur eggshells are many millions of years
old, if you take birds into account you could find
dinosaur eggshells in your backyard!
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