Riley the Paleontologist

Hi! I am Riley Chandler. I'm your 12 Year Old Paleontologist.



   Giganotosaurus (meaning - giant southern reptile); pronounced GEE-gah-note-oh-sore-us.

Giganotosaurus was a carnivore (meat eater).  It was about 40-46 feet long, weighed about 8 tons, and stood 12 feet tall at the hips.  It is one of the largest meat eating dinosaurs ever discovered in Argentina in 1994.  Paleontologist have found 70 percent of the skeleton.  Near the Giganotosaurus, fossils were found of a 75 foot long plant eater.  Some paleontologist think the plant eater found was a victim of this Giganotosaurus. 


Giganotosaurus walked on two legs, had very large jaws with 8 inch long serrated teeth in a 6 foot long skull, and had a brain the size of a banana.  Giganotosaurus was a theropod that lived in the Late Cretaceous period.  It is thought to be one of the last living dinosaurs toward the end of the Mesozoic Era.



Lesothosaurus (meaning - Lizard from Lesotho, South Africa); pronounced Le-soe-toe-sore-uss.

Lesothosaurus was a herbivore (plant eater).  It was about 3 feet long, weighed about 8 pounds, and lived from the Late Triassic to the Early Jurassic period. It was a tiny cat-sized dinosaur that lived in Africa and South America.

Lesothosaurus had long hind legs, and short, stubby front arm-like legs. It walked on two legs, had four toed feet, five toed hands, a long pointed tail, a flexible neck, and a small head. It had sharp, pointed front teeth and arrow shaped cheek teeth. It's lower jaw ended in toothless bone.  

Paleontologist believe this dinosaur was a very fast runner because it was so small.



Coelophysis (meaning - hollow form); pronounced SEE-low-FIE-sis.

Coelophysis was a carnivore (meat eater).  It was about 9 feet long, weighed about 77 pounds, and lived in the Late Triassic period. In 1947, t

housands of Coelophysis' bones were found in a small area in New Mexico.  These dinosaurs probably all died together in some type of natural disaster.  

Coelophysis had a light-weight body and a long neck.  This predator was very quick and agile so that it could chase down its prey and escape from its enemies. This dinosaur 
 shares many features with early birds, including hollow bones and a beak-like mouth.

Ceolophysis goes to Space!!!  A Coelophysis skull from the Carnegie Museum of Natural History was brought into space by the space shuttle Endeavor on January 22, 1998.  It traveled to the space station Mir before returning to earth.  (Maisaura beat Coelophysis into space making Coelophysis the second dinosaur in space.)


Utahceratops (meaning - Utah horned face); pronounced YOU-tah-SEH-rah-tops.

Utahceratops was a herbivore (plant eater).  It was about 20 feet long, weighed about 3-4 tons, and lived in the Late Cretaceous period.  

Utahceratops was in the ceratopsian family.  This herbivore had a single, rhino-like horn projecting from the top of its snout, as well as a pair of horns extending out sideways from the top of it's eyes.  The skull of Utahceratops was about 7 feet long.  This large skull has prompted one paleontologist to describe this dinosaur as "a giant rhino with a ridiculously supersized head."

Utahceratops was first named by Scott D. Sampson, one of my favorite paleontologist, Mark Loewen, Andrew Farke, Eric Roberts, Catherine Forster, Joshua Smith, and Alan Titus in 2010.




Giraffatitan (meaning - Giant Giraffe); pronounced jih-RAFF-ah-TIE-tan.







































Giraffatitan was a herbivore (plant eater).  It was about 75 feet long, weighed about 60,000 pounds, and lived in the Late Jurassic period. 

Giraffatitan was a sauropod.  Sauropods are a group of dinosaurs that have long necks and tails and a small brains.  Giraffatitan had a giraffe-like build, with long forelimbs and a very long neck.  Its skull had a tall arch over its eyes and chisel shaped teeth.  The first toe on its front foot and first three toes on its back feet were clawed.  Giraffatitan is similar to the Brachiosaurus.




Amargasaurus (meaning - Lizard from La Amarga, Argentina); pronounced Ah-mar-gah-sore-uss.







































Amargasaurus was a herbivore (plant eater).  It was about 35 feet long, weighed about 14,000 pounds, and lived in the Early Cretaceous period. 

Amargasaurus gained its name from La Armaga, a canyon in Argentina where its fossils were found. It had two rows of spines that stretched from its neck to its tail.  My theory is that the spines along its back and tail were covered with skin forming sails.  These sails would have been used to control this sauropods temperature by absorbing and releasing heat, for mating purposes, and for making the dinosaur appear larger than it was to predators.


                                                                                                                                                               Amargasaurus walked on four legs, had a small head, and a long neck and tail.  Its front legs were shorter than its back legs.  All the legs had elephant-like, five-toed feet.  One toe on each foot had a thumb claw that could have been used for protection.  It may have also used its whip-like tail for protection. 



Sinovenator (greek for "Chinese Hunter"); pronounced SIGH-no-VEN-ate-or.







































Sinovenator was about 3 feet long, weighed 5 to 10 pounds, and lived in the Early Cretaceous period. 

Sinovenator is one of many dinosaur birds dug up in China.  Although Sinovenator was closely related to the Troodon,  this small, feathered theropod had the raised single claw on each hind foot characteristic of raptors.  It is possible Sinovenator may represent an intermediate form between early raptors and later troodonts.


Sinovenator appears to have been a fast, agile predator that probably hunted its fellow theropods (and was hunted by them in turn).



Anserimimus (greek for "Goose Mimic"); pronounced AN-ser-ih-MIME-us.







































Anserimimus was about 14 feet long, weighed 250 to 500 pounds, and lived in the Late Cretaceous period.

Anserimimus was a rare ornithomimid that is only known from a single, incomplete skeleton found in the Gobi Desert.  This incomplete skeleton consisted of a hindlimb and a forelimb but no skull.  Anserimimus probably had no teeth and would have survived on small insects, reptiles, and mammals.  Anserimimus was probably omnivorous. 

Anserimimus probably did not look like a goose, after which it was named.  This is because the paleontologist who described it wanted to follow the ornithomimid tradition of naming new genera after existing birds.





Aucasaurus (greek for "Auca lizard"); pronounced AW-cah-SORE-us.







































Aucasaurus was about 13 feet long, weighed about 500 pounds, and lived in the Late Cretaceous period. An almost complete skeleton of this dinosaur was found in Argentina.  It was smaller than its relative Carnotaurus. 




Aucasaurus had very small arms and almost totally lacked fingers.  This carnivore is thought to be a pack hunter that would have fed on sauropods.



Therizinosaurus (meaning reaping or scythe lizard); pronounced THER-uh-ZEEN-oh-SAUR-us.







































Therizinosaurus was about 23 feet long, 10 ft tall at the hips, and lived in the late Cretaceous period. It has huge arms that were about 8 feet ling, and it's claws grew up to 28 inches long.  The finger bones are larger that any other animal in history.  When Therizinosaurus was found, it was thought to be a giant turtle, not a dinosaur.

No one knows for sure, but some paleontologists think it could have been an insectivore, while others think it was an herbivore.  More evidence points to the idea that Therizinosaurus was a herbivore than an insectivore.


Mamenchisaurus (meaning Mamenxi "Ferry" Lizard); pronounced Ma-man-chee-sore-uss.

Mamenchisaurus was a long-necked, long-tailed, quadrupedal, plant-eating dinosaur.  Mamenchisaurus had the longest neck of any know dinosaur, except the newly found Sauroposeidon.  Mamenchisaurus' neck was about 46 feet long.  It had 19 vertebrae in its neck, more than any other known dinosaur.  Mamenchisaurus was about 70 to 80 feet long and weight about 12 tons.

Its hind legs were longer than the front legs; these hind legs were similar to the legs of Diplodocus.  Its skull however, was box-shaped.




Ornithosuchus (meaning Bird Crocodile); pronounced Orn-ith-oh-SOO-kuss.

Ornithosuchus lived in the Late Triassic Period.  This carniovore could walk on all four legs, or if in a hurry, it could stand up, and run on its hind legs.  It was 12 feet long, and weighed 200 pounds.

Ornithosuchus was capable of rearing up on its hind legs, and it had a long, powerful, crocodile-like snout.  As for how the "bird" reference crept into its name, is a mystery! 




Liliensternus (after Dr. Hugo Ruhle von Lilienstern); pronounced LIL-ee-en-STERN-us.

Liliensternus lived in the Late Triassic Period.  This carniovore had long five fingered hands and a long head crest.  It was 15 feet long, and weighed 200 pounds. 

Liliensternus was one of the largest bipedal predators of its time that could reach respectable speeds in pursuit of prey.  It probably fed on small, herbivorous dinosaurs such as Sellosaurus and Efraasia.  Liliensternus was a close relative to other early theropods such as Coelophysis and Dilophosaurus.





(meaning "Emu Mimic"); pronounced Drom-es-say-owe-mim-uss) 

Dromiceiomimus lived in the Late Cretaceous Period.  This carniovore had a toothless, beaked mouth, and weak jaws and would have ate insects, eggs, and small meat.  It was 12 feet long, and weighed 220 to 330 pounds.

Dromiceiomimus was a fast moving bi-pedal dinosaur that could run up to 40 mph. This ornithomimid (a bird-like theropod) had extremely long limbs and large eyes. Dromiceiomimus also had an exceptionally large brain.





(meaning "Niger Lizard"); pronounced (NYE-jer-SORE-us)

Nigersaurus lived in the Early Cretaceous Period.  This herbivore was 30 feet long, and weighed 5 tons.

Nigersaurus was a rather unusual sauropod with a relatively short neck compared to its tail.  It also had a flat vacuum-shaped mouth packed with hundreds of teeth, arranged in about 50 columns.  Judging by these odd characteristics, Nigersaurus was well adapted to low browsing.  It probably swept its neck back and forth parallel to the ground, vacuuming up all vegetation within easy reach.






(meaning "Good Mother Lizard"); pronounced (MY-ah-SORE-ah) 

Maiasaura lived in the Late Cretaceous Period.  This herbivore was 30 feet long, 6 to 8 feet tall, and weighed 3 to 4 tons. 

Maiasaura was a duck-billed dinosaur with a flat skull and small crests in front of the eyes.  This plant-eater had a toothless beak, cheek pouches, and many self-sharpening cheek teeth; hard enamel was found on both the outer surface of the upper teeth and the inner surface of the lower teeth.  The hands each had four fingers and the feet had hoof-like claws.

Maiasaura was the first dinosaur in space.  A bone fragment and piece of eggshell from Maiasaura flew with astronaut Loren Acton on a 8-day mission (Spacelab 2) in 1985. 





(meaning "Burrowing Runner"); pronounced (RICK-toe-DROE-mee-us)

Oryctodromeus lived in the Middle Cretaceous Period.  This herbivore was 6 feet long, and weighed about 50 to 100 pounds. 

Oryctodromeus was a small, swift dinosaur.  It is the only ornithopod proven to have lived in burrows.  The adults dug deep holes in the forest floor, where they hid from predators and probably laid their eggs.  Oryctodromeus did not have long arms for digging, but paleontologists think it may have used its pointed snout as a digging tool. It also had a flexible tail that made it easier for the dinosaur to curl up in its underground burrows.





(meaning "Savage Lizard"); pronounced (TOR-vo-SAWR-us)


Torvosaurus lived in the Late Jurassic Period.  This carnivore was 33 to 40 feet long, 8 feet tall at the hips,  and weighed about 3 tons. 

Cool Fact:  Torvosaurus walked on two powerful legs. It had strong, short arms; the forearms were about half the length of the upper arms. It had huge thumb claws and large, sharp teeth. Torvosaurus ate large plant-eating dinosaurs like stegosaurs and sauropods

Torvosaurus was found by Jim Jensen and Kenneth Stadtman in 1972, in the Dry Mesa quarry in western Colorado.  Fossils have also been found in Utah and Wyoming.




(meaning "hollow-backed-tailbone"); pronounced (Owe-piss-thoe-seel-ee-cawd-ee-ah)

Opisthocoelicaudia lived in the Late Cretaceous Period.  This herbivore was up to 40 feet long, and weighed about 20 tons. 

This large sauropod was discovered in 1965 in the Gobi Desert. This animal was shorter than many other sauropods, but was also heavier than most, meaning that its body was large and compact.  The fossils found lacked the skull and most of the neck.



Majungatholus(meaning "Mahajanga Lizard"); pronounced (mah-JUNG-ge-SOR-es)

Majungatholus lived in the Late Cretaceous Period.  This carnivore was up to 30 feet long and was at the top of the food chain in its locale. Majungatholus was found recently on the island of Madagascar, off the east coast of Africa.

Majungatholus belongs to the group of dinosaurs called abelisaurids, which until now were only found in India and South America.  It is especially similar to the horned dinosaur Carnotaurus, which is found in Argentina.  Finding this Majungatholus in Madagascar, far from its relatives in India and South America, has implications for plate tectonics.  In particular, the continent of Gondwanaland may have had a connecting land-bridge from South America through Antarctica to India-Madagascar from longer than believed, allowing animals like Majungatholus to slowly migrate to new, far flung habitats.


Nqwebasaurus (Greek for "Nqweba Lizard"); pronounced (en-KWEB-ah-SAWR-us)

Nqwebasaurus lived in the Early Cretaceous Period.  This carnivore was 2.5 feet long, 15 inches tall, and weighed 1.3 pounds. This dinosaur was found in Africa.

This little African meat-eater is very important because it provides many clues about African dinosaurs in the Cretaceous period.  Nqwebasaurus lived at the very beginning of the Cretaceous Period, when Africa, South America, Australia, and Antarctica were still one giant island continent called Gondwana.  This is the oldest know dinosaur from the family that includes T. rex to be found on one of the continents that once made up Gondwana.  This little hunter, who probably ate bugs and lizards, was the great grandfather of many larger predators.



Kosmoceratops (Greek for "ornate horned lizard"); pronounced (KOZ-mo-SARA-tops)

Kosmoceratops lived in the Late Cretaceous Peroid.  This herbivore was 15 feet long, 6 feet tall, and weighed 2 1/2 tons. 

Unearthed in 2010 Kosmoceratops is part of series of discoveries that have recently expanded the number of species in the ceratopsia, or horned-face, family of herbivorous dinosaurs. The most ornate skull of any known dinosaur with 10 hooks extending from the short, broad neck frill and 15 horn-like structures, Kosmoceratops is closely allied with Chasmosaurus from Alberta.



Micropachycephalosaurus (Greek for "tiny thick-headed lizard"); pronounced MY-cro-PACK-ee-SEFF-ah-low-SORE-us.

Micropachycephalosaurus lived in the Late Cretaceous Peroid (80 - 70 million years ago).  This herbivore was 2 feet long and weighed 5-10 pounds. 

The name Micropachycephalosaurus may seem like a mouthful, but it's not so bad if you break it down into its constituent Greek words: micro, pachy, cephalo, saurus. That translates into "tiny thick-headed lizard," and fittingly, Micropachycephalosaurus is the smallest of all the known pachycephalosaurs (otherwise known as boneheads). For the record, the dinosaur with the shortest name--Mei--was also bite-sized; make of that what you will!

Because Micropachycephalosaurus has been reconstructed from incomplete remains dug up in China, the possibility looms that this genus may one day be "downgraded"--that is, paleontologists will agree that it's another type of pachycephalosaur entirely (recently, experts figured out that the shape of pachycephalosaur skulls changed as these dinosaurs aged, makes classification mistakes all the more likely). If that happens, some other multisyllabic dinosaur (possibly Brachytrachelopan) will rise up to assume the "world's longest name" title.


Appalachiosaurus (Greek for "Appalachia lizard"); pronounced ah-pah-LAY-chee-oh-SORE-us.

It's not often that dinosaurs are dug up in the southeastern U.S., so the discovery in 2005 of Appalachiosaurus was big news. The fossil, believed to be of a juvenile, measured about 23 feet long, and the dinosaur that left it probably weighed a bit less than a ton. Abstracting from other tyrannosaurs, paleontologists believe a full-grown adult might have measured about 25 feet long and weighed about two tons.

Weirdly, Appalachiosaurus shares a distinctive feature--a series of ridges on its snout--with an Asian tyrannosaur, Alioramus. However, experts believe Appalachiosaurus is most closely related to another North American predator, the even larger Albertosaurus. (By the way, the specimen of Appalachiosaurus, as well as one of Albertosaurus, show evidence of Deinosuchus bite marks--indicating that this Cretaceous crocodile occasionally tried to take down big dinosaurs!)


Atlascopcosaurus means "Atlas Copco Lizard".  It was about 10 feet long and weighed about 300 pounds.  It lived in the Early to Middle Cretaceous period in Australia. Atlascopcosaurus was one of the few dinosaurs to be named after a corporation (Atlas Copco, and Australian manufacturer of mining eqiupment).  Atlascopcosaurus was a small ornithopod that bore a marked resemblance to Hypsilophodon.  This dinosaur was discovered and described by the husband and wife team of Tim and Patricia Vickers-Rich, who diagnosed Atlascopcosaurus on the basis of widely scattered fossil remains, almost 100 separate bone fragments consisting mostly of jaws and teeth.


Nanotyrannus (meaning "dwarf tyrant") lived in the Late Cretaceous, about 70 million years ago.  It was about 17 ft long and weighed half a ton. 

When the skull of Nanotyrannus  was discovered in 1942, it was identified as belonging to another dinosaur, Albertosaurus, but upon closer study, researchers speculated that it might have been left by an entirely new genus of tyrannosaur. Today, opinion is divided into two camps: some paleontologists believe Nanotyrannus indeed deserves its own genus, while others insist it's a juvenile Tyrannosaurus Rex.

Further complicating matters, it's possible that Nanotyrannus wasn't a tyrannosaur at all, but a dromaeosaur (the class of small, carnivorous, bipedal dinosaurs better known as raptors). Until more fossils are found--and until now, the evidence has been scanty at best--the arguments will likely continue.


Tapejara (meaning "old being" in Tupi) was a pterosaur that dates from the early Cretaceous period, about 132 to 100 million years ago. This flying reptile ate fish and lived near the sea. A Pterodactyloid, it had a wingspan of about 16.5 feet and a short tail. It had a large head crest formed by skin stretched between two bony crests on its head, one above the nostrils, the other behind and above the eyes. The tip of its lower jaw turned downward. Fossils have been found in Northeast Brazil.



Masiakasaurus means "vicious lizard" that dates back to the Late Cretaceous period, about 70 to 65 million years ago. This dinosaur was found and named by my favorite Paleontologist, Dr. Scott Sampson.  Masiakasaurus was about 6 feet long and weighed about 80 lbs. This dinosaur is famous for its buck teeth.

Interesting Fact:  Masiakasaurus was a small, bipedal, meat-eating dinosaur that had forward-pointing teeth, a long neck, and a long tail. It was about the size of a really big dog. Masiakasaurus's species name, knopfleri, was named for Mark Knopfler, a guitarist and singer from the rock band Dire Straits. The paleontologists who discovered this dinosaur were listening to Knopfler's music when they found and dug up Masiakasaurus.




Pachycephalosaurus was a dome-headed dinosaur. Its huge head housed an incredibly thick skull, a tiny brain, and large eyes. Its rounded skull was up to 10 inches thick. 

Pachycephalosaurus grew to be about 15 feet long and may have weighed roughly 950 pounds. Pachycephalosaurus probably had a good sense of smell. It had bumpy knobs on its snout and along the rear of its skull. This plant-eater had short forelimbs and a stiff tail (which had a distinctive mesh of interwoven tendons surrounding its rear portion).

Pachycephalosaurus lived during the late Cretaceous period, about 76 to 65 million years ago, toward the end of the Mesozoic, the Age of Reptiles.  




Leptoceratops was discovered in North America in 1924 by Barnum Brown. Leptoceratops is a primitive horned dinosaur, who has the features of the earlier dinosaurs of this type. However, he lived much later, around 68 million years ago.

Scientists believe that Leptoceratops was a late surviving primitive horned dinosaur.

Leptoceratops had a small head frill, and no horns. He usually walked on all fours, but could also stand and run on two legs. Leptoceratops' front digits had the ability to grasp, and were probably used to pull branches and other food towards its mouth. 




Huayangosaurus means reptile of Huayang.  It was about 14 Ft. long and weighed about 1200 lbs.  Huanygosaurus belongs to a group of smaller plated dinosaurs known as the huayangosauridaes. These dinosaurs tended to live earlier (around the Jurassic Period) than their larger cousins. They also have only been found in Asia.




Carnotaurus was a large, bipedal, meat-eating dinosaur that looked a bit like a bull. It had two, knobby eyebrow-horns (hence its name), a small skull, extremely tiny arms (even smaller than those of T-Rex), and a long, thin tail. It may have had partial binocular vision (unlike most other dinosaurs) since the eyes were set facing slightly forwards .

Carnotaurus was 25ft long, 6.5 tall at the hips, and weighed 1 ton.Carnotaurus means "flesh(-eating) bull"



Xiaosaurus was a small, lightly-built dinosaur. It was an herbivore (a plant-eater) and a fast, agile runner. It was small and lizard-like, about 5 feet long. It walked on two long legs, had four-toed feet, five-fingered hands, short arms, a long, stiff, pointed tail, a flexible neck, and a small head with large eyes. It had leaf-shaped cheek teeth.

Xiaosaurus lived during the middle Jurassic period, about 169-163 million years ago.


Yangchuanosaurus means "Lizard from Yang-ch'uan, China".  Yangchuanosaurus was a large, powerful meat-eater. It walked on two large, muscular legs, had short arms, a strong, short neck, a big head with powerful jaws, and large, serrated teeth. It had a long, massive tail that was about half of its length. Its feet had three toes, each with a large claw. Its arms were short, and it had three clawed fingers on each hand.

Yangchuanosaurus was up to 33 feet long (10 m). It weighed roughly 5200 pounds (2350 kg). It had a large skull up to 3.5 feet (1.1 m) long with ridges and a bony knob on its snout. It was slightly smaller but very similar to its close relative Allosaurus

Yangchuanosaurus lived during the late Jurassic period to the early Cretaceous period, about 163-145 million years ago. 


Tuojiangosaurus lived in Asia, which is where scientists believe that plated dinosaurs called stegosauridaes initially evolved.

Like other plated dinosaurs, Tuojiangosaurus had a series of plates and spikes protruding out of its back, neck, and tail. These bones were connected to the skin of Tuojiangosaurus and did not actually attach to the skeleton.

Tuojiangosaurus had four large sharp spikes at the end of its tail, which it could use to defend itself. Strong tail muscles made it dangerous for enemies to get in the way of Tuojiangosaurus tail.

Tuojiangosaurus had longer hind legs, and shorter front legs, as well as an arched back, and a small head.