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Description
108 million years ago during the early Cretaceous period in what is now the Cloverly Formation of Montana, USA, a pair of 3.4-meter long predatory theropod dinosaurs, Deinonychus antirrhopus, make an attempt to hunt a prey item larger and more defended than their usual targets. The armored herbivorous dinosaur Tatankacephalus cooneyorum grows slightly longer than a Deinonychus, but with its bulky form and defensive bony studs (osteoderms) on its back it weighs quite a lot more than the gracile carnivore. One Deinonychus jumps onto the back of the Tatankacephalus and attempts to inflict damage by biting and stabbing with its toes, but its teeth and sharp claws are hardly hurting the armoured herbivore and this hunt may take a while to complete.

Drawing made because apparently today (February 25) is Deinonychus Day (mobile.twitter.com/KingRexy328… ).

One of the most well-known and studied dinosaurs, the dromaeosaur (or colloquially 'raptor') Deinonychus was an important fossil discovery that changed the way dinosaurs were viewed. In the past dinosaurs were commonly seen as slow and stupid giant reptiles that died out because they were 'inferior' to the more active and smart mammals, but when the remains of Deinonychus were first published in the 1960s this greatly changed. From the multiple rather complete skeletons it was clear that Deinonychus was a fast animal that lived an active lifestyle, and being 3.4 meters long it wasn't gigantic for a dinosaur (but as far as the dromaeosaur family goes it is above average size). The large braincase also hinted that it may have been as smart as certain modern birds (probably not corvid-level smart but still), and as skeletons of multiple individuals were found around the remains of one Tenontosaurus (a 6 to 8 meter long herbivorous dinosaur) it has also been suggested that they were social and hunted cooperatively in packs. That last statement has since been greatly contested though, and over the years many have argued back and forth over whether dromaeosaurs hunted in packs and the possible scenarios that led to those individuals dying together, but still it remains a significant discovery that kickstarted the 'Dinosaur Renaissance'. Today, Deinonychus is known to have also been feathered like all dromaeosaurs rather than scaly as it was formerly portrayed, and its most distinctive feature, the retractable claw on each foot that earned it the name meaning 'terrible claw', is deemed a likely stabbing weapon used in killing and dismembering prey.

Described in 2009, Tatankacephalus was an ankylosaur dinosaur known only from a partial skull measuring 32 centimeters long. Like other ankylosaurs it would have been covered in bony studs called osteoderms over its back which protected it from predators, but since only a skull is known the arrangement of said osteoderms is speculative. Its exact position within the Ankylosauria suborder has been uncertain, but currently it is thought to be a basal nodosaurid, perhaps closely related to Gastonia, and assuming similar proportions between the two it would have grown 3 to 4 meters long. As far as ankylosaurs go this is rather small, many other ankylosaurs getting 6 meters or more, and in fact Tatankacephalus did coexist with a larger ankylosaur: the 5 to 6-meter long Sauropelta. Since they all coexisted in the Cloverly Formation, Sauropelta has been depicted in a few artworks fighting packs of Deinonychus, but given how much larger and armoured an adult Sauropelta was I quite doubt even a full pack of Deinonychus would take one on unless in great desperation (that is, assuming they did hunt in packs, it's quite a controversial topic). While a Tatankacephalus would still be a large and difficult prey item for Deinonychus, the smaller size of this ankylosaur does make such a hunt sound more plausible and doable for maybe 2 or 3 Deinonychus if they tried really hard. Still unlikely that it would commonly be on the menu, smaller ornithischian dinosaurs such as Zephyrosaurus, Aquilops and juvenile Tenontosaurus are more likely main prey items of the dromaeosaur (a full-grown Tenontosaurus would be quite hard for even a pack of the dromaeosaurs to kill despite what is commonly portrayed).

Description
108 million years ago during the early Cretaceous period in what is now the Cloverly Formation of Montana, USA, a pair of 3.4-meter long predatory theropod dinosaurs, Deinonychus antirrhopus, make an attempt to hunt a prey item larger and more defended than their usual targets. The armored herbivorous dinosaur Tatankacephalus cooneyorum grows slightly longer than a Deinonychus, but with its bulky form and defensive bony studs (osteoderms) on its back it weighs quite a lot more than the gracile carnivore. One Deinonychus jumps onto the back of the Tatankacephalus and attempts to inflict damage by biting and stabbing with its toes, but its teeth and sharp claws are hardly hurting the armoured herbivore and this hunt may take a while to complete.

Drawing made because apparently today (February 25) is Deinonychus Day (mobile.twitter.com/KingRexy328… ).

One of the most well-known and studied dinosaurs, the dromaeosaur (or colloquially 'raptor') Deinonychus was an important fossil discovery that changed the way dinosaurs were viewed. In the past dinosaurs were commonly seen as slow and stupid giant reptiles that died out because they were 'inferior' to the more active and smart mammals, but when the remains of Deinonychus were first published in the 1960s this greatly changed. From the multiple rather complete skeletons it was clear that Deinonychus was a fast animal that lived an active lifestyle, and being 3.4 meters long it wasn't gigantic for a dinosaur (but as far as the dromaeosaur family goes it is above average size). The large braincase also hinted that it may have been as smart as certain modern birds (probably not corvid-level smart but still), and as skeletons of multiple individuals were found around the remains of one Tenontosaurus (a 6 to 8 meter long herbivorous dinosaur) it has also been suggested that they were social and hunted cooperatively in packs. That last statement has since been greatly contested though, and over the years many have argued back and forth over whether dromaeosaurs hunted in packs and the possible scenarios that led to those individuals dying together, but still it remains a significant discovery that kickstarted the 'Dinosaur Renaissance'. Today, Deinonychus is known to have also been feathered like all dromaeosaurs rather than scaly as it was formerly portrayed, and its most distinctive feature, the retractable claw on each foot that earned it the name meaning 'terrible claw', is deemed a likely stabbing weapon used in killing and dismembering prey.

Described in 2009, Tatankacephalus was an ankylosaur dinosaur known only from a partial skull measuring 32 centimeters long. Like other ankylosaurs it would have been covered in bony studs called osteoderms over its back which protected it from predators, but since only a skull is known the arrangement of said osteoderms is speculative. Its exact position within the Ankylosauria suborder has been uncertain, but currently it is thought to be a basal nodosaurid, perhaps closely related to Gastonia, and assuming similar proportions between the two it would have grown 3 to 4 meters long. As far as ankylosaurs go this is rather small, many other ankylosaurs getting 6 meters or more, and in fact Tatankacephalus did coexist with a larger ankylosaur: the 5 to 6-meter long Sauropelta. Since they all coexisted in the Cloverly Formation, Sauropelta has been depicted in a few artworks fighting packs of Deinonychus, but given how much larger and armoured an adult Sauropelta was I quite doubt even a full pack of Deinonychus would take one on unless in great desperation (that is, assuming they did hunt in packs, it's quite a controversial topic). While a Tatankacephalus would still be a large and difficult prey item for Deinonychus, the smaller size of this ankylosaur does make such a hunt sound more plausible and doable for maybe 2 or 3 Deinonychus if they tried really hard. Still unlikely that it would commonly be on the menu, smaller ornithischian dinosaurs such as Zephyrosaurus, Aquilops and juvenile Tenontosaurus are more likely main prey items of the dromaeosaur (a full-grown Tenontosaurus would be quite hard for even a pack of the dromaeosaurs to kill despite what is commonly portrayed).