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Thread: Interesting fossilized skeleton of mammal from the Age of the Dinosaurs uncovered

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    Evolution is God's ID rogue06's Avatar
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    Interesting fossilized skeleton of mammal from the Age of the Dinosaurs uncovered

    A bit of hyperbole in its description, but it certainly is different

    Source: Ancient 'crazy beast' from Madagascar had mismatched body and teeth from 'outer space'


    qE5FfRLViCvfwSp8UfT4e5-650-80.jpg
    This life-like reconstruction of Adalatherium hui from the late Cretaceous of
    Madagascar shows off the creature’s weird-looking body and plentiful whiskers.

    The oldest complete mammal fossil from the Southern Hemisphere is puzzling scientists with its mismatched body, strange skull holes and teeth that look like they're "from outer space."

    The new fossil, reported today (April 29) in the journal Nature, is the oldest (and only) nearly complete skeleton from an extinct group of mammals known as Gondwanatherians. This mysterious bunch lived alongside the dinosaurs on the southern supercontinent of Gondwana. They're known from a smattering of teeth and bone fragments, a single skull and the new, remarkable skeleton of an animal whose discoverers have dubbed the "crazy beast."

    The fossil is from northwestern Madagascar and dates back 66 million years, to the end of the Cretaceous period. Madagascar was already an island at the time, having drifted away from Africa by 88 million years ago, and the animals that lived there were completely bizarre, said David Krause, the senior curator of vertebrate paleontology at the Denver Museum of Nature & Science, who led the new research.

    ...

    It took months to remove the possum-size skeleton from the rock, but the results are unprecedented. Most of the skeleton is preserved, except for part of the back of the skull and some pieces of the hips. Never before has so much of a Gondwanatherian been found. The previous best-preserved specimen was a skull of a large-eyed herbivore reported in the journal Nature in 2014 by Krause and his team. The researchers attribute the pristine preservation of the newfound A. hui to a mudflow that suddenly buried the creature. Such mudflows seem to have occurred seasonally in Madagascar at the time.

    "It was probably buried alive by one of these mudflows," Rogers said.

    The name of the mammal comes from the Malagasy word for "crazy" and the Latinized Greek for "beast." The species name hui is in honor of Yaoming Hu, a vertebrate paleontologist who died in 2008.

    Weird Mammal

    A. hui probably looked a bit like a badger, but it was like no mammal alive today. Most early mammals had sprawled-out legs, a bit like those of today's crocodiles. A. hui's back legs were sprawled out, too. But its front legs were aligned under its body, like a cat's or a dog's.

    This alignment is so unheard-of that the researchers studying A. hui have no idea how the creature would have moved. It had strong back muscles that indicate that its back probably wiggled side-to-side as it walked, said study co-researcher Simone Hoffmann, an anatomist at the New York Institute of Technology.

    "It probably means it walked really differently from anything that lived in the past or that is living today," Hoffmann told reporters.

    A. hui's teeth were similarly confounding, said Krause, who compared them to something from outer space. Their bumps and ridges match no known teeth patterns in any extinct or living mammals. The animal had prominent incisors, something like a rodent, but the incisors are strange, with enamel only on the cheek side. Still, Krause said, the teeth suggest the animal was likely an herbivore that used its incisors for gnawing.

    The skull of A. hui was weirdly pockmarked with holes. Some of these were clearly openings to allow nerves and blood vessels to pass to the snout. The number of these holes was indicative of a very sensitive snout, Krause said, leading the researchers to suspect that Adalatherium's nose was well-whiskered. The animal's strong claws suggest it was a digger, so perhaps these nerves detected rich sensations in dark underground burrows, Krause speculated.

    Another of the holes, a large opening on top of the snout, is a complete mystery, Krause said. Nothing like it has been seen on a mammal skull before. It was probably covered with cartilage, but researchers don't know why it existed.

    Z272w3igsjucB4HM7LnB85-650-80.jpg
    A mounted cast skeleton of Adalatherium hui. This early mammal would have
    wiggled from side to side as it moved during the late Cretaceous period

    Evolution of mammals

    No living descendants of A. hui survive today. In fact, none of today's mammals on Madagascar are related to the Cretaceous mammals found so far on the island, Krause said. This suggests that all of Madagascar's mammals died off in the end-Cretaceous asteroid impact that also destroyed the non-avian dinosaurs. Today's Madagascar mammals probably descended from animals that later floated on giant rafts of vegetation from coastal Africa, Krause said.

    But the discovery of Adalatherium suggests that even when the dinosaurs roamed, islands led to weird evolution. Scientists have long known that species isolated on islands tend to evolve in strange ways. Islands might spawn giants like the fearsome Komodo dragon, for example, or miniatures like the now-extinct pygmy mammoths that once roamed Crete. The Cretaceous weirdos of Madagascar suggest something similar was going on. A. hui, for example, weighed around 6.8 lbs. (3.1 kilograms), 100 times heavier than the mouse-sized mammals that make up most of the earliest mammals on Earth, Krause said. It is the third-largest mammal ever found from the Southern Hemisphere Mesozoic (the era spanning from 250 million to 65 million years ago).

    Researchers are still working to understand A. hui's manner of movement and weird adaptations. They also have plenty more fossils from Madagascar to work through. Since 1993, the team has excavated more than 20,000 fossil specimens from the region. Highlighting the rarity of a find like A. hui, only 12 of those are mammal specimens.



    Source

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    The full paper with abstract is available at Skeleton of a Cretaceous mammal from Madagascar reflects long-term insularity. Here is the abstract:

    The fossil record of mammaliaforms (mammals and their closest relatives) of the Mesozoic era from the southern supercontinent Gondwana is far less extensive than that from its northern counterpart, Laurasia. Among Mesozoic mammaliaforms, Gondwanatheria is one of the most poorly known clades, previously represented by only a single cranium and isolated jaws and teeth. As a result, the anatomy, palaeobiology and phylogenetic relationships of gondwanatherians remain unclear. Here we report the discovery of an articulated and very well-preserved skeleton of a gondwanatherian of the latest age (72.1–66 million years ago) of the Cretaceous period from Madagascar that we assign to a new genus and species, Adalatherium hui. To our knowledge, the specimen is the most complete skeleton of a Gondwanan Mesozoic mammaliaform that has been found, and includes the only postcranial material and ascending ramus of the dentary known for any gondwanatherian. A phylogenetic analysis including the new taxon recovers Gondwanatheria as the sister group to Multituberculata. The skeleton, which represents one of the largest of the Gondwanan Mesozoic mammaliaforms, is particularly notable for exhibiting many unique features in combination with features that are convergent on those of therian mammals. This uniqueness is consistent with a lineage history for A.hui of isolation on Madagascar for more than 20 million years.


    One more picture:


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  2. Amen Juvenal amen'd this post.
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    tWebber shunyadragon's Avatar
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    Interesting discovery that reflects the diversity of mammals before the extinction of the dinosaurs. They were not just mouse sized critters running around and hiding.
    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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    Evolution is God's ID rogue06's Avatar
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    Quote Originally Posted by shunyadragon View Post
    Interesting discovery that reflects the diversity of mammals before the extinction of the dinosaurs. They were not just mouse sized critters running around and hiding.
    We've known for awhile now that some even preyed on dinosaurs. The remains of a badger-sized Repenomamus giganticus was found with parts of a juvenile Psittacosaurus (an early ceratopsian dinosaur, the most famous of which was Triceratops) in its stomach.


    I'm always still in trouble again

    "You're by far the worst poster on TWeb" and "TWeb's biggest liar" --starlight (the guy who says Stalin was a right-winger)
    "Of course, human life begins at fertilization that’s not the argument." --Tassman

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    tWebber shunyadragon's Avatar
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    Quote Originally Posted by rogue06 View Post
    We've known for awhile now that some even preyed on dinosaurs. The remains of a badger-sized Repenomamus giganticus was found with parts of a juvenile Psittacosaurus (an early ceratopsian dinosaur, the most famous of which was Triceratops) in its stomach.

    Thank you! Good photos
    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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