What Is the 70 Million Year Gap in Flower Evolution?

TL;DR

The 70 million year gap in flowering plant evolution refers to the discrepancy between the fossil record, which indicates angiosperms first appeared around 130 million years ago, and molecular clock estimates suggesting origins as early as 209 million years ago. This gap may stem from incomplete fossil records or inaccuracies in genetic models, with ongoing research needed to reconcile these findings.

Transcript

Thanks to CuriosityStream for supporting this episode of SciShow. Go to CuriosityStream.com/scishow to learn more. {♫Intro♫} More than 90% of the plants on Earth are angiosperms, flowering plants whose seeds are enclosed inside fruit. And they’re everywhere -- but exactly how and when these plants came to be so ubiquitous is one of the most stubbor... Read More

Key Insights

• 🌱 Over 90% of plants on Earth are angiosperms, making their origin a significant scientific mystery.
• 🫤 The fossil record suggests the earliest flowering plants appeared in the Early Cretaceous, around 130 million years ago.
• 🫤 Molecular clock estimates based on genetic data place the origin of flowering plants much earlier, in the Late Triassic, around 209 million years ago.
• ⏰ The discrepancy between the fossil record and DNA evidence may be due to incomplete fossils or incorrect assumptions in molecular clock analysis.
• 🛟 Some researchers believe there is a "Jurassic angiosperm gap," suggesting that earlier angiosperms have not been preserved as fossils.
• 🪈 A study of fossil pollen supports the idea that angiosperms evolved in the Early Cretaceous in the order predicted by genetic studies.
• 😌 The true answer to the origin of flowering plants may lie somewhere between the fossil record and molecular clock estimates.

Questions & Answers

Q: Why is there a discrepancy between the fossil record and DNA evidence when it comes to the origin of flowering plants?

The fossil record is incomplete, and not all plants fossilize equally. It's possible that there are early angiosperms that haven't been found or preserved. Alternatively, the molecular clock analysis used in DNA studies may have incorrect inputs or assumptions.

Q: What evidence supports the idea that angiosperms evolved in the Early Cretaceous?

A study of fossil pollen from the Early Cretaceous period indicates that angiosperm pollen appeared in the order we would expect based on genetic studies. This suggests that angiosperms did exist during this time.

Q: Could the true answer lie somewhere between the fossil record and molecular clock estimates?

Yes, molecular clock estimates often provide a range of possible answers. Some estimates suggest that angiosperm origins could have occurred in the Middle or Late Jurassic Period. It's also possible that earlier angiosperms existed but have not been adequately preserved as fossils.

Q: Why is it important to resolve the mystery of flowering plant origins?

Understanding the origins of flowering plants helps us understand past environmental changes and the evolution of other organisms, such as insects that evolved alongside flowering plants.

Summary & Key Takeaways

• More than 90% of plants on Earth are angiosperms, but their origins remain a mystery and a subject of debate in the scientific community.

• The fossil record suggests that the oldest flowering plants date back to the Early Cretaceous Period, around 130 million years ago.

• However, molecular clock estimates based on genetic data place the origin of flowering plants in the Late Triassic Period, around 209 million years ago.