Euhelopus

Type Species: Euhelopus zdanskyi

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

Time Period: Early Cretaceous

Location: China

Diet: Herbivore

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

Giraffatitan

Type Species: Giraffatitan brancai

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

Time Period: Late Jurassic 

Location: Africa

Diet: Herbivore

Giraffatitan was originally thought to be a species of Brachiosaurus but has since been given freedom to stand on its own. It was one of the largest sauropods of the Late Jurassic, averaging between 72 and 74 feet in length but capable of reaching up to 85 feet snout-to-tail. Its neck, held vertical, reached up to forty feet in length. It had a giraffe-like build (hence its name) with long forelimbs and a long neck. It had chisel-like ‘spatulate’ teeth and the first three toes on its hind feet were clawed. Its distinctive high-crested skull was once thought to be characteristic of the brachiosaurids, to which Giraffatitan originally belonged; however, it’s possible that many brachiosaurs didn’t have this feature, since this feature is known only from African specimens now assigned to Giraffatitan – all this to say that the classic portrayal of Brachiosaurus may actually not represent Brachiosaurus at all, at least as far as the skull design goes. Like other sauropods, Giraffatitan had a sacral enlargement above the hip; scientists of an earlier age thought this housed a ‘second brain,’ given that sauropods had pretty small brains to begin with, but it’s know believed to be the location of glycogen bodies. Giraffatitan likely roamed the sweeping conifer forests of the Tendaguru Formation, avoiding the coastal environments of brackish coastal lakes, ponds, and pools where vegetation would be harder to come by. 

Giraffatitan’s nostrils were once thought to be located on the top of its head, lending earlier scientists to speculate that it was a water-dweller, snorkeling in the burgeoning North Atlantic. However, studies have shown that the water pressure placed on the rib cage would make it extremely difficult for a submerged Giraffatitan to breathe; extended time submerged would undoubtedly lead to drowning. Studies of the skull in 2001 suggested that while the nasal openings in the skull were above the eyes, this didn’t mean that the nostrils wouldn’t emerge at the tip of the snout. In this case, Giraffatitan’s tall ‘crests’ may have housed a fleshy resonating chamber. 

Australodocus

Type Species: Australodocus bohetii

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

Time Period: Late Jurassic 

Location: Africa

Diet: Herbivore

The 56-foot-long and 8800-pound sauropod Australodocus was originally classified as a diplodocid but has since been reclassified as an early titanosauriform, making it more closely related to Brachiosaurus than Diplodocus. Australodocus is currently considered one of the first specimens of the somphospondyls, a sauropod lineage that would give birth in the Cretaceous to the larger-than-life armored titanosaur sauropods. This ‘large-nosed’ macronarian roamed the dense conifer forests of Africa’s Tendaguru Formation, separated to the south of North America by the widening strip of water that would eventually become the Atlantic Ocean. While the Morrison Formation in North America was dominated by diplodocids, the Tendaguru Formation was dominated by macronarians, likely as a result of the different environments. The Morrison was a savannah-like floodplain cut by lakes and rivers that were forested on the peripheries; the Tendaguru, however, was more densely-packed with thick conifer forests. The low-lying foliage of the Morrison was perfect eating for low-browsing diplodocids whereas macronarians with vertically-oriented necks did better with the plentiful trees of the Tendaguru. 

Barosaurus

Type Species: Barosaurus lentus
Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea – Flagellicaudata – Diplodocidae
Time Period: Late Jurassic
Location: North America
Diet: Herbivore

The North American Barosaurus was one of the largest sauropods of the savannah-like Morrison Formation during the Tithonian Stage of the Late Jurassic. While most individuals were already larger-than-life, clocking in at 82-89 feet in length and weighing between twelve and twenty tons, at least one specimen may have reached up to 157 feet in length with a 49-foot neck. Barosaurus was closely related to the more popular Diplodocus, though it had some significant differences: it had a longer neck, a shorter tail, and its skeleton was less robust than its contemporaneous cousin. Additionally, Barosaurus’ cervical vertebrae were designed in such a way that it had a lot of side-to-side flexibility at the cost of up-and-down flexibility. This indicates it ate by sweeping its neck in crescent-shaped arcs over the low foliage, which would’ve been a perfect feeding method for the savannah-like conditions of the Morrison Formation. While its neck and skull have not been recovered, it’s assumed that, due to its close relationship with Diplodocus, Barosaurus had a whip-like tail and a skull with an elongated, sloping snout with peg-like teeth.

Lusotitan

Type Species: Lusotitan atalaiensis

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

Time Period: Late Jurassic 

Location: Europe 

Diet: Herbivore

The Late Jurassic sauropod Lusotitan lived in prehistoric Portugal as part of Portugal’s Lourinha Formation, which resembled North America’s Morrison Formation and which emerged as a result of the genesis of the Atlantic Ocean. This brachiosaurid was related to the North American Brachiosaurus, and it grew up to seventy to eighty feet in length. Lusotitan walked on four pillar-like legs; its front legs were longer than its back legs, so that its body sloped downwards towards its short tail. Some scientists believe it could rear back on its hind legs to reach super high foliage, though some believe it kept its four legs on the ground at all times. Lusotitan’s neck reached vertical rather than horizontal like diplodocids. This gave it a feeding advantage: whereas most of its sauropod contemporaries were low-browsing diplodocids, Lusotitan could browse foliage up to fifty feet off the ground to feed on high conifers and ginkgoes. It undoubtedly practiced niche partitioning alongside the low-browsing diplodocid Dinheirosaurus. As part of the Lourinha Formation, it also lived alongside large predators such as Allosaurus and Torvosaurus, stegosaurs such as Dacentrurus and Miragaia, the early ankylosaur Dracopelta, and numerous early ornithopods. 

Dinheirosaurus

Type Species: Dinheirosaurus lourinhanensis

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea – Flagellicaudata – Diplodocidae – Diplodocinae

Time Period: Late Jurassic 

Location: Europe 

Diet: Herbivore

The Late Jurassic sauropod Dinheirosaurus lived in prehistoric Portugal as part of Portugal’s Lourinha Formation, which resembled North America’s Morrison Formation and which emerged as a result of the genesis of the Atlantic Ocean. Dinheirosaurus had the general diplodocid form: a slender body, long neck carried low over the ground, and a long, whip-like tail. Its squared snout, similar in appearance to its North American relatives Diplodocus and Supersaurus, indicates that it was a non-specific low-browsing herbivore. It grew up to eighty feet in length, the same length as Diplodocus but smaller than Supersaurus, to whom it was more closely related. Dinheirosaurus is one of the few sauropods for whom gastroliths have actually been found alongside the type specimen. This sauropod lived alongside large predators such as Allosaurus and smaller ones such as Aviatyrannus (the latter of which could be squashed under Dinheriosaurus’ feet if it lacked spatial awareness). Other herbivores of the environment included the stegosaur Dacentrurus, the early ankylosaur Dracopelta, and numerous early ornithopods. 

Supersaurus

Type Species: Supersaurus vivianae

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea – Flagellicaudata – Diplodocidae – Diplodocinae

Time Period: Late Jurassic 

Location: United States 

Diet: Herbivore

Supersaurus was a Late Jurassic diplodocid of the Morrison Formation. Though remains have been discovered from several individuals, these remains have been scanty, and so little is known about Supersaurus apart from its length and weight. From this scientists have deduced that it was the largest sauropod of the Morrison Formation, reaching up to 112 feet in length and weighing up to forty tons. We can assume that it behaved like other diplodocids, traveling in herds across the floodplains and savannahs of Late Jurassic western North America and feeding nonstop in order to provide enough energy for its massive size. It would’ve had few predators, as it would’ve dwarfed even Allosaurus and Torvosaurus, but Supersaurus would’ve been vulnerable in its early growth stages. Given its sheer size, it may be that Supersaurus herds were greedily eyed and followed by roving theropods looking to pick off the aged or weak. A Supersaurus carcass could’ve fed dozens of large theropods. 

Camarasaurus

Type Species: Camarasaurus supremus  

Classification: Dinosauria – Saurischia – Sauropoda - Gravisauria - Eusauropoda - Neosauropoda – Macronaria – Camarasauridae 

Time Period: Late Jurassic 

Location: United States 

Diet: Herbivore

Camarasaurus was the most common sauropod of the Morrison Formation; vast herds roamed the floodplains and valleys of Late Jurassic North America. Herding behavior is attested in the fossil record: a group of two adults and a forty-foot-long juvenile died together around 150 million years ago in what is now Wyoming. It appears their bodies were washed by a flooding river and buried in sediment. This find implies that Camarasaurus traveled in herds or at least in family groups, though the discovery of Camarasaurus eggs laid in lines rather than nests suggests that Camarasaurus didn’t tend to its young. It’s possible that Camarasaurus embraced an R-strategy for survival, in which overwhelming numbers of young were hatched in the hope that some of them made it to adulthood. Juveniles, having survived the many predators of the Morrison Formation, may have ‘linked in’ with roving herds for safety. The size of herds is pure speculation, for unlike some ceratopsians of the Cretaceous, vast Camarasaurus bone-beds haven’t been discovered. 

Camarasaurus could grow up to sixty feet in length, though some specimens reached up to seventy-five feet. Skeletal studies indicate that these sauropods reached sexual maturity around twenty years of age. Camarasaurus had a blunt, box-like head that, despite its bulldog appearance, was filled with lots of air cavities (called fenestrae) which helped lighten the skull’s weight. Its teeth were seven and a half inches long, and they were stronger than those of most sauropods. These sturdy, spoon-like, deep-rooted teeth extended nearly into the cheeks, in contrast with the front-only teeth of some sauropods such as Diplodocus. Studies on the plentiful teeth have revealed that they were used vigorously in chewing and were replaced on average every two months; the lack of gastrolith fossils in the numerous specimens indicate that Camarasaurus chewed its food down to a pulp prior to swallowing. When scientists performed clumped isotope thermometry on the enamel covering the teeth of several genera of Jurassic sauropods, including Camarasaurus, it revealed temperatures of 90.3-98.4 degrees Fahrenheit, comparable to that of modern mammals. Its neck was held up high so that the head were at a level where Camarasaurus could eat from the tree canopy like its contemporary cousin Brachiosaurus; the numerous fenestrae in its skull would’ve lightened the weight, enabling it to hold it higher off the ground. 

Camarasaurus’ legs were about equal length (the forelegs were only slightly shorter than the hind-legs), unlike Brachiosaurus’ long forelegs and Diplodocus’ longer hind-legs. The fact that its forelegs were slightly shorter than the hind-legs would’ve made its back slope forward, but its high shoulders off-balanced this so that its body ran nearly parallel to the ground. Its neck and tail were relatively short for sauropods, and like most sauropods its inner toe bore a large, sharp claw. Camarasaurus’ name comes from the Greek word for ‘chamber,’ referring to the chambers discovered in its vertebrae. These air-filled cavities made its bones pneumatic, and their purpose has been approached in two ways: the air-filled cavities (pleurocels) may have served to reduce the weight of its skeleton, or they may have even been air sacs that were part of the sauropods’ respiratory system. These features are found in plenty of other sauropods as well as in theropods; it may very well be a common feature of the saurischian lineage that leads to the avian respiratory system in which birds use similar air sacs to increase their breathing potential. If this is the case for Camarasaurus, the air sacs would’ve provided a super-efficient airflow down the long neck so that the fresh air went down one network of sacs whilst oxygen-depleted air went up another. This would result in a constant supply and exchange of breathable air despite the distance of the lungs from the mouth and nostrils. 

Haplocanthosaurus

Type Species: Haplocanthosaurus priscus 

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea – Flagellicaudata – Diplodocidae

Time Period: Late Jurassic 

Location: United States 

Diet: Herbivore

Haplocanthosaurus is known from four specimens belonging to two species, and none of these specimens has provided a skull. It was one of the smallest sauropods of the Morrison Formation, reaching only fifty feet in length. Its position in the sauropod family tree is debated, as it is seemingly a primitive form of either the diplodocids with their long and thin build or of the taller, shorter, and stockier macronarians (it's currently classified as a diplodocid, but the debate continues). That this primitive sauropod lived side-by-side with far more advanced diplodocids and macronarians is bewildering, and scientists speculate that it was a type of sauropod that appeared much earlier in the Jurassic – perhaps during the ‘paleontological black hole’ of the Middle Jurassic – but continued into the Late Jurassic. 

Haplocanthosaurus was originally named Haplocanthus by paleontologist John Bell Hatcher, but he later found out about a fish genus that sounded just like this, and thinking that the name was already taken, he changed it to Haplocanthosaurus. Ironically, he had no need of changing the name: the fish was actually named Haplacanthus (spelled with an ‘a) rather than Haplocanthus (spelled with an ‘o’). This wasn’t noticed until years later when the name Haplocanthosaurus was in regular use, and the ICZN – the scientific body which oversees the naming of animals – granted a Green Light to the Haplocanthosaurus designation because of its wide usage. 

Diplodocus

Type Species: Diplodocus longus 

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea – Flagellicaudata – Diplodocidae – Diplodocinae

Time Period: Late Jurassic 

Location: United States 

Diet: Herbivore   

Diplodocus is an infamous dinosaur, a childhood icon, for at least two reasons: for a long time it was thought to be the largest dinosaur, and it’s one of the earliest dinosaurs about which scientists could say a lot. Its remains were first discovered in the late 19th century, and Othniel Charles Marsh studied it immensely during the ‘bone wars.’ He named it Diplodocus longus – meaning ‘long double beam’ – after a pair of long bone growths on the underside of the caudal vertebra (while Marsh thought these features were unique to this sauropod, they’re actually fairly common among sauropods). Diplodocus had the standard sauropod body plan: a long tail, a large body supported by four pillar-like legs, and a long neck. Because its hind legs were longer than its front legs, its body sloped slightly forward. While it could reach up to eighty feet in length, most of that length was accomplished via its long neck and whip-like tail. Its whip-like tail may have served as a defensive weapon or as a tool by which it could ‘crack’ the sound barrier to communicate to other of its kind or ward off predators. Diplodocus may have had keratinous spines running the length of its back; evidence of such spines has been found in later specimens, and they’re known to be present in other closely-related sauropods. 

Herds of Diplodocus roamed the low-lying drainage basins that swallowed runoff from the emergent Rocky Mountains in western North America. This lowland environment – which stretched from New Mexico to Canada and is known as the Morrison Formation – was scarred by crisscrossing streams and rivers and was dotted with swamplands, lakes, and floodplains. Diplodocus’ contemporaries included other sauropods such as Apatosaurus, Brachiosaurus, and Camarasaurus; ornithischians like Camptosaurus, Dryosaurus, and Stegosaurus; and carnivorous theropods such as Stokesosaurus and Ornitholestes. The largest predators were Ceratosaurus, Allosaurus, and Torvosaurus. Though a full-grown Diplodocus would’ve likely been nigh invulnerable to these predators, juvenile sauropods or the aged, weak, and sick would’ve been easier prey; some scientists believe that the vulnerability of young sauropods implies that Diplodocus reproduced with an R-strategy of having large nests with lots of young in the hope that even just a few survive into adulthood. If this is the case, it could very well be the case that young sauropods were a prime staple of the predators’ diet in this Late Jurassic ecosystem. Crocodylomorphs such as Hoplosuchus prowled the lowlands, and pterosaurs such as Harpactognathus and Mesadactylus roamed the skies. The aquatic elements of the lowlands were inhabited by ray-finned fishes, frogs, salamanders, and turtles; bivalves and aquatic snails were plentiful. Plant life included green algae, fungi, mosses, horsetails, cycads, ginkgoes, and several kinds of conifers. The nature of the vegetation changed upon ones location in the Morrison Formation: there were river-hugging forests of tree ferns, gallery forests of ferns, and fern savannahs dotted with the occasional conifer. Paleontologists believe Diplodocus stuck mostly to the floodplains and sparsely-wooded areas on the fringes of denser forests that may have been too overgrown for them to navigate; though older interpretations put Diplodocus and its sauropod contemporaries in swamps and lakes, it’s now known they were fully terrestrial creatures. 

Diplodocus was likely a low-browser, carrying its long neck above the ground to graze on ferns and cicads; however, some scientists speculate that it could raise its neck up to a forty-five degree angle without putting too much stress on its heart or vertebrae. It may even have been able to ‘rear up’ on its hind legs by using its tail as a tripod. Diplodocus’ peg-like teeth pointed forward, and in adults toothwear is limited to the forward portion of its mouth; this indicates that it was a ‘leaf-stripper’ who fed by closing its mouth around vegetation, capturing the stems of the plant between its teeth, and then pulling back so that as the stems ran through the peg-like teeth, the leaves were stripped off and swallowed. Its snout was longer than those of other sauropods, so that it could fit more plants in its mouth. Interestingly, toothwear of juvenile Diplodocus had teeth in the backs of their mouths, indicating they may have fed by moving their head side-to-side as they stripped stems of leaves. This may have been an easier method of feeding in their young age, a method they rejected as they grew older. As a low-browser, Diplodocus would’ve competed with its contemporary Stegosaurus, but if it could indeed raise its neck higher off the ground, it could feed on plants unavailable to stegosaurs. Some scientists believe Diplodocus may have fed on aquatic plants by standing on the sides of a lake or river and using its long neck to reach out over the water and dip its head beneath the surface to pull up softer water weeds. It likely fed at multiple points during the day and night, as its scleral rings indicate it was cathemeral, active for periods throughout both the day and night; this feeding schedule may have been necessary to keep up with its incredible caloric needs. 

Brachiosaurus

Type Species: Brachiosaurus altithorax

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

Time Period: Late Jurassic 

Location: United States and Europe

Diet: Herbivore 

The sauropod Brachiosaurus traveled in herds in the western United States during the Late Jurassic. Its stomping grounds consisted of low-lying drainage basins that swallowed runoff from the emergent Rocky Mountains to the west. These lowlands were scarred by crisscrossing streams and rivers and were dotted with swampy lowlands, lakes, river channels, and floodplains. (Brachiosaurus remains have also been allegedly found in Portugal). This infamous sauropod walked on four pillar-like legs; its front legs were longer than its back legs, so that its body sloped downwards towards its short tail. Its name means ‘arm reptile,’ in reference to the fact that its arms (forelegs) were longer than its rear legs. Some scientists believe it could rear back on its hind legs to reach super high foliage, though some believe it kept its four legs on the ground at all times. 

Brachiosaurus’ neck reached vertical rather than horizontal like diplodocids. This gave it a feeding advantage: whereas most of its sauropod contemporaries were low-browsing diplodocids, Brachiosaurus could browse foliage up to fifty feet off the ground to feed on high conifers and ginkgoes. Air sacs along the neck and trunk of Brachiosaurus lightened the strain needed to keep its neck vertical. These air sacs connected to its lungs, thus lowering the body density. Brachiosaurus couldn’t chew its food, as its jaws were only capable of opening and closing (it couldn’t move its jaws side-to-side in a grinding motion). Its 52 spatulate (spoon-like) teeth cropped conifer needles, palm-fronds, ginkgo leaves, and even towering horsetails that grew along the many waterways of the Morrison. It would’ve needed to consume up to 440 pounds of food each day, and this food was swallowed unchewed and passed into a gizzard where gastroliths (stomach stones) crushed the food to a pulp for digestion. 

Fossils similar to those of North America’s Brachiosaurus were discovered in Africa’s Tendaguru Formation in 1914; scientists believed the fossils to represent a new species of Brachiosaurus, but further study indicated significant morphological differences, so the fossils became a new genera altogether: Giraffatitan. Giraffatitan’s crest bone, rising from the top of the skull, is much larger than that in Brachiosaurus (interestingly, most modern depictions of Brachiosaurus include a crest bone more in line with that of Giraffatitan than Brachiosaurus). While it was once believed Brachiosaurus’ nostrils were set atop its skull crest, modern reconstructions place them lower down on the high forehead, right above the eyes, in a kink that angled from the forehead into the low snout. This reconstruction has led some scientists to postulate that the crest was a resonating chamber that could’ve amplified Brachiosaurus’ vocalizations. 

a scene from the Morrison Formation; Brachiosaurus in the foreground,
Camarasaurus in the background, and early ornithopods along the forest floor

Kaatedocus

Type Species: Kaatedocus siberi

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea – Flagellicaudata – Diplodocidae – Diplodocinae

Time Period: Late Jurassic 

Location: North America

Diet: Herbivore   

Until 2012 this sauropod was believed to be a variant of Barosaurus; only when it was determined by intense study that the remains belonged to a new genera (albeit one closely related to Barosaurus) was this sauropod coined. Kaatedocus was fifty feet long, making it much smaller than its cousin Diplodocus, which could reach up to ninety feet in length. Kaatedocus had a gracile body, a whip-like tail, a very long neck, a small head, and a toothy grin thanks to overly large teeth. Its teeth were pencil-shaped like those of other diplodocids, but they were much larger, giving Kaatedocus a clownish appearance. The pencil-like teeth were designed to strip foliage off plants rather than to chew the plant material; the ‘chewing’ happened in Kaatedocus’ gut where gastroliths – swallowed stones – worked to pulverize the plant material for further digestion.  

Galeamopus

an unfortunate Galeamopus succumbs to the circle of life

Type Species: Galeamopus hayi

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea – Flagellicaudata – Diplodocidae – Diplodocinae

Time Period: Late Jurassic 

Location: North America

Diet: Herbivore   

Until 2015, the nearly complete skeleton with an associated skull of a certain diplodocid of the Morrison Formation was assumed to be a species of Diplodocus; the change came when researchers determined that these skeletal remains had enough differences from Diplodocus – at least eight! – to determine it as a new species. Thus Galeamopus was born. This sauropod closely resembled its contemporary Diplodocus, and they share the same family group. Galeamopus was lightly-built and most likely had a whip-like tail capable of cracking the sound barrier. Researchers believe this sauropod also had a series of short keratinous spines running down the length of its body, as these are present in many other species of diplodocid sauropods. Galeamopus’ long neck was probably held close to the ground, swinging in crescent-shaped arcs as it fed on low-growth foliage in the wetlands and savannahs of Late Jurassic North America. 

Europasaurus

Type Species: Europasaurus holgeri

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

Time Period: Late Jurassic 

Location: Europe (Germany)

Diet: Herbivore   

Europasaurus was a tiny sauropod that, in adulthood, reached only twenty feet in length, stood as tall as an eight-year-old human at the hips, and whose head reached only ten feet above the ground. Its small size has been attributed to ‘insular dwarfism,’ in which animals evolve to shrink in size in order to cope with diminished resources. Germany at this point in the Late Jurassic was mostly underwater; higher elevations emerged from the sea in a string of island archipelagos, the largest of which was only 120,000 square miles. Even an island that large likely couldn’t support a herd of normal-sized sauropods; hence Europasaurus grew smaller in order to survive. Bone analysis shows that while gigantic sauropods reached their massive size by growing quickly, Europasaurus had an unusually slow rate of growth. Other instances of ‘insular dwarfism’ have been documented from Europe around this time; in Romania, for example, we’ve discovered a dwarf titanosaur Magyarosaurus and a dwarf hadrosaur Telmatosaurus. 

Europasaurus’ remains were found in a richly marine environment that faced a large German island coated with conifers, ferns, and cycads. Pterosaurs flew about among the trees, hopping island-to-island, and early mammals scurried in the underbrush. Fossilized turtles, fish, hybodont sharks, and marine crocodylomorphs are common. At least 450 bones from Europasaurus were recovered from the Langenberg Quarry, and about a third of them had tooth marks. These tooth marks match the teeth of fish, sharks, and marine crocodylomorphs, but none were made by theropods. Scientists believe that a herd of Europasaurus were crossing a tidal zone and drowned. Other dinosaur material in the vicinity includes remains from an unknown diplodocid, a stegosaur, and multiple indeterminate theropods. Isolated teeth show that there were at least four different types of theropods living on the island, including the megalosaur Torvosaurus as well as an indeterminate megalosaur, an allosaur, and a ceratosaur. Interesting, teeth that seem to belong to Velociraptorinae, which would put the genesis of this dromaeosaur subgroup in the Late Jurassic rather than the (proposed) Early Cretaceous. 

this graphic highlights European bone-beds with their Late Jurassic counterparts
The Langenberg Quarry is #7

Dinosaur footprints preserved at the quarry have led researchers to propose a reason for Europasaurus’ eventual demise. Footprints located sixteen feet above the Europasaurus burial ground shows that 35,000 years after their burial (well into the Cretaceous), sea level dropped and allowed for what’s called a ‘faunal overrun.’ The theropods that coexisted with Europasaurus were, by and large, about thirteen feet in length; but the theropods that were able to cross to the former island via a land bridge revealed by sinking sea levels were around twenty-five feet in length (based upon their footprints). These larger theropods made windfall on the previously-isolated island: the creatures who had grown small to survive amid diminished resources were now easy pickings for large Cretaceous predators. Europasaurus wouldn’t have stood a chance in the bloodletting. 

Dicraeosaurus

Type Species: Dicraeosaurus hansemanni

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea - Flagellicaudata – Dicraeosauridae

Time Period: Late Jurassic

Location: Africa (Tanzania) 

Diet: Herbivore   

The small-sized sauropod Dicraeosaurus lived in eastern Africa in what is now modern Tanzania. Its remains have been uncovered in the Tendago Formation, which dates from the Middle Jurassic to the Early Cretaceous and which is divided into six ‘zones’ corresponding to different time periods. The Tendagu Formation of the Late Jurassic was located in the subtropical southern hemisphere, and it would’ve been a semi-arid environment with seasonal rainfall. The Tendagu has given us a wealth of fossils from this period in earth’s history, not only dinosaurs but also early mammals, crocodylomorphs, amphibians, fish, invertebrates, and flora. The environment in which Dicraeosaurus lived included a coastal region of beaches and lagoons; further inland were coastal plains with brackish lakes and ponds. Dicraeosaurus lived among other herbivores such as the brachiosaurid Giraffatitan and the stegosaur Kentrosaurus; it may have been hunted by the carcharodontosaur theropod Veterupristisaurus. 

Dicraeosaurus’ name means ‘two forks’ in reference to the neural spines of the backbone that branched (or ‘forked’) in two. In life, this was likely a ridged back of fleshy skin. This type of backbone design is rare, and it’s far more pronounced in the later Amargasaurus. The ridged back came from the neural spines that projected upwards from its backbone, running from its tail to its neck. Each spine opened out at the top to form a ‘Y’ shape to which muscles were attached. Some scientists believe these were bony anchors for a thin, low, sail-like structure. The sail would’ve made it look bigger in profile as a deterrent to predators; or it may have served as a display for species recognition or attracting mates, in which case it was likely brightly colored or vibrantly patterned; another theory is that the sail would’ve served for thermoregulation. In the latter case, the large area of the sail, when positioned at a right angle to the rising sun, would’ve absorbed warmth and passed it, via the blood flowing through it, into the animal’s system. This would quickly raise the animal’s body temperature to allow more and faster activity after the cool of night; conversely, standing in the shade and at a right angle to the breeze would cool the body. 

Dicraeosaurus had a relatively short, wide neck with only twelve vertebrae, less than any other late Jurassic sauropods other than Brachytrachelopan. Its tail had the typical diplodocid ‘whiplash,’ though it was nowhere near as ‘whippy’ as more derived (and larger) diplodocids. Its eyes were set high atop its skull; its snout was long, low, and horse-like; and its teeth were fine and pencil-shaped, set in two curved clusters toward the front of the jaws. These teeth were designed for stripping foliage. The design of its neck – coupled with its low stature – meant that it fed at ground level up to ten feet off the ground.

Brachytrachelopan

Type Species: Brachytrachelopan mesai

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea - Flagellicaudata - Dicraeosauridae

Time Period: Late Jurassic

Location: South America (Argentina)

Diet: Herbivore   

Brachytrachelopan’s name translates as ‘short-necked Pan,’ Pan being the god of the shepherds (for this sauropod was discovered by an Argentinean shepherd). This short-necked sauropod is infamous because its neck is forty percent shorter than other dicraeosaurids of its lineage (quite a feat, given that the dicraeosaurids are known for short necks in comparison to other sauropods!); indeed, Brachytrachelopan has the shortest neck of any known sauropod. Dicraeosaurids in general had a tendency towards short necks, which scientists speculate was due to them being low browsers and specializing on certain food sources. Brachytrachelopan’s cervical neural arches were designed in such a way that they restricted neck movement, so that this sauropod was specialized to a diet of plants about one to two meters off the ground. Such a specialized diet might be a factor in why the dicraeosaurids didn’t reach large sizes. An interesting theory is that the dicraeosaurids of Gondwana dominated the ecological niches that elsewhere belonged to the ornithopods; it’s noteworthy that dicraeosaurids flourished in southern Gondwana but are virtually absent where ornithopods can be found. This may indicate that larger ornithopods and dicraeosaurids were ‘ecological analogs,’ in that they both underwent evolutionary adaptations from different lineages to dominate the same type of ecosystem. 

Bellusaurus

Type Species: Bellusaurus sui

Classification: Dinosauria – Saurischia – Sauropoda - Gravisauria - Eusauropoda - Neosauropoda - Macronaria

Time Period: Middle Jurassic

Location: China

Diet: Herbivore

Bellusaurus’ name is derived from the Latin bellus, meaning ‘small, delicate, beautiful.’ Seventeen individuals of this sauropod were found in a single quarry, suggesting that the herd had been killed in a flash flood. While this is tragic in its own right, the tragedy is compounded by the fact that they all appear to be juveniles. They measured only sixteen feet long, and bone studies indicate that they weren’t fully grown. One must wonder where the adults were when tragedy struck. Because there were no such things as ‘sauropod day cares’ (at least according to our understanding of sauropod social behavior), we must assume that the juveniles traveled with a much larger herd. One explanation is that when the flood hit, the larger adults were able to ‘weather the storm,’ but the lighter and smaller juveniles were swept away underfoot, only to be deposited miles away in a jumbled, rotting mess. A tragedy indeed. 

Lingwulong

Type Species: Lingwulong shenqi

Classification: Dinosauria – Saurischia – Sauropoda – Gravisauria - Eusauropoda - Neosauropoda - Diplodocoidea - Flagellicaudata - Dicraeosauridae 

Time Period: Early Jurassic

Location: China

Diet: Herbivore

Lingwulong was a sauropod that lived in southern Laurasia sometime between the late Toarcian stage of the Early Jurassic and through the Bajocian stage of the Middle Jurassic. The fossils discovered belong to seven to ten individuals at different stages of growth, indicating that they belonged to a family herd. These sauropods had U-shaped snouts and grew up to fifty feet in length. Lingwulong is considered a ‘neosauropod’ (or ‘new sauropod’), the group to which most sauropods belong. The neosauropods are composed of two subgroups: Diplodocoidea and Macronaria. The neosauropods were the largest land animals to have ever lived, and Lingwulong is the earliest known of the group. It’s considered a dicraeosaurid, a ‘sister group’ to the diplodocids. Dicraeosaurids are differentiated from the diplodocids by their relatively small body size and short necks.