30-Day Retrosaur Challenge: Day 22

    The appalling Dryptonychus ("tearing claw") was one of the most formidable and rapacious predators of the Late Cretaceous of western North America, from 76-71 million years ago. This specific Tiny Tyrant was one of the larger species of Tiny Tyrant, reaching lengths of up to 16 feet (5 meters) and weighing around 700-800 pounds (0.35-0.4 tons) as an adult, and nearly as tall as the average adult male human being. The holotype fossil specimens of this dreadful predator were initially uncovered in the early 1960s by a small band of amateur paleontologists in the Lance Formation of Wyoming, who discovered a massive bonebed containing the remains of at least 10 or 11 individual Dryptonychus (including 6 adult specimens and several juveniles) and possibly two Duck-Billed Goliaths, indicating that the medium-sized predators were probably cooperatively hunting together as a pack prior to their sudden simultaneous death (perhaps by a mudslide or flash flood). This particular retrosaur was a an exemplary member of the Dryptonychosauria, a vast and pandemic branch of the Tiny Tyrant family tree that are distinguished from others of their kin by the large, sickle-shaped talons located on the second toe of each foot, their relatively-large heads for their body size, and their long, spindling arms with dexterous grasping fingers to grab hold of their unfortunate prey items. The dryptonychosaurians, in addition to the distantly-related struthiotherians, are also unique in the fact that they are among the very few groups that share similar structural similarities to birds, even though they are not the direct ancestors of birds nor are they closely-related to birds themselves. These specific retrosaurs were also a rather imperative part of the "Retrosaur Renaissance", a period of time from the 1960s to the 1980s in which paleontologists and other scientists came to the realization that perhaps not species of retrosaurs were slow, sluggish, and dim-witted animals, but perhaps a few varieties were intelligent and fleet-footed reptiles that were warm-blooded, as opposed to many other groups of reptiles.

 As mentioned previously, Dryptonychus was one of the larger varieties of Tiny Tyrant, and was in fact one of the largest members of the Dryptonychosauria, a group of carnivorous retrosaurs that contains particular species that were typically under 12.5 feet (3.8 meters) in length. Although fossils of Dryptonychus have only been unearthed in Wyoming and northern Colorado (with possible Dryptonychus teeth being discovered in Alberta, Canada) thus far, it can be assumed it would have been a moderately widespread carnivore in western North America, perhaps residing in regions that were within close proximity of the westernmost seaboard of the Western Interior Seaway. In said regions, packs of Dryptonychus traveling together were probably not an uncommon sight, and isolated stragglers from these packs were a rarity. Dryptonychus packs usually contained up to 23 members, being headed by a mated matriarch female and patriarch male who are the largest and most powerful individuals of these gangs, and have utter control over the rest of the group. They are typically the only members of the pack who are allowed to breed multiple times, whereas lower-ranking individuals in these gangs normally breed only once in their entire lives due to this hierarchy. Dryptonychus likely inhabited the open wooded glades and badlands of its time, regions where this formidable pack hunter can easily herd, corner, and bring down its prey items. Smaller prey items of this carnivore likely included small mammals, lizards, snakes, birds, smaller Flying Tyrants (if it got the chance), and young herbivorous retrosaurs, while larger prey items included several species of Duck-Billed Goliaths (including Telmatosetes) and young Horned Goliaths, creatures that would have required skilled pack-hunting techniques and plenty of effort to successfully bring down. With its quick wits, razor-sharp "tools of the trade", and alarming speed and agility, any selected victims of this medium-sized Tiny Tyrant would have been quickly and discretely subdued (most of the time). Nonetheless, Dryptonychus would have occasionally have faced competition from contemporary dynamosaurids for larger food sources. Due to the smaller size and stature of the former, battles between packs of Dryptonychus and larger dynamosaurids likely did not occur, but the crushed skull of a subadult Dryptonychus with the teeth of a much larger dynamosaurid embedded in it uncovered in northern Colorado seems to suggest that at least on some occasions squabbles between these two distinct carnivorous retrosaurs would have taken place.

    Dryptonychus and other dryptonychosaurians were among the most successful and widespread members of the Tiny Tyrant clade, even though they had evolved at a later point in time than other varieties, sometime during the Early Cretaceous, approximately 120 million years ago. Remains of these small yet gruesome carnivores have been uncovered in North America, Europe, Asia, South America, and quite possibly Africa as well. Their fruitfulness was likely due to their high level of intelligence as compared to other retrosaur species, their speed and agility, and their ability to cooperatively hunt in packs in order to overwhelm and ultimately slaughter animals several times larger than themselves. Most of the dryptonychosaurian were rather diminutive creatures, such as the North American Megadontosaurus and the Asian Mongololestes (with the former being about the size of a coyote and the latter being around the size of a German shepherd), but a few members of this group were about as large as some of the smallest of the True Tyrants, such as Dryptonychus itself. These sickle-clawed predators are also a paramount part in understanding the anatomy and physiology of Tiny Tyrants and Egg Thieves, and proving to the world that retrosaurs are far from being dim-witted and sluggish creatures. However, the long-lived success of these pack-hunting retrosaurs would not last forever, as they would suffer the same fate as all other retrosaur species at the end of the Cretaceous, about 66 million years ago.

- Dryptonychus formidabilis ("formidable tearing claw")

    Yep, after all this time, I'm finally back to doing the 30-Day Retrosaur Challenge. Sorry for such a long wait, for those of you who enjoy my retrosaur-related content, but I've been preoccupied with a bunch of other stuff over the past few months, such as schoolwork and other personal projects of mine, but now that the school year for me has drawn to a close, I will hopefully be able to complete the remainder of the challenge during my summer break. Anyways, the inspiration for this pack-hunting beastie mostly comes from olden, vintage-style restorations of the famous dromaeosaur Deinonychus, and of course, the overrated and oversized Velociraptors of the Jurassic Park/Jurassic World franchise. However, I desired this particular retrosaur to be more than just a typical JP-style raptor; I decided to give it a little more flare to make it look unique. Therefore, I decided to give this carnivorous reptile keratinous brow ridges above the eyes, an iguana-like dewlap on its neck region, and quills on its neck, arms, and back. I also drew a little bit of inspiration from the fearsome hybrid Indoraptor, the supposed main antagonist of the upcoming Jurassic World: Fallen Kingdom for its design. The colors and patterns of the large male Dryptonychus in the front are mostly inspired by the misplaced Utahraptors from the fourth episode of the Walking With Dinosaurs miniseries ("Giant of the Skies"), those of the large female in the back are inspired by the huge Utahraptor action figure from Kenner's original Jurassic Park toyline, and for the juvenile female just in front of her, I decided to give it a somewhat more original color scheme to set it apart from the others.