Therizinosaurs or segnosaurs were unique bipedal sauropod-esque reptiles. Similar with lengthy neck vertebrae and large bellies, but with defining features such as downy feathers (preserved in some specimens) and famous sickle-shaped claws. The claws itself grew up to a meter in some species. The hands flexed inward greatly but did not spread apart much and the wrists folded back like that of bird wings. They were specialized tools perhaps for feeding or foraging also capable of defense like in ground sloths. Though, more likely used as impressive threat displays that alone would deter most, rather, they probably relied in groups for protection in numbers.
Even primitive segnosaurs proved sociable animals that died and lived amongst each other as evidenced from China fossil finds. Eggs were semi-spherical and babies were readily fledged shortly from the nest. Advanced segnosaurs grew very large, up to five tons perhaps by herbivorous diets due to changing toothless beaks. Possibly omnivorous, they would have been opportunistic scavengers than active hunters.
Alxasaurus elesitaiensis, the “Alxa Desert Lizard” live 100-110 million years ago in what is now Mongolia. This theropod was four meters in length and weighed almost half a ton. Its semi-toothed jaw and build made it an intermediate link from primitive species such as falcarius to more advanced ones such as therizinosaurus. The unusual theropods were distantly related to the raptors.
One of the most completed clubbed dinosaurs to be named, zuul crurivastator, resembles its movie monster counterpart with its gargoyle-esque features. Following the trend of lavishly Latin named discoveries, zuul is aptly given one for its fierce face. Although the similarities end there, as ankylosaurs are much larger animals built low, wide, armored, with heavy weaponry.
What is remarkable is the tail club accompanying the original type specimen, which measures even larger than the skull itself slightly at 52 cm. Large on the scale spectrum for ankylosaurs, zuul is 2 tons and 6 meters of dinosaur with half being dedicated to tail length. The biggest tail club found was a 60 cm one belonging to an estimated 7 metered individual; large ankylosaurs carry even larger clubs which shape and size could change with age. Interestingly enough, babies are born without one; perhaps using defensive tactics instead, as there are many clubless varieties of ankylosaurs.
Clubless or not, ankylosaurs evolved both heavy offense and defenses to deal with predation. Living species shows us that heavily armored animals tend to be slower moving, instead of evading predators they may defend or maim; a niche to gaining access to territory and food otherwise. Spiky osteoderms similar to the ones found on stegosaurs, using a similar strategy in deterring attackers, can cut or puncture and still remain perpetually sharp if sides overlapped sharpening one another. The clubbed ankylosaurs may have lived in wide open areas to accommodate for their wide width and choice of weapon.
Camouflage may have been found in ankylosaurs as pigments suggest a reddish and white pattern on some well preserved nodosaur scales. Some fossils even show well developed nasal cavities which would aid in finding edible resources, avoiding predators, resonating calls, and even cooling air in passage ways.
Of tail clubs, ankylosaurs could easily strike to fracture large theropod leg bones and reach to crush ribcages of mid-sized ones. All theropods did have hollow skulls so an unlucky or lucky hit (depending on who you’d asked) could be fatal or at least dislocate jaws and teeth. The tail moves best sideways in 100 degree arcs flexing at the base while the end remaining relatively inflexible, forming a rigid handle supporting the club itself. Ankylosaurs had partial stereoscopic vision as decent club and eye coordination would prove useful in wielding such weapons. Fossilized clubs have even been found with damage, suggesting forces powerful enough to break bone, rock, and even other ankylosaurs as well.
Clubs can have other uses such as a blunt tool for breaking open food sources or quickly shocking tall trees into dislodging many seeds or leaves with relative ease; a niche for ankylosaurian kind and perhaps only large sauropods. Its broad beak shoveled while small leaf-like teeth shredded nutrients efficiently, whereas gastroliths were used for digestion in other dinosaurs. The numerous osteoderms would require much calcium supplemented mostly from foraging mineral deposits, even bones, and perhaps eggshells; easily sniffed out and uncovered by digging.
For more than a century torosaurus and triceratops still remain as separate species, for now. They were among the first dinosaurs to be discovered, late 1800s respectively, even earlier than T. rex. The trend of growing ceratopsians species is strong in this decade of the horned dinosaurs as their lineage have substantially increased just over the last few years. With regaliceratops, perhaps forming a seperate branch and the most completed torosaurus fossils recently discovered.
Closely resembling each other torosaurs are obscure compared to its much more famed relative the triceratops. Both lack full stages of proper transitional fossils to be considered one, so Torosaurus or “Bull Lizard” won’t be traditionally dropped yet, as triceratops was discovered three years prior. Where there are many fossils showing consistent and full transitional stages among young, juvenile, sub-adult, and adult triceratops specimens, there hasn’t been valid transitional specimens of “toromorphs” where there should be. The much scarcer torosaurus fossils do show perforated frills and a short nasal horn as the only difference other than slight ranges in geography. Both species, however, show wild variation in individual sizes with skulls of very large specimens still showing unfused bones. Arguments point to torosaurus’s identity crisis as a chronospecies, an earlier relative of triceratops which would explain the transitional fossil gaps; or due to behaviors unknown perhaps maturing individuals just simply migrate into habitats where fossilization rarely ever occurs. Whatever the cause, many cases of dinosaur groups show slight but enough differences to be consider separate species although none as controversal as triceratops and torosaurus.
Late into the Cretceous scene ceratopsians evolved confined to what is now the americas, unlike most dinosaurs as the land masses had separated. Elaborate species have emerged to form the largest in the ceratopsids: thechasmosaurines and centrosaurines.