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 day vampire squid (hell Vampyroteuthis) can thrive in deep, oxygen-poor seawater, unlike many other squid species that require lower habitats along continental shelves. Few fossil ancestors of today’s vampire squid survive, however, so scientists are not sure when these elusive squid developed the ability to live with a little oxygen.
The new fossil analysis helps fill a gap of 120 million years in the evolution of vampire squid and reveals that the ancestors of modern vampire squid already lived in the deep oceans of the Oligocene 23 million to 34 million years ago. These squid probably developed adaptations to deoxygenated water during the Jurassic, said study co-author Martin Košťák, a paleontologist at Charles University in Prague.
Related: Pictures of the vampire squid from hell
“Living in stable oxygen levels with low oxygen brings evolutionary benefits ̵
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 fossils from octopus fathers. The fossil was originally discovered in 1942 by the Hungarian paleontologist Miklós Kretzoi, who identified it as an octopus dating back about 30 million years and named it Necroteuthis hungarica. Later researchers, however, claimed that it was an ancestor of squid fish. In 1956, during the Hungarian revolution, the museum was burned down and it was thought that the fossil was destroyed. The rediscovery was a happy surprise.
“It was a great moment,” Košťák said of the rediscovery, “to see something previously suggested would be lost.”
Košťák and his colleagues studied the fossil with scanning electron microscopy and conducted a geochemical analysis. They first found out that Kretzoi’s original identification was correct: the fossil is from an octopus, not an octopus father. The animal’s inner shell, or gladius, which forms the backbone of its body, was approx. 15 cm long, which indicates that the squid grew to approx. 35 cm long with arms included. It is just slightly larger than modern vampire squid, reaching about 28 cm in total body length.
The sediment around the fossil showed no trace of microfossils often found on the ocean floor, suggesting that the squid did not live in shallow water. The researchers also analyzed levels of variation in carbon in the sediment and found that the sediment probably originated from an anoxic or oxygen-poor environment.
These conditions are characteristic of the deep seabed. By looking at rock layers over where the fossil was deposited outside what is today Budapest, the researchers were also able to show that the squid probably could not have survived in the lower seas of the time. The shallow ocean deposits showed very high levels of a particular plankton that thrives in low-salt environments and nutrients – conditions that modern vampire squid do not tolerate.
(Researchers at the Monterey Bay Research Institute found that while lurking in the deep ocean, these squid do not behave like the nightmare trolls their name suggests, but rather wait in their dark habitats for crumbs of organic matter to flow down. So they catch these bits with mucus-covered pacifiers, found MBARI.)
Adaptation to depth
The new research, published Thursday (February 18) in the journal Communication Biology, suggests how ancestors of vampire squid learned to live where other squid could not. If you look deeper into the fossil record, the oldest fossils from this group of octopuses are found in Jurassic periodbetween 201 million and 174 million years ago, Košťák said, and they are typically found in anoxic sediments.
“The main differences are that these oxygen-depleted conditions were established on the shelf, [a] low water environment, “he said. This means that the ancestors were inhabitants of shallow water, but they were already adapted to oxygen-poor conditions. ”
There is a hole in the fossil record in the Lower Cretaceous that started about 145 million years ago. The squid may have already shifted to the deeper sea by this time, Košťák said, marked by their experience of anoxic conditions in law. This deep-water lifestyle might explain why the octopus survived the crisis that killed the non-avian dinosaurs at the end of the Cretaceous, he added.
The deep-seated squid from 30 million years ago helps connect recent history with the deep past, Košťák said. He and his colleagues are now trying to create similar connections to squid, a group of cute, color-changing squid whose origins are similarly dark.
Originally published on WordsSideKick.com.