Acrocanthosaurus
Acrocanthosaurus atokensis
Pronounced:
ak-ro-KANTH-uh-sawr-us
Diet: Carnivore
(Meat-Eater)
Name Means: "High
Spined Lizard"
Length: 40 feet
(13 m)
Height: 16 feet
(5 m)
Weight: 3.5 to 5
tons (3,200 to 4,500 kg)
Time: Early
Cretaceous - 110 mya
Fossil remains for this Dinosaur
have been found in Southwestern United
States
Called Acro for short, this dinosaur is a
Therapod (a two-legged meat-eater) which had 68
long, knife-like teeth in its 5 foot long head.
At 40 feet long, this dinosaur ruled the land
about 35 million years before there were any T.
rex's. Unlike T. rex, this dinosaur had larger,
more powerful arms that could grab, hold and
crush other dinosaurs. It could probably lift a
small car off the ground!
 There is one very interesting feature about the
Acro, and that is the high spines along its back and
neck. In fact the name Acrocanthosaurus means 'high
spined lizard' in Greek (the last part of its name,
atokensis, refers to Atoka County in Oklahoma where
the only full skeleton was discovered).
The spines
are not nearly as big as those on some dinosaurs
that have 'sails' on their back, like Spinosaurus
Instead, Acro's spines, the longest of which is
about 2 feet, were anchors to which huge muscles
were attached. This made Acro very strong and
powerful. And Acros probably needed to be very
strong because there is evidence that it hunted huge
sauropod dinosaurs. In Texas, there are dinosaur
tracks that show a large Acro tracking and hunting a
large brachiosaur called Pleurocoelus Some
modern animals have a similar type of spine along
their back to give them strength: horses, elephants
and buffaloes all have this type of muscle
suspension.
Acro had relatively small feet for a large
dinosaur. This was because it lived in a drier
climate and did not need a large surface area to
keep it from sinking in mud. Although similar in
size and weight to T. rex, its feet were only about
half the size. T. rex lived in a much wetter
environment and probably spent a lot of time walking
through marshy ground. The teeth of an Acro were
typical of the large meat-eaters of the late
Jurassic and Early Cretaceous. They were long (as
much as 9 or 10 inches if you include the root) and
fairly thin, curving slightly inward with serrations
along the front and back edges. This means that Acro
did not necessarily use its teeth as a killing tool.
Teeth like this were most likely used to rip big
pieces of flesh from prey which it was holding with
its powerful arms and feet. Unlike T. rex, Acro
teeth could not have been used to crunch bone as
they would break too easily. When its teeth did
break, Acro had new teeth waiting. Like many
dinosaurs, it was constantly shedding old teeth and
replacing them with new.
Acrocanthosaurus is in the same family of
dinosaurs as the Allosaurus which was a very
successful family of dinosaurs. It was most likely
the dominant North American predator of the Early
Cretaceous. It is known primarily from one specimen,
nicknamed 'Fran' which was discovered in Atoka
County, Oklahoma by Cephis Hall and Sid Love in
1983. The specimen showed a number of interesting
pathologies, including a hole in the right scapula
(shoulder blade) that had become infected. The ribs
beneath and in front of this scapula appear to have
been broken and healed, indicating that the animal
had been injured. Scattered remains of
Acrocanthosaurus have been found in Oklahoma, Texas,
Utah and Arizona.
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