Although modern reptiles were once thought to be the closest relatives of Tyrannosaurus rex, more recent evidence indicates a closer relationship between T-rex and the ostrich.
Similarities Between Tyrannosaurus Rex and the Ostrich
Tyrannosaurus rex had large powerful hindlimbs, long in proportion to their bodies. The ostrich also has heavy long powerful legs, strong enough to kill a lion.
The fossil skeleton of an early tyrannosaurid found in China appeared to be coated with filamentous structures identified as the precursors of feathers. It was suggested that, despite not having discovered any large tyrannosaural specimens with protofeathers, it is possible they existed.
The head, neck and legs of the ostrich are scaled and unfeathered. Only the torso has plumage.
Very small in relation to its overall body size, Tyrannosaurus rex had short forelimbs with two clawed fingers.
Ostrich wings are also very small. Two of the wing fingers end in claws.
Tyrannosaurus rex had many hollow bones throughout its skeleton. T-rex bones contained large airspaces connected to air sacs within its body cavity.
The respiratory system of the ostrich includes a system of air sacs originating in the thorax and extending into hollow bones. It was once thought only flighted birds benefited from hollow bones but hollow bones in large animals keep them light.
Some scientists speculate that despite its immense size, the large leg muscles of the tyrannosaurus coupled with the hollow bones that would have lightened its body, enabled the creature to attain speeds of up to 45mph.
The ostrich has large leg muscles and hollow bones and has been known to reach speeds in excess of 45mph, making it the world's fastest two-legged animal.
Ostrich and Tyrannosaurus Rex Link
Perhaps the most thrilling evidence of a close relationship between these two animals was discovered in 2003. Paleontologist Mary H. Schweitzer and her team unearthed the skeleton of a young Tyrannosaurus rex in eastern Montana and found soft, pliable tissue inside a dense thigh bone. Dr. Schweitzer noticed the fragment had not been completely fossilized. Upon examination of the tissue with a scanning electron microscope the dinosaur blood vessels were found to be "virtually indistinguishable" from those recovered from ostrich bones.
A later-discovered hadrosaur skeleton was found to also contain transparent, hollow, flexible vessels. Some of the vessls had cell-like structures and others a red substance that looked like degraded ostrich blood.
Dr. Lawrence Witmer, a paleontologist at Ohio University, said that if scientists could examine unfossilized tissues there was potential for extracting DINA. He added, "It's very exciting."
Resources:
Montana State University News Service, April 2009
Honolulu Zoo
University of California, Museum of Paleontology
Encyclopedia Britannica
New York Times, March 24, 2005
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