----- Original Message -----
Sent: Sunday, February 11, 2001 3:59
AM
Subject: CHEEKS AGAIN
2: Cheeks were extensive
throughout the Ornithischia and were possibly absent
in only the most
basal forms such as Lesothosaurus and
Pisanosaurus.
What
about Stegosaurs?
In
"Vertebrate Paleontology in Utah" there is an articles of S.A. Czerkas
in which the author stated that the more derived Stegosaurs (es. Kentrosaurus,
Chungkingosaurus and Stegosaurus) possess a derived condition known as the
"dorsal lamina", which is a thin plate of bone formed by the dorsal
margin of the dentary, it lies lateral to the teeth row and obscured at least
the posterior half of the teeth row in lateral view. Apparently this condition
is much less developed in the most basal Stegosaurs such as Emausaurus,
Regnosaurus and Huayangosaurus, and in the latter it's so small that most of
the dentary teeth are visible in lateral view, except for portion of the last
few. Czerkas stated that this "dorsal lamina" could imply that the more
dervied Stegosaurs possess a extended beak along the dentary that
excluded the possession of cheeks.
By
____________________________________________
Marisa
Alessandro
"Volounteer of Paleontological Museum of Monfalcone"
Via
Achille Grandi nÂ18
38068 ROVERETO (TN) ITALY
Tel:039-0464-434658 Email
amaris@tin.it
____________________________________________