Phylogenetic Trees Bundle - Free Printable

Let’s work through this step by step.

We’re looking at a phylogenetic tree worksheet that shows how different animals are related based on shared traits. The goal is to understand how scientists use “derived traits” (new features that evolved in certain groups) to build these trees and figure out who’s more closely related to whom.

First, let’s look at the table of derived traits:

| Name of taxon | Hinged jaw | Lungs | Amniote egg | Hair / fur |
|---------------|------------|-------|-------------|----------|
| Platypus | 1 | 1 | 1 | 1 |
| Salmon | 1 | 0 | 0 | 0 |
| Cat | 1 | 1 | 1 | 1 |
| Crocodile | 1 | 1 | 1 | 0 |
| Newt | 1 | 1 | 0 | 0 |
| Lamprey | 0 | 0 | 0 | 0 |

Remember:
- “1” means the trait is present.
- “0” means the trait is absent.

Now, we need to label each branch of the tree with the correct derived trait — starting from the bottom (oldest) to the top (most recent).

The rule given:
> “The lowest scoring taxon goes first, then the next lowest, etc.”
This means we start with the trait that appears in the fewest animals (lowest number of 1s), and move up to traits that appear in more animals.

Let’s count how many animals have each trait:

- Hinged jaw: Present in everyone except Lamprey → 5 out of 6 → HIGH score
- Lungs: Present in Platypus, Cat, Crocodile, Newt → 4 out of 6
- Amniote egg: Present in Platypus, Cat, Crocodile → 3 out of 6
- Hair/fur: Present only in Platypus and Cat → 2 out of 6 → LOWEST score

Wait — but the instruction says “lowest scoring taxon goes first”. Actually, re-reading: it probably means the trait that evolved earliest (appears in most descendants) should be placed lower on the tree. But the note says: “The lowest scoring taxon goes first, then the next lowest, etc.” — which might mean the trait with the FEWEST occurrences (rarest) goes last? That doesn’t make sense for building a tree.

Actually, looking at the example doodle notes and standard phylogenetic tree construction:

Traits that are shared by MORE organisms are older (evolved earlier). Traits shared by FEWER organisms are newer (evolved later).

So we should place traits from BOTTOM (oldest) to TOP (newest) based on how widespread they are.

Let’s reorder traits by how many taxa have them (from MOST to LEAST):

1. Hinged jaw – 5 taxa (all except Lamprey) → OLDEST → goes at the bottom
2. Lungs – 4 taxa (Platypus, Cat, Crocodile, Newt)
3. Amniote egg – 3 taxa (Platypus, Cat, Crocodile)
4. Hair/fur – 2 taxa (Platypus, Cat) → NEWEST → goes at the top

But wait — the tree has branches labeled already with some traits:

Looking at the right-hand page, under “Doodle the species!”, there’s a blank tree with labels pointing to branches:

From bottom to top, the labels are:

- Four legs
- Big ears
- Wings
- Pig ears
- Hair/fun (probably meant “Hair/fur”)
- Amniotic egg
- Lungs
- Hinged jaw

Wait — that seems backwards. Let me check again.

Actually, in the section “Using derived traits to create phylogenetic trees!”, there’s an example tree with labels:

It shows:

At the very bottom (closest to root): Hinged jaw

Then above that: Lungs

Then: Amniotic egg

Then: Hair/fur

And also other traits like “Four legs”, “Wings”, etc., but those may be for different parts.

In our case, we’re working with the six animals: Lamprey, Salmon, Newt, Crocodile, Platypus, Cat.

Let’s map their traits onto the tree structure shown in the “Complete the table...” section.

The tree diagram has branches leading to each animal. We need to put the trait names on the branches where that trait FIRST evolved.

Standard method: Start from the root (common ancestor of all). The first trait that appears in any descendant goes on the first branch after the root.

Lamprey has NO derived traits (all 0s) → so it branches off first, before any traits evolve.

Then, the next common ancestor evolves hinged jaw → because Salmon, Newt, Crocodile, Platypus, Cat all have it.

So branch leading to Salmon + others gets “Hinged jaw”.

Then, among those, Newt, Crocodile, Platypus, Cat have lungs → so next branch gets “Lungs”.

Then, Crocodile, Platypus, Cat have amniote egg → next branch gets “Amniote egg”.

Then, Platypus and Cat have hair/fur → final branch gets “Hair/fur”.

That matches the order: Hinged jaw → Lungs → Amniote egg → Hair/fur.

Now, looking at the actual tree drawing in the worksheet (right side, middle), it has lines with blanks to fill in.

The tree starts with Lamprey branching off alone.

Then the rest go to a node, then split.

The labels to fill in are along the branches.

Based on standard practice and the example, the correct order from bottom (root) to top (tips) should be:

1. Hinged jaw (after Lamprey splits off)
2. Lungs (before Newt splits off)
3. Amniote egg (before Crocodile splits off)
4. Hair/fur (only for Platypus and Cat)

Also, note that Salmon does NOT have lungs, so it must branch off BEFORE the “lungs” trait evolves.

Similarly, Newt does not have amniote egg, so it branches off before that.

Crocodile does not have hair/fur, so it branches off before that.

So the tree should look like:

Root → splits to Lamprey (no traits)

Remaining lineage → evolves Hinged jaw → splits to Salmon (has hinged jaw, no lungs)

Remaining lineage → evolves Lungs → splits to Newt (has lungs, no amniote egg)

Remaining lineage → evolves Amniote egg → splits to Crocodile (has amniote egg, no hair/fur)

Remaining lineage → evolves Hair/fur → splits to Platypus and Cat

Therefore, labeling the branches from bottom to top:

- First branch (after Lamprey): Hinged jaw
- Second branch (after Salmon): Lungs
- Third branch (after Newt): Amniote egg
- Fourth branch (after Crocodile): Hair/fur

Now, looking at the actual worksheet image (even though I can't see it, based on description), the tree likely has four blank lines to fill in, corresponding to these four traits in that order.

Also, in the “Doodle the species!” section, there are cartoon animals with traits labeled, but that’s separate.

For the main task — completing the tree with derived traits — the answer is to write the traits in order from oldest to newest along the branches.

Final Answer:
Hinged jaw, Lungs, Amniote egg, Hair/fur