Meat Eating Dinosaur
Dryptosaurus aquilunguis (Cope)
Description: At Big Brook, Dryptosaurus is very rarely represented by its teeth and other identifiable bones.

The teeth of this dinosaur are somewhat similar in construction to the teeth of mosasaurs and about the same size but they have
some differences. The main difference is in the cross sections. Since
Dryptosaurus was a meat-eating dinosaur, their teeth have
a highly compressed lens shaped cross section with strong serrated carinae. Most teeth are about 2 cm (about .75 in) in length.

Only a few confirmed bones from
Dryptosaurus exist from this site. Much of the possible material from this dinosaur is very
beaten, worn, and scrappy. This is mostly due to conditions before and after fossilization. No doubt, a larger amount of
dinosaur material occurs but is to broken, worn, or fragmentary to be recognized. Some paleontologists believe that
Ornithomimus, the "bird mimic" dinosaur, that might be found at this locality is actually the juvenile remains of Dryptosaurus.
This is probably true because even out west where the exposures are better exposed, little or no Ornithomimus skull material
has been recovered, especially in association with the rest of the skeleton (Paleontologists use skull material to positively identify

Commonality: Teeth and other identifiable material are very rare.

Similar fossils: The teeth are similar to mosasaur teeth but Dryptosaurus teeth have a compressed lens shaped cross section
and the presence of large serrated carinae. The teeth of mosasaurs mostly have an oval cross section with low carinae that
mostly do not have prominent serrations.

Size: Its length reached no more than 6 meters (about 20 feet) in length.

Notes: The presence of this predatory dinosaur is only based on fragmentary evidence. There has been other identifiable
material from
Dryptosaurus found at a few other streams from older formations in the state. The first occurrence of this
awesome dinosaur was from the Navesink formation of Barnsboro, New Jersey. This skeleton was partially complete and
probably represents the second most complete dinosaur from New Jersey.

Unfortunately, this skeleton suffered from what is known as "Pyrite's disease". Crystals of the mineral marcasite continues to
grow in the spaces of the bone.  The stress will build up until the bone disintegrates.

Dryptosaurus was a medium built bipedal meat eating dinosaur. They had the general build of Tyrannosaurus rex with the
large head filled with sharp teeth and massive legs built for speed but had proportionally longer arms.  Interestingly, this
carnivorous dinosaur possessed a unique and complex ankle design. This led Edward Cope to the conclusion that this dinosaur
leaped onto its prey. He named it
Laelaps aquilunguis for the mythological Laelaps, which was quite an accomplished leaper.  
Later Othanial Marsh, Cope's arch rival in the "Bone war", pointed out that the name Laelaps was already used to name a fly
and infuriated Cope by renaming this dinosaur
Dryptosaurus.  Dryptosaurus probably preyed on the duckbills and other
dinosaurs of the time.
Painting of Dryptosaurus by
Charles R. Knight
Toe Bone
a. Side View  b. Top View
Claw Core and Toe Bone
(Cast of the original Barnsboro specimen)
Reconstruction of skeleton with the fossil
parts that have been found.
(State Muesum Specimen, Trenton)
Found at Ellisdale Site
Jaw Bone
(Cast of the original Barnsboro specimen)