MEANING: Sand dragon
PERIOD: Late Cretaceous
CONTINENT: Asia
Harenadraco is a small troodontid dinosaur from the Late Cretaceous of what is now Mongolia. It was small and lightly built, typical for troodontids, but Harenadraco had uniquely slender legs. This adaptation, which allowed for skilled running abilities, implies that it could have hunted highly agile prey. Harenadraco was about 1 m in length, and most likely covered in feathers, which further aided in its agility while running and hunting.
Abstract from paper: Among non-avian dinosaurs, troodontids are relatively rare but diverse. The Nemegt Basin in the Mongolian Gobi Desert, which incorporates three of the most fossiliferous beds in the world, is one such region with high troodontid diversity and has also produced eight troodontid taxa until now. The diversity of troodontids is biased towards the two formations, Nemegt and Djadochta. Despite its rich vertebrate fossil record, no troodontids have been described from the Baruungoyot Formation. This faunal absence is perplexing as the Baruungoyot Formation has often been considered intermediate between the other two units in stratigraphy and paleoenvironment, but there are no definite troodontid materials that could fill this ‘gap.’ Here, we report a new troodontid, Harenadraco prima gen. et sp. nov., from the Baruungoyot Formation in Hermiin Tsav, Mongolia. It is represented by an incomplete skeleton that mainly consists of partially articulated left hind limb elements. Harenadraco is small and lightly built like other troodontids, but its tarsometatarsus exhibits extreme slenderness comparable only to Philovenator among cursorial non-avian maniraptorans. It also implies high cursoriality that could be an adaptation of Harenadraco to its environment where potential prey animals like mammals and predators such as eudromaeosaurs were likely to be agile. The discovery of Harenadraco confirms the presence of troodontids in all three formations in the Nemegt Basin.
Harenadraco is from the Cretaceous. The Cretaceous is a geological period that lasted from about 145 to 66 million years ago. It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin creta, "chalk", which is abundant in the latter half of the period.
The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct flora and fauna, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth by the end of the Cretaceous, coincident with the decline and extinction of previously widespread gymnosperm groups.
The Cretaceous (along with the Mesozoic) ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary (K–Pg boundary), a geologic signature associated with the mass extinction that lies between the Mesozoic and Cenozoic Eras.
Harenadraco is a troodontid. Troodontidae is a family of theropod dinosaurs which are closely related to birds. Many genera are known only from teeth, and this has led to much debate and reclassification over the course of the history of paleontology. The oldest definitive troodontid is known from the Late Jurassic of Wyoming. Over the Cretaceous, they radiated throughout western North America, Asia, and Europe, suggesting a mostly Laurasian distribution.
Troodontids are small, bird-like, gracile maniraptorans. They have unique skull features, such as large numbers of closely spaced teeth in the lower jaw. They are also equipped with sickle-claws and raptorial hands, similar to the closely related dromaeosaurs. Troodontids also had unusually large brains and eyes, suggesting that they were behaviourally advanced and had keen senses.
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