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10-limbed Octopus ancestor uncovered

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  • 10-limbed Octopus ancestor uncovered

    In what was once a shallow bay of what is now central Montana, in the Carboniferous (Mississippian) Bear Gulch Lagerstätte, what is now recognized as the oldest ancestors of vampyropods, a group that includes vampire squids and octopuses. The exceptionally well preserved specimen lived between 325 to 328 mya which pushes back the earliest evidence of the group by nearly 82 million years.

    Like so many fossil discoveries, it was donated decades ago (1988) to a museum (Royal Ontario Museum in Canada) until it was rediscovered.

    The torpedo-like body of the creature is just under 4¾" (12cm) long and possessed fins and rows of suckers to grasp prey, as well as a triangular pen of hard tissue inside its body for support. But what makes it really interesting is that it also had ten "arms" making it the, as lead author Christopher Whalen, a researcher at the American Museum of Natural History and Yale University, noted, the "first and only known vampyropod to possess ten functional appendages." One of the pair of arms were considerably longer than the others, similar to modern-day squids and cuttlefish, and likely were used to capture prey.

    The researchers named the creature Syllipsimopodi bideni, derived from the Greek words "syllípsimos" for "prehensile" and "podi" for "foot," along with the species name “bideni” after Joe Biden -- who was inaugurated 46th president of the U.S. when the paper was submitted.

    Vampire squids -- which are not squids but close relatives of octopuses -- have eight limbs along with a pair of stringy filaments, thought to be vestigial appendages. The discovery of the ten-limbed Syllipsimopodi bideni supports the contention that all cephalopods originally had ten limbs and that as they evolved over time lost two of them.

    Other researchers have urged caution, noting that this new analysis relies heavily on visual methods leaving open many questions which could be resolved with chemical analyses.


    Source: Oldest-known octopus relative lived 328 million years ago and had 10 arms


    The oldest ancestor of modern octopuses lived 328 million years ago and had 10 arms, according to a new study. Researchers have named the previously unknown species Syllipsimopodi bideni after US President Joe Biden.

    The creature's discovery pushes back the time frame when vampyropods, the group to which cephalopods like octopuses belong, appeared in the ocean by almost 82 million years.

    The study published Tuesday in the journal Nature Communications.

    Vampyropods are known for having eight legs, an internal shell made of chitin and a soft body -- the last of which doesn't show up often in the fossil record because it tends to deteriorate more quickly than hard structures like bone.

    A well-preserved fossil was discovered in Montana's Bear Gulch Limestone formation and donated to Canada's Royal Ontario Museum in 1988. The specimen represents the earliest-known ancient relative of these creatures, a new analysis of the fossil revealed.

    "This is the first and only known vampyropod to possess 10 functional appendages," said study author Christopher Whalen, a postdoctoral researcher in the American Museum of Natural History's Division of Paleontology, in a statement.

    "All previously reported fossil vampyropods preserving the appendages only have eight arms, so this fossil is arguably the first confirmation of the idea that all cephalopods ancestrally possessed ten arms."

    Syllipsimopodi is the best known fossil for understanding how vampyropods originated, as well as helping researchers to trace their evolution, said Whalen, who is also a National Science Foundation postdoctoral fellow in Yale University's Department of Earth & Planetary Sciences.

    It has long been thought by researchers that the vampyropods began with 10 arms and eventually lost two of them over time -- and now, scientists have direct evidence.

    Tiny but mighty


    The detailed fossil clearly shows a creature about 4.7 inches (12 centimeters) long with 10 arms, with the suckers still attached -- an incredibly rare find since these arms were essentially just muscle. Two of those arms seem to be longer than the other eight, and its body was shaped like a torpedo, similar to modern squid. The researchers also found remnants of its ink sac.

    Soft-bodied cephalopods are divided into vampyropods and decabrachians.

    Vampyropods include octopuses and vampire squids, both of which are different from actual squid. Vampire squid basically look like octopuses with a built-in parachute because they have a membrane that stretches between and connects their arms. They also have two structures to help them feed called filaments in addition to their eight arms.

    Meanwhile, decabrachians include modern squids and cuttlefish, which have 10 arms, including 2 tentacles. There are a number of differences that separate cephalopods like squid and octopuses, but the number of arms is one of the most recognizable.

    So why is this fossil considered to be a vampyropod, even though it has 10 arms?

    The team's phylogenetic analysis, which indicates evolutionary relationships, placed the species within the vampyropod side of the evolutionary tree, Whalen said.

    The new species also had several key anatomical traits that mark it as a vampyropod, including the loss of a chambered cephalopod shell used to regulate buoyancy, called a phragmocone, which is seen in existing creatures like nautilus.

    "The age makes the fossil very significant -- it indicates that vampyropods (and by extension decabrachians) are much older than was previously thought (at least 82 million years older)," Whalen said. "It indicates that there is a long interval of time during which fossil vampyropods must have existed but have not yet been found."

    What's in a name


    Syllipsimopodi likely used its longest pair of arms to capture prey and the rest of its shorter arms to hold small creatures and pry them from their shells. It also had fins, which probably helped it maintain stability and swim.

    "Syllipsimopodi may have filled a niche more similar to extant squids, a midlevel aquatic predator," said study coauthor Neil Landman, a curator emeritus in the American Museum of Natural History's Division of Paleontology, in a statement.

    The team was surprised to discover that Syllipsimopodi had a gladius, or the tongue-shaped and semitransparent part of a cephalopod's internal shell.

    "The gladius functions to provide structural support, as a rigid structure that the muscles can pull against, and as an anchor for the fins (the overall function is similar to our bones)," Whalen wrote in an email.

    "A gladius is considered a rather advanced feature in the grand scheme of cephalopod evolution. Today, only squids and their relatives, and vampire squid, have a gladius. Octopods have reduced it to a fin support or stylets, which are small, hard, bar-shaped structures."

    The creature's genus name, Syllipsimopodi, is a nod to the Greek word "syllípsimos," meaning "prehensile," and "pódi" for foot because it's the oldest cephalpod discovered so far to have suckers on its arms. And the species name, bideni, is in honor of Biden, who had just been inaugurated when the study was first submitted for publication.

    "I was encouraged by the plans President Biden put forward to counter anthropogenic climate change, and his general sentiment that politicians should listen to scientists," Whalen said.





    Source

    © Copyright Original Source



    Yeah, the picture was upside down in the article too.

    The abstract for Fossil coleoid cephalopod from the Mississippian Bear Gulch Lagerstätte sheds light on early vampyropod evolution is below and the full paper can be read by clicking the hyperlink provided.

    Abstract

    We describe an exceptionally well-preserved vampyropod, Syllipsimopodi bideni gen. et sp. nov., from the Carboniferous (Mississippian) Bear Gulch Lagerstätte of Montana, USA. The specimen possesses a gladius and ten robust arms bearing biserial rows of suckers; it is the only known vampyropod to retain the ancestral ten-arm condition. Syllipsimopodi is the oldest definitive vampyropod and crown coleoid, pushing back the fossil record of this group by ~81.9 million years, corroborating molecular clock estimates. Using a Bayesian tip-dated phylogeny of fossil neocoleoid cephalopods, we demonstrate that Syllipsimopodi is the earliest-diverging known vampyropod. This strongly challenges the common hypothesis that vampyropods descended from a Triassic phragmoteuthid belemnoid. As early as the Mississippian, vampyropods were evidently characterized by the loss of the chambered phragmocone and primordial rostrum—traits retained in belemnoids and many extant decabrachians. A pair of arms may have been elongated, which when combined with the long gladius and terminal fins, indicates that the morphology of the earliest vampyropods superficially resembled extant squids.


    a Schematic drawing of Syllipsimopodi bideni gen. et sp. nov.; teal = gladius, orange = head (including arms), brown = buccal apparatus,
    gray = ink sac, blue = conus, magenta = fin support, patterned yellow = scale-like patches (possible connective tissue remnant).
    b Increased contrast false color image of Syllipsimopodi, holotype ROMIP 64897. Scale = 1 cm. c Artistic reconstruction showing suckers
    Last edited by rogue06; 03-08-2022, 04:48 PM.

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  • #2
    Thank you for the detailed reference!
    Glendower: I can call spirits from the vasty deep.
    Hotspur: Why, so can I, or so can any man;
    But will they come when you do call for them? Shakespeare’s Henry IV, Part 1, Act III:

    go with the flow the river knows . . .

    Frank

    I do not know, therefore everything is in pencil.

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