By any reasonable definition, 
T. Rex
 is more closely related to sparrows than to 
Stegosaurus
. 

[[A cladistic tree showing a single origin point which branches on one to a second point which branches into  "
Stegosaurus
" and "
Triceratops
", and on the other side branches into a second point which branches into "
T. Rex
" and "sparrow". Each label's vertical distance from the origin point  represents "separation by time", the Steogsaurus being closest, the Triceratops and T. Rex on the same level in the middle, and "sparrow" furthest. The distance of their label from their closest common relative represent "phylogenetic distance". Below this tree are sketches of a Stegosaurus, T. Rex, and sparrow skeleton. A box surrounds the T. Rex and sparrow skeletons, showing they are physically similar.]]

Birds aren't 
descended
 from dinosaurs, they 
are
 dinosaurs.

Which means the fastest animal alive today is a small carnivorous dinosaur, 
Falco peregrinus
. 
[[A silhouette of a falcon flying toward a smaller prey bird.]]
It preys mainly on other dinosaurs, which it strikes and kills in midair with its claws.

This is a good world.

{{Title text: Sure, T. rex is closer in height to Stegosaurus than a sparrow. But that doesn't tell you much; 'Dinosaur Comics' author Ryan North is closer in height to certain dinosaurs than to the average human.}}