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Dinosaurs and Birds
Are They Related?

General Information

Scientists from many disciplines have long debated the connection between dinosaurs and birds. Did birds descend from dinosaurs, or are modern birds actually living dinosaurs?

The largest Tyrannosaurus rex ever found is now on display at the Field Museum in Chicago. Modern birds lack the long tail and teeth of dinosaurs, but many features of these fearsome prehistoric creatures are amazingly bird like. Let's take a look at some of the similarities between a T. rex and a modern bird. 


This T. rex is named Sue after its discoverer, Sue Hendrickson. Sue is 42 feet long, 13 feet high at the hip, and in life weighed about 7 tons. Sue was found in the Hell Creek Formation in western South Dakota.

A Tyrannosaurus rex named Sue
Figure 1 - A Tyrannosaurus rex named Sue


Bird Like Foot of a T. rex
Figure 2 - Bird Like Foot of a T. rex


One of the notable features of many dinosaurs is that they walked or ran on their toes. Note that Sue has a bird like foot with three toes forward, one toe back, and a distinct claw on each toe. Consider the 7 ton weight that these toes had to support when Sue stood on one foot!

The feet of most birds have three toes forward and one back, and most birds also walk or run on their toes. Compare the bird's toe nails to a dinosaur's toe nails. The similarities are quite striking.

Bird Foot
Figure 3 - Bird Foot


T. rex Wishbone
Figure 4 - T. rex Wishbone


Another feature that was discovered with Sue is that she had a wishbone. It can be seen here as the thin, slightly curved horizontal bone between the two massive shoulder bones.

One of the distinguishing characteristics of birds is their wishbone. The two small long bones running side by side across the middle of this picture are the wishbone of this bird.

Bird Wishbone
Figure 5 -  Bird Wishbone


Sue's neck
Figure 6 - Sue's neck


Sue had an "S" curved neck and a long shoulder bone. 

Birds too have an "S" curved neck and a long thin shoulder bone that can be seen here between the wing bones and the spine.

Bird Neck and Shoulder Bone
Figure 7 - Bird Neck and Shoulder Bone


Sue's Leg and Sacrum
Figure 8 - Sue's Leg and Sacrum


Sue's hind leg and sacrum can be seen in this photo. Fusion of the vertebral bones in the sacral area provide a massive bar of bone that helped support the enormous weight that had to be carried across this joint. Dinosaurs, like modern birds, have hollow long bones that make them lighter while still retaining strength. 

Birds have a similar leg and sacral structure. As in T. rex, fusion of the back bones in the sacral area provide strength to support the weight at this joint. One major difference between modern birds and dinosaurs is that birds lack the long tail.

Bird Sacrum and Leg
Figure 9 - Bird Sacrum and Leg


T. rex face
Figure 10 - T. rex face


What did Sue actually look like? We will probably never know for sure, but a sculptor's rendition is probably pretty accurate. Note that Sue's eyes faced forward, giving her good depth perception.

Sue's brain had very large olfactory lobes. This would indicate that she had a good sense of smell. Most birds today have a very poorly developed sense of smell, but some birds like Kiwis, Turkey Vultures and tubed nose seabirds do have large olfactory lobes and a good sense of smell.

Sue's brain
Figure 11 - Sue's brain


Bone Pathology
Figure 12 - Bone Pathology

Sue's skeleton shows many injuries to her legs, tail, ribs and skull. Note here the broken ribs and the swollen bone growth as the bones tried to heal. Was she a very old dinosaur with arthritis, or did she have some sort of disease? Are her injuries from combat with other dinosaurs, or from an accident such as a fall. Did she get hit and thrown down by the massive tail of a 90 ton Supersaurus?

Whatever happened, the skeleton shows that Sue survived her injuries long enough to do some healing, but she was probably in quite a bit of pain. 


One of the bizarre and mysterious aspects of the Tyrannosaurids and other carnosaurs are the small forelimbs with two claws. What was their function? They are too short to lift food to their mouth. Did they use them to care for eggs and young? Were they used in mating displays, or was there some other function?

T. rex Forelimbs
Figure 13 - T. rex Forelimbs


T. rex skull
Figure 14 - T. rex skull


Many dinosaurs have a massive skull and fearsome teeth, and a heavy long tail. Modern birds, on the other hand, have a light skull, no teeth, and no tail.


Many scientists now believe that birds are actually survivors of the great extinctions of the dinosaur age.

Did other prehistoric creatures including dinosaurs also survive the great extinction and persist into early historical times? The prehistoric Coelacanth did, and was not discovered until the mid 1930's. There are literally thousands of legends from cultures around the world of fearsome dinosaur like dragons both in the sea and on land, and of famous heroes of old that slew dragons and saved cities.

The Old Testament describes an interesting creature called the Leviathan (Job chapter 41).

"If you lay a hand on him, you will remember the struggle and never do it again! Any hope of subduing him is false; The mere sight of him is overpowering." (v 8-9)

"Who dares open the doors of his mouth ringed about with his fearsome teeth?" (v 14)

"When he raiseth himself up, the mighty are afraid; by reason of consternation they purify themselves." (v 25)

"He makes the depths churn like a boiling caldron and stirs up the sea like a pot of ointment. Behind him he leaves a glistening wake [a bioluminescent wake?]; one would think the deep had white hair. Nothing on earth is his equal, a creature without fear." (v 31-33)

Some might consider this is a description of a whale, but ancient mariners successfully hunted whales. This creature appears to be something more than a whale. Is this a description of T. rex, or perhaps a marine plesiosaur? The largest plesiosaurs were powerful marine predators more than 60 feet long, and were undoubtedly the largest predators ever to exist on Earth! An encounter with one would surely have been a fearsome experience!

Another unusual creature mentioned in chapter 40 of Job is the behemoth.

"Look at the behemoth, which I made along with you and which feeds on grass like an ox. What strength he has in his loins, what power in the muscles of his belly! His tail sways like a cedar; the sinews of his thighs are close-knit. His bones are tubes of bronze, his limbs like rods of iron. He ranks first among the works of God."

Note the description of the behemoth's tail. That large tail rules out any idea that this is a description of an elephant or hippo, and this creature ranks first (largest?)Can you think of a massive creature past or present that had a tail as large as a the cedar trees that grew in the ancient middle east?

Imagine encountering a T. rex like Sue!

Imagine trying to band Sue for a study project!

I think I will sit that one out!

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