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.

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. 

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. 

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. 

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.