Open a drawer of real museum skulls, compare them trait by trait, and sort them into nested groups to show which animals are most closely related.
Every skull here is a real specimen, scanned from the bone in a museum collection.
In the Primates drawer the skulls are shown at their real sizes, so a skull that looks bigger on the screen is bigger in real life too. In Animals past and present they are not. Those nine skulls come from several collections that measured them differently, so each is shown at a size chosen to be read beside the others.
Model details
Each mesh was simplified so it can run on a classroom computer. None of the meshes carry color, so every skull renders in a single bone tone, whatever color the real specimen was.
The white-tailed deer skull is a cast: a molded copy of a real skull, not the original bone.
The Primates drawer compares living primates with each other. Animals past and present sets six extinct animals beside three that are alive today.
Specimens and sources
The skulls in the Primates drawer were scanned by the Smithsonian and released into the public domain. Animals past and present draws on several collections.
Every specimen below carries its catalogue number, the collection that holds it, and its license.
Standards
- MS-LS4-2 Apply scientific ideas to construct an explanation for the anatomical similarities and differences among modern organisms and between modern and fossil organisms to infer evolutionary relationships.
Design intent
- Tagging is optional. A student can group any two skulls at any time. Tags only help them decide. The sim never labels a trait for them, so every tag is their own reading of the skull.
- Premolar count is built into the drawer as a trap. Three premolars puts the lemurs with the New World monkeys and the deer. Two puts the sifaka with the apes. Only a pattern of several traits sorts the animals correctly.
- Check my groups never shows a score. A group scientists name becomes a printed slip carrying that name, the animals' everyday names and a photograph of each. A group that holds only part of a named group is told that a bigger group holds it. Only a group mixing animals from different parts of the tree is marked as no group at all.
- Animals past and present carries two traps of its own. The thylacine is a marsupial whose skull is very nearly a dog's, and the raccoon and the raccoon dog look alike while only one of them is a dog. Neither can be settled from the skull alone, which is the point.
- Dinictis belongs to the nimravids, an extinct family of cat-like hunters. The key puts them under Cat-like carnivorans, inside the order that holds cats, dogs and bears, following Wesley-Hunt and Flynn. Some analyses place the nimravids just outside that order. Either way, Dinictis is not a cat.
- The answer key at the foot of this tab is the reference. Read it before the lesson. The lesson is the talk that follows: after their first check a student presses Show the scientists’ tree, and the skulls move into the scientists’ groups. Ask where the two trees differ and which trait led them there. Back to my groups puts every skull back where the student left it.
Discussion prompts
- Did counting premolars put any two animals in one group that the family tree separates?
- Why does a single shared trait sometimes point to the wrong group?
- Checking the groups shows where yours match the scientists' family tree and where they differ. What evidence would change your mind about a group that did not match?
Answer key: how the skulls are grouped
This is what Check my groups compares against. Both drawers are listed, so you can answer a question about either one while the class works on the other.
A group with only one animal under it cannot be built, since a group needs two. It is listed because where that animal sits is part of the answer.