What type of discovery would make this cladogram valid?

Question

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Horsetails that are less than 375 million years old

Fossils of lycopods that are less than 400 million years old.

Algae that is 300 million years old

Cycads that are more than 300 million years old

Answer 1

To determine what type of discovery would make the cladogram valid, we need to consider the relationships and time frames represented within the cladogram.

1. Horsetails that are less than 375 million years old: This could help situate horsetails in the timeline but does not specifically validate any evolutionary relationships if horsetails are already established in the cladogram.

2. Fossils of lycopods that are less than 400 million years old: If lycopods are placed based on their ancestry in the cladogram, finding younger fossils might not validate or invalidate the cladogram unless they uncover new lineages.

3. Algae that is 300 million years old: Algae being introduced is significant but might not provide direct support for the cladogram unless there's a direct lineage indicated.

4. Cycads that are more than 300 million years old: Discovering cycad fossils older than 300 million years could place them in their proper evolutionary context, helping clarify the evolutionary tree.

The most impactful discovery would likely be the Cycads that are more than 300 million years old. This could validate the cladogram by demonstrating that cycads, which may share a common ancestor with other groups in the cladogram, are indeed older than previously thought, providing a more complete picture of the evolutionary history and relationships depicted.

To narrow down or validate the tree especially in relation to differing ages of lineage splits, finding cycad fossils that are more than 300 million years old would clarify the divergence points, thus making the cladogram more valid.