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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:
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By Thom Holmes
Enslow Publishers
Library Binding (128 pages; 1)
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Books LLC
Paperback (76 pages)
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Purchase includes free access to book updates online and a free trial membership in the publisher's book club where you can select from more than a million books without charge. Chapters: Pachycephalosaurus, Pachycephalosauria, Dracorex, Stygimoloch, Prenocephale, Homalocephale, Sphaerotholus, Stegoceras, Wannanosaurus, Micropachycephalosaurus, Alaskacephale, Stenopelix, Gravitholus, Tylocephale, Hanssuesia, Goyocephale, Colepiocephale, Texacephale, Ferganocephale, Ornatotholus, Microcephale. Excerpt: Alaskacephale Fossil range: Late Cretaceous Alaskacephale was a genus of pachycephalosaurid dinosaur that lived in the late Campanian stage of the Late Cretaceous (around 80 to 70 million years ago). Alaskacephale was named by Robert Sullivan in 2006. The genus name refers to Alaska , where the fossil was found in the Prince Creek Formation. The species name, gangloffi , honors paleontologist Roland Gangloff. The only known specimen of A. gangloffi is the holotype , a nearly complete left squamosal with a characteristic array of polygonal nodes. The dimensions of this bone suggest that A. gangloffi was about half the size of Pachycephalosaurus wyomingensis or three quarters the size of Prenocephale prenes , and about the same size as Prenocephale edmontonensis and Prenocephale brevis (Gangloff et al. 2005). The specimen was previously described by Gangloff et al. (2005) as an unnamed pachycephalosaurid, possibly a Pachycephalosaurus . Gangloff et al. described the squamosal as having a suture with the quadrate, a feature previously described only in Pachycephalosaurus . Sullivan (2006) opined that this "suture" is instead a breakage point in both Alaskacephale and Pachycephalosaurus , so it could not be used to unite the two taxa. References (URLs online) A hyperlinked version of this chapter is at Colepiocephale Colepiocephale was a genus of pachycephalosaurid dinosaur . The type species , C. lambei , was originally described by Sternberg (in 1945 as Stegoceras la... |
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By Henrich Incorporated
Henrich Incorporated
CD-ROM
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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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