Euhelopus

Type Species: Euhelopus zdanskyi

Classification: Dinosauria – Saurischia – Sauropoda - Gravisauria - Eusauropoda - Neosauropoda – Macronaria – Titanosauriformes – Somphospondyli – Euhelopodidae

Time Period: Early Cretaceous

Location: China

Diet: Herbivore

The Chinese sauropod Euhelopus was the first Chinese dinosaur to be scientifically studied in 1923. It is the namesake for the family group of Euhelopopidae, all of which are found in East Asia. Euhelopus had longer forelegs than hindlegs, and it is one of the few sauropods found with a relatively complete skull. Euhelopus was a large-sized macronarian sauropod, weighing in between 17-22 tons and reaching up to 49 feet in length. 

Nqwebasaurus

Type Species: Nqwebasaurus thwazi

Classification: Dinosauria – Saurischia – Theropoda – Tetanurae – Coelurosauria – Tyrannoraptora – Maniraptoromorpha – Ornithomimosauria

Time Period: Early Cretaceous

Location: South Africa  

Diet: Herbivore or Omnivore

The African dinosaur Nqwebasaurus – whose full name means ‘fast runner of the Kirkwood district’ – lived during the earliest stage of the Early Cretaceous. This is the only named coelurosaur discovered in Africa, and it shows that coelurosaurian dinosaurs lived in Gondwana 50 million years earlier than previously thought. 

This ornithomimosaur was small, only about a foot high and three feet in length. Its long, three-fingered hands had a partially opposable thumb and a recurved claw. Unlike most theropods – but in keeping with some other ornithomimosaurs – its first and second digits were recurved while the third claw was not. Ornithomimosaurs ran the gauntlet of dietary styles, and Nqwebasaurus was likely an herbivore, as it lacked serrations on its maxillary teeth and used gastroliths to assist in pulverizing its food. Skeptics point out that some predators use gastroliths – particularly those that eat fish and invertebrates; thus Nqwebasaurus may have been an omnivore.  Nqwebasaurus also had fewer teeth than most other theropods; ornithomimosaurs ran the gauntlet of teeth types, with some having few teeth, others having lots of teeth, and even some, like Gallimimus, who had no teeth but a keratinous bill! Some scientists speculate that Nqwebasaurus was partially feathered or had a feather coat for insulation; this reasoning is based on its relationship to other feathered dinosaurs.

Xuanhuaceratops

Type Species: Xuanhuaceratops niei

Classification: Dinosauria – Ornithischia – Marginocephalia – Ceratopsia – Chaoyangsauridae 

Time Period: Late Jurassic 

Location: China

Diet: Herbivore

Xuanhuaceratops was a small, bipedal herbivore that scurried among the thick forests of Late Jurassic China, dodging predators by hiding in thick undergrowth and running speedily away on two legs. It’s known from four fragmentary skeletons, hinting at a family group. Though it looks alien compared to the later and famous ceratopsians of the Cretaceous Period, Xuanhuaceratops had already developed the classic sharp, cropping beak of the ceratopsians and had the beginnings of the neck frill that would become a trademark of Cretaceous ceratopsians. 

Chaoyangsaurus

Type Species: Chaoyangsaurus youngi

Classification: Dinosauria – Ornithischia – Marginocephalia – Ceratopsia – Chaoyangsauridae 

Time Period: Late Jurassic 

Location: China

Diet: Herbivore

While little remains for this small herbivorous dinosaur have been discovered, those remains indicate that it was an early ceratopsian. Chaoyangsaurus was a small, bipedal herbivore whose lineage lies along the lay-lines that would eventually spawn one of the most dominant dinosaurs of the Cretaceous, the ceratopsians. Chaoyangsaurus is the namesake of the group that includes the earliest ceratopsians, such as Hulianceratops, Yinlong, and Xuanhuaceratops. All are from the Late Jurassic China, and they inform us that the ceratopsian lineage began there before radiating throughout the entire world during the Cretaceous Period. 

Chilesaurus

Type Species: Chilesaurus diegosuarezi

Classification: Dinosauria 

Time Period: Late Jurassic 

Location: South America 

Diet: Herbivore

Chilesaurus is an oddball of a dinosaur. Reaching ten and a half feet in length, it had spatula-shaped, elongated teeth that obliquely pointed forward, a design perfect for eating plants. Its herbivorous lifestyle is also attested by its backward-pointing pubic bone, which made room for a large gut. Its hind limb wasn’t well adapted for running, and its broad feet had a weight-bearing front toe. It had strong arms with a large claw that could be extended outwards, just as is seen in the sauropodomorphs. All this to say, it looks like a cross between a theropod and an ornithischian, and no one really knows where to place it in the dinosaur family tree. 

Those who argue for a theropod lineage point out that it’s not uncommon – although it’s certainly not usual – for theropods to adapt herbivorous lifestyles. We see this with the therizinosaurs, who became herbivorous, and with the ornithomimosaurs, who became omnivorous. Perhaps Chilesaurus is simply a theropod that went vegan. Others, however, consider the mixture of traits between theropods and ornithischians as evidence that we’ve got the dinosaur family tree all wrong. The current cladogram, which subdivides Dinosauria into the lizard-hipped Saurischians and the bird-hipped Ornithischians, wasn’t the only cladogram proposed; another was proposed by Thomas Huxley in 1869 (and revived by some scientists in 2017). Huxley argued that Dinosauria should be subdivided into Saurischia and Ornithoscelida. In his proposal, Saurischia contained all the sauropodomorphs, and Ornithoscelida contained the theropods and the ornithischians. In Huxley’s scheme, theropods are more closely related to ornithischians than to the sauropodomorphs. Proponents of his view point to Chilesaurus as evidence that his thesis is not only justifiable but correct, and that Chilesaurus, despite its relatively late appearance in the fossil record, is evidence of a ‘vestigial’ family line that eventually gave rise to both ornithischians and theropods. 

Kentrosaurus

Type Species: Kentrosaurus aethiopicus

Classification: Dinosauria – Ornithischia – Thyreophora – Stegosauria – Stegosauridae

Time Period: Late Jurassic 

Location: Africa

Diet: Herbivore

The African stegosaur Kentrosaurus was closely related to Stegosaurus though it was half its size, clocking in at around fifteen feet in length. Kentrosaurus had a small, elongated head with a beak that it used to sever tough plant material to be digested in its barrel-like gut. Its skin was covered in bony osteoderms, and it had small plates on its neck. These small plates were dwarfed by the plates that ran along its back in a series of fifteen rows. These plates were elongated with a thickened section in the middle, as if they were modified spines, and they were probably covered in horn. These plates gradually merged into spikes on the hip and tail. The longest spikes were on the end of its tail, and it would’ve used its thagomizer as a defensive weapon. It also had a long spike on each shoulder. Because the thigh bones come in two different types, it’s likely that males and females differed in their stoutness (a case of sexual dimorphism). 

Kentrosaurus is considered a low-browsing herbivore, and it likely roamed the thick conifer forests of northern Africa’s inland woodlands and may have even browsed on foliage in the less-lush coastal regions. If it ate while on all fours, it could reach up to five and a half feet off the ground; if it was capable of rearing back on its hind legs to eat, it could access food up to eleven feet off the ground. As a low-browser, it would’ve shared its niche with the iguanodont Dysalotosaurus, leaving the higher foliage to macronarian sauropods such as Giraffatitan. 

Kentrosaurus shared its environment with predators such as Elaphrosaurus, Allosaurus, and Veterupristisaurus. The former was too small to pose any real threat, but Allosaurus and Veterupristisaurus were a different story. The forty-foot-long Veterupristisaurus was the top predator in its environment, and it’s likely that Kentrosaurus would’ve faced-off with this predator on numerous occasions, and those plates and spikes would’ve come in good use. Scientists estimate that it could swing its tail up to speeds of 30 miles per hour, and continuous rapid swings wouldn’t only discourage attacks but could deal massive damage as the spikes ripped open its attackers’ skin, punctured its soft tissues, and broke ribs or facial bones. Repeated blows could even fracture the sturdy limb bones of the stoutest predator. With its ability to pivot quickly round on its hind legs, it would be adept at keeping its spikes pointed towards the attacker. If Kentrosaurus were a herding animal, the family group may have ‘circled-the-wagons’ with their tail spikes facing out to ward off curious predators. Such a wall of spikes would be virtually impenetrable and would likely be enough to discourage even a pack of hungry Allosaurus. Some scientists speculate that a lone Kentrosaurus, when under attack, might have charged backwards, using its tail spines like a spear, much in the manner of modern porcupines. 

Ostafrikasaurus

Type Species: Ostafrikasaurus crassiserratus

Classification: Dinosauria - Saurischia - Theropoda - Carnosauria – Megalosauroidea – Megalosauria – Spinosauridae – Baryonychinae

Time Period: Late Jurassic 

Location: Africa

Diet: Carnivore

Ostafrikasaurus is known only by a single tooth, and yet that lone tooth changed a theropod lineage forever. The single took, discovered in the Tendaguru Formation of Tanzania, is different from those of most theropods and more aligned with the unique teeth of the spinosaurs. Because all other spinosaurs date from the Cretaceous Period, the presence of a spinosaur tooth in the Tendaguru Formation pushed their genesis back into the Late Jurassic. Whereas most theropods have recurved, blade-like teeth with serrations for cutting through meat, spinosaur teeth were straighter, more conical, and had few if any serrations. Ostafrikasaurus’ teeth had a few serrations, indicating that these serrations were lost as the spinosaur family evolved. This may be because spinosaurs embraced a pescetarian (fish-hunting) lifestyle: conical, spear-like teeth are seen in modern fish-hunting gharials, as their design lends them to piercing and maintaining grip on slippery aquatic prey that can be swallowed whole rather than torn apart. The estimated 28-foot-long Ostafrikasaurus likely hunted in the coastal environments of northern Africa, hunting fish and even snagging the occasional pterosaur or two. Though its skull hasn’t been found, it’s likely that it had the crocodile-like snouts of its descendants. However, given its early placement in the spinosaurid family, it may have resembled non-spinosaurid theropods, as well. Until more remains are found, we can only speculate as to what it looked like fleshed-out. 

The spinosaurs are divided into two subfamilies: Baryonychinae and Spinosaurinae. Baryonchines have slightly curved, finely-serrated teeth with more oval cross-sections, whereas spinosaurines have straight, fluted teeth with reduced or absent serrations. Given the fact that Ostafrikasaurus’ teeth are more in line with the former, it’s been placed with the baryonychines and likely represents a primitive form of that subfamily.