Nobu Tamura (http://spinops.blogspot.com), CC BY 3.0, via Wikimedia Commons

Type:	Sauropod
Lived:	Early Cretaceous, 99 – 97 million years ago
Weight:	7,000 – 40,000kg
Length	14 – 26m / 46 – 85ft
Diet:	Herbivorous

FURTHER RESEARCH AND STUDY

• D. A. Russell (1996). Isolated dinosaur bones from the Middle Cretaceous of the Tafilalt, Morocco.
• Calvo & Salgado (1995). Rebbachisaurus tessonei sp. nov. A new sauropod from the Albian-Cenomanian of Argentina; new evidence on the origin of the Diplodocidae.
• Wilson & Allain (2015). Osteology of Rebbachisaurus garasbae Lavocat, 1954, a diplodocoid (Dinosauria, Sauropoda) from the early Late Cretaceous–aged Kem Kem beds of southeastern Morocco.

Rebbachisaurus (Reb-bok-e-sore-us) meaning Rebbach lizard was a herbivorous sauropod dinosaur genus of the subfamily Diplodocoidea that lived in the Cretaceous epoch and inhabited Africa. It was up to 65 feet (20 meters) long. Its fossils have been discovered in Béchar (Algeria), Morocco, and Béchar (Algeria), and it lived between 113 and 93.5 million years ago. As only the dorsal vertebrae (backbone), scapula, humerus, and sacrum are known, reconstructions are highly speculative. However, we know that its backbone had enormous spines that may have supported a sail.’ It is distinguishable from other sauropods by a tall ridge running down its back, similar to other members of its family. It possessed a whip-like tail and a long, beautiful neck. Rayososaurus, a near relative from South America, supports the hypothesis that Africa and South America were linked during the Cretaceous period, as do several other dinosaurs from both continents.

As this species is thought to be herbivorous, its ecological range would have included the lush grasslands that were plentiful and everlasting during the early Cretaceous and late Cretaceous periods. Rebbachisaurus would most likely be found in big groups because it was a herbivorous species. Its fossil record is based on the remains of several individuals.

Eleven vertebrae, ten ribs, a shoulder blade, a sacrum, and a humerus, two bones probably belonging to the pelvis were among the first Rebbachisaurus fossils discovered in Morocco. The dorsal vertebrae of this species are the fossils that have been researched since when they were discovered. A second specimen consists of a fragmentary spine that, if complete, might stand up to 1.45 meters (4.8 feet) tall (also found in Aoufous). This sauropod dinosaur’s typical length is 46-85.3 feet (14-26 m). They are quite large, as seen by the size of their bodies. Conflicting opinions and theories exist about the typical weight of this African dinosaur.

If we add together the weight ranges offered by each expert, this monster from Earth’s past would weigh between 7.7 and 44 short tonnes (7-40 metric tons). Rebbachisaurus garasbae members have a long, slender neck that can be used to reach the top foliage of trees. No sharp teeth have been discovered in any of the fossil sites, implying that the animal was not carnivorous or even omnivorous.

Rebbachisaurus is classified as a multi-class animal. Dinosauria, Diplodocoid, and Sauropoda are the three classes to which they belong. These early Cretaceous dinosaurs may have been confined to Africa, as evidence of their presence has only been found in Africa, namely in the Kem Kem beds of South Eastern Morocco. The discovery of this species and subsequent research imply that natural disasters caused the sauropods to become extinct between 95 and 99 million years ago.

National Park Service/Jeff Martz, Public domain, via Wikimedia Commons

Type:	Ornithpod
Lived:	Late Triassic 225 – 200 million years ago
Weight:	Unknown
Length	Unknown
Diet:	Herbivorous

Only fossil teeth of Revueltosaurus have been found in New Mexico and Arizona, USA. Revueltosaurus was originally described as an ornithischian dinosaur based on several discoveries of teeth, but was reclassified when a partial skeleton was discovered in 2004.

At the time, the newly discovered full skeleton of a Revueltosaurus made it clear that the teeth were not of a plant-eating dinosaur, but of a herbivorous or perhaps an omnivorous crocodilian ancestor living a mostly terrestrial life in the uplands of the Late Triassic. It may have been a good source of meat for the developing theropods that were around the world.

The animal, which was one of the many creatures from the Late Triassic, was known only from its teeth, and was thought to be an ancestor of the plant-eating ornithischian dinosaurs like Stegosaurus and Triceratops, which roamed the world millions of years later in the Jurassic and Cretaceous period. Due to their teeth looking like those we know from herbivorous ornithischians, people assigned them to the dinosaurs.

Tomopteryx, CC BY-SA 3.0, via Wikimedia Commons

Type:	Ornithopod
Lived:	Late Cretaceous, 70 – 66 million years ago
Weight:	1,000 – 3,000kg
Length	4m / 13.1ft
Diet:	Herbivorous

Rhabdodon (RAB-doe-don) was a genus of Ornithopod dinosaur that lived in the Campanian age during the Upper Cretaceous period 83 – 65 million years ago in Europe including Austria, France, Romania and Spain. It is unclear whether Rhabdodon was an Iguanodont or a Hypsilophodont, and may be a ‘missing link’ between the two.

Rhabdodon measured around 12 feet (4 metres) in length. It was actually smaller than its relatives,  this was possibly due to the insular environment that existed in Europe during the Cretaceous period. Rhabdodon had a blunt head and large, rod-shaped teeth. Its hind limbs were longer than its fore limbs and they were all probably clawed. This bipedal dinosaur had a long stiff tail which was used to counter-balance itself. Being a small dinosaur, it would have probably been able to run fast.

Rhabdodon was a herbivore and ate prehistoric plant material to sustain itself.

Image source: Australian Museum

Type:	Sauropod
Lived:	Mid Jurassic, 177 – 169 million years ago
Weight:	9,000kg
Length	15m / 49ft
Diet:	Herbivorous

Rhoetosaurus, (REET-oh-SAWR-us) was a genus of Sauropod dinosaur that lived in the Bathonian to Callovian Ages during the Middle Jurassic Period, 181 to 175 million years ago in what is now Queensland, Australia. This dinosaur is very similar to other sauropods of that age, such as Shunosaurus from China.

Rhoetosaurus measured a huge 60 feet (18 metres) in length and weighed 20 tons. It had a long tail and a very long neck with a small, box-like head. Its body was heavily built and bulky and it stood on 4 powerful, trunk-like legs. It would have probably had hoof-like feet, much like todays modern elephants. Rhoetosaurus would have had many cheek teeth that were suitably adapted to grinding up tough vegetation. It may have had gastroliths (stomach stones) in its stomach to help digest tough plant material.

Rhoetosaurus was a herbivore and would have eaten a huge amount of plant matter to sustain its great size.

Image: © Andrey Atuchin. Image source

Type:	Small theropod
Lived:	Late Cretaceous, 72 – 68 million years ago
Weight:	71kg
Length	1.5m / 5ft
Diet:	Omnivorous

FURTHER READING AND STUDY

• Rinchen Barsbold (1986). Raubdinosaurier Oviraptoren.
• Maleev (1955). New carnivorous dinosaurs from the Upper Cretaceous of Mongolia.
• Barsbold (1997). Oviraptorosauria.

Rinchenia (Rin-chen-e-ah) was a theropod omnivorous dinosaur species that belonged to the oviraptorid genus. It lived during the Cretaceous epoch and roamed Asia’s terrestrial areas. Its fossils have been discovered in areas like Mongolia, and China and existed from 72.1 million to 66 million years ago. Rinchenia mongoliensis, the type (and only known) species, was previously classified as a species under the genus Oviraptor (called Oviraptor mongoliensis by Rinchen Barsbold in 1986), but a re-examination by Barsbold in 1997 revealed enough differences to warrant a new genus. Barsbold coined the name Rinchenia for this new genus in 1997, but he did not describe it in full, and the term remained a nomen nudum until utilized by other scientist in 2004.  

It is only known from a skull and partial postcrania, therefore reconstructions based on related dinosaurs are highly speculative. They balanced a highly developed head comprising many bones on a fairly frail skeletal structure, according to fossil reconstructions. Rinchenia had a fast frame for chasing prey, as well as a crest on its skull that could have been utilized to lure mates.

While Oviraptor’s crest is ambiguous due to poor fossil preservation, Rinchenia possessed a well-preserved, highly developed dome-like casque that encompassed several bones in the skull that are missing from Oviraptor’s crest.

This dinosaur’s characteristics matched those of other oviraptorids, according to a single fossil depiction. The skull of this species was small yet complete, with distinguishing features. A full skull and lower jaw, partial forelimbs and shoulder girdle, a partial vertebral column, partial hind limbs and pelvis, and a furcular were all found in this dinosaur’s fossils. These dinosaurs reproduced by laying eggs because they were oviparous. An adult Rinchenia was 5-8 feet long on average (1.5-2.5 m).

These dinosaurs most likely lived in forests and grasslands with a few small bodies of water nearby.  These dinosaurs, like most other Theropods, were thought to be swift and nimble in their movements. Given their varied diet, which included fish, lizards, eggs, and plant materials, these dinosaurs were aggressive and predatory. As a result, it’s safe to infer they possessed robust teeth. The reason for their extinction is thought to be some kind of natural disaster.

No machine-readable author provided. Deivid assumed (based on copyright claims)., CC BY-SA 3.0, via Wikimedia Commons

Type:	Sauropod
Lived:	Late Triassic 221 – 210 million years ago
Weight:	800kg / 1,800Ibs
Length	10m / 33ft
Diet:	Herbivorous

Riojasaurus (ree-OH-ha-SAWR-us) was a prosauropod dinosaur that lived during the Late Triassic and Early Jurassic periods 221 – 210 million years ago in La Rioja Province in Argentina. Riojasaurus is the only known Riojasaurid to live in South America.

Riojasaurus measured 33 feet (10 metres) in length and weighed 1.1 tons. It was heavily built and had a bulky body and was quadrupedal, moving slowly around on 4 thickly built legs. Its leg bones were dense and massive for a prosauropod and its hinds limbs and fore limbs were not much different in size. Riojasaurus had relatively longer hands and feet than a sauropod and more of its digits were tipped with claws.

Riojasaurus had a very long neck and a long tail. No skull was actually found with the first skeleton of Riojasaurus, but because of its long slender neck, this suggests that its head was small. Its vertebrae were made lighter by hollow cavities, and unlike most prosauropods, Riojasaurus had 4 sacral vertebrae instead of 3.

Riojasaurus was a plant eater (herbivore) and fed up on foliage on tall conifer trees, raking off the leaves and needles with its spoon-like teeth. Riojasaurus used its flattened teeth to cut and grind plants. This huge dinosaur would have had to eat huge amounts of vegetation to sustain itself.

Retlaw095, CC BY-SA 4.0, via Wikimedia Commons

Type:	Large theropod
Lived:	Late Cretaceous 95 million years ago
Weight:	750kg / 1,650Ibs
Length	6m / 19.7ft
Diet:	Carnivorous

FURTHER READING AND STUDY

• Paul (2010). The Princeton Field Guide to Dinosaurs
• Sereno et al, (2004). New dinosaurs link southern landmasses in the Mid-Cretaceous
• Grillo & Delcourt (2016). Allometry and body length of abelisauroid theropods: Pycnonemosaurus nevesi is the new king.

Rugops (Roo-gops) meaning wrinkle face was a tiny theropod carnivore that lived in Africa during the late Cretaceous period, between 100.5 million and 93.9 million years ago. Rugops is an unusual dinosaur name for a carnivore. The name derives from the numerous impressions in the skull bone left by enormous blood veins that formerly flowed over the bone surface, giving it a wrinkled look. These extra vessels are considered to have been there to deliver extra oxygenated blood to distinctive facial display elements not seen in any other theropod. These blood veins may have also provided Rugops with a steady supply of blood, allowing it to flush blood into the soft tissue of its snout for a vibrant color show. Rugops could also have had some form of armor coating on its face.

The finding of a Rugops skull in Niger in 2000 was a watershed moment in our knowledge of theropod development in that region, demonstrating that this continent was still connected to Gondwana at the time. Scientists have only unearthed the remains of this creature in this area, leading us to think that they were endemic to Niger.

Only one fossil of these carnivorous species has been identified, showing that they lived alone. Rugops skulls were around 1 foot long (0.30 m). The tiny skull suggests that this was a scavenger rather than an attacking dinosaur like Tyrannosaurus. Rows of holes in the skull could suggest the presence of a crest. Rugops has only one known fossil, a single skull, from which most of the known details have been extrapolated.

It was estimated to be approximately 20 feet (6 meters) long and stood just above the head of an adult male human. Like many other theropods, its arms were likely vestigial and served little utility. Only one skeleton has been found so far for this animal. With only a half skull and a left maxilla, the Rugops skeleton is incomplete. In comparison to their close cousins, scientists believe that these African theropods were speedy, agile, and fierce warriors. Rugops’ speed was measured at around 15 mph despite this (24.1 kph). It was critical for them to be fast as predators.

Rugops weighed around 900 pounds on average (408.2 kg). Rugops can grow up to 6 feet tall (1.8 m). It stands apart from its cousins not only because of its brief name and small size but also because of its anatomy, specifically Rugops jaw structure.

The Rugops, unlike many other carnivores, has a history of devouring carcasses or dead meat. This is because most other carnivores in the past preferred to eat only fresh meat, and only scavengers ate dead meat or leftovers. The Rugops, on the other hand, were thought to eat both sorts of meat, leaving scientists with many doubts regarding its nutrition. Because they are smaller than most predators, they are unable to hunt larger animals.

The Cenomanian period existed between 100.5 and 93.9 million years ago. As a result, this theropod was thought to have died out near the end of the Cenomanian epoch. This makes it one of the oldest dinosaurs known to have existed.