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Dog-size Jakapil kaniukura dinosaur discovered in Argentina

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A species of dinosaur recently discovered in Argentina had an armored back, distinctive jaw and tiny arms — and was roughly the size of a dog.

Fossils dated to the humid Late Cretaceous period — almost 100 million years ago — suggest that the Jakapil kaniukura walked on two feet, unlike most other dinosaurs in its family. The plant-eating creature had armored plates to protect it from predators and weighed about as much as a Boston terrier, according to research published last week in the journal Scientific Reports.

The jakapil discovery sheds light on a previously unknown lineage of dinosaurs from the thyreophora family, which includes the much larger stegosaurus, in the Southern Hemisphere.

“For Argentines, Jakapil completes, in a vast succession of discoveries, the missing letter for our dinosaur alphabet, and we can, for the first time, show an alphabet of dinosaurs that lived in Argentina,” researcher Sebastián Apesteguía said in a statement.

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The jakapil’s name comes from the crest on the lower part of the dinosaur’s jaw, the function of which is unknown. “Kaniukura” means “crest of stone” in the language of the Indigenous Mapuche people, the researchers said.

The jakapil’s teeth were also unusual. While most herbivorous dinosaurs had leaf-shaped teeth that were similar on both jaws, the newly discovered dinosaur’s teeth were shaped differently on each jaw. Its teeth also appear worn down, which the researchers said indicates that it processed food more efficiently than other members of its family.

The path to reconstructing the dinosaur’s body began in 2012, when Apesteguía toured La Buitrera Paleontological Area — where other dinosaurs have been discovered — and found two small bones that he could not identify. Two years later, he and other scientists found a skeleton with unusual teeth and a block-like jaw.

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A researcher recognized the fossil as a type of armored dinosaur and continued collecting bones until 2020, when they finished rebuilding the structure of the species. The desert region is uninhabitable for many species, so it tends to have fossils of few animals, Apesteguía said in the statement.

“Jakapil is a small and very rare dinosaur, and, obviously, he liked to travel through desert environments,” Apesteguía said.

The scientists shared a video reconstruction of the species on Twitter. In it, two jakapils trod along a desert landscape, stretch upward and emit soft guttural growls.

Dinosaur discoveries are somewhat common; paleontologists identify dozens of species every year. In 2021, Australian scientists announced the discovery of a dinosaur the size of a basketball court.

But many dinosaurs would not have been fossilized, which means that we will almost certainly never discover all the kinds that existed, Gizmodo reported. The fact that a dinosaur needs to have died in just the right circumstances for its remains to be findable makes every discovery a notable event.

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A newly-discovered dog-size dinosaur was covered in armor and had tiny arms

Argentina has recently become a locus for weird dinosaur fossils. Last year, paleontologists in the country found dinosaur bones so big, they believe they may have belonged to the largest land animal of all time. Now they’ve found something much smaller, and perhaps odder still: a dinosaur that is only as big as a dog — but is covered in so much plated armor that it sort of resembles an oversized armadillo.

The newly-discovered dinosaur has been given the taxonomic name Jakapil kaniukura, as paleontologists detailed in a recent article in the journal Scientific Reports. Jakapil kaniukura lived roughly 97 to 94 million years ago; walked with two legs instead of four; had tiny arms which resembled chicken wings; possessed a short beak used to deliver sharp bites; and was equipped with a unique ring of armor around its neck.

“The neck armor of this dinosaur is unique, and it protected that delicate area from predator attacks,” explained one of the study’s co-authors, Sebastián Apesteguía. “The bones that are preserved from the arms show us that they were tiny,” which is unusual for dinosaurs from the group to which Jakapil kaniukura belonged — known as thyreophorans. Thyreophorans are defined as the group of “armored” dinosaurs, which are characterized by thick plates of bony armor that lined their bodies. Notorious thyreophorans include stegosaurus, which had a series of mohawk-like spikes running down its back and to its tail; and anklyosaurus, which resembled a huge version of the extant horned toad, albeit with a tail shaped like a mace. 

If Jakapil kaniukura sounds like the stuff of nightmares, rest easy: Even if it weren’t extinct, it would almost certainly pose no threat to you. Like its thyreophora relatives the stegosaurus and the ankylosaurus, Jakapil kaniukura is believe to have been a herbivore, meaning that it ate plants instead of meat. Even if it had been a carnivore, however, Jakapil kaniukura was not very big — indeed, roughly only as long as a retriever-size dog (less than 5 feet).


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The discovery of Jakapil kaniukura is also scientifically significant for a number of reasons. As the paper’s authors explain, the diminutive dinosaur has some “unusual anatomical features” that include many traits not usually associated with the thyreophorans from that period. It is also the first definitive thyreophoran species from the Argentinian Patagonia” — which is remarkably southward for a thyreophoran, given how they had previously only been discovered in the northern hemisphere. This is, in fact, the thyreophoran known to have been unearthed anywhere on the southern side of the equator. 

In addition, while most thyreophoran walked on four legs, Jakapil kaniukura “seems to show a bipedal stance,” researchers write — meaning that it only walked on two legs, much like humans. The dinosaur is also noteworthy because its discovery in the southern hemisphere hints that thyreophorans were much more widely distributed than previously believed. They also survived until the Late Cretaceous in South America, which was between 100.5 million and 66 million years ago — right before the famous mass extinction of the dinosaurs.

The dinosaur’s scientific name is also noteworthy, as it utilizes indigenous languages. The word “Jakapil” is derived from a term that means “shield bearer” in the Puelchean or northern Tehuelchean Indigenous language of Argentina. Similarly the word “Kanikura” is derived from the Indigenous Mapudungun words for “crest” and “stone.”

Paleontologists are also pleased to have received a surprisingly comprehensive fossil of the dinosaur, as they were able to recover some of the spikes that ran along the animal’s back, an almost intact lower jaw, as well as its leg and arm bones and neck, back and tail vertebrae.

The scientists also posted a video online showing a computer-simulated reconstruction of Jakapil kaniukura as presented by Chilean palaeoartist and palaeontology student at the Río Negro National University Gabriel Díaz Yantén.



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Ancient dog-size sea scorpion unearthed in China

A 3.3 foot-long (1 meter) sea scorpion prowled the seas of what is now China some 435 million years ago, using its giant, spiny arms to ensnare prey.

Archaeologists recently discovered the remains of this scorpion (Terropterus xiushanensis), which was a eurypterid — an ancient arthropod closely related to modern arachnids and horseshoe crabs, the researchers wrote in the Nov. 30 issue of the journal Science Bulletin.

Related: See images of a primordial sea scorpion

Its barbed limbs “were presumably used for prey-capture, and analogies can be drawn with the ‘catching basket’ formed by the spiny pedipalps of whip spiders … among the arachnids,” study co-author Bo Wang from the Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment at the Chinese Academy of Sciences, and colleagues wrote in the new study. Pedipalps are the front-most appendages of arachnids. Usually dedicated to transferring sperm from male spiders to female mates, in some arachnids, such as whip spiders, pedipalps have become adapted to snatch prey.

The fossilized appendages of the sea scorpion, accompanied by an artist’s recreation. (Image credit: Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences)

The fearsome beastie lived during the Silurian period, between approximately 443.8 million and 419.2 million years ago. At this time, the scorpions would have been the apex predators in their underwater stalking grounds, pouncing on unsuspecting fish and mollusks; scooping them up in their pedipalps; and shoving them into their mouths. 

Eurypterids came in many sizes, with the smallest about the size of a human hand and the largest as big as an adult human, Live Science previously reported. The newly described species, T. xiushanensis, is the first discovered belonging to the family Mixopteriade in 80 years, the researchers say.

“Our knowledge of these bizarre animals is limited to only four species in two genera described 80 years ago: Mixopterus kiaeri from Norway, Mixopterus multispinosus from New York, Mixopterus simonsoni from Estonia and Lanarkopterus dolichoschelus from Scotland,” Wang and colleagues wrote in the study.

T. xiushanensis is also the first mixtopterid to be discovered in what would have been the supercontinent of Gondwana, which formed after the larger supercontinent Pangaea cracked in two.

“Our first Gondwanan mixopterid — along with other eurypterids from China and some undescribed specimens — suggests an under-collecting bias in this group,” the researchers wrote in their study. “Future work, especially in Asia, may reveal a more cosmopolitan distribution of mixopterids and perhaps other groups of eurypterids.”

Originally published in Live Science.

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