Vampire squid have been lurking in the dark corners of the ocean for 30 million years, a new analysis of a long-lost fossil find.
Modern vampire squid (infern Vampyroteuthis) can thrive in deep, oxygen-poor ocean waters, unlike many other squid species that require shallow habitat along continental shelves.
Few fossil ancestors of today’s vampire squid survive, so scientists are unsure when these runaway cephalopods evolved their ability to live on low oxygen.
The new fossil analysis helps fill a 120-million-year gap in the evolution of vampire squid, revealing that the ancestors of today’s vampire squid already lived in the deep oceans during the Oligocene, between 23 and 34 million years ago. years.
These squid probably developed adaptations to low-oxygen water during the Jurassic, said study co-author Martin Košťák, a paleontologist at Charles University in Prague.
“Life at stable low oxygen levels brings evolutionary advantages: low predation pressure and less competition,” Košťák wrote in an email to Live Science.
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A rediscovered fossil
Košťák and his colleagues found the long-lost fossil in the collections of the Hungarian Museum of Natural History in 2019 while searching for cuttlefish ancestor fossils. The fossil was originally discovered in 1942 by Hungarian paleontologist Miklós Kretzoi, who identified it as a squid dating back to about 30 million years ago and named it Necroteuthis hungarica. However, later researchers argued that it was a cuttlefish ancestor.
In 1956, during the Hungarian Revolution, the museum was burned and the fossil was thought to have been destroyed. The rediscovery was a happy surprise.
“It was a fantastic moment,” Košťák said of the rediscovery, “to see something that was previously suggested would be lost for good.”
The fossil. (Košťák et al., Communications Biology, 2021)
Košťák and his colleagues studied the fossil with scanning electron microscopy and performed a geochemical analysis. They first found that Kretzoi’s initial identification was correct: the fossil comes from a squid, not a cuttlefish ancestor.
The inner shell of the animal, or gladius, which forms the backbone of its body, was about 15 inches long, suggesting that the squid grew up to about 35 inches long with its arms included. This is slightly larger than modern vampire squid, reaching a total body length of about 11 inches (28 cm).
The sediments surrounding the fossil showed no trace of microfossils that are often found on the seabed, suggesting that the squid did not live in shallow water. The researchers also analyzed the levels of carbon variations in the sediment and found that the sediment probably came from an anoxic or low-oxygen environment.
These conditions are characteristic of the deep ocean floor. By looking at layers of rock above where the fossil was deposited outside present-day Budapest, researchers were also able to show that squid probably would not have been able to survive in the shallower seas of the time.
Shallow deposits showed very high levels of a particular plankton blooming in low-salt, high-nutrient environments, conditions that current vampire squid cannot tolerate.
(Researchers at the Monterey Bay Research Institute found that while hiding in the deep sea, these squid do not behave like the predatory nightmares their name suggests; rather, they wait for their dark habitats to flow. crumbs of organic matter.catch these pieces with suckers covered in mucus, found MBARI.)
Adapting to the deepest
The new research, published Thursday (February 18) in the journal Biology of Communications, hints at how the ancestors of vampire squid learned to live where other squid could not.
Looking deeper into the fossil record, the oldest fossils of this group of squid are found in the Jurassic period, between 201 million and 174 million years ago, Košťák said, and are usually found in anoxic sediments.
“The main differences are that these depleted oxygen conditions were established on the platform, [a] “This means that the ancestors were inhabitants of a shallow water environment, but that they were already adapted to low oxygen conditions.”
There is a gap in the Lower Cretaceous fossil record, which began about 145 million years ago. Squid may have already moved into the deeper ocean at this point, said Košťák, prepared for his experiences with anoxic conditions in the Jurassic. This deep-water lifestyle could explain why the squid survived the crisis that killed non-avian dinosaurs in the late Cretaceous period, he added.
The squid with deep life 30 million years ago helps link recent history to the deep past, Košťák said. Now he and his colleagues are trying to make similar connections for cuttlefish, a group of sympathetic, color-changing cephalopods whose origins are similar to turbid.
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This article was originally published by Live Science. Read the original article here.