Hadrosaurus

Audrey.m.horn, CC BY-SA 4.0, via Wikimedia Commons

 (HAD-row-SORE-us) was an Ornithischia dinosaur who lived near what is now the coast of New Jersey, USA, in the Campanian – Maastrichtian stages during the late Cretaceous Period around 80 million years ago.

Hadrosaurus measured 23 to 32 feet (7 – 10 metres) in length and weighed around 7 tons. It had a bulky body, a stiff tail and 4 legs and Its teeth suggest it ate twigs and leaves.

Hadrosaurus was a bipedal dinosaur for the purpose of running, however, it could use its forelimbs to support itself while grazing. Their rear legs were much larger than their front legs and they had hoof-like nails on their feet.

Hadrosaurus foulkii was the only species in this genus and, as of 1991, was the official state dinosaur of New Jersey – a decision brought about by a local teacher, Joyce Berry.

Hagryphus

Jens Lallensack, CC BY-SA 4.0, via Wikimedia Commons

FURTHER READING AND STUDY

• Lindsay and Scott (2005). A New Oviraptorosaur of Utah.

• Zanno and Sampson (2003). A new caenagnathid specimen from the Kaiprowits Utah.

• Lamanna, M. C.; et al. (2014). A New large-bodied oviraptorosaurian theropod dinosaur from the latest Cretaceous of western North America

The Hagryphus (Ha-grif-us) was an oviraptorosaurian theropod dinosaur that lived between 100.5 and 66 million years ago. It was a feathered, beaked omnivore. Only one Hagryphus species has been named, the type species Hagryphus giganteus, by Lindsay Zanno and Scott Sampson in 2005. This theropod, represented by a nearly entire left hand, part of the left radius, and parts of the foot, lived 75 million years ago preserved in Utah’s Grand Staircase-Escalante National Monument. The generic name is derived from Egyptian Ha, the name of the god of the western desert, and a Latinized Greek (gryps) meaning ‘gryphon’ (a mythological bird-like creature), while the species name is Latin for ‘gigantic.’

The dinosaur’s fossil remains indicate that it was one of the largest oviraptorosaurs, with an average weight and length of roughly 110 lb (50 kg) and 8-10 ft (2.5-3 m), respectively. This species’ hand was also estimated to be about 1 ft (31 cm) length.   The incomplete left hand, a distal component of the left radius, and a few portions of the foot discovered imply that the species lived in swampy areas. Wetland peat swamps, ponds, and lakes dominated the plateau where the species lived, which was surrounded by hills. The climate was moist and humid, allowing a wide variety of creatures to thrive. This formation has one of the best and longest records of Late Cretaceous terrestrial life anywhere on the planet

These dinosaurs’ toothless jaws indicate that their diet comprised eggs, as well as vegetation and tiny animals. Paleontologists determined that they were real birds based on their lifestyle and physical characteristics. The head of Hagryphus was relatively small. The dinosaur was similarly bipedal and had feathers. The species had three digits with sharp claws on their appendage. The species’ sharp beak was probably utilized to eat eggs, plants, and tiny animals. The feathered dinosaur is thought to be a dangerous creature.

The species was known as a merciless thief, similar to other theropods, and the term oviraptor means ‘egg thief.’ The species’ toothless beak, muscular limbs, and intimidating claws are its most recognizable features. Paleontologists determined that they were real birds based on their lifestyle and physical characteristics. Troodontid dinosaurs like Talos, and especially tyrannosaurs like Teratophoneus, may have posed a serious threat to Hagryphus. Beside this, natural disasters cal also a cause of their extinction. The species is thought to have gone extinct during the Campanian period (76.1-74 million years ago).

Haplocanthosaurus

FunkMonk (Michael B. H.), CC BY-SA 3.0, via Wikimedia Commons

FURTHER READING AND STUDY

• Hatcher ( 1903). A new name for the dinosaur Haplocanthus
• Wilson &  Sereno (1998).  Early evolution and higher level phylogeny of sauropod dinosaurs.
• Forster & Wedel (2014). Haplocanthosaurus (Saurischia: Sauropoda) from the lower Morrison Formation (Upper Jurassic) near Snowmass, Colorado.

Haplocanthosaurus (Hap-loe-kan-foe-sore-us) was a sauropod dinosaur that lived between 155 and 152 million years ago, during the Kimmeridgian stage of the Late Jurassic period. The genus Haplocanthosaurus includes two species: Haplocanthosaurus delfsi and Haplocanthosaurus priscus. John Bell Hatcher gave it the name “Haplocanthus,” but he subsequently recognized that it sounded like a fish genus. Because of this, John grew concerned about the name, and it was changed from Haplocanthus to Haplocanthosaurus. The first specimen was discovered in the Morrison Formation’s lowest stratum in Colorado, the United States. In Montana, another specimen known as ‘Big Monty’ was unearthed. It is reasonable to assume that the dinosaur lived in the United States, Canada, Mexico, and other countries.

One of the smallest sauropods, Haplocanthosaurus is known. The average length of sauropods is roughly 66 feet (20 meters), while the Haplocanthosaurus was around 49 feet (15 meters) long and weighed around 14 tonnes (12791 kg). The dinosaur was renowned for its vertebrae, which had a single dorsal neural spine, unlike most Diplodocus sauropods, which had double-pierced V-shaped dorsal neural spines. The dorsal neural spine of the neck vertebrae was tall, with high neural arches, and the thigh bones were longer than the shin bones.  The thigh bones were far longer than the shin bones, indicating them as slow-moving dinosaurs.

They were known to reside near freshwater ponds, lakes, and rivers, but they also thrived in lush forests, grasslands, and Rocky Mountains. They were social creatures who preferred to live in groups. Haplocanthosaurus, like other sauropods, probably ate conifers and ginkgos, seed ferns, cycads, Bennett Italian, ferns, clubmosses, and horsetails as a secondary meal. Unlike most dinosaurs in its lineage, the dinosaur was shorter and stockier. It had a short neck and ate plants that were close to the ground. The species lacked sharp teeth and did not bite one another.

Only the Haplocanthosaurus delfsi specimen is completely mounted out of the four dinosaur specimens. Happy, the Museum’s Late Jurassic sauropod is the only known adult specimen intact enough to be displayed in its entirety. This dinosaur was likely more than 72 feet long and 14 feet tall at the hips, weighing around 25 tonnes in life. To feed itself, this plant-eating creature would have needed a vast amount of plant material. This 70-foot-long, 14-foot-high mounted skeleton has over half of its bones made of actual fossil material.

To put it another way, the dinosaur was a massive spined lizard. The dinosaur should also not be confused with Acrocanthosaurus, a carnivorous dinosaur that lived mostly in North America. These sauropods must have gone extinct sometime between 155 and 152 million years ago, during the Kimmeridgian stage of the Late Jurassic period. The cause of extinction is unknown at this time, however, they must have perished as a result of multiple catastrophic disasters.

Harpymimus

cc-by-2.5, CC BY-SA 3.0, via Wikimedia Commons

FURTHER READING AND STUDY

• Kobayashi & Barsbold (2005). Anatomy of Harpymimus okladnikovi Barsbold and Perle 1984
• Peter et al., (2004). Ornithomimosauria
• Bob Strauss. (2009). Ornithomimids – The Bird Mimic Dinosaurs.

Harpymimus (Har-pee-MIEM-us) is a name in reference to  Greek mythology’s fearsome Harpy  a derivation of the Greek words harpiya, which means “harpy,” and mimos, which means “mimic.” They inhabited terrestrial areas of Asia and existed 109 million years ago in Cenomanian Age. Harpymimus was a basal ornithomimosaurian theropod that lived in what is now Mongolia during the Early Cretaceous Period around 107-100 million years ago. Harpymimus had teeth, although they appeared to be confined to the dentary of the lower jaw, unlike later, more evolved ornithomimosaurs. In 1981, a Soviet-Mongolian expedition discovered a theropod skeleton in the Gobi Desert. A complete but crushed skull and fragmentary skeleton fossils characterize this dinosaur.

This dinosaur, sometimes known as the ostrich dinosaur, imitates birds. These small-to-medium-sized theropods were called after huge, flightless birds like ostriches and emus, rather than flying birds like pigeons and sparrows. The classic Harpymimus had long legs and tail, a large, rounded trunk, and a small head placed on a narrow neck, much like a modern ostrich. Having long legs Paleontologists believe these dinosaurs were the quickest, capable of reaching speeds of up to 50 mph.

 As they evolved, their diet shifted from meat to plants, and ornithomimosaurs lost nearly all of their teeth, implying that they were primarily herbivores. Because the top jaw is toothless, and the only teeth left in the lower jaw are short and cylindrical, these teeth are better adapted to holding small animals and maybe plant portions to be swallowed than slicing and tearing flesh. This species lived in large groups. According to scholars, the origins of ornithomimosaurs were likely in Europe or eastern Asia before the Barremain stage of the Early Cretaceous and subsequently relocated to North America at some point in the Late Cretaceous. The type specimen’s skull is mostly entire, but extensively crushed, obscuring some data about Harpymimus’ anatomy. Harpymimus may have become extinct during the Cretaceous-Paleogene mass extinction 60 million years ago due to some natural disasters.

Herrerasaurus

Fred Wierum, CC BY-SA 4.0, via Wikimedia Commons

Herrerasaurus (herr-ray-rah-SORE-us) was one of the earliest carnivorous dinosaurs. It lived in woodlands in what is now Argentina in the Carnian stage during the Late Triassic Period around 230 million years ago.

Herrerasaurus measured 15 feet (5 metres) in length, 3.3 feet (1.1 metres) height at the hip and weighed around 350 kilograms (772 pounds). Herrerasaurus was a lightly built bipedal carnivore, which most likely fed on small and medium-sized animals.

It had strong hind limbs with long feet and short thighs. This means that it was most likely a good swift runner. Its forearms were equipped with sharp claws.

Hesperosaurus

AntoninJury, CC BY-SA 4.0, via Wikimedia Commons

FURTHER READING AND STUDY

• Carpenter & Cloward (2001). New primitive stegosaur from the Morrison Formation, Wyoming.

• Maidment et al (2018). A new specimen of the ornithischian dinosaur Hesperosaurus mjosi from the Upper Jurassic Morrison Formation of Montana.

• Raven & Maidment (2017). A new phylogeny of Stegosauria (Dinosauria, Ornithischia)

Hesperosaurus (Hes-per-o-sore-us) meaning western lizard, the word Hesperosaurs comes from two Classical Greek words i.e. hesperos meaning western and sauros meaning lizard. This herbivorous stegosaurian dinosaur lived during the Kimmeridgian era of the Jurassic period, roughly 156 million years ago. It was named by K. Carpenter, C. A. Miles , and K. Cloward in 2001. Hesperosaurus was closely related to Stegosaurus, and it was proposed that it be renamed Stegosaurus mjosi to make it a species of Stegosaurus. The Hesperosaurus bone specimen revealed that it had 13 neck vertebrae instead of 10, 13 back vertebrae instead of seven, and 20 maxillary teeth on each side, which was less than the Stegosaurus. So, this specie was named by K. Carpenter, C. A. Miles and K. Cloward in 2001.

This species lived throughout the Jurassic epoch’s Kimmeridgian to Tithonian periods, according to the specimen. Hesperosaurus fossils were discovered in the Morrison Formation in Montana and Wyoming in the United States of America. From the Kimmeridgian through the Tithonian periods of the Jurassic Age. This plant-eating dinosaur discovered in the Morrison formations appears to have enjoyed terrestrial climates in heavily planted forests, particularly near rivers where they can eat ferns, small mosses, cycads, horsetails, and conifers. These were armored dinosaurs with backplates formed like spoons and spines on the tip, with a typical huge stegosaur physical look.

It had a broad cranium, a low, rounded bone plate, and a smaller stature. It has a tiny brain, indicating that it lacked advanced intellect and was not a particularly active creature. This specimen shows the first-ever impression of a horn sheath on the backplate of a large-size stegosaur dinosaur estimated to be 6.5 meters long and weighing 3.5 tones. On the back, they featured two rows of alternating plates that were larger in the front and smaller towards the tail. The plate was in the shape of an angled oval with a tapering upper end. These plates, combined with their scaly bodies and spines at the base of their tails, were employed to protect and regulate their bodies’ temperature. It evolved into a more agile and quicker dinosaur. To deal with flanking attackers the Hesperosaurus must swing its tail wildly behind it as a defensive weapon. On the end of its tail, this monster featured a four-pronged thagomizer.

This specimen also has 13 neck and back vertebrae, three sacral vertebrae, 44 tail vertebrae, chevrons, left shoulder blade, neck ribs, ten neck and back plates, a full pelvis, and dorsal ribs. This dinosaur’s baby is known as a juvenile. These stegosaurs would have died out about 156 million years ago, according to the fossil records.

Heterodontosaurus

FunkMonk (Michael B. H.), CC BY-SA 3.0, via Wikimedia Commons

FURTHER READING AND STUDY

• Radermacher et al., (2021). A new Heterodontosaurus specimen elucidates the unique ventilatory macroevolution of ornithischian dinosaurs.

• Norman et al., (2011). The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962.

• Kidadl et al., (2021) Heterodontosaurus Fact File.

Heterodontosaurus (Heh-tuh-row-don-toe-saw-rus) is a dinosaur genus that existed between 200 and 190 million years ago. Heterodontosaurus tucki, the only known member species, was described in 1962 after a skull was unearthed in South Africa. Because of its distinctive, heterodont dentition, the genus name means “different toothed lizard.” One of the first ornithischian dinosaurs was Heterodontosaurus. This bipedal dinosaur was discovered in 1966 on the northern slopes of the Krommerspruit Mountain near Voisana, Republic of South Africa, in the Lower Jurassic Upper Red Beds, Stronberg series, which date back 200 million years. The dinosaur lived in a partly desert habitat, according to scientists. Heterodontosaurus was most likely found around watering holes, where vegetation was more abundant.

The dinosaur Heterodontosaurus was a little one. It was a turkey-sized dinosaur that weighed up to 2.5 kilograms and measured around 1 meter in length. Because of the bone structure of its hind legs, this dinosaur is assumed to be connected to birds. Its leg and foot bones are fused together, and its toes have a claw-like shape rather than the traditional hoofs seen in other ornithischians. Its tail was long and therefore contained up to 37 vertebrae. The skull was narrow, elongated, and was triangular when viewed from the side. The teeth of Heterodontosaurus were its most noticeable trait. They had three types of teeth, unlike other dinosaurs. The first set of teeth was little and sharp, and they were found at the top jaw’s front. In the front, its bottom jaw formed a horny beak. Long canine tusks emerged out of the top and bottom jaws in the second type. The third species had square-shaped cheek teeth in the back, which were comparable to present mammalian molars. Heterodontosaurus could shred, bite, and grind its meal with these varied teeth.

Heterodontosaurus was a dinosaur that ate plants but the teeth variation shows that they were able to eat insects also. It ate ferns and underground roots and tubers, as well as low-growing plants like ferns.  Plants were grasped, roots and tubers were dug up, and termite mounds were ripped open with their clawed paws. It nipped leaves and stems from plants with its sharp beak. It could keep a huge amount of plant material in its cheek pouches while chewing, ensuring that nothing dropped out of its mouth. Heterodontosaurus was threatened or pursued by larger, meat-eating dinosaurs, as well as mammalian-like reptiles and dry-land crocodilians. Heterodontosaurus are thought to have existed until around 190 million years ago because no remains of these animals have been discovered after then.

Heyuannia

Danny Cicchetti, CC BY-SA 4.0, via Wikimedia Commons

FURTHER READING AND STUDY

• Wiemann et al., (2017). Dinosaur origin of egg color: oviraptors laid blue-green eggs

• Lu (2002). A new oviraptorosaurid (Theropoda: Oviraptorosauria) from the Late Cretaceous of southern China.

• Paul (2010). The Princeton Field Guide to Dinosaurs.

Heyuannia (hey-u-an-ne-ah) is a medium sized oviraptorid dinosaur genus named after Heyuan. They are estimated to have lived in the world during the Maastrichtian of the Late Cretaceous period, around 66 million years ago, and populated Asia, based on the fossils of the Theropoda Oviraptorosauria family. H. huangi and H. yanshini are the two species that have been identified. The Heyuannia fossils have led to the conclusion that the species existed in the Dalangshan Formation, which is now the Chinese province of Guangdong. The Heyuannia dinosaur was also the country’s first oviraptorid discovery. The majority of the other oviraptorids discovered were from Mongolia, a neighbouring nation. The Heyuannia huangi fossil depiction consists of a fragmentary skull, mandible, and most of the postcranial skeleton. There have since been numerous more skeletal fossils discovered, one of which is thought to contain reproductive organs. Thousands of eggs were also discovered at the site, some of which are thought to have been laid by this Theropoda Oviraptorosauria.

Heyuannia is thought to have lived on terrestrial grounds. The Cretaceous epoch was characterized by a warm climate, which resulted in high eustatic sea levels, resulting in numerous shallow inland seas. Oviraptosaurus was a group of feathered maniraptoran dinosaurs. Oviraptorid skulls were reported to be small, beaked, and parrot-like, with or without bone crests atop their heads. Heyuannia huangi were known to have a small, beaked, parrot-like cranium with or without bony crests on their heads. Their toothless skulls are also thought to have been short, having a steep snout. It is also thought to have had relatively short arms and digits, with a decreased fist digit. Heyuannia’s shoulder shape shows that, like other oviraptosaurians, this Cretaceous species from southern China was primarily a flightless bird.

The pigments biliverdin and protoporphyrin were preserved in Heyuannia eggshells, indicating that they were blue-green in color. This color, which is also observed in American robins and ratites, provided for both hiding and sexual signaling. Heyuannia’s eggshell layout shows a partially open nest design, as well as suggesting it engaged in increased parental care. Heyuannia’s skull is toothless, which, like other oviraptorid taxa, means that the exact diet of Heyuannia is unknown in the lack of proven stomach contents. Some scientists thought that they would be omnivorous and some thought they were carnivorous and most likely ate small animals such as frogs, insects, mammals, reptiles, and early birds. The major threat to their survival was natural disasters. The Heyuannia dinosaur is thought to have gone extinct around 66 million years ago, during the Late Cretaceous period, based on their fossil description.

Homoalocephale

FunkMonk, CC BY 3.0, via Wikimedia Commons

FURTHER READING AND STUDY

• Maryańska and Osmólska (1974).  Pachycephalosauria, a new suborder of ornithischian dinosaurs

• Carpenter and Kenneth (1997). Agonistic behavior in pachycephalosaurs (Ornithischia:Dinosauria): a new look at head-butting behavior.

• Holtz and Thomas (2008). Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages

Homalocephale (Home-ah-loh-sef-ah-lee) named after two Greek words: homalos, “even,” and kephal, “head.” These dinosaurs were relatively small in size, about the size of a large dog. This dinosaur genus existed during the late Cretaceous period of what is now Mongolia, 80 million years ago wandering Mongolia’s wooded areas in search of ground-level vegetation. These highly forested habitats may have also enabled Homalocephale to conceal from larger carnivores in the area. H. Calathocercos is the only species in the genus, which was first described in 1974 by Osmólska & Maryaska. Homalocephale was herbivorous and 1.8 meters (6 feet) long.

A fragmentary skull, as well as pieces of the legs and vertebrae, have been discovered in Homalocephale. It has a wedge-shaped flattened cranium. The top of its skull was somewhat raised, and it had numerous spikes and bumps on the top and sides. There were also big eye sockets on the head, possibly due to the dinosaur’s massive eyes, and a pelvis that was exceptionally broad compared to other dinosaurs. Many paleontologists initially assumed it gave birth to live young, but it appears more likely that it protected crucial organs during head-butting competitions. It had lengthy legs, indicating that it could run quickly, and huge eyes, indicating that sight was one of its primary senses. The rest of the body was discovered in certain skeleton specimens, and its abdomen, thorax, and pelvis were discovered to be wider than those of other dinosaur species. This dinosaur had a short tail and leaf-shaped teeth. Because its forelimbs were shorter than its hind legs, scientists believe it walked on its hind legs while keeping its back level to the ground. This dinosaur had a short tail and leaf-shaped teeth. Because its forelimbs were shorter than its hind legs, scientists believe it walked on its hind legs while keeping its back level to the ground.

When a Homalocephale’s skull was unearthed, it was revealed that it had a big space where the olfactory nerve, or smelling nerve, would have been. As a result, it has been determined that this dinosaur also had a keen sense of smell along with sight, which would have been useful in spotting predators nearby and allowing them to flee. Given that they lived at the same time, these dinosaurs would have been preyed upon by a vast number of predators. Homalocephale may tolerate a social group of up to ten other Homalocephale and can survive in an enclosure with up to twenty other dinosaurs. Homalocephale ate soft vegetation, fruit, and seeds as a herbivore. Their thick skulls were supposed to have been utilized for ramming rivals during mating and dominance battles, luring mates, and as last-ditch self-defense against predators for a long time. A paleontologist examined their cranium and found no signs of healed injuries. Also, when put under extreme pressure, the thick skull bone is porous and weak, according to close examination. Their disappearance could have been caused by the 66 million-year-old Cretaceous-Paleogene extinction event, which wiped out three-quarters of Earth’s species and flora.

Huayangosaurus

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

Huayangosaurus (hoy-YANG-oh-SORE-us) was a stegosaurian from Middle Jurassic in China. It derives its name from ‘Huayang’ an alternate name for Sichuan, the province it was discovered.

Huayangosaurus lived 170 million years ago, some 20 million years before its famous relative, Stegosaurus appeared in North America.

Huayangosaurus measured 14 feet (4.5 metres) in length, weighed 500 kilograms and was much smaller than its famous relative. Like many other stegosaurians it had plates lining its back, and a spiked tail.

Hylaeosaurus

Benjamin Waterhouse Hawkins, Public domain, via Wikimedia Commons

FURTHER READING AND STUDY

• Gideon Mantell (1833).The Geology of the South-East of England
• Carpenter (2001). Skull of the polacanthid ankylosaur Hylaeosaurus armatus Mantell, 1833, from the Lower Cretaceous of England
• Barret (1996). The first known femur of Hylaeosaurus armatus and reidentification of ornithopod material in The Natural History Museum.

Hylaeosaurus (hy-lee-o-sor-s) is the first herbivorous ankylosaurian (armoured) dinosaur discovered by science. It is named from two Greek words: hylaios “forest” and sauros “lizard.” Hylaeosaurus was an herbivorous ankylosaurian dinosaur that lived around 136 million years ago in England’s early Cretaceous period, during the late Valanginian stage. Gideon Mantell found Hylaeosaurus in 1832, making it one of the first dinosaurs ever discovered. It was one of three dinosaurs on which Richard Owen founded the Dinosauria in 1842. In the genus, four species have been identified. Around 140-136 million years ago, it was the first member of the Ankylosauridae family. Four species have been identified within the genus.

The Hylaeosaurus dinosaurs were found in several parts of the United Kingdom, particularly in London, England. The specimen of fossils buried in a limestone block was discovered in the Tilgate forest in England, and the fossils are kept at the Natural History Museum of London. The dinosaur’s natural habitat was mostly woods and forests. Dinosaurs either lived alone or in groups of two, three, or four. Because the Hylaeosaurus was a gregarious creature, it was likely found in groups. The dinosaur’s body was covered in spikes and had many oval-shaped armour plates. It had a beak-like pointy nose and a narrow head with horns over it. It possessed a long tail and five-toed feet on short legs. Spikes ran down its shoulder, sides, and top of its body, going all the way to its long tail. The Hylaeosaurus’ look was created using fossilised skull, neck, shoulder vertebrae, bony plates, mouth, teeth, and a limb bone. It was inspired by modern lizards. Gideon Mantell described it as a “vast consarn of bites and boanes” since the fossil remains were roughly 50 pieces.

Hylaeosaurus was possibly a primitive nodosaur, albeit it is more commonly thought of as a polacanthine. Hylaeosaurus would not have developed a tail club like the later ankylosaurids because of this.  Gideon Mantell described it as a “vast consarn of bites and boanes” since the fossil remains were roughly 50 pieces. The fragmentary skeleton originally unearthed includes the Hylaeosaurus skull, neck, shoulder vertebrae, and many bony armour plates covering the shoulder, the mouth, teeth, and a limb bone, though the exact quantity of bones is unknown. The earliest estimate of the length of the Hylaeosaurus was made by George Mantell, who stated that it may be as long as 25 feet (7.6 m). Hylaeosaurus species ranged in size from 10 to 25 feet long (3-7.6 m). Dinosaur speed is determined by examining the space between their tracks; its characteristics suggest that it may have moved quickly.

There are no unique binomial names for this group of dinosaurs that highlight the species’ sex. An herbivore diet was documented for the armored dinosaur. Plants were the mainstay of the Hylaeosaurus’ diet, particularly low-lying flora. Rows of bony spines clothed the Hylaeosaurus, with at least three lengthy spines surrounding its shoulder. Spikes on its body, on the other hand, were not thought to have hurt others, and the Hylaeosaurus was not regarded to be aggressive. The horn-covered plates also provided protection from their predators, allowing it to live a longer and healthier life. Predation, habitat loss, natural disasters, and a shortage of food were all thought to be key factors in the extinction of these dinosaurs that once roamed England.

Hypacrosaurus

Debivort, CC BY-SA 3.0, via Wikimedia Commons

Hypacrosaurus (High-pah-kroe-sore-uss) was a duck-billed hadrosaur dinosaur similar in appearance to the Corythosaurus dinosaur. It lived in Canada, Alberta and Montana, North America in the Upper Cretaceous period around 76 – 68 million years ago towards the end of the Mesozoic, the Age of Reptiles.

Hypacrosaurus measured around 30 feet (9 metres) in length and would have weighed more than 4 – 5 tons. Like other duck-billed dinosaurs, Hypacrosaurus was a bipedal who moved around on its hind legs and probably only went on all 4 legs to forage low-lying vegetation.

Hypsilophodon

User:ArthurWeasley, CC BY-SA 3.0, via Wikimedia Commons

Hypsilophodon (hip-sih-LOH-foh-don) was an ornithopod dinosaur genus from the Barremian Age during the Early Cretaceous Period around 130 – 125 million years ago and is one of the smallest dinosaurs found on the Isle of Wight. This dinosaur was also found in Spain and fossils of large groups have been found, so it is likely that the animals moved in herds

Early paleontologists modeled the body of this small, bipedal, herbivorous dinosaur in various ways. In 1882 some paleontologists suggested that, like a modern kangaroo, Hypsilophodon might have been able to climb trees in order to seek shelter. Hypsilophodon was a relatively small dinosaur and was only around 2.3 metres in length. It would have reached approximately waist-height on a modern man and would have weighed about the same, at 50-70 kg.

The shape of its skull, with its teeth at the back of its jaw, meant that it might have had cheeks which was an advanced feature that meant it could chew its food. There were twenty-eight to thirty ridged teeth in the animal’s jaw which, due to their alternate arrangement, appear to have been self-sharpening also the teeth were continuously replaced.

Hypsilophodon was a relatively small dinosaur and was only around 6 Feet (2.3 metres) in length and weighed 50 – 70 kilograms (110 – 150 pounds). Like most small dinosaurs, Hypsilophodon was bipedal and ran on 2 legs.

Hesperornis

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

Hesperornis (HES-per-OR-nis) is an extinct genus of flightless aquatic bird that lived during the Coniacian to Maastrichtian sub-epochs of the Late Cretaceous, 89 – 65 million years ago.

Hesperornis was a huge bird that measured 6.5 feet (2 metres) in length. They had virtually no wings and hunted in the waters of the North American Inland Sea, swimming with powerful hind legs. Its feet were likely to be lobed rather than being webbed as in todays grebes.

It was discovered by the famous Paleontologist Othaniel Marsh in 1871 while he was in Canada with a group of students in what was his second western expedition. He described the finding of a large bird that was over five foot high and missing its head.