3 Cretaceous Dinosaurs

So, this post is about 3 Creataceous dinos but there are 4 new drawings to print and color.  Go to the "Paleontology" button above and scroll down to the bottom to find the free printable version.  

T. rex Hunts with Offspring

Tyrannosaurus rex is thought to be a good parent.  In fact, it is now thought that there were T. rex packs and that males and females may have mated for life.  So both parents may have cared for their offspring.  When Theropod (carniverous dinosaurs) eggs were found the baby dinosaurs inside had tiny teeth but clearly could not take care of themselves.  So, like birds, that evolved from Theropod dinosaurs, the Theropod dinosaurs were caring parents.  It is even thought that T. rex parents may have carried their chicks in their mouths. . . like modern crocodiles and alligators do.  Of course the adults would not have carried adolescents.  The above drawing is of an adult and an adolescent of about 5-6 years.  If they did indeed live in a pack then adults and older adolescents would have taught the younger T. rex to hunt.  That is what is being depicted in the above drawing.  

By looking at the inside of Theropod bones we know that a T.rex grew to adulthood in about 18 years.  Some new research has upped the size of the adult T. rex.  They think that adult T. rex might have weighed up to 18 tons.  These paleontologists estimate that a young T. rex chick grew 3,950 lbs per year.  That would be 1,790 kg per year.  These researchers used the Ford Motor Company ct (X-ray) scanner to scan the huge  3 foot (1 meter) skull of Sue, a South Dakota T. rex now housed in the the Field Museum in Chicago.  They also scanned the rest of the skeleton.  They then used digital technology to put muscles and skin etc. on the bones.  The results were a weight of T. rex of 9 tons or 18,000 lbs.  That would be 8,164 kg.  

T. rex Parent Caring for Chicks

Actually bigger than T. rex..was the enormous dinosaur known as Spinosarus.  There was more than one species of Spinosaur.  These dinosaurs are close to 60 feet or 18 meters long. They ate primarily fish.  There is a fairly new documentary available called Bigger Than T. rex.   It tells of how a new skeleton of Spinosaurus was found in Morocco.  This is very fortunate because during World War II the Nazi headquarters was right across the street from the museum where the only know at the time Spinosaurus bones were on display.  Allied bombers aimed to bomb the Nazi headquarters and also hit the museum so the original bones are lost to science.  This new specimine has told us a lot about Spinosaurus.  They were huge.  The biggest Theropod.  But they probably walked on all four legs most of the time AND they ate primarily fish.  They have sensors on the end of their snout to detect motion in the water.  This is an adaptation that crocodilians also have.  Spinosaurs are the only known dinosaurs to have this motion in water sensing organs.  Being Theropods, Spinosaurs also probably also took care of their young.  The below picture shows a Spinosaurus parent hunting with young.  Hunting would be something they would do if the fishing was poor. 

Spinosauruss Hunting with Young

Parasaurolophus Female

Parasurolophus was a Hadrosaur.  Hadrosaurs were the duck-billed dinosaurs.  Parasaurolophus had a long crest that was longer in males and shorter in females.  The crest was used as a sounding chamber so females had a higher pitched trumpeting voice than the males' deep bass voice.  The above young female Parasaurolophus would have had a smaller crest or sounding chambe than the males of the herd.