New research led by scientists at the American Museum of Natural History and Yale shows that the earliest ancestors of the group of animals that includes octopuses and vampire squids had not eight but 10 arms .
The study, published in the journal Nature Communications , describes a new species of vampire based on a fossil that is 328 million years old and therefore predates the dinosaurs , which had not been previously described. The discovery supposes to go back the age of the animal group in almost 82 million years.
“This is the first and only known vampire to possess 10 functional appendages ,” said lead author Christopher Whalen, a postdoctoral researcher in the Museum’s Division of Paleontology and a National Science Foundation postdoctoral fellow in the Department of Earth and Planetary Sciences. from Yale.
And who are the vampires? Vampiropods are soft-bodied cephalopods characterized by having eight arms and an internalized chitinous shell or fin supports. Since they do not have hard structures, they are not well represented in the fossil record. The fossil object of this study is exceptionally well preserved and belongs to the collections of the Royal Ontario Museum, to which it was donated in 1988. It was found in the state of Montana, in the United States.
Whalen and study co-author Neil Landman, curator emeritus in the Museum’s Division of Paleontology, identified the fossil specimen as an entirely new genus and species dating to about 328 million years, making it the oldest vampire known and extends the fossil record of the group by about 82 million years. In the new study, they also describe their 10 arms, all with corresponding suckers, corroborating previous scientific arguments that the common ancestor of vampires also had 10 arms.
“Arm count is one of the defining characteristics of the 10-arm line of squid and cuttlefish ( Decabrachia ) from the eight-arm line of octopus and vampire squid ( Vampyropoda ). We’ve long known that octopuses get all eight arms thanks to the removal of the two filaments in the vampire squid, and that these filaments are vestigial arms,” Whalen said. “However, all previously reported fossil vampiropods with appendages only have 8 arms, so this fossil is possibly the first confirmation of the idea that all cephalopods ancestrally possessed 10 arms .”
Two of the arms of the cephalopod studied seem to have been elongated in relation to the other eight, and its torpedo-shaped body is reminiscent of modern squid.
The fossil has been named Syllipsimopodi bideni . The name of the genus derives from the Greek word “syllípsimos”, which means “prehensile”, and “pódi”, which means “foot”, because it is the oldest known cephalopod that has developed suckers, which allow the arms, which are modifications of the foot of molluscs, to better grasp prey and other objects. The chosen species name, bideni , is a choice in honor of the current President of the United States, Joe Biden.
” Syllipsimopodi may have occupied a niche more similar to living squid, a mid-level aquatic predator,” Landman said. “It is not inconceivable that it could have used its sucker-laden arms to pry small ammonoids from their shells or venture further inland to prey on brachiopods, bivalves, or other shell-bearing marine animals.”
Based on age, characters, and phylogenetic position, the fossil challenges prevailing arguments about the origins of vampiropods, and the authors propose a new model for the evolution of coleoids (cephalopods with internal shells).
Referencia: Whalen, Christopher D. Et al. 2022. Fossil coleoid cephalopod from the Mississippian Bear Gulch Lagerstätte sheds light on early vampyropod evolution. Nature Communications. https://doi.org/10.1038/s41467-022-28333-5
