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Pachycephalosaur Dinosaurs
The Pachycephalosauria (meaning "thick-headed lizards")
are an infraorder of dinosaurs, that
were characterized by having bony domes
on their heads.
The Pachycephalosauria infraorder, together with the infraorders of
Ceratopsia ("horned faces")
and
Ornithopoda ("bird feet"),
form the the suborder Cerapoda of the
Ornithischian
dinosaurs.
Pachycephalosaurs are sometimes grouped together with
Ceratopsian
as the Marginocephalia ("fringed heads"), since the
these two infraorders share some common features and appear to be related.
Pachycephalosaurs probably first appeared during the the
Jurassic period
(when they originated remains a subject of research and debate),
and survived until the
end of the
Cretaceous period.
Some Pachycephalosaurs would have been among the last non-avian dinosaurs
which died out during the
mass extinction
which took place about 65 million years ago.
All Pachycephalosaurs were herbivores (plant-eaters)
and were bipedal (walked on two legs).
The feature that Pachycephalosaurs are
best known for, and the defining characteristic
of the group is the bony roofs of their skulls.
All Pachycephalosaurs had skulls like this,
although the exact size and shape did vary between species.
In some
species of Pachycephalosaurs,
the skull has a bony dome several inches thick,
in some the skull is flat or wedge-shaped, and in several
species their are bony knobs/horns on the skull.
The purpose of Pachycephalosaurs'
skull adaptations have been a subject of much debate
- it has in the past been asserted that animals must have engaged
in head-on butting contests for mates (like thick-headed sheep and other
animals do today), but the structure of the neck (which could not have
been orientated in a straight line would have made it poor for transmitting
force) and the shape of the domes (rounded domes would have resulted in
glancing blows which transmitted force poorly) seems to refute this
hypothesis. If not used for head-on butting, the bony domes could perhaps
have been used for flank butting - the structure of the horns in some
species of Pachycephalosaurs seems to be consistent with this hypothesis.
Pachycephalosaur Timeline:
Pachycephalosaurs first appeared during the Jurassic, perhaps about 150 million years ago, and survived until the end of the Cretaceous period, about 65 million years ago
Types of Pachycephalosaurs
Here is a list of some Pachycephalosaurs:
Related Information & Resources
See Also
Pachycephalosaur Books
Here are some books from Amazon.com:
Disclosure: Products details and descriptions provided by Amazon.com. Our company may receive a payment if you purchase products from them after following a link from this website.
By Thom Holmes
Enslow Publishers
Library Binding (128 pages; 1)
 | List Price: $26.60*
Lowest New Price: $26.60*
Lowest Used Price: $0.53*
Usually ships in 2 to 5 weeks*
*(As of 09:15 Pacific 12 Mar 2010 More Info)
Click Here |
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By Henrich Incorporated
Henrich Incorporated
CD-ROM
| List Price: $19.95*
Lowest New Price: $15.56*
Temporarily out of stock. Order now and we'll deliver when available. We'll e-mail you with an estimated delivery date as soon as we have more information. Your credit card will not be charged until we ship the item.*
*(As of 09:15 Pacific 12 Mar 2010 More Info)
Click Here | Product Description:
CD-ROM TPachycephalosaur Craft Pack featuring five extraordinary hands-on museum quality projects |
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Enslow Publishers
Unknown Binding
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