Where Are All The Squid Fossils?

Summary

This video explores the mystery of missing squid fossils in the cephalopod family. Despite squids being as old as their relatives, like belemnites, no soft tissue fossils have been found, raising questions for paleontologists. The key to the mystery is discovered through taphonomy experiments, which show that squids decay differently than octopuses due to a high ammonia content in their bodies, preventing fossilization. This unique adaptation helps squids remain buoyant in the water but also explains the absence of squid fossils. The research sheds light on the broader fossilization challenges for cephalopods, including ammonites, with a rare soft tissue ammonite fossil offering hope for future discoveries.

Takeaways

• 😀 Cephalopods, including octopuses, squids, and nautiluses, have a relatively good fossil record, primarily based on their hard parts like hooks and shells.
• 😀 The mystery of the missing squid fossils persisted for 30 years, despite the existence of squid-like relatives, like belemnites, in the fossil record.
• 😀 Cephalopods are divided into two groups: coleoids (which have soft bodies) and nautiloids (with hard outer shells).
• 😀 Fossils from the 1800s were misclassified as squids due to their internal shells, but paleontologists later realized many were not true squids.
• 😀 A squid is only considered a true squid if it has eight arms and two tentacles, a distinction that was crucial in reclassifying cephalopod fossils.
• 😀 In the 1980s, two paleontologists redefined a group of cephalopods called Vampyromorpha, which includes octopuses and vampire squids.
• 😀 No definitive fossil of a true squid with eight arms and two tentacles has been found to date, despite the existence of ancient relatives.
• 😀 In 2017, taphonomy research revealed that squids decay very quickly and do not fossilize well due to their body composition, particularly their high pH.
• 😀 Squid bodies are largely made up of ammonia, which gives them buoyancy but also raises the pH of their decaying bodies, preventing fossilization.
• 😀 Octopuses, in contrast, live on the seafloor and lack the buoyancy adaptation found in squids, leading to a different pH balance in their decay, which helps with fossilization.
• 😀 The discovery of a soft tissue fossil of an ammonite in 2021 has given hope for finding a soft-bodied squid fossil in the future.

Q & A

What is the primary reason for the mystery of missing squid fossils?

The mystery arises because, despite squids being around since the Late Jurassic Period, no fossil evidence of squids with the characteristic eight arms and two tentacles has been found, even though other cephalopod fossils, such as belemnites, exist.

What is the significance of taphonomy in solving the mystery of missing squid fossils?

Taphonomy, the study of the decay process and how organisms become fossilized, played a key role in solving the mystery. Experiments showed that squids decay much faster than other cephalopods like octopuses, making it unlikely for their soft tissue to fossilize.

Why do octopuses and squids decay differently?

Octopuses decay in a way that allows for some soft tissue preservation, while squids fall apart rapidly due to their high ammonia content. This high ammonia level in squids raises the pH of their decaying bodies, preventing fossilization.

How does ammonia in squids contribute to the absence of fossil squid remains?

Ammonia, which makes up a significant portion of a squid's body, increases the pH of their decaying bodies. This prevents the necessary conditions for fossilization, as soft tissue fossilization requires a low pH.

What adaptation do squids have that is related to their buoyancy?

Squids retain ammonia in their bodies to help with buoyancy. Ammonia is lighter than water, allowing squids to stay afloat without expending too much energy.

How do scientists define the two main groups of living cephalopods?

Living cephalopods are divided into two groups: coleoids (octopuses, squids, and cuttlefish) that have soft bodies and reduced or no internal shell, and nautiloids (like the nautilus) that possess a hard outer shell.

What role did the reclassification of cephalopod fossils in the 1980s play in the mystery?

In the 1980s, two paleontologists reclassified cephalopod fossils, recognizing that many specimens previously thought to be true squids lacked the defining squid trait of eight arms and two tentacles, leading to the creation of a new group, the Vampyromorpha.

Why is it important that squids are classified by their eight arms and two tentacles?

The classification of squids based on their unique anatomy—eight arms and two tentacles—helps scientists accurately trace their evolutionary history and distinguish them from similar creatures like belemnites or other cephalopods.

What breakthrough discovery in 2021 offered hope for finding soft-bodied cephalopod fossils?

In January 2021, a soft tissue fossil of an ammonite, a close relative of squids, was discovered. This rare find showed the preservation of the animal’s soft body, giving hope that similar discoveries of soft-bodied squids might eventually be made.

How did the discovery of the soft tissue ammonite fossil relate to the mystery of squid fossils?

The discovery of the ammonite's soft tissue fossil suggests that, while soft-bodied squids may be rare in the fossil record, they are not impossible to find. This finding provides hope that squids may one day be discovered in a similar state of preservation.