card
029

Cladistics

OLogy Series
biology
card
029

Cladistics

OLogy Series
biology

Science is like a giant jigsaw puzzle with many of the pieces missing. To try to piece together how organisms are related, Museum scientists use cladistics (cluh-DIS-tiks). In this system, animals that share unique features, such as a backbone, are grouped together on an evolutionary tree called a cladogram.

Walking the Cladogram
Before 1995, a walk in the Dinosaur Halls at the American Museum of Natural History was a "walk through time" following the evolution of early to late dinosaurs. Museum scientists Mark Norell and Lowell Dingus came up with a new idea: to organize the exhibition halls according to cladistics. This would give visitors a chance to explore the dinosaur family tree. Before 1995, dinosaurs that lived at the same time were grouped together. Now the dinosaurs are grouped according to the characteristics they share. For example, stegosaurs, duckbills, and ankylosaurs are all in the Ornithischian Hall because of their similar hip structure. The giant sauropods, bipedal carnosaurs, and birds are all in the Saurischian Hall because their hand structure is alike.

Both cladistics and cladogram start with "clad." What does "cladistics" mean?

branch

group

bone

Are you right?

Correct!

"Clad" refers to the branches on the evolutionary tree.

What is a cladogram (CLAY-doh-gram)?

an urgent telegram sent to a scientist in the field

a diagram that shows how living organisms are related

a special tool that scientists use to observe animals in the field

Are you right?

Correct!

A cladogram is like an evolutionary family tree that shows how different groups of organisms with common features are related to each other.

All living creatures are related to each other.

Fact
or
Fiction
?

Fact

All living organisms share a common ancestor. Cladograms allow us to look at the history of life on Earth.

Pronunciation: cluh-DIS-tiks
What It Is: a system to link organisms that have similar characteristics to a common ancestor in an evolutionary tree
Significance: gives scientists a way to diagram how animals and plants have changed over time without depending on the fossil record alone

Image credits: courtesy of AMNH.