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Description
Pikaia gracilens
The Cambrian was the era in which life truly began to proliferate at a breakneck pace. Countless invertebrates diversified from Trilobites to Radiodonts, but another group that showed up were the first vertebrates. One of the most unique animals found in Cambrian Formations was a fish no bigger than a minnow, known as Pikaia gracilens.

History and Discovery:

In 1911 the administrator of the Smithsonian, Charles Walcott was hiking through the Burgess Shale formation in Alberta. Largely, he was prospecting for fossils given Alberta was starting to become a hotbed of paleontology. On one hike, he stopped in his tracks because a fossil on the ground caught his eye. Kneeling down he picked up a stone and found entombed in a rock, a small animal. Taking it back to the museum, he noted the lithe and thin body in the rock, and how it had an eel-like body.

Upon taking it back to America, he described it further in detail and called it Pikaia gracilens. A latinized version of the nearby Pika Peak and “gracilens” after the gracile body the animal had. Despite its eel-like nature, he classified it as anelid worm, an invertebrate. And dubbed Pikaiid family within the class.

In 1977 however, Conway Morris and his professor, Harry Whittington reanalyzed the fossil and found that this animal was not a invertebrate, they posited instead it was a chordate noting the complexity of the animal. It was published in the Scientific American in 1979. While accepted, it was contested for more than 3 decades, until microscopes finally confirmed evidence of the spinal column. It was primitive but it was there.

Description:

Pikaia was a small animal. With large individuals reaching 2 inches long and weighing 1oz.

The animal was basically an eel sans the head. At the tip of the “head” (will be explained). A dorsal fin runs the length of the animal while the ventral fin runs roughly half of that. There were 9 pairs of appendages at the front of the animal. What these were for is unknown, but most paleontologists think they were gill appendages. A pair of small tentacle likely used for capturing small prey and plankton has been found in some of the fossils.

Pikaia is unique as it looks like there’s the beginning of a “head” that is forming. In fact in the original description, Walcott said there were 2 small eyes at the front of the animal. However, no evidence has emerged showing any sign of eyes in the fossil record. It’s believed it emerged largely due to how this animal swam

Classification:

Contrary to popular belief, Pikaia was not the earliest ancestor of all vertebrates.

However, theorize that this animal is a lancelet. These are basal vertebrates who filter feed in open ocean environments. There is some warrant to this as a group known as the Branchistomatid Lancelets have features that strongly resemble Pikaia. However, molecular analysis indicates that lancelets are not the closest relatives to modern vertebrates and Branchistomatids are more derived than Pikaia.

Another theory is that these animals are basal relatives to Craniata. The clade that includes hagfish and lampreys. However, these animals are also more derived compared to other stem vertebrates.

Most paleontologists view this animal as a basal chordate with no living ancestors. Stephen Jay Gould, a noted paleontologist, said that Pikaia had "revised views of evolution, ecology and development," and remarked: "So much for chordate uniqueness marked by slightly later evolution." This is because the age of the animal, being over 510,000,000 years old, had changed the view of evolution as early vertebrates were not known at the time.

However, Gould did not believe that Pikaia itself was unique as an early chordate or that it was "the actual ancestor of vertebrates;" he presumed that there could be undiscovered fossils that are more closely linked to vertebrate ancestry.

And his view would be vindicated as animals like Metaspriggina and the Myllokunmingiids would emerge from the fossil record.

As with many things in paleontology, Pikaia's exact placement in the tree of life will continue to be debated as the years go by.

Extinction:

Pikaia would die out some 508,000,000 years ago, or at least, that is where it vanishes from the shale. However, its basic blueprint for other proto-vertebrates would pan out in spades given that… well, you’re reading this profile now, so that should tell you something.

___________________________________________________________________________________________

Bit of a wildcard y’all. Both of the profile tonight and of the animal as well One of the most primitive chordates ever and a extrapolation on its history and details of classification. I got this model from BuffZoo and his discord and found a lot of prehistoric marine animals so thought I’d use them here.

One of the more unique animals I’ve done. It won't be in PMP obviously since no one could survive in the environment and I've got no intention of rescuing live fish from the past.

Original Model by Buffzoo from their Discord:
discord.com/channels/624994150…

Description
Pikaia gracilens
The Cambrian was the era in which life truly began to proliferate at a breakneck pace. Countless invertebrates diversified from Trilobites to Radiodonts, but another group that showed up were the first vertebrates. One of the most unique animals found in Cambrian Formations was a fish no bigger than a minnow, known as Pikaia gracilens.

History and Discovery:

In 1911 the administrator of the Smithsonian, Charles Walcott was hiking through the Burgess Shale formation in Alberta. Largely, he was prospecting for fossils given Alberta was starting to become a hotbed of paleontology. On one hike, he stopped in his tracks because a fossil on the ground caught his eye. Kneeling down he picked up a stone and found entombed in a rock, a small animal. Taking it back to the museum, he noted the lithe and thin body in the rock, and how it had an eel-like body.

Upon taking it back to America, he described it further in detail and called it Pikaia gracilens. A latinized version of the nearby Pika Peak and “gracilens” after the gracile body the animal had. Despite its eel-like nature, he classified it as anelid worm, an invertebrate. And dubbed Pikaiid family within the class.

In 1977 however, Conway Morris and his professor, Harry Whittington reanalyzed the fossil and found that this animal was not a invertebrate, they posited instead it was a chordate noting the complexity of the animal. It was published in the Scientific American in 1979. While accepted, it was contested for more than 3 decades, until microscopes finally confirmed evidence of the spinal column. It was primitive but it was there.

Description:

Pikaia was a small animal. With large individuals reaching 2 inches long and weighing 1oz.

The animal was basically an eel sans the head. At the tip of the “head” (will be explained). A dorsal fin runs the length of the animal while the ventral fin runs roughly half of that. There were 9 pairs of appendages at the front of the animal. What these were for is unknown, but most paleontologists think they were gill appendages. A pair of small tentacle likely used for capturing small prey and plankton has been found in some of the fossils.

Pikaia is unique as it looks like there’s the beginning of a “head” that is forming. In fact in the original description, Walcott said there were 2 small eyes at the front of the animal. However, no evidence has emerged showing any sign of eyes in the fossil record. It’s believed it emerged largely due to how this animal swam

Classification:

Contrary to popular belief, Pikaia was not the earliest ancestor of all vertebrates.

However, theorize that this animal is a lancelet. These are basal vertebrates who filter feed in open ocean environments. There is some warrant to this as a group known as the Branchistomatid Lancelets have features that strongly resemble Pikaia. However, molecular analysis indicates that lancelets are not the closest relatives to modern vertebrates and Branchistomatids are more derived than Pikaia.

Another theory is that these animals are basal relatives to Craniata. The clade that includes hagfish and lampreys. However, these animals are also more derived compared to other stem vertebrates.

Most paleontologists view this animal as a basal chordate with no living ancestors. Stephen Jay Gould, a noted paleontologist, said that Pikaia had "revised views of evolution, ecology and development," and remarked: "So much for chordate uniqueness marked by slightly later evolution." This is because the age of the animal, being over 510,000,000 years old, had changed the view of evolution as early vertebrates were not known at the time.

However, Gould did not believe that Pikaia itself was unique as an early chordate or that it was "the actual ancestor of vertebrates;" he presumed that there could be undiscovered fossils that are more closely linked to vertebrate ancestry.

And his view would be vindicated as animals like Metaspriggina and the Myllokunmingiids would emerge from the fossil record.

As with many things in paleontology, Pikaia's exact placement in the tree of life will continue to be debated as the years go by.

Extinction:

Pikaia would die out some 508,000,000 years ago, or at least, that is where it vanishes from the shale. However, its basic blueprint for other proto-vertebrates would pan out in spades given that… well, you’re reading this profile now, so that should tell you something.

___________________________________________________________________________________________

Bit of a wildcard y’all. Both of the profile tonight and of the animal as well One of the most primitive chordates ever and a extrapolation on its history and details of classification. I got this model from BuffZoo and his discord and found a lot of prehistoric marine animals so thought I’d use them here.

One of the more unique animals I’ve done. It won't be in PMP obviously since no one could survive in the environment and I've got no intention of rescuing live fish from the past.

Original Model by Buffzoo from their Discord:
discord.com/channels/624994150…