Uncovered Fossil Uncovers Shared Behavior between Dinosaurs and Birds
Newly discovered dinosaur fossil reveals remarkable birdlike sleeping behavior, shedding light on a potential widespread occurrence of this behavior among early avian relatives The nearly intact specimen offers intriguing insights into the fascinating behaviors of dinosaurs (350 characters)
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In the wild, mortality is often accompanied by brutality and violence. However, unlike the norm, one diminutive dinosaur resembling a bird experienced a tranquil demise during the late Cretaceous Period. It peacefully nestled into slumber and never roused again.
This is the interpretation that scientists have derived from studying the fossilized skeleton of the dinosaur. The dinosaur's head is curled over its limbs and its tail is wrapped tightly around its body, resulting in a comfortable posture reminiscent of birds at rest. This suggests that these dinosaurs not only had a bird-like appearance, but they may have also exhibited similar behavior.
Life reconstruction of Fujianvenator prodigiosus with other aquatic and semiaquatic vertebrates from a new Jurassic terrestrial fauna.
Chuang Zhao
Researchers reported in the journal PLOS One that paleontologists discovered the skull and nearly complete skeleton of a bird-like dinosaur in the Gobi Desert at the Barun Goyot Formation in Mongolia. Interestingly, most of the bones were found in the dinosaur's original death pose.
The animal's neck extended around the right side of its body, while its head was tucked beside its right knee. Its hind legs were folded beneath it, and the majority of its tail curved along the left side of its body.
The researchers classified it as an alvarezsaurid, a species of small theropod (bipedal carnivorous dinosaur) characterized by a lengthy tail and legs, and short front limbs. Alvarezsaurids belong to the maniraptoran dinosaur group, which also encompasses birds and birdlike dinosaurs, making them their closest relatives.
The posture of the small alvarezsaurs resembled that of two other dinosaur fossils discovered in Mongolia, namely Sinornithoides youngi and Mei long, both of which were also curled up in birdlike sleeping positions. Unlike alvarezsaurs, these two fossils belong to the troodontids, a dinosaur group within maniraptorans that is more closely related to birds.
Jaculinykus yaruui existed approximately 70 million years in the past. (A) Depicted is a photograph showcasing the fossilized remains discovered in Mongolia's Gobi Desert. (B) Complementary to the image, a diagram provides an explanation of the skeletal components, with the skull highlighted in green and the pectoral girdle and forelimbs depicted in red. (C) Additionally, a reconstructed representation of the dinosaur is included, with areas in gray indicating the presence of missing portions.
The researchers reported that the new fossil indicates that this sleeping behavior may have been more widespread than anticipated among the non-avian relatives of the earliest birds.
"Observing ducks sleeping with their heads tucked under their wings is a familiar sight. It is intriguing to discover a small dinosaur exhibiting the exact same sleeping posture," noted Dr. Jingmai OConnor, paleontologist and associate curator of fossil reptiles at the Field Museum of Natural History in Chicago.
"This fossil specimen is undeniably a concrete manifestation of behaviors that set it apart from other bird species. Consequently, it is no longer accurate to deem this feature as distinctive solely to avian creatures," explained O'Connor, a non-participant of the study, in an interview with CNN.
Nearly complete fossil specimen
The fossil was analyzed by scientists who concluded that it belonged to a previously unknown species. They named it Jaculinykus yaruui, taking inspiration from the mythical dragon Jaculus and the Greek word onykus, which signifies "claw". The species name, yaruui, is derived from the Mongolian term for "hasty" or "speedy".
Following the Chicxulub impact several weeks or months earlier, the surviving non-avian dinosaurs are now struggling to survive. The intense heat caused by the falling debris initially resulted in a rapid rise in temperature, causing the death of many animals within a matter of days. As time passes, the Earth's atmosphere becomes heavily polluted with soot, dust, and other substances, blocking out the Sun and causing a significant drop in global temperatures. Due to the lack of sunlight for photosynthesis, plant life rapidly declines worldwide, leading to the collapse of the entire food chain. In this desolate setting, a single wounded and severely malnourished Dakotaraptor surveys the remnants of her territory, which will eventually be famous as Hell Creek, 66 million years later.
The asteroid that led to the extinction of the dinosaurs had a significant impact on a crucial factor for life on Earth, according to scientists. Living approximately 70 million years ago near the conclusion of the Cretaceous Period, Jaculinykus yaruui was around 1 meter long and was identified by Kohta Kubo, a paleontologist and the main researcher of the study conducted by the Paleobiology Research Group at Hokkaido University in Japan.
"This specimen, initially classified as a partial skeleton upon discovery, has now been meticulously prepared, revealing a remarkably well-preserved and fully articulated skeleton that accurately depicts its original upright posture," Kubo informed CNN via email. "Notably, this represents the first definitive evidence of such a posture in both alvarezsaurs and early branching maniraptoran dinosaurs."
According to Kubo, Jaculinykus yaruuis shares its closest relationship with a small alvarezsaurid known as Shuvuuia deserti. However, several distinguishing features differentiate it from its relative, including the unique shape of its nostrils, the attachment of jaw muscles within the skull, and the overall structure of its limb bones.
"Its a nice specimen, and its always exciting to have new dinosaur diversity, especially in the alvarezsaurids," OConnor said.
Birdlike behaviors in dinosaurs
Alvarezsaurids, although not widely recognized, have intrigued scientists due to their significantly reduced forelimbs and hands. In certain species, these limbs end in a single prominent finger adorned with a claw resembling a spike. O'Connor expressed enthusiasm about the rarity of well-preserved fossils that provide insight into the behaviors of these dinosaurs. The additional evidence confirms that the sleeping posture observed is more prevalent among alvarezsaurids.
Ian Berry/CNN
Giant flying carnivorous heads and other ancient sky-dwelling creatures
The study suggests that similar to modern birds, maniraptoran dinosaurs, including alvarezsaurs, curled up at bedtime to conserve body heat. As these dinosaurs evolved, they gradually became smaller in size. This substantial decrease in size may have prompted non-avian dinosaurs to adopt the same thermoregulatory strategy as their avian relatives, Kobu stated.
Moreover, the discovery of the sleepy little Jaculinykus yaruui sheds light on the fact that this avian-like thermoregulatory behavior existed before the development of powered flight remarks the scientist. "Jaculinykus serves as a significant illustration that alvarezsaurids not only share osteological features but also behavioral traits with modern birds," he further explains.
Mindy Weisberger, a science writer and media producer, has contributed her expertise to various renowned publications like Live Science, Scientific American, and How It Works magazine.
