Death in the wild is often brutal and violent. But for one small, birdlike dinosaur in the late Cretaceous Period, the end of its life was relatively peaceful \u2014 it curled up to take a nap and never woke up. <\/p>\n
That\u2019s what scientists have interpreted from the pose of the dinosaur\u2019s fossil skeleton. With the creature\u2019s head tucked over its limbs and tail snugly wrapped around its body, its cozy posture resembled those of modern birds at rest, hinting that these dinosaurs didn\u2019t just look like birds \u2014 they may have behaved like them, too. <\/p>\n
Paleontologists excavated the dinosaur\u2019s skull and nearly complete skeleton in the Gobi Desert at the Barun Goyot Formation in Mongolia, and most of the bones were still arranged in the animal\u2019s original death pose, researchers reported Wednesday in the journal PLOS One. <\/p>\n
The animal\u2019s long neck wrapped around the right side of its trunk, and its head was tucked close to its side, resting atop the right knee. The hind limbs were folded underneath it, and most of the tail curved around the body\u2019s left side. <\/p>\n
The study authors identified it as an alvarezsaurid, a type of small theropod (bipedal meat-eating dinosaur) with a long tail and legs and short front limbs. Alvarezsaurids are part of a larger dinosaur group called maniraptorans, which includes birds and birdlike dinosaurs that were their closest relatives. <\/p>\n
The small alvarezsaur\u2019s posture emulated that of two other dinosaur fossils found in Mongolia that were also curled up in birdlike sleeping poses: Sinornithoides youngi and Mei long. Those two are troodontids, another type of dinosaur in the maniraptoran group, and one that\u2019s more closely related to birds than alvarezsaurs were. <\/p>\n
The new fossil suggests that this sleeping behavior may have been more common than expected among the non-avian relatives of the earliest birds, the researchers reported. <\/p>\n
\u201cWe\u2019ve all seen ducks sleeping with their heads tucked under their wings. And then you see this little dinosaur with the exact same sleeping posture,\u201d said paleontologist Dr. Jingmai O\u2019Connor, associate curator of fossil reptiles at the Field Museum of Natural History in Chicago. <\/p>\n
The scientists who examined the fossil determined it was a species new to science and gave it a fierce name: Jaculinykus yaruui. The genus name comes from Jaculus, a mythical dragon, and onykus, which means claw in ancient Greek, while its species name originates from yaruu, the Mongolian word for hasty or speedy. <\/p>\n
Jaculinykus yaruui lived around 70 million years ago toward the end of the Cretaceous Period (about 145 million to 66 million years ago) and would have measured just over 3 feet (1 meter) long from nose to tail tip, said lead study author and paleontologist Kohta Kubo, a doctoral candidate in the Paleobiology Research Group at Hokkaido University in Japan. <\/p>\n
Jaculinykus yaruui\u2019s closest relative is a tiny alvarezsaurid named Shuvuuia deserti, Kubo said. Among the features that set it apart are the shape of its nostrils, the attachment of jaw muscles in the skull, and the shapes of its limb bones. <\/p>\n
\u201cIt\u2019s a nice specimen, and it\u2019s always exciting to have new dinosaur diversity, especially in the alvarezsaurids,\u201d O\u2019Connor said. <\/p>\n
Alvarezsaurids aren\u2019t the best-known dinosaur group, but they have long fascinated scientists with their drastically shortened forearms and hands, which in some species terminate in a single massive finger sprouting a claw like a spike. <\/p>\n
\u201cThese types of fossils that are so well-preserved that they record behaviors are incredibly rare,\u201d O\u2019Connor said. \u201cIt\u2019s great to have some additional evidence that definitely shows that this sleeping posture was more widespread.\u201d <\/p>\n
In modern birds, such behavior helps them to conserve body heat; it likely served a similar purpose for maniraptoran dinosaurs that also curled up at bedtime, according to the study. Over the course of their evolution, alvarezsaurs shrank in size. This \u201cdrastic miniaturization\u201d may have led the non-avian dinosaurs to adopt the same thermoregulatory strategy used by their avian cousins, Kobu said. <\/p>\n
What\u2019s more, sleepy little Jaculinykus yaruui \u201chighlights that this avian-like thermoregulatory behavior evolved prior to the origin of powered flight,\u201d he added. \u201cJaculinykus is an important example that alvarezsaurids possess more similarities with living birds \u2014 not only in osteological features but also behavioral traits.\u201d <\/p>\n
Mindy Weisberger is a science writer and media producer whose work has appeared in Live Science, Scientific American and How It Works magazine.<\/em> <\/p>\n\n Death in the wild is often brutal and violent. But for one small, birdlike dinosaur in the late Cretaceous Period, the end of its life was relatively peaceful \u2014 it curled up to take a nap and never woke up. That\u2019s what scientists have interpreted from the pose of the dinosaur\u2019s fossil skeleton. With the <\/p>\n","protected":false},"author":0,"featured_media":11866,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23],"tags":[],"class_list":{"0":"post-11865","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-world"},"_links":{"self":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts\/11865","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/comments?post=11865"}],"version-history":[{"count":0,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/posts\/11865\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/media\/11866"}],"wp:attachment":[{"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/media?parent=11865"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/categories?post=11865"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/shareperformanceinsight.com\/index.php\/wp-json\/wp\/v2\/tags?post=11865"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}