>I recently bought Philip Whitfield's "Children's Guide to Dinosaurs and
>other prehistoric animals" and noticed that he has classified Nodosaurs
>and Ankylosaurs as one family in the introduction, yet for individuals
>they are either a nodosaur or an ankylosaur. What's the difference
>between them?>
The Ankylosauridae (common name: ankylosaurids) and Nodosauridae (common
name: nodosaurids) together make up the Ankylosauria (common name:
ankylosaurians, although some people confusingly use ankylosaurs).
Ankylosaurids have tail clubs, relatively small-to-no spines, and heads
which are very broad and not very long, with triangular hornlets at the
rear. Nodosaurids have no tail club, have medium-to-long spines, and bumpy
or smooth heads which are long and not very broad. There is a third family
of ankylosaurian, the "Polocanthidae" (in quotations since the family
hasn't been formally named yet), which have tail clubs, large spines,
shields over the hips, and (probably) a head intermediate between
nodosaurids and ankylosaurids.
Thomas R. Holtz, Jr.
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile Phone: 703-648-5280
U.S. Geological Survey FAX: 703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA 22092
U.S.A.