[ad_1]
The vampire squid has been hiding in the dark corners of the ocean for 30 million years, a new analysis of a long-lost fossil find.
Modern vampire squid (Hell Vampyroteuthis) can thrive in deep, oxygen-poor ocean waters, unlike many other squid species that require shallower habitat along continental shelves. However, few fossil ancestors of today’s vampire squid survive, so scientists are not sure when these elusive cephalopods developed the ability to live on low oxygen.
New fossil analysis helps close a 120-million-year gap in vampire squid evolution, revealing that the ancestors of modern vampire squids already lived in deep oceans during the Oligocene, 23 to 34 million ago million years ago. These squids likely evolved adaptations to low-oxygen water during the Jurassic, said study co-author Martin Košťák, a paleontologist at Charles University in Prague.
Related: Hell vampire squid pictures
“Living in stable, low oxygen levels brings evolutionary advantages – low predation pressure and less competition,” Košťák wrote in an email to Live Science.
A rediscovered fossil
Košťák and his colleagues found the long-lost fossil in the collections of the Hungarian Natural History Museum in 2019 while searching for fossils of cuttlefish ancestors. The fossil was originally discovered in 1942 by Hungarian paleontologist Miklós Kretzoi, who identified it as a squid dating back around 30 million years and named it Necroteuthis hungarica. More recent researchers, however, have argued that it was an ancestor of the cuttlefish. In 1956, during the Hungarian Revolution, the museum was burnt down and the fossil was reportedly destroyed. The rediscovery was a happy surprise.
“It was a great moment,” Košťák said of the rediscovery, “to see something that had previously suggested being lost permanently.”
Košťák and his colleagues studied the fossil by scanning electron microscopy and performed a geochemical analysis. They first discovered that Kretzoi’s initial identification was correct: the fossil came from a squid, not a cuttlefish ancestor. The animal’s internal shell, or gladius, which forms the backbone of its body, was about 15 centimeters long, suggesting that the squid reached about 13.7 inches (35 cm) long with the arms included. . It’s just a bit bigger than the modern vampire squid, which grows to around 11 inches in total body length.
The sediments surrounding the fossil showed no trace of microfossils often found on the seabed, suggesting that the squid did not live in shallow water. The researchers also analyzed the levels of variation carbon in the sediment and found that the sediment likely originated from an anoxic or low oxygen environment.
These conditions are characteristic of the deep ocean floor. By observing the rock layers above where the fossil was deposited outside of what is now Budapest, the researchers were also able to show that the squid likely could not have survived in lesser seas. deep at the time. Deposits from the shallow sea have shown very high levels of a particular plankton that flourishes in environments low in salt and high in nutrients – conditions that modern vampire squids cannot tolerate.
(Researchers at the Monterey Bay Research Institute have found that when they hide in the deep sea, these squids don’t behave like the nightmarish predators their name suggests; instead they wait in their dark habitats for crumbs of organic matter to float around. Then they capture these lumps with suction cups covered in mucus, MBARI found.)
Adapt to the depths
The new research, published Thursday, February 18 in the journal Communications biology, shows how the ancestors of the vampire squid learned to live where other squid couldn’t. Looking deeper into the fossil record, the oldest fossils of this squid group are found in the Jurassic period, between 201 million and 174 million years ago, Košťák said, and they are usually found in anoxic sediments.
“The main difference is that these oxygen depletion conditions were established on the plateau, [a] “Shallow water environment,” he said. “This means that the ancestors were inhabitants of the shallow water surroundings, but they were already adapted to the low oxygen conditions.
There is a gap in the fossil record from the Lower Cretaceous Period, which began around 145 million years ago. The squid may have already moved to the deeper ocean by this point, said Košťák, primed by their experiences with anoxic conditions in the Jurassic. This deep-sea lifestyle could explain why the squid survived the crisis that killed non-avian dinosaurs in the late Cretaceous, he added.
The deep-living squid 30 million years ago helps connect recent history to the deep past, Košťák said. He and his colleagues are now trying to make similar connections for the cuttlefish, a group of cute, color-changing cephalopods whose origins are just as murky.
Originally posted on Live Science.
[ad_2]
Source link