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Re: Funny bones



Jeff Martz [or should I say, LNJ? :)] wrote:
 
  <"SUPRAORBITALS" are described as an 'arch of bones"
at the sides of the frontal, prefrontal, and
postfrontal, and partially lying underneath the bones
of the skull roof. In one specimen, they are described
as "curved into an arc to simulate sclerotic plates".>

  Supraorbitals are found in a great deal of animals
and are general dermal bones that ossify along with
dermal armor or in conjunction with palpedrals in some
animals (including crocodiles, ankylosaurs, and
stegosaurs, and also pachycephalosaurs).
Supraorbitals, for some reason, are "only" present
when there is an "absence" of palpedrals. Well, I have
my two cents about _that_ ... Taxa have been described
with both supraorbitals and sclerical ossicles
(including falconiforms), so they are not contiguous.

  <Also, what direction does "mesial" refer to?
DINOSAURIA defines it for use in describing teeth as
"the edge of the tooth toward the symphysis or
premaxillary midline", but I see it being used in
describing bones. Is it the same as "anterior",
"medial", or something else?>

  In a multitude of cases, mesial refers to the jaws
and the jaws (or teeth) alone: 1> the anterior/rostral
teeth of a jaw are more mesial than those closer to
the articular hinge; 2> the mesial margin of a tooth
is the one that faces towards the anterior/rostral
portion of the jaws.

  In some cases, they overlap in definition, but use
requires security: "mesial" should be confined to use
in the jaws and teeth alone, rather than any other
cranial portion, including the palate; similarly,
"rostral" is a cranial equivalent to "cranial", for
use in describing _only_ the skull, while "cranial"
should be used _only_ for the postcrania, and
"anterior" depends on orientation.

  "Caudal" can be used for both cranial and
postcranial material, as it depends on not including
the tail intrisically; however, should the use of
"caudal" in describing the tail be safe? Proximal and
distal, cranial and distal, etc. may be suitiable
alternatives, as they do not require a portion of
anatomy to define their position. "Ventral" and
"dorsal", refering to the belly and back,
respectively, may be different cases, but would work
communicatively as long as they are not included in
describing limbs, in which orientation differs distinctly.

=====
Jaime "James" A. Headden

  Dinosaurs are horrible, terrible creatures! Even the
  fluffy ones, the snuggle-up-at-night-with ones. You think
  they're fun and sweet, but watch out for that stray tail
  spike! Down, gaston, down, boy! No, not on top of Momma!

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