A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Appendix

Saichania
Taxon: Ankylosauria Ankylosauridae
Name means: “beautiful one”
Pronounced: sie-KAHN-ee-uh
Length: 24 ft (7 m)
Time: Late Cretaceous, 79 – 75 mya
Place: Mongolia

Fossil remains of this heavily-armored, club-tailed ankylosaur were so well preserved that they revealed new features which may apply to other species in the ankylosaurid family. For example, along with the usual armored back-plates, Saichania bore bony armor on its belly, leading paleontologists to wonder whether stomach armor may have been more common than previously thought. The structure of this dinosaur’s nostils and nasal cavities indicate that it may have had a keen sense of smell. Like all ankylosaurs, Saichania was a low-slung, tank-like plant-eater. The genus was named in 1977.

Saltasaurus
Taxon: Sauropoda Titanosauridae
Name means: “Salta Province lizard”
Pronounced: SAWL-tuh-SAW-rus
Length: 40 ft (12 m)
Time: Late Cretaceous, 83 – 79 mya
Place: Argentina

When Saltasaurus was excavated in Argentina, paleontologists were astounded to discover that this long-necked sauropod carried armor plates of bone on its body. The first of the armored titanosaurids to be found, Saltasaurus was discovered in association with only eight pieces of armor, suggesting that the entire body was not plated. The 4.5-inch-long plates may have been scattered across the dinosaur’s back to defend it against large predators. About 550 quarter-inch bony nodules were also discovered with the skeleton. These bumps appear to have acted as a light protective covering over the dinosaur’s back and sides. Named in 1980, Saltasaurus appears to have been related to Neuquensaurus.

Sanpasaurus
Taxon: possibly Iguanodontidae and Sauropoda
name means: “Sanba lizard”
pronounced: SAN-puh-SAW-rus
Length: Large
time: Middle Jurassic
place: China

Named in 1946 for Sanba, the ancient title of the Sichuan Province of China, the fossils associated with this dinosaur of mysterious origins appear to have come from two different species. Fragmentary remains, apparently from both an iguanodontid and a sauropod, initially led scientists to speculate that Sanpasaurus might have been a large member of either family. If some of the bones did come from an iguanodontid, then it was the first of those dinosaurs to be found in China. Most scientists consider the name “Sanpasaurus” to properly belong to the sauropod material, which seems to have come from a young long-necked plant-eater.

Sarcolestes
Taxon: Ankylosauria Nodosauridae
name means: “flesh robber”
pronounced: SAHR-koh-LES-teez
Length: Moderate
time: Middle Jurassic
place: England

Originally described and named as a meat-eating theropod, the poorly-preserved fossils of Sarcolestes actually belonged to a plant-eating armored nodosaur of as-yet-undetermined size. Its thick skull was similar to those of the bone-headed pachycephalosaurs, perhaps indicating that Sarcolestes engaged in head-butting behavior. Sarcolestes was named in 1893 and was quite similar to Sauropelta.

Sarcosaurus
Taxon: Theropoda
Name means: “flesh lizard”
Pronounced: SAHR-ko-SAWR-us
Length: 12 ft (3.5 m)
Time: Early Jurassic, 206 – 200 mya
Place: England

This meat-eating dinosaur may have carried crests or horns on its skull if, as has been suggested, it was one of the ceratosaurs. Unfortunately, the fossils of this genus are too fragmentary to draw many conclusions about this poorly-known dinosaur’s anatomy and classification. Sarcosaurus was named by Andrews in 1921.

Saturnalia
Taxon: Sauropodomorpha
Name means: “carnival dinosaur”
Pronounced: sat-uhr-NAYE-lee- uh
Length: 5 ft (1.5 m)
Time: Late Triassic, 227 – 221 mya
Place: Brazil

Named in 1999 for the Roman holiday of Saturnalia, this primitive plant-eater was discovered in the Santa Maria Formation of southern Brazil. This small sauropodomorph was described based on limited but partially-articulated skeletal material including the right hindlimb, including the foot and pelvic bone, the small skull, and serrated and leaf-shaped teeth. Saturnalia may have shared common traits with Herrerasaurus, another primitive South American dinosaur.

Saurolophus
Taxon: Hadrosaurinae
Name means: “lizard crest” or “crested lizard”
Pronounced: SAW-ruh-LOH-fus
Length: about 32 ft (10 m)
Time: Late Cretaceous, 72 – 68 mya
Place: Alberta, Mongolia

Found with a nearly-complete skeleton, this Canadian duckbill discovery even included fossilized skin impressions. As part of the hadrosaurine family, Saurolophus lacked the hollow head-crest of the lambeosaurine duckbills but bore a bony, spike-like crest above and between its eyes. It may be that only one gender, male or female, had this probably ornamental feature. The excavation of a strikingly similar hadrosaurid fossil in Mongolia supports the theory that ancient land-bridges connected the separating continents during the Late Cretaceous. Saurolophus was named in 1912 by Barnum Brown.

Sauropelta
Taxon: Ankylosauria Nodosauridae
Name means: “lizard shield”
Pronounced: SAW-ruh-PEL-tuh
Length: 19 ft (6 m)
Time: Early Cretaceous, 116 – 91 mya
Place: Montana, Wyoming, Utah

Sauropelta was a medium-sized armored nodosaur which fed on plants and lacked the bony clubbed tail of the related ankylosaurids. The dinosaur’s long hind legs gave it an arched spine. Sharp triangular spikes were strategically placed just in front of the shoulders to ward off unwary predators. Sauropelta was named by John Ostrom in 1970.

Saurophaganax
Taxon: Allosauridae
Name means: “lizard-eater master” or “king of the lizard-eaters”
Pronounced: SAW-ro-FAG-a-nacks
Length: 49 ft (15 m)
Time: Late Jurassic, 154 – 151 mya
Place: Oklahoma

Paleontologist Dan Chure suggested this name in 1995 for fossil material attributed to an extremely large meat-eating allosaurid discovered in Oklahoma. A similar dinosaur had once been named “Saurophagus,” but that genus is no longer considered to be scientifically valid. Huge for an allosaurid, Saurophaganax was likely a superb hunter-killer, using its bladelike teeth and talons to bring down even the largest prey.

Sauroplites
Taxon: possibly Ankylosauria Nodosauridae
name means: “shield-carrier lizard”
pronounced: SAW-ruh-PLYE-teez
Length: Moderate
time: Late Cretaceous
place: China

This large, bulky armored dinosaur was identified from only a few, fragmentary fossils, including plates from its back and ribcage. Named in 1953, Sauroplites may have been a plant-eating, four-legged nodosaurid, lacking the tail club of the related ankylosaurid dinosaurs.

Sauroposeidon
Taxon: Sauropoda
Name means: “lizard Poseidon” (for the Greek god Poseidon)

A newly-discovered, Brachiosaurus-like sauropod, the titanic Sauroposeidon was named for the Greek god of the sea and earthquakes. An estimated 60 feet (20 meters) tall from the toes of its forefeet to the top of its head, this may be the tallest dinosaur yet known

Saurornithoides
Taxon: Theropoda Coelurosauria Troodontidae
Name means: “lizard bird form” or “lizard with birdlike rostrum”
Pronounced: SAWR-or-ni-THOY-deez
Length: 6.5 – 11.5 ft (2 – 3.5 m)
Time: Late Cretaceous, 85 – 77 million years ago
Place: Mongolia

As Osborn studied the skull of Saurornithoides, he noted that it bore similarities to the skulls of toothed birds. Named for those similarities, this large-brained biped was indeed a very birdlike dinosaur. Swift, agile, and much like its North American cousin Troodon, Saurornithoides likely stalked the Gobi Desert of the Cretaceous in search of a meal of small mammals or reptiles. The great similarity between the two troodontids provides evidence that a land bridge connected the continents when their closest common ancestor lived. Saurornithoides was named in 1924.

Saurornitholestes
Taxon: Theropoda Dromaeosauridae
Name means: “lizard-bird robber”
Pronounced: SAWR-or-NITH-uh-LES-teez
Length: 6 ft (1.8 m)
Time: Late Creataceous, 76 – 73 mya
Place: Alberta

This small, lightly-built carnivore had a large head with a narrow snout. Highly flexible wrists and long forelimbs gave Saurornitholestes excellent dexterity, and the extendable sickle-claw on the second toe of each foot made it a lethal predator. A long, stiff tail provided balance for running and leaping. Very similar to Velociraptor and Deinonychus, relatives from Asia and North America, Saurornitholestes provides yet more evidence for the presence of Late Cretaceous land bridges between the continents. This genus was named in 1978.

Scelidosaurus
Taxon: Scelidosauridae
Name means: “hind-limb lizard”
Pronounced: SKEL-ey-duh-SAW-rus
Length: 13.5 ft (4 m)
Time: Early Jurassic 208 – 200 mya
Place: England

Sir Richard Owen knew that Scelidosaurus had powerful hind legs. What he didn’t realize when he named this genus in 1859 was that it was, in actuality, a primitive armored quadruped which walked on all four limbs. Scelidosaurus carried both bony armor and small, rounded scales. Skin impressions were found with the dinosaur’s fossilized bones, offering scientists a rare peek at the arrangement of those plates and scales in life. The apparently slow-moving Scelidosaurus might have at times reared up to walk on those two powerful hind limbs for which it was named.

Scipionyx
Taxon: Coelurosauria
Name means: “Scipio’s claw”
Pronounced: sip-ee-ON-icks
Length: juvenile, 2 ft (60 cm); adult estimated at 6.5 – 10 ft (2 – 3 m)
Time: Early Cretaceous, 121 – 112 mya
Place: Italy

Named in 1998 in honor of 18th-century Italian geologist Scipione Breislak, this small, carnivorous coelurosaur is related to the “killer-clawed” meat-eaters. The first dinosaur material ever discovered in Italy, the fossils from which Scipionyx was described belonged to tiny juvenile that appears to have died very shortly after it hatched. Complete except for a portion of its tail, this remarkable skeleton appears to include the rarest of the rare – fossil evidence of soft tissue, in the form of impressions in the rock of several internal organs, including the liver. Although the lungs were not preserved, the placement of the liver helps scientists to estimate their size and positioning, providing a means for reconstructing the dinosaur’s respiratory system. The gut seems to have been small, indicating that Scipionyx had a fast, efficient metabolism that processed food quickly. Adult members of this genus may have been six feet long or more.

Scolosaurus
Name means: “spiny lizard”
Pronounced: SKOH-luh-SAWR-us

This dinosaur is now known to be EUOPLOCEPHALUS.

Scutellosaurus
Taxon: Thyreophora
Name means: “little-shield lizard”
Pronounced: SKOO-tuh-luh-SAW-rus
Length: 4 ft (1.2 m)
Time: Early Jurassic, 208 – 200 mya
Place: Arizona

This small plant-eater had a very long tail and carried more fully-developed armor than any other known primitive dinosaur. More than 300 plates with six different shapes were found with the fossilized skeleton of Scutellosaurus. Long hind limbs suggest that Scutellosaurus may have been bipedal, walking on its rear legs. The dinosaur’s wide pelvis and long torso, on the other hand, indicate that it may have moved on all fours. Named by Colbert in 1981, Scutellosaurus was a distant ancestor, or closely related to thar ancestor, of the plated and armored dinosaurs of the Jurassic and Cretaceous.

Secernosaurus
Taxon: Hadrosauridae
Name means: “separated lizard”
Pronounced: suh-KUR-nuh-SAW-rus
Length: 10 ft (3 m)
Time: Late Cretaceous, 73 – 65 mya
Place: Argentina

Named by Michael Brett-Surman in 1979, this small duckbilled dinosaur was scientifically described as a genus based on the fossilized remains of a braincase and a few pelvic bones. Without the rest of the skull, it has proven difficult to tell whether Secernosaurus carried a crest on its head. This plant-eater was one of the first hadrosaurids to be discovered in the Southern Hemisphere.

Segisaurus
Taxon: Theropoda
Name means: “Segi lizard”
Pronounced: SEG-ih-SAW-rus
Length: juvenile, about 3.3 ft (1 m)
Time: Early Jurassic, c. 206 - 200 mya
Place: Arizona

This very small carnivore was found with its hind limbs and feet flexed beneath its body. This unusual posture has led scientists to believe that Segisaurus could squat down like a modern-day chicken. The bipedal dinosaur’s feet were especially well-adapted for clawing, and the fingers of its short forelimbs seem well-designed for raking a meal of insects or small animals out of the ground. Segisaurus was scientifically described and named in 1936.

Segnosaurus
Taxon: Therizinosauroidea Segnosauridae
Name means: “slow lizard”
Pronounced: SEG-nuh-SAW-rus
Length: 13 – 29.5 ft (4 – 9 m)
Time: Late Cretaceous, c. 97.5 - 88.5 mya
Place: Mongolia, Alberta

Segnosaurus was the first member of the mysterious and perplexing Segnosauridae familu to be discovered. This medium-sized dinosaur appears to have had characteristics of both two-legged and four-legged animals. Some elements of its anatomy suggest a diet of plants, while others indicate that the dinosaur was a meat-eater. Segnosaurus seems to have been a strong but slow-moving dinosaur, with a long neck, bulky body and limbs, and a lengthy tail. Although segnosaurids were members of the generally carnivorous theropod dinosaur group, their diet and lifestyle remains a puzzle to paleontologists. Segnosaurus was named in 1979.

Seismosaurus
Taxon: Sauropoda Diplodocidae
Name means: “earthquake lizard” or “earth-shaker lizard”
Pronounced: SIES-mo-SAWR-us
Length: about 131 – 164 ft (40 - 50 m)
Time: Late Jurassic, 156 – 145 mya
Place: New Mexico

This massive plant-eating sauropod was named as an earth-shaker for good reason. As long as a football field, the titanic Seismosaurus must have weighed hundreds of tons. Although fossil material remains limited for the moment, Seismosaurus appears to have been a lengthy, low-slung dinosaur much like the whip-tailed Barosaurus and Diplodocus. Sauropods lacked the necessary teeth and jaw structure for chewing, and a group of smooth, rounded stones discovered in the sauropod’s stomach region indicates that Seismosaurus ingested small rocks, adding them to a bird-like crop or gizzard which crushed plants that the dinosaur had eaten into an easily-digested pulp. One of these stones was exceptionally large, leading some scientists to theorize that the mighty Seismosaurus may have choked to death while attempting to swallow it. David Gillette named this genus in 1991.

Sellosaurus
Taxon: Prosauropoda Plateosauridae
Name means: “saddle lizard”
Pronounced: SEL-uh-SAW-rus
Length: 20 ft (6 m)
Time: Late Triassic, 219 – 208 mya
Place: Germany

This plant-eating prosauropod was medium-sized for its group of primitive sauropod relatives. Stout and primitive, Sellosaurus was named for its wide, flat tail vertebrae by von Huene in 1908.

Shamosaurus
Taxon: Ankylosauria Ankylosauridae
Name means: “desert lizard”
Pronounced: - SHAM-uh-SAW-rus
Length: 23 ft (7 m)
Time: Early Cretaceous, 119 – 97.5 mya
Place: Mongolia

An Asian ankylosaur discovered in the Gobi Desert, Shamosaurus is the earliest-known club-tailed armored dinosaur from China. Its small skull was ornamented with small, raised bumps of bone. The four-legged, plant-eating, arnor-plated Shamosaurus resembled Saichania and may have been an evolutionary link between the plain-tailed nodosaurs and the club-tailed ankylosaurs. This genus was named in 1983.

Shanshanosaurus
Taxon: Theropoda
Name means: “Shanshan lizard”
Pronounced: shan-SHAN-uh-SAW-rus
Length: 8.5 ft (2.5 m)
Time: Late Cretaceous, c. 83 – 65 mya
Place: China

This small, bipedal meat-eater is something of a mystery. It seems to have been an active, agile predator, but its classification within the dinosaur family tree remains poorly-understood. Some paleontologists believe that Shanshanosaurus belongs in its own distinct family. Others argue that the dinosaur is an Aublysodon, similar to both the large carnivores of South America and the smaller Asian and North American dromaeosaurids, Shanshanosaurus was named in 1977.

Shantungosaurus
Taxon: Hadrosauridae
Name means: “Shandong lizard”
Pronounced: shan-TUNG-uh-SAW-rus
Length: about 51 ft (15 m)
Time: Late Cretaceous, 83 – 73 mya
Place: China

Shantungosaurus is among the largest of all known duckbilled dinosaurs. Apart from its unusual size, this four-legged plant-eater was very much like North America’s Edmontosaurus. Like all flat-headed hadrosaurs, Shantungosaurus had a long, broad skull with a short beak and densely-packed tooth batteries for efficiently crushing plants. The only known specimen of this genus was named in 1977 for the Shangdong Province of China where it was found.

Shanxia
Taxon: probably Ankylosauria Ankylosauridae
Name means: “for Shanxi,” after Shanxi Province in China
Pronounced: shahn-SHEE-a
Length: about 12 ft (3.6 m)
Time: Late Cretaceous, c. 99 – 65 mya
Place: China

Excavated in the Hiquanpu Formation of northeastern China, this incomplete skeleton appears to be that of an armored ankylosaur. Vertebrae, leg bones, a single armored scute and fragments of the animal’s broad skull indicate that Shanxia was a sturdy four-legged plant-eater. Distinctive elongated, slender and triangular horns protruded from the back of the dinosaur’s head. Shanxia was named in 1998 for the Shanxi Province in China.

Shanyangosaurus
Taxon: Theropoda
Name means: “Shanyang lizard”
Pronounced: shan-yahng-o-SAW-rus
Length: Small
Time: Late Cretaceous, c. 99 – 65 mya
Place: China

Named in 1996 for the Shanyang Formation in China, this small theropod was described based mostly on the fossilized bones of its front and hind limbs. Little else is known about the meat-eating Shanyangosaurus at this time.

Shunosaurus
Taxon: Sauropoda Cetiosauridae
Name means: “Sichuan lizard”
Pronounced: SHOO-nuh-SAW-rus
Length: about 29.5 – 46 ft (9 - 14 m)
Time: Middle Jurassic, 175 – 163 mya
Place: China

This unusual sauropod had a surprise in store for paleontologists. The long-necked browser had a spiked, bony club at the end of its slender tail. This small but solid weapon, previously unknown in sauropod dinosaurs, could have been lashed by the whip-like tail to devastating effect in defense against predatory dinosaurs. Shunosaurus was named in 1983.

Shuvosaurus
Taxon: possibly Theropoda
Name means: “Shuvo’s lizard”
Pronounced: SHOO-vo-SAW-rus
Length: Small
time: Late Triassic
place: Texas

Shuvosaurus was named by Sankar Chatterjee in 1993 to honor his son, Shuvo. Some scientists have suggested that the skull of this presumed ornithomimosaur may have actually belonged to a small bipedal rauisuchian reptile. The rest of the skeleton appears to have come from a two-legged theropod predator.

Shuvuuia
Taxon: possibly Theropoda
Name means: “bird”
Pronounced: shu-VOO-ee-a
Length: 3.3 ft (1 m)
Time: Late Cretaceous, c. 83.5 - 71 mya
Place: Mongolia

This unusual, Mononykus-like meat-eater had a birdlike skull. Its snout contained joints which allowed it to flex upward. Although this turkey-sized animal has been described as a small theropod dinosaur, many experts believe that it is actually an alvarezsaurid or primitive, flightless bird. Shuvuuia was named in 1998 by Norell and Clark based on fossil material which included two very well-preserved skulls.

Siamosaurus
Taxon: Theropoda Spinosauria Spinosauridae
Name means: “Siamese lizard”
Pronounced: sye-AM-uh-SAW-rus
Length: Large
Time: Late Jurassic, 163 – 145 mya
Place: Thailand

Known only from teeth that closely resemble those of the North African meat-eater Spinosaurus, this large carnivore may have lived primarily on fish. Named in 1986, Siamosaurus had smooth, compressed teeth, similar to those of fish-eating marine reptiles like plesiosaurs and amphibious crocodiles. These teeth were better suited for piercing than for slicing or tearing flesh, and could allow a quickly snapping jaw to firmly grip a mouthful of wriggling fish. Like other spinosaurids, Siamosaurus had three-fingered hands and tall back spines which may have supported a sail in life.

Siamotyrannus
Taxon: Theropoda Tyrannosauridae
Name means: “Siamese tyrant”
Pronounced: sye-AM-uh-ti-RAN-us
Length: 21 ft (6.5 m)
Time: Early Cretaceous, c. 144 – 99 mya
Place: Thailand

Siamotyrannis, the earliest known tyrannosaurid to have stalked the Earth, was discovered in northeastern Thailand. Little is known so far about this meat-eating theropod, which was named in 1996.

Sigilmassasaurus
Taxon: Theropoda
name means: “Sijilmassa lizard”
pronounced: see-jil-MAH-sah-SAW-rus
Length: Moderate
time: Middle Cretaceous
place: Africa

This meat-eating theropod was named in 1996 by Russell. Sigilmassasaurus was named for the once-thriving South African town of Sijilmassa, now a mecca in ruins. The remains of this poorly-known dinosaur were found in that same region of southern Morocco. Some scientists believe that the Sigilmassasaurus fossils may have actually belonged to a member of Carcharodontosaurus.

Siluosaurus
Taxon: probably Ornithopoda Hypsilophodontidae
Name means: “Silk Road lizard”
Pronounced: sih-LOO-o-SAW-rus
Length: Small
Time: Early Cretaceous, 121 – 99 mya
Place: China

Fossil hunters found Siluosaurus, seemingly the smallest known member of the plant-eating hypsilophodontids, upon the historic Silk Road – a route through China and Central Asia which was traveled by ancient silk traders. The classification of this genus was made based on the discovery of just two teeth, so details about the dinosaur remain unknown. Siluosaurus was named in 1996.

Silvisaurus
Taxon: Ankylosauria Nodosauridae
Name means: “forest lizard”
Pronounced: SIL-vi-SAW-rus
Length: 10.7 – 13 ft (3.25 – 4 m)
Time: Late Cretaceous, 116 – 113 mya
Place: Kansas

Perhaps named “forest lizard” due to its resemblance to Hylaeosaurus, this armored dinosaur had large protective spikes on its sides but, like all nodosaurs, carried no club on its tail. A primitive member of the ankylosaurs, Silvisaurus may have been ancestral to Edmontonia. Perhaps most distinctive about this dinosaur were the large sinus chambers of its skull. These may have amplified the dinosaur’s sounds in much the same way as a human’s voicebox. Silvisaurus was named in 1960.

Sinocoelurus
Taxon: probably Coelurosauria
name means: “Chinese coelurid”
pronounced: SYE-noh-si-LOOR-us
Length: Small
time: Early or Middle Jurassic
place: China

This small carnivorous reptile was named based on teeth found in the Sichuan Province of China. Those four slender teeth were unlike the teeth of most meat-eating dinosaurs. They lacked serrations, making it difficult to assign them to a particular animal. If Sinocoelurus is indeed the meat-eating dinosaur that some experts believe it to be, then it is the first Jurassic coelurosaur ever found in China. Without more and better fossil material, however, it is difficult to classify Sinocoelurus as a dinosaur at all with certainty.

Sinornithoides
Taxon: Theropoda Coelurosauria Troodontidae
Name means: “Chinese bird form”
Pronounced: sie-NOR-ni-THOI-deez
Length: 3.6 ft (1.1 m)
Time: Early Cretaceous, 121 – 99 mya
Place: China

Named by Russell and Dong in 1993, this bird-hipped dinosaur was a “killer-clawed” theropod from Asia. Similar to its North American cousin Troodon, Sinornithoides was probably a slender, large-brained hunter of small mammals and lizards.

Sinornithosaurus
Taxon: Theropoda Coelurosauria Maniraptora Dromaeosauridae
Name means: “Chinese bird lizard”
Pronounced: SIEN-or-nith-o-SAW-rus
Length: about 5 ft (1.5 m)
Time: Early Cretaceous, c. 16.5 mya
Place: China

Scientists who found this small, birdlike dromaeosaurid in the Yixian Formation of northeastern China say that its slender arms not only had the range of motion of a bird’s wings, but that they bore a feather-like covering as well, preserved in the form of fossil impressions. Patches of feathery strands about 40 mm long were found around different parts of this fascinating dinosaur’s body. As the downy coat was not completely preserved, it is unknown whether it may have covered the head and most of the body as well. Sinornithosaurus was described based on a fairly complete but disarticulated skeleton, including a skull just over five inches long. Its birdlike shoulders and forelimbs have been said to be very much like those of the much smaller, flying Archaeopteryx. A sharp-taloned predator, Sinornithosaurus was obviously not equipped for flight, so the feathery layer must have served some other function, possibly to keep the dinosaur warm or to provide a display for attracting a mate. This dinosaur’s forelimbs are about 80% as long as the hind limbs, making them proportionally the longest arms on a theropod to date. Portions of the right foot at the end of one strong, sleek leg show that Sinornithosaurus carried the slashing sickle-claw of its dromaeosaurid relatives. The genus was named in 1999.

Sinosauropteryx
Taxon: Theropoda Coelurosauria, probably Compsognathidae
Name means: “Chinese lizard wing”
Pronounced: SIEN-o-sawr-OP-ter-icks
Length: 4 ft (1.3 m), 2.3 ft (70 cm) juvenile
Time: Early Cretaceous or Late Jurassic, c. 14.5 mya
Place: China

This remarkable little dinosaur was found in the sediments of an ancient lake in the Liaoning Province of northeastern China. So well-preserved were the remains of Sinosauropteryx that even tiny, feather-like structures lining the back and tail were clearly visible on the stone slab in which the bones were fossilized. Initially misidentified as a primitive bird, Sinosauropteryx is in fact a small theropod, closely related to Compsognathus. Three individuals have been unearthed to date. These finds are of special significance because traces of soft tissue were preserved along with the bone. Eyes, internal organs, stomach contents, and even unlaid eggs still in the oviducts make this one of the most astounding dinosaurs ever found. In addition, Sinosauropteryx has the longest tail of any known theropod. The first of its three fingers ended in an enlarged slashing claw. Proto-feather filaments appear to have covered most of the dinosaur’s body in life, perhaps serving to keep the small animal warm. Examination of the preserved stomach contents shows that Sinosauropteryx ate small prey including lizards and mammals, and paired eggs within a female’s body indicate that Sinosauropteryx laid two eggs at a time, as Troodon is believed to have done. Named in 1996, this revolutionary creature was probably a quick, agile and alert hunter. Dinosaur science still has much to learn from Sinosauropteryx.

Sinosaurus
Taxon: possibly Theropoda
Name means: “Chinese lizard”
Pronounced: SYE-nuh-SAW-rus
Length: Unknown
Time: Early Jurassic
Place: China

The poorly-known Sinosaurus was named based on a partial jaw which appears to have belonged to a theropod, but not all paleontologists are convinced that it was a dinosaur at all. The teeth of this meat-eater were long, serrated and sharply-pointed, much like the teeth of a primitive thecodontian reptile. Sinosaurus was named in 1948.

Sinraptor
Taxon: Theropoda Carnosauria Sinraptoridae
Name means: “Chinese plunderer”
Pronounced: sien-RAP-tor
Length: 23 ft (7 m)
Time: Late Jurassic, 154 – 144 mya
Place: China

This large carnivorous dinosaur was discovered in northwestern China. Likely a capable hunter with two powerful legs and a complement of sharp teeth and claws, Sinraptor was named in 1993.

Sonorasaurus
Taxon: Sauropoda Brachiosauridae
Name means: “Sonora lizard,” after the Sonoran Desert
Pronounced: so-NORE-uh-SAWR-us
Length: 51 ft (15.5 m)
Time: Early Cretaceous, 112 – 99 mya
Place: Arizona

This medium-sized sauropod was about 30% smaller than its more famous relative, Brachiosaurus. Like other brachiosaurids, Sonorasaurus had high front legs, a sloping back, and a long neck that it held high in the air. Excavated about 40 miles southeast of Tuscon, Arizona, the dinosaur was identified from fossilized fragments of its limbs, pelvis, vertebrae and a collection of the stomach-stones called gastroliths. Sonorasaurus had only two small claws on its hind feet, while some brachiosaurids, including Pleurocoelus, had four. A tooth of the giant theropod Acrocanthosaurus was found embedded in the bones of Sonorasaurus, suggesting that the carnivore feasted on the dead or dying long-necked plant-eater. Found in 1995, Sonorasaurus was named in 1998. Before being officially published, the brachiosaurid was mistakenly identified as first a hadrosaurid, then a prosauropod, and finally a therizinosauroid.

Sphenospondylus
Name means: “wedge vertebra”
Pronounced: SFEE-noh-SPON-dih-lus
This is now known to be IGUANODON.

Spinosaurus
Taxon: Theropoda Spinosauria Spinosauridae
Name means: “spine lizard”
Pronounced: SPYE-nuh-SAW-rus
Length: about 39 ft (12 m)
Time: Late Cretaceous, c. 97.5 – 95 mya
Place: Egypt, Morocco

This giant, sail-backed meat-eater may have been among the largest carnivores ever to walk the earth. The bones of its back were longer than those of Tyrannosaurus rex. Even more notably, those vertebrae were topped with very tall spines of bone. In life, these spines may have been connected by a membrane of skin, giving this two-legged dinosaur a distinctive sail-like structure similar to that of the famous mammal-like reptile, Dimetrodon. The function of this fin remains unknown. It may have served as a display to attract mates, or acted as a heat regulator to cool the dinosaur down on hot days. Like other spinosaurids, Spinosaurus had narrow jaws full of sharp, conical teeth. The genus was named in 1915.

Spondylosoma
Taxon: possibly Saurischia
Name means: “vertebral body”
Pronounced: SPON-di-luh-SOH-muh
Length: Unknown
time: Middle Triassic
place: Brazil

Fragmentary fossils including two teeth helped define this strange dinosaur. Spondylosoma is generally thought to have been a primitive meat-eater, with long neck vertebrae and a small head similar to those of saurischians of the time. Without better fossil material, it is impossible to say more about this early genus, which was named in 1942.

Staurikosaurus
Taxon: Theropoda
Name means: “Southern Cross lizard”
Pronounced: STAW-rick-o-SAWR-us
Length: 7 ft (2 m)
Time: Late Triassic, 231 – 225 mya
Place: Brazil, possibly Argentina

Named for an astronomical constellation, this small South American theropod appears to have been among the earliest and most primitive of all dinosaurs. Like Herrerasaurus, a possible relative, Staurikosaurus had a slender neck and long, muscular legs with five-toed feet. Its forearms were small, with four-fingered hands. Later, more advanced theropod dinosaurs would lose these extra digits, walking on three toes and grasping or slashing with three-clawed hands (or, in the case of the advanced tyrannosaurids, only two). The Staurikosaurus genus was named in 1970.

Stegoceras
Taxon: Pachycephalosauria Pachycephalosauridae
Name means: “roof horn”
Pronounced: ste-GOS-er-us
Length: 7 ft (2 m)
Time: Late Cretaceous, 76 - 65 mya
Place: Alberta, Montana

Like all of the dome-skulled pachycephalosaurs, this small member of the group bore a dense layer of protective bone atop its skull. Unlike most dinosaurs, pachycephalosaurs like Stegoceras appear to have been able to hold their short necks parallel to their spines and tails, all the better to absorb the bone-jarring force of a head-on impact with another thick-headed dinosaur or a predator. The thickened skull bone of Stegoceras was originally mistaken for the bony core of a ceratopsian dinosaur’s horn, hence the dinosaur’s misleading naming in 1902.

Stegopelta
Name means: “roof shield”
Pronounced: STEG-o-PEL-ta

This dinosaur is now considered to be NODOSAURUS.

Stegosaurus
Taxon: Stegosauria Stegosauridae
Name means: “roofed lizard”
Pronounced: STEG-o-SAWR-us
Length: 23 – 29.5 ft (7 – 9 m)
Time: Late Jurassic, 156 – 145 mya
Place: Colorado, Utah, Wyoming

Stegosaurus was the first of the plate-backed dinosaurs to be discovered, and it remains the largest of that group known so far. A small-headed, plant-eating quadruped, Stegosaurus carried two rows of alternating bony plates, the largest more than two feet tall, arranged along its back from neck to tail. A pair of long spikes projected from each side of the tail near the tip; these could likely be swiped powerfully back and forth as a deterrent to predators. Small bony discs embedded in the dinosaur’s skin provided some protection for its vulnerable throat and hips, and may have covered other parts of the body as well. The function of the flattened, diamond-shaped back plates remains uncertain; popular theories suggest that they were adapted for defense from tall carnivores, display to attract a mate or compete with rivals, or perhaps for heat regulation, cooling the dinosaur down when it became too warm. There was once a popular misconception that this dinosaur had two brains. In actuality, the second “brain” was a nerve center in the hips, a feature shared with other dinosaurs. The Stegosaurus genus was named in 1877.

Stenonychosaurus
Name means: “narrow claw lizard”
Pronounced: ste-NON-ik-o-SAWR-us

This dinosaur is now considered to be the same animal as TROODON.

Stenopelix
Taxon: Ornithischia, probably Marginocephalia
Name means: “narrow pelvis”
Pronounced: sten-OP-eh-liks
Length: 5 ft (1.5 m)
Time: Early Cretaceous, c. 144 – 138 mya
Place: Germany
Date: 1857

One of Germany’s most complete dinosaur finds, Stenopelix is nonetheless fairly poorly-known. Once believed to have been related to the two-legged Hypsilophodon, it was later grouped with the primitive horned dinosaurs, the parrot-beaked psittacosaurs. Subsequently, the dinosaur was reclassified again as a thick-skulled marginocephalian pachycephalosaur. Given its shared anatomical characteristics, it may be that Stenopelix was related to the common ancestor of both the horned and the dome-skulled dinosaurs. The genus was named in 1857.

Stenotholus
Name means: “narrow dome”
Pronounced: STEN-o-THOL-us or ste-NOTH-o-lus

This dinosaur is now considered to be STYGIMOLOCH.

Stephanosaurus
Name means: “crown lizard”
Pronounced: STEF-an-o-SAWR-us

The material originally used to describe this now-invalid genus actually came from several different kinds of duckbilled hadrosaurs, including the crested Lambeosaurus.

Stereocephalus
Name means: “solid head” or “paired head”
Pronounced: STER-ee-o-SEF-a-lus

This dinosaur is now known as EUOPLOCEPHALUS.

Sterrholophus
Name means: “solid crest”
Pronounced: ster-ROL-o-fus

This dinosaur is now known to be TRICERATOPS.

Stokesosaurus
Taxon: Theropoda
Name means: “Stokes’ lizard,” for William Lee Stokes
Pronounced: STOHK-so-SAWR-us
Length: 4 m (13.5 feet)
Time: Late Jurassic, 156 – 145 mya
Place: Utah

Named for American paleontologist William Lee Stokes in 1974, this two-legged, meat-eating theropod had a strange vertical ridge running down the middle of its pelvic bone. It may also have had a short, stubby snout, but the fragmentary nature of its limited fossil material makes Stokesosaurus a fairly poorly-known dinosaur. It may have been a very early tyrannosaurid or carnosaur.

Strenusaurus
Name means: “vigorous lizard”
Pronounced: STREN-yuh-SAWR-us
This is now known as RIOJASAURUS.

Streptospondylus
Taxon: possibly Theropoda
Name means: “reversed vertebra”
Pronounced: STREP-to-SPON-di-lus
Length: Unknown

This carnivorous reptile, based on very fragmentary remains, may have been predatory allosaurid. Some paleontologists believe that it was a crocodylomorph, an archosaurian reptile, but not a dinosaur at all.

Struthiomimus
Taxon: Ornithomimidae
Length: “ostrich mimic”
Pronounced: STROOTH-ee-o-MIME-us
Length: 13 ft (4 m)
Time: Late Cretaceous, 76 – 70 mya
Place: Alberta

Because this bird-like bipedal dinosaur’s skull, neck, leg and foot structures so closely resembled those of the modern-day ostrich, Osborn named it for that large flightless bird in 1916. An average-sized, toothless member of the swift ornithomimid dinosaurs, the largely-defenseless Struthiomimus had to rely on its speed and eyesight to hunt for food and evade predators. Its hands were large and powerful, equal in length to its upper arm and bearing three deft, clawed fingers. The dinosaur’s skeleton was surprisingly light, contributing to its sprinting ability. Struthiomimus likely ate what meat it could catch and devour with its toothless, beak-like jaws, perhaps favoring small mammals, reptiles and insects.

Struthiosaurus
Taxon: Ankylosauria Nodosauridae
Name means: “ostrich lizard”
Pronounced: STROO-thee-o-SAWR-us
Length: 7 ft (2 m)
Time: Late Cretaceous, 83 – 65 mya
Place: Austria, France, Hungary, possibly Spain

First assigned to the Ornithocephala, an odd new order of “bird-headed” reptiles, then described as a meat-eating theropod dinosaur, Struthiosaurus was finally classified as a member of the armored ankylosaurs. Known originally only from a skull fragment, Struthiosaurus appears to have been a primitive, club-less nodosaur and is the smallest ankylosaurian dinosaur known so far. Only a quarter the size of the North American nodosaurids, Struthiosaurus may have been the last of its kind to survive in Europe. This plant-eating genus was named in 1870.

Stygimoloch
Taxon: Pachycephalosauria
Name means: “Styx demon” or “Hell Creek demon,” after the mythical River Styx of the Underworld and the demonic sun god Moloch
Pronounced: STIG-ih-MOL-uck or STIJ-i-MOL-ock
Length: 7 ft (2 m)
Time: Late Cretaceous, 68 – 65 mya
Place: Montana

Named for the River Styx, a mythical underground river that passed through the Greek underworld, and for the horned Moloch, an ancient, demonic sun god, this ferocious-looking dinosaur with a crown of long spikes was actually a relatively small plant-eater. Found in Hell Creek, Montana and named in 1983, Stygimoloch was a dome-headed pachycephalosaur with a distinctive array of long spikes rising from its skull. The largest of these horns is nearly four inches long. The use of the River Styx in the dinosaur’s name is not so much a comment on its dramatic appearance as a reference to the Hell Creek formation in Montana, where Stygimoloch was discovered.

Stygivenator
Taxon: Theropoda Tyrannosauridae
Name means: “Styx hunter” or “Hell Creek hunter”
Pronounced: STIJ-I-vee-NAY-tor
Length: 13 – 16 ft (4 – 5 m)
Time: Late Cretaceous, 71 – 65 mya
Place: Montana

The meat-eating Stygivenator was named for the Styx (a mythical underworld river in the ancient Greek afterlife), an allusion to the “Hell Creek Formation” in Montana where the specimen was discovered. Named in 1995, this dinosaur was once called the “Jordan Theropod” and referred to the genus Aublysodon.

Styracosaurus
Taxon: Centrosaurinae
Name means: “spike lizard”
Pronounced: STYE-rak-o-SAW-rus
Length: 18 feet (5.25 m)
Time: Late Cretaceous, 77 – 73 mya
Place: Alberta, Montana

This magnificent-looking ceratopsian dinosaur was named for its ornate frill and horn configuration. The bony neck-frill of the horned Styracosaurus positively bristled with long, tapering spikes. Perhaps the fearsome frill array evolved in order to make the small, horned plant-eater seem larger and more intimidating to predators like Albertosaurus, which also roamed Late Cretaceous North America. The large collar of frill spikes may also have helped the dinosaur to put on a display of dominance in competition over territory or mating rights with other member of its own species. Lambe named this spectacular genus in 1913.

Suchomimus
Taxon: Spinosauridae
Name means: “crocodile mimic”
Pronounced: SOOK-o-MIEM-us
Length: sub-adult, 36 ft (11 m)
Time: Early Cretaceous, 121 – 112 mya
Place: Niger

When its partial skull was discovered, the long, narrow snout of this large theropod gave it a rather crocodilian appearance. Paul Sereno and his team therefore named it Suchomimus, ‘the crocodile-mimic,’ in 1998. Suchomimus was a spinosaurid, very much like England’s Baryonyx. The teeth in its four-foot-long skull are curved and finely-serrated, unlike the smooth, needle-like spearing teeth of another relative, Spinosaurus. Suchomimus shares with Baryonyx a pair of robust forearms with large, curving talons and a massive thumb-claw, ideal for gaffing fish or tearing into other prey. Tall spines along the dinosaur’s back may have been connected in a sail over its hips in life. If, as its skull shape suggests, Suchomimus was a fish-eating piscivore, it may have waded into rivers like a bear, using its hooked thumb claws and crocodile-like snout to catch a meal. Suchomimus might also have been able to swim, using its powerful hind legs and tail to propel it through the water.

Supersaurus
Taxon: Diplodocidae
Name means: “super lizard”
Pronounced: SOO-pur-SAW-rus
Length: 98 – 138 ft (30 – 42 m)
Time: Late Jurassic, 154 – 144 mya
Place: Colorado

This astoundingly long sauropod was found in Colorado’s Dry Mesa Dinosaur Quarry and named based on incomplete fossil material. Even incomplete, however, the sheer size of Supersaurus cannot be denied. The shoulder bone alone is more than eight feet long. Weighing an estimated fifty tons, this massive, four-legged plant-eater had a narrow head and a remarkably long neck and whip-like tail. Supersaurus was found in 1973 by “Dinosaur” Jim Jensen and named in 1985.

Syngonosaurus
Name means: “kindred lizard”
Pronounced: sing-GON-o-SAWR-us

This dinosaur is now known as ANOPLOSAURUS.

Syntarsus
Taxon: Theropoda Podokesauridae
Name means: “fused tarsus,” after its fused ankle bones
Pronounced: sin-TAHR-sus
Length: 10 ft (3 m)
Time: Early Jurassic, 208 – 194 mya
Place: Zimbabwe (Africa), Arizona

Named for the fact that its ankle and foot bones are fused together, this small, bipedal meat-eater was built for speed. Closely related to New Mexico’s Coelophysis, it had a small head, a long, sinuous neck, and large, well-developed hands with three dexterous clawed fingers. The remains of thirty Syntarsus individuals were excavated from a single locality in Zimbabwe, South Africa. Two skeletal types appear to both represent adults of the same species. They may indicate physical differences between the genders. Most paleontologists believe that the more robust specimens were female, and the lighter ones male. The presumed-female dinosaurs were as much as 15% larger than those considered to be males. As it is unusual for the skeletons of so many dinosaurs of the same species to be found all together, it is assumed that this group died under sudden and catastrophic circumstances. Syntarsus was named in 1969.

Syrmosaurus
Name means: “crawling lizard”
Pronounced: SUR-moh-SAW-rus

This dinosaur is now known as PINOCOSAURUS.

Szechuanosaurus
Taxon: Theropoda Allosauridae
name means: Sichuan lizard
pronounced: SECH-oo-WAN-nuh-SAW-rus
Size: 20 ft (6 m)
time: Late Jurassic
place: China

This medium-sized meat-eater has been assigned to the allosaurid family. With its massive head, short neck, and arms bearing three large, sharp claws, Szechuanosaurus was likely a capable hunter. The genus was named in 1942 for the Sichuan Province of China.